Prepare release of v0.24.1

Co-authored-by: Artem Vorotnikov <artem@vorotnikov.me>

.github/workflows/main.yml

@@ -0,0 +1,85 @@
+on: [push, pull_request]
+
+name: Continuous integration
+
+jobs:
+  check:
+    name: Check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+      - uses: actions-rs/cargo@v1
+        with:
+          command: check
+          args: --all-features
+
+  test:
+    name: Test Suite
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --manifest-path tarpc/Cargo.toml --features serde1
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --manifest-path tarpc/Cargo.toml --features tokio1
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --manifest-path tarpc/Cargo.toml --features serde-transport
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --manifest-path tarpc/Cargo.toml --features tcp
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --all-features
+
+  fmt:
+    name: Rustfmt
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+      - run: rustup component add rustfmt
+      - uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+      - run: rustup component add clippy
+      - uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+          args: --all-features -- -D warnings

.travis.yml

@@ -1,34 +0,0 @@
-language: rust
-sudo: false
-
-rust:
-    - nightly
-
-os:
-    - linux
-
-addons:
-  apt:
-    packages:
-    - libcurl4-openssl-dev
-    - libelf-dev
-    - libdw-dev
-
-before_script:
-- |
-    pip install 'travis-cargo<0.2' --user &&
-    export PATH=$HOME/.local/bin:$PATH
-
-script:
-- |
-    travis-cargo build -- --features tls && travis-cargo test -- --features tls && travis-cargo bench -- --features tls &&
-    rustdoc --test README.md -L target/debug/deps -L target/debug &&
-    travis-cargo build && travis-cargo test && travis-cargo bench
-
-after_success:
-- travis-cargo coveralls --no-sudo
-
-env:
-  global:
-    # override the default `--features unstable` used for the nightly branch
-    - TRAVIS_CARGO_NIGHTLY_FEATURE=""

Cargo.toml

@@ -1,56 +1,7 @@
-[package]
-name = "tarpc"
-version = "0.12.0"
-authors = ["Adam Wright <adam.austin.wright@gmail.com>", "Tim Kuehn <timothy.j.kuehn@gmail.com>"]
-license = "MIT"
-documentation = "https://docs.rs/tarpc"
-homepage = "https://github.com/google/tarpc"
-repository = "https://github.com/google/tarpc"
-keywords = ["rpc", "network", "server", "api", "tls"]
-categories = ["asynchronous", "network-programming"]
-readme = "README.md"
-description = "An RPC framework for Rust with a focus on ease of use."
-
-[badges]
-travis-ci = { repository = "google/tarpc" }
-
-[dependencies]
-bincode = "1.0"
-byteorder = "1.0"
-bytes = "0.4"
-cfg-if = "0.1.0"
-futures = "0.1.11"
-lazy_static = "1.0"
-log = "0.4"
-net2 = "0.2"
-num_cpus = "1.0"
-serde = "1.0"
-serde_derive = "1.0"
-tarpc-plugins = { path = "src/plugins", version = "0.4.0" }
-thread-pool = "0.1.1"
-tokio-codec = "0.1"
-tokio-core = "0.1.6"
-tokio-io = "0.1"
-tokio-proto = "0.1.1"
-tokio-service = "0.1"
-
-# Optional dependencies
-native-tls = { version = "0.1", optional = true }
-tokio-tls = { version = "0.1", optional = true }
-
-[dev-dependencies]
-chrono = "0.4"
-env_logger = "0.5"
-futures-cpupool = "0.1"
-clap = "2.0"
-serde_bytes = "0.10"
-
-[target.'cfg(target_os = "macos")'.dev-dependencies]
-security-framework = "0.2"
-
-[features]
-default = []
-tls = ["tokio-tls", "native-tls"]
-unstable = ["serde/unstable"]
-
 [workspace]
+
+members = [
+    "example-service",
+    "tarpc",
+    "plugins",
+]

README.md

@@ -1,9 +1,20 @@
-## tarpc: Tim & Adam's RPC lib
-[![Travis-CI Status](https://travis-ci.org/google/tarpc.png?branch=master)](https://travis-ci.org/google/tarpc)
-[![Coverage Status](https://coveralls.io/repos/github/google/tarpc/badge.svg?branch=master)](https://coveralls.io/github/google/tarpc?branch=master)
-[![Software License](https://img.shields.io/badge/license-MIT-brightgreen.svg)](LICENSE)
-[![Latest Version](https://img.shields.io/crates/v/tarpc.svg)](https://crates.io/crates/tarpc)
-[![Join the chat at https://gitter.im/tarpc/Lobby](https://badges.gitter.im/tarpc/Lobby.svg)](https://gitter.im/tarpc/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Crates.io][crates-badge]][crates-url]
+[![MIT licensed][mit-badge]][mit-url]
+[![Build status][gh-actions-badge]][gh-actions-url]
+[![Discord chat][discord-badge]][discord-url]
+
+[crates-badge]: https://img.shields.io/crates/v/tarpc.svg
+[crates-url]: https://crates.io/crates/tarpc
+[mit-badge]: https://img.shields.io/badge/license-MIT-blue.svg
+[mit-url]: LICENSE
+[gh-actions-badge]: https://github.com/google/tarpc/workflows/Continuous%20integration/badge.svg
+[gh-actions-url]: https://github.com/google/tarpc/actions?query=workflow%3A%22Continuous+integration%22
+[discord-badge]: https://img.shields.io/discord/647529123996237854.svg?logo=discord&style=flat-square
+[discord-url]: https://discord.gg/gXwpdSt
+
+# tarpc
+
+<!-- cargo-sync-readme start -->
 
 *Disclaimer*: This is not an official Google product.
 
@@ -26,286 +37,132 @@ architectures. Two well-known ones are [gRPC](http://www.grpc.io) and
 
 tarpc differentiates itself from other RPC frameworks by defining the schema in code,
 rather than in a separate language such as .proto. This means there's no separate compilation
-process, and no cognitive context switching between different languages. Additionally, it
-works with the community-backed library serde: any serde-serializable type can be used as
-arguments to tarpc fns.
+process, and no context switching between different languages.
+
+Some other features of tarpc:
+- Pluggable transport: any type impling `Stream<Item = Request> + Sink<Response>` can be
+  used as a transport to connect the client and server.
+- `Send + 'static` optional: if the transport doesn't require it, neither does tarpc!
+- Cascading cancellation: dropping a request will send a cancellation message to the server.
+  The server will cease any unfinished work on the request, subsequently cancelling any of its
+  own requests, repeating for the entire chain of transitive dependencies.
+- Configurable deadlines and deadline propagation: request deadlines default to 10s if
+  unspecified. The server will automatically cease work when the deadline has passed. Any
+  requests sent by the server that use the request context will propagate the request deadline.
+  For example, if a server is handling a request with a 10s deadline, does 2s of work, then
+  sends a request to another server, that server will see an 8s deadline.
+- Serde serialization: enabling the `serde1` Cargo feature will make service requests and
+  responses `Serialize + Deserialize`. It's entirely optional, though: in-memory transports can
+  be used, as well, so the price of serialization doesn't have to be paid when it's not needed.
 
 ## Usage
-**NB**: *this example is for master. Are you looking for other
-[versions](https://docs.rs/tarpc)?*
-
 Add to your `Cargo.toml` dependencies:
 
 ```toml
-tarpc = "0.12.0"
-tarpc-plugins = "0.4.0"
+tarpc = "0.24"
 ```
 
-## Example: Sync
+The `tarpc::service` attribute expands to a collection of items that form an rpc service.
+These generated types make it easy and ergonomic to write servers with less boilerplate.
+Simply implement the generated service trait, and you're off to the races!
 
-tarpc has two APIs: `sync` for blocking code and `future` for asynchronous
-code. Here's how to use the sync api.
+## Example
+
+This example uses [tokio](https://tokio.rs), so add the following dependencies to
+your `Cargo.toml`:
+
+```toml
+futures = "1.0"
+tarpc = { version = "0.24", features = ["tokio1"] }
+tokio = { version = "1.0", features = ["macros"] }
+```
+
+In the following example, we use an in-process channel for communication between
+client and server. In real code, you will likely communicate over the network.
+For a more real-world example, see [example-service](example-service).
+
+First, let's set up the dependencies and service definition.
 
 ```rust
-#![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
 
-#[macro_use]
-extern crate tarpc;
+use futures::{
+    future::{self, Ready},
+    prelude::*,
+};
+use tarpc::{
+    client, context,
+    server::{self, Handler},
+};
+use std::io;
 
-use std::sync::mpsc;
-use std::thread;
-use tarpc::sync::{client, server};
-use tarpc::sync::client::ClientExt;
-use tarpc::util::{FirstSocketAddr, Never};
-
-service! {
-    rpc hello(name: String) -> String;
-}
-
-#[derive(Clone)]
-struct HelloServer;
-
-impl SyncService for HelloServer {
-    fn hello(&self, name: String) -> Result<String, Never> {
-        Ok(format!("Hello, {}!", name))
-    }
-}
-
-fn main() {
-    let (tx, rx) = mpsc::channel();
-    thread::spawn(move || {
-        let mut handle = HelloServer.listen("localhost:0", server::Options::default())
-            .unwrap();
-        tx.send(handle.addr()).unwrap();
-        handle.run();
-    });
-    let client = SyncClient::connect(rx.recv().unwrap(), client::Options::default()).unwrap();
-    println!("{}", client.hello("Mom".to_string()).unwrap());
+// This is the service definition. It looks a lot like a trait definition.
+// It defines one RPC, hello, which takes one arg, name, and returns a String.
+#[tarpc::service]
+trait World {
+    /// Returns a greeting for name.
+    async fn hello(name: String) -> String;
 }
 ```
 
-The `service!` macro expands to a collection of items that form an
-rpc service. In the above example, the macro is called within the
-`hello_service` module. This module will contain `SyncClient`, `AsyncClient`,
-and `FutureClient` types, and `SyncService` and `AsyncService` traits.  There is
-also a `ServiceExt` trait that provides starter `fn`s for services, with an
-umbrella impl for all services.  These generated types make it easy and
-ergonomic to write servers without dealing with sockets or serialization
-directly. Simply implement one of the generated traits, and you're off to the
-races! See the `tarpc_examples` package for more examples.
-
-## Example: Futures
-
-Here's the same service, implemented using futures.
+This service definition generates a trait called `World`. Next we need to
+implement it for our Server struct.
 
 ```rust
-#![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
-
-extern crate futures;
-#[macro_use]
-extern crate tarpc;
-extern crate tokio_core;
-
-use futures::Future;
-use tarpc::future::{client, server};
-use tarpc::future::client::ClientExt;
-use tarpc::util::{FirstSocketAddr, Never};
-use tokio_core::reactor;
-
-service! {
-    rpc hello(name: String) -> String;
-}
-
+// This is the type that implements the generated World trait. It is the business logic
+// and is used to start the server.
 #[derive(Clone)]
 struct HelloServer;
 
-impl FutureService for HelloServer {
-    type HelloFut = Result<String, Never>;
+impl World for HelloServer {
+    // Each defined rpc generates two items in the trait, a fn that serves the RPC, and
+    // an associated type representing the future output by the fn.
 
-    fn hello(&self, name: String) -> Self::HelloFut {
-        Ok(format!("Hello, {}!", name))
+    type HelloFut = Ready<String>;
+
+    fn hello(self, _: context::Context, name: String) -> Self::HelloFut {
+        future::ready(format!("Hello, {}!", name))
     }
 }
+```
 
-fn main() {
-    let mut reactor = reactor::Core::new().unwrap();
-    let (handle, server) = HelloServer.listen("localhost:10000".first_socket_addr(),
-                                  &reactor.handle(),
-                                  server::Options::default())
-                          .unwrap();
-    reactor.handle().spawn(server);
-    let options = client::Options::default().handle(reactor.handle());
-    reactor.run(FutureClient::connect(handle.addr(), options)
-            .map_err(tarpc::Error::from)
-            .and_then(|client| client.hello("Mom".to_string()))
-            .map(|resp| println!("{}", resp)))
-        .unwrap();
+Lastly let's write our `main` that will start the server. While this example uses an
+[in-process channel](rpc::transport::channel), tarpc also ships a generic [`serde_transport`]
+behind the `serde-transport` feature, with additional [TCP](serde_transport::tcp) functionality
+available behind the `tcp` feature.
+
+```rust
+#[tokio::main]
+async fn main() -> io::Result<()> {
+    let (client_transport, server_transport) = tarpc::transport::channel::unbounded();
+
+    let server = server::new(server::Config::default())
+        // incoming() takes a stream of transports such as would be returned by
+        // TcpListener::incoming (but a stream instead of an iterator).
+        .incoming(stream::once(future::ready(server_transport)))
+        .respond_with(HelloServer.serve());
+
+    tokio::spawn(server);
+
+    // WorldClient is generated by the macro. It has a constructor `new` that takes a config and
+    // any Transport as input
+    let mut client = WorldClient::new(client::Config::default(), client_transport).spawn()?;
+
+    // The client has an RPC method for each RPC defined in the annotated trait. It takes the same
+    // args as defined, with the addition of a Context, which is always the first arg. The Context
+    // specifies a deadline and trace information which can be helpful in debugging requests.
+    let hello = client.hello(context::current(), "Stim".to_string()).await?;
+
+    println!("{}", hello);
+
+    Ok(())
 }
 ```
 
-## Example: Futures + TLS
-
-By default, tarpc internally uses a [`TcpStream`] for communication between your clients and
-servers. However, TCP by itself has no encryption. As a result, your communication will be sent in
-the clear. If you want your RPC communications to be encrypted, you can choose to use [TLS]. TLS
-operates as an encryption layer on top of TCP. When using TLS, your communication will occur over a
-[`TlsStream<TcpStream>`]. You can add the ability to make TLS clients and servers by adding `tarpc`
-with the `tls` feature flag enabled.
-
-When using TLS, some additional information is required. You will need to make [`TlsAcceptor`] and
-`client::tls::Context` structs; `client::tls::Context` requires a [`TlsConnector`]. The
-[`TlsAcceptor`] and [`TlsConnector`] types are defined in the [native-tls]. tarpc re-exports
-external TLS-related types in its `native_tls` module (`tarpc::native_tls`).
-
-[TLS]: https://en.wikipedia.org/wiki/Transport_Layer_Security
-[`TcpStream`]: https://docs.rs/tokio-core/0.1/tokio_core/net/struct.TcpStream.html
-[`TlsStream<TcpStream>`]: https://docs.rs/native-tls/0.1/native_tls/struct.TlsStream.html
-[`TlsAcceptor`]: https://docs.rs/native-tls/0.1/native_tls/struct.TlsAcceptor.html
-[`TlsConnector`]: https://docs.rs/native-tls/0.1/native_tls/struct.TlsConnector.html
-[native-tls]: https://github.com/sfackler/rust-native-tls
-
-Both TLS streams and TCP streams are supported in the same binary when the `tls` feature is enabled.
-However, if you are working with both stream types, ensure that you use the TLS clients with TLS
-servers and TCP clients with TCP servers.
-
-```rust,no_run
-#![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
-
-extern crate futures;
-#[macro_use]
-extern crate tarpc;
-extern crate tokio_core;
-
-use futures::Future;
-use tarpc::future::{client, server};
-use tarpc::future::client::ClientExt;
-use tarpc::tls;
-use tarpc::util::{FirstSocketAddr, Never};
-use tokio_core::reactor;
-use tarpc::native_tls::{Pkcs12, TlsAcceptor};
-
-service! {
-    rpc hello(name: String) -> String;
-}
-
-#[derive(Clone)]
-struct HelloServer;
-
-impl FutureService for HelloServer {
-    type HelloFut = Result<String, Never>;
-
-    fn hello(&self, name: String) -> Self::HelloFut {
-        Ok(format!("Hello, {}!", name))
-    }
-}
-
-fn get_acceptor() -> TlsAcceptor {
-    let buf = include_bytes!("test/identity.p12");
-    let pkcs12 = Pkcs12::from_der(buf, "password").unwrap();
-    TlsAcceptor::builder(pkcs12).unwrap().build().unwrap()
-}
-
-fn main() {
-    let mut reactor = reactor::Core::new().unwrap();
-    let acceptor = get_acceptor();
-    let (handle, server) = HelloServer.listen("localhost:10000".first_socket_addr(),
-                                            &reactor.handle(),
-                                            server::Options::default().tls(acceptor)).unwrap();
-    reactor.handle().spawn(server);
-    let options = client::Options::default()
-                                   .handle(reactor.handle())
-                                   .tls(tls::client::Context::new("foobar.com").unwrap());
-    reactor.run(FutureClient::connect(handle.addr(), options)
-            .map_err(tarpc::Error::from)
-            .and_then(|client| client.hello("Mom".to_string()))
-            .map(|resp| println!("{}", resp)))
-        .unwrap();
-}
-```
-
-## Tips
-
-### Sync vs Futures
-
-A single `service!` invocation generates code for both synchronous and future-based applications.
-It's up to the user whether they want to implement the sync API or the futures API. The sync API has
-the simplest programming model, at the cost of some overhead - each RPC is handled in its own
-thread. The futures API is based on tokio and can run on any tokio-compatible executor. This mean a
-service that implements the futures API for a tarpc service can run on a single thread, avoiding
-context switches and the memory overhead of having a thread per RPC.
-
-### Errors
-
-All generated tarpc RPC methods return either `tarpc::Result<T, E>` or something like `Future<T,
-E>`. The error type defaults to `tarpc::util::Never` (a wrapper for `!` which implements
-`std::error::Error`) if no error type is explicitly specified in the `service!` macro invocation. An
-error type can be specified like so:
-
-```rust,ignore
-use tarpc::util::Message;
-
-service! {
-    rpc hello(name: String) -> String | Message
-}
-```
-
-`tarpc::util::Message` is just a wrapper around string that implements `std::error::Error` provided
-for service implementations that don't require complex error handling. The pipe is used as syntax
-for specifying the error type in a way that's agnostic of whether the service implementation is
-synchronous or future-based. Note that in the simpler examples in the readme, no pipe is used, and
-the macro automatically chooses `tarpc::util::Never` as the error type.
-
-The above declaration would produce the following synchronous service trait:
-
-```rust,ignore
-trait SyncService {
-    fn hello(&self, name: String) -> Result<String, Message>;
-}
-```
-
-and the following future-based trait:
-
-```rust,ignore
-trait FutureService {
-    type HelloFut: IntoFuture<String, Message>;
-
-    fn hello(&mut self, name: String) -> Self::HelloFut;
-}
-```
-
-## Documentation
+## Service Documentation
 
 Use `cargo doc` as you normally would to see the documentation created for all
 items expanded by a `service!` invocation.
 
-## Additional Features
+<!-- cargo-sync-readme end -->
 
-- Concurrent requests from a single client.
-- Compatible with tokio services.
-- Run any number of clients and services on a single event loop.
-- Any type that `impl`s `serde`'s `Serialize` and `Deserialize` can be used in
-  rpc signatures.
-- Attributes can be specified on rpc methods. These will be included on both the
-  services' trait methods as well as on the clients' stub methods.
-
-## Gaps/Potential Improvements (not necessarily actively being worked on)
-
-- Configurable server rate limiting.
-- Automatic client retries with exponential backoff when server is busy.
-- Load balancing
-- Service discovery
-- Automatically reconnect on the client side when the connection cuts out.
-- Support generic serialization protocols.
-
-## Contributing
-
-To contribute to tarpc, please see [CONTRIBUTING](CONTRIBUTING.md).
-
-## License
-
-tarpc is distributed under the terms of the MIT license.
-
-See [LICENSE](LICENSE) for details.
+License: MIT

RELEASES.md

@@ -1,21 +1,176 @@
+## 0.24.1 (2020-12-28)
+
+### Breaking Changes
+
+Upgrades tokio to 1.0.
+
+## 0.24.0 (2020-12-28)
+
+This release was yanked.
+
+## 0.23.0 (2020-10-19)
+
+### Breaking Changes
+
+Upgrades tokio to 0.3.
+
+## 0.22.0 (2020-08-02)
+
+This release adds some flexibility and consistency to `serde_transport`, with one new feature and
+one small breaking change.
+
+### New Features
+
+`serde_transport::tcp` now exposes framing configuration on `connect()` and `listen()`. This is
+useful if, for instance, you want to send requests or responses that are larger than the maximum
+payload allowed by default:
+
+```rust
+let mut transport = tarpc::serde_transport::tcp::connect(server_addr, Json::default);
+transport.config_mut().max_frame_length(4294967296);
+let mut client = MyClient::new(client::Config::default(), transport.await?).spawn()?;
+```
+
+### Breaking Changes
+
+The codec argument to `serde_transport::tcp::connect` changed from a Codec to impl Fn() -> Codec,
+to be consistent with `serde_transport::tcp::listen`. While only one Codec is needed, more than one
+person has been tripped up by the inconsistency between `connect` and `listen`. Unfortunately, the
+compiler errors are not much help in this case, so it was decided to simply do the more intuitive
+thing so that the compiler doesn't need to step in in the first place.
+
+
+## 0.21.1 (2020-08-02)
+
+### New Features
+
+#### #[tarpc::server] diagnostics
+
+When a service impl uses #[tarpc::server], only `async fn`s are re-written. This can lead to
+confusing compiler errors about missing associated types:
+
+```
+error: not all trait items implemented, missing: `HelloFut`
+ --> $DIR/tarpc_server_missing_async.rs:9:1
+  |
+9 | impl World for HelloServer {
+  | ^^^^
+```
+
+The proc macro now provides better diagnostics for this case:
+
+```
+error: not all trait items implemented, missing: `HelloFut`
+ --> $DIR/tarpc_server_missing_async.rs:9:1
+  |
+9 | impl World for HelloServer {
+  | ^^^^
+
+error: hint: `#[tarpc::server]` only rewrites async fns, and `fn hello` is not async
+  --> $DIR/tarpc_server_missing_async.rs:10:5
+   |
+10 |     fn hello(name: String) ->  String {
+   |     ^^
+```
+
+### Bug Fixes
+
+#### Fixed client hanging when server shuts down
+
+Previously, clients would ignore when the read half of the transport was closed, continuing to
+write requests. This didn't make much sense, because without the ability to receive responses,
+clients have no way to know if requests were actually processed by the server. It basically just
+led to clients that would hang for a few seconds before shutting down. This has now been
+corrected: clients will immediately shut down when the read-half of the transport is closed.
+
+#### More docs.rs documentation
+
+Previously, docs.rs only documented items enabled by default, notably leaving out documentation
+for tokio and serde features. This has now been corrected: docs.rs should have documentation
+for all optional features.
+
+## 0.21.0 (2020-06-26)
+
+### New Features
+
+A new proc macro, `#[tarpc::server]` was added! This enables service impls to elide the boilerplate
+of specifying associated types for each RPC. With the ubiquity of async-await, most code won't have
+nameable futures and will just be boxing the return type anyway. This macro does that for you.
+
+### Breaking Changes
+
+- Enums had _non_exhaustive fields replaced with the #[non_exhaustive] attribute.
+
+### Bug Fixes
+
+- https://github.com/google/tarpc/issues/304
+
+  A race condition in code that limits number of connections per client caused occasional panics.
+
+- https://github.com/google/tarpc/pull/295
+
+  Made request timeouts account for time spent in the outbound buffer. Previously, a large outbound
+  queue would lead to requests not timing out correctly.
+
+## 0.20.0 (2019-12-11)
+
+### Breaking Changes
+
+1. tarpc has updated its tokio dependency to the latest 0.2 version.
+2. The tarpc crates have been unified into just `tarpc`, with new Cargo features to enable
+   functionality.
+   - The bincode-transport and json-transport crates are deprecated and superseded by
+     the `serde_transport` module, which unifies much of the logic present in both crates.
+
+## 0.13.0 (2018-10-16)
+
+### Breaking Changes
+
+Version 0.13 marks a significant departure from previous versions of tarpc. The
+API has changed significantly. The tokio-proto crate has been torn out and
+replaced with a homegrown rpc framework. Additionally, the crate has been
+modularized, so that the tarpc crate itself contains only the macro code.
+
+### New Crates
+
+- crate rpc contains the core client/server request-response framework, as well as a transport trait.
+- crate bincode-transport implements a transport that works almost exactly as tarpc works today (not to say it's wire-compatible).
+- crate trace has some foundational types for tracing. This isn't really fleshed out yet, but it's useful for in-process log tracing, at least.
+
+All crates are now at the top level. e.g. tarpc-plugins is now tarpc/plugins rather than tarpc/src/plugins. tarpc itself is now a *very* small code surface, as most functionality has been moved into the other more granular crates.
+
+### New Features
+- deadlines: all requests specify a deadline, and a server will stop processing a response when past its deadline.
+- client cancellation propagation: when a client drops a request, the client sends a message to the server informing it to cancel its response. This means cancellations can propagate across multiple server hops.
+- trace context stuff as mentioned above
+- more server configuration for total connection limits, per-connection request limits, etc.
+
+### Removals
+- no more shutdown handle.  I left it out for now because of time and not being sure what the right solution is.
+- all async now, no blocking stub or server interface. This helps with maintainability, and async/await makes async code much more usable. The service trait is thusly renamed Service, and the client is renamed Client.
+- no built-in transport. Tarpc is now transport agnostic (see bincode-transport for transitioning existing uses).
+- going along with the previous bullet, no preferred transport means no TLS support at this time. We could make a tls transport or make bincode-transport compatible with TLS.
+- a lot of examples were removed because I couldn't keep up with maintaining all of them. Hopefully the ones I kept are still illustrative.
+- no more plugins!
+
 ## 0.10.0 (2018-04-08)
 
-## Breaking Changes
+### Breaking Changes
 Fixed rustc breakage in tarpc-plugins. These changes require a recent version of rustc.
 
 ## 0.10.0 (2018-03-26)
 
-## Breaking Changes
+### Breaking Changes
 Updates bincode to version 1.0.
 
 ## 0.9.0 (2017-09-17)
 
-## Breaking Changes
+### Breaking Changes
 Updates tarpc to use tarpc-plugins 0.2.
 
 ## 0.8.0 (2017-05-05)
 
-## Breaking Changes
+### Breaking Changes
 This release updates tarpc to use serde 1.0.
 As such, users must also update to use serde 1.0.
 The serde 1.0 [release notes](https://github.com/serde-rs/serde/releases/tag/v1.0.0)
@@ -28,7 +183,7 @@ clients. No breaking changes.
 
 ## 0.7.2 (2017-04-22)
 
-## Breaking Changes
+### Breaking Changes
 This release updates tarpc-plugins to work with rustc master. Thus, older
 versions of rustc are no longer supported. We chose a minor version bump
 because it is still source-compatible with existing code using tarpc.
@@ -39,7 +194,7 @@ This release was purely doc fixes. No breaking changes.
 
 ## 0.7 (2017-03-31)
 
-## Breaking Changes
+### Breaking Changes
 This release is a complete overhaul to build tarpc on top of the tokio stack.
 It's safe to assume that everything broke with this release.
 

benches/latency.rs

@@ -1,58 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-#![feature(plugin, test, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
-
-#[macro_use]
-extern crate tarpc;
-#[cfg(test)]
-extern crate test;
-extern crate env_logger;
-extern crate futures;
-extern crate tokio_core;
-
-use tarpc::future::{client, server};
-use tarpc::future::client::ClientExt;
-use tarpc::util::{FirstSocketAddr, Never};
-#[cfg(test)]
-use test::Bencher;
-use tokio_core::reactor;
-
-service! {
-    rpc ack();
-}
-
-#[derive(Clone)]
-struct Server;
-
-impl FutureService for Server {
-    type AckFut = futures::Finished<(), Never>;
-    fn ack(&self) -> Self::AckFut {
-        futures::finished(())
-    }
-}
-
-#[cfg(test)]
-#[bench]
-fn latency(bencher: &mut Bencher) {
-    let _ = env_logger::try_init();
-    let mut reactor = reactor::Core::new().unwrap();
-    let (handle, server) = Server
-        .listen(
-            "localhost:0".first_socket_addr(),
-            &reactor.handle(),
-            server::Options::default(),
-        )
-        .unwrap();
-    reactor.handle().spawn(server);
-    let client = FutureClient::connect(
-        handle.addr(),
-        client::Options::default().handle(reactor.handle()),
-    );
-    let client = reactor.run(client).unwrap();
-
-    bencher.iter(|| reactor.run(client.ack()).unwrap());
-}

example-service/Cargo.toml

@@ -0,0 +1,33 @@
+[package]
+name = "tarpc-example-service"
+version = "0.8.0"
+authors = ["Tim Kuehn <tikue@google.com>"]
+edition = "2018"
+license = "MIT"
+documentation = "https://docs.rs/tarpc-example-service"
+homepage = "https://github.com/google/tarpc"
+repository = "https://github.com/google/tarpc"
+keywords = ["rpc", "network", "server", "microservices", "example"]
+categories = ["asynchronous", "network-programming"]
+readme = "../README.md"
+description = "An example server built on tarpc."
+
+[dependencies]
+clap = "2.33"
+env_logger = "0.8"
+futures = "0.3"
+serde = { version = "1.0" }
+tarpc = { version = "0.24", path = "../tarpc", features = ["full"] }
+tokio = { version = "1", features = ["full"] }
+
+[lib]
+name = "service"
+path = "src/lib.rs"
+
+[[bin]]
+name = "server"
+path = "src/server.rs"
+
+[[bin]]
+name = "client"
+path = "src/client.rs"

example-service/src/client.rs

@@ -0,0 +1,61 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+use clap::{App, Arg};
+use std::{io, net::SocketAddr};
+use tarpc::{client, context, tokio_serde::formats::Json};
+
+#[tokio::main]
+async fn main() -> io::Result<()> {
+    env_logger::init();
+
+    let flags = App::new("Hello Client")
+        .version("0.1")
+        .author("Tim <tikue@google.com>")
+        .about("Say hello!")
+        .arg(
+            Arg::with_name("server_addr")
+                .long("server_addr")
+                .value_name("ADDRESS")
+                .help("Sets the server address to connect to.")
+                .required(true)
+                .takes_value(true),
+        )
+        .arg(
+            Arg::with_name("name")
+                .short("n")
+                .long("name")
+                .value_name("STRING")
+                .help("Sets the name to say hello to.")
+                .required(true)
+                .takes_value(true),
+        )
+        .get_matches();
+
+    let server_addr = flags.value_of("server_addr").unwrap();
+    let server_addr = server_addr
+        .parse::<SocketAddr>()
+        .unwrap_or_else(|e| panic!(r#"--server_addr value "{}" invalid: {}"#, server_addr, e));
+
+    let name = flags.value_of("name").unwrap().into();
+
+    let mut transport = tarpc::serde_transport::tcp::connect(server_addr, Json::default);
+    transport.config_mut().max_frame_length(4294967296);
+
+    // WorldClient is generated by the service attribute. It has a constructor `new` that takes a
+    // config and any Transport as input.
+    let mut client =
+        service::WorldClient::new(client::Config::default(), transport.await?).spawn()?;
+
+    // The client has an RPC method for each RPC defined in the annotated trait. It takes the same
+    // args as defined, with the addition of a Context, which is always the first arg. The Context
+    // specifies a deadline and trace information which can be helpful in debugging requests.
+    let hello = client.hello(context::current(), name).await?;
+
+    println!("{}", hello);
+
+    Ok(())
+}

example-service/src/lib.rs

@@ -0,0 +1,13 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+/// This is the service definition. It looks a lot like a trait definition.
+/// It defines one RPC, hello, which takes one arg, name, and returns a String.
+#[tarpc::service]
+pub trait World {
+    /// Returns a greeting for name.
+    async fn hello(name: String) -> String;
+}

example-service/src/server.rs

@@ -0,0 +1,80 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+use clap::{App, Arg};
+use futures::{future, prelude::*};
+use service::World;
+use std::{
+    io,
+    net::{IpAddr, SocketAddr},
+};
+use tarpc::{
+    context,
+    server::{self, Channel, Handler},
+    tokio_serde::formats::Json,
+};
+
+// This is the type that implements the generated World trait. It is the business logic
+// and is used to start the server.
+#[derive(Clone)]
+struct HelloServer(SocketAddr);
+
+#[tarpc::server]
+impl World for HelloServer {
+    async fn hello(self, _: context::Context, name: String) -> String {
+        format!("Hello, {}! You are connected from {:?}.", name, self.0)
+    }
+}
+
+#[tokio::main]
+async fn main() -> io::Result<()> {
+    env_logger::init();
+
+    let flags = App::new("Hello Server")
+        .version("0.1")
+        .author("Tim <tikue@google.com>")
+        .about("Say hello!")
+        .arg(
+            Arg::with_name("port")
+                .short("p")
+                .long("port")
+                .value_name("NUMBER")
+                .help("Sets the port number to listen on")
+                .required(true)
+                .takes_value(true),
+        )
+        .get_matches();
+
+    let port = flags.value_of("port").unwrap();
+    let port = port
+        .parse()
+        .unwrap_or_else(|e| panic!(r#"--port value "{}" invalid: {}"#, port, e));
+
+    let server_addr = (IpAddr::from([0, 0, 0, 0]), port);
+
+    // JSON transport is provided by the json_transport tarpc module. It makes it easy
+    // to start up a serde-powered json serialization strategy over TCP.
+    let mut listener = tarpc::serde_transport::tcp::listen(&server_addr, Json::default).await?;
+    listener.config_mut().max_frame_length(4294967296);
+    listener
+        // Ignore accept errors.
+        .filter_map(|r| future::ready(r.ok()))
+        .map(server::BaseChannel::with_defaults)
+        // Limit channels to 1 per IP.
+        .max_channels_per_key(1, |t| t.as_ref().peer_addr().unwrap().ip())
+        // serve is generated by the service attribute. It takes as input any type implementing
+        // the generated World trait.
+        .map(|channel| {
+            let server = HelloServer(channel.as_ref().as_ref().peer_addr().unwrap());
+            channel.respond_with(server.serve()).execute()
+        })
+        // Max 10 channels.
+        .buffer_unordered(10)
+        .for_each(|_| async {})
+        .await;
+
+    Ok(())
+}

examples/concurrency.rs

@@ -1,208 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-#![feature(plugin, never_type, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
-
-extern crate chrono;
-extern crate clap;
-extern crate env_logger;
-extern crate futures;
-#[macro_use]
-extern crate log;
-extern crate serde_bytes;
-#[macro_use]
-extern crate tarpc;
-extern crate tokio_core;
-extern crate futures_cpupool;
-
-use clap::{Arg, App};
-use futures::{Future, Stream};
-use futures_cpupool::{CpuFuture, CpuPool};
-use std::{cmp, thread};
-use std::sync::{Arc, mpsc};
-use std::sync::atomic::{AtomicUsize, Ordering};
-use std::time::{Duration, Instant};
-use tarpc::future::{client, server};
-use tarpc::future::client::ClientExt;
-use tarpc::util::{FirstSocketAddr, Never};
-use tokio_core::reactor;
-
-service! {
-    rpc read(size: u32) -> serde_bytes::ByteBuf;
-}
-
-#[derive(Clone)]
-struct Server {
-    pool: CpuPool,
-    request_count: Arc<AtomicUsize>,
-}
-
-impl Server {
-    fn new() -> Self {
-        Server {
-            pool: CpuPool::new_num_cpus(),
-            request_count: Arc::new(AtomicUsize::new(1)),
-        }
-    }
-}
-
-impl FutureService for Server {
-    type ReadFut = CpuFuture<serde_bytes::ByteBuf, Never>;
-
-    fn read(&self, size: u32) -> Self::ReadFut {
-        let request_number = self.request_count.fetch_add(1, Ordering::SeqCst);
-        debug!("Server received read({}) no. {}", size, request_number);
-        self.pool.spawn(futures::lazy(move || {
-            let mut vec = Vec::with_capacity(size as usize);
-            for i in 0..size {
-                vec.push(((i % 2) << 8) as u8);
-            }
-            debug!("Server sending response no. {}", request_number);
-            Ok(vec.into())
-        }))
-    }
-}
-
-const CHUNK_SIZE: u32 = 1 << 10;
-
-trait Microseconds {
-    fn microseconds(&self) -> i64;
-}
-
-impl Microseconds for Duration {
-    fn microseconds(&self) -> i64 {
-        chrono::Duration::from_std(*self)
-            .unwrap()
-            .num_microseconds()
-            .unwrap()
-    }
-}
-
-#[derive(Default)]
-struct Stats {
-    sum: Duration,
-    count: u64,
-    min: Option<Duration>,
-    max: Option<Duration>,
-}
-
-/// Spawns a `reactor::Core` running forever on a new thread.
-fn spawn_core() -> reactor::Remote {
-    let (tx, rx) = mpsc::channel();
-    thread::spawn(move || {
-        let mut core = reactor::Core::new().unwrap();
-        tx.send(core.handle().remote().clone()).unwrap();
-
-        // Run forever
-        core.run(futures::empty::<(), !>()).unwrap();
-    });
-    rx.recv().unwrap()
-}
-
-fn run_once(
-    clients: Vec<FutureClient>,
-    concurrency: u32,
-) -> impl Future<Item = (), Error = ()> + 'static {
-    let start = Instant::now();
-    futures::stream::futures_unordered(
-        (0..concurrency as usize)
-            .zip(clients.iter().enumerate().cycle())
-            .map(|(iteration, (client_idx, client))| {
-                let start = Instant::now();
-                debug!("Client {} reading (iteration {})...", client_idx, iteration);
-                client
-                    .read(CHUNK_SIZE)
-                    .map(move |_| (client_idx, iteration, start))
-            }),
-    ).map(|(client_idx, iteration, start)| {
-        let elapsed = start.elapsed();
-        debug!(
-            "Client {} received reply (iteration {}).",
-            client_idx,
-            iteration
-        );
-        elapsed
-    })
-        .map_err(|e| panic!(e))
-        .fold(Stats::default(), move |mut stats, elapsed| {
-            stats.sum += elapsed;
-            stats.count += 1;
-            stats.min = Some(cmp::min(stats.min.unwrap_or(elapsed), elapsed));
-            stats.max = Some(cmp::max(stats.max.unwrap_or(elapsed), elapsed));
-            Ok(stats)
-        })
-        .map(move |stats| {
-            info!(
-                "{} requests => Mean={}µs, Min={}µs, Max={}µs, Total={}µs",
-                stats.count,
-                stats.sum.microseconds() as f64 / stats.count as f64,
-                stats.min.unwrap().microseconds(),
-                stats.max.unwrap().microseconds(),
-                start.elapsed().microseconds()
-            );
-        })
-}
-
-fn main() {
-    env_logger::init();
-    let matches = App::new("Tarpc Concurrency")
-        .about(
-            "Demonstrates making concurrent requests to a tarpc service.",
-        )
-        .arg(
-            Arg::with_name("concurrency")
-                .short("c")
-                .long("concurrency")
-                .value_name("LEVEL")
-                .help("Sets a custom concurrency level")
-                .takes_value(true),
-        )
-        .arg(
-            Arg::with_name("clients")
-                .short("n")
-                .long("num_clients")
-                .value_name("AMOUNT")
-                .help("How many clients to distribute requests between")
-                .takes_value(true),
-        )
-        .get_matches();
-    let concurrency = matches
-        .value_of("concurrency")
-        .map(&str::parse)
-        .map(Result::unwrap)
-        .unwrap_or(10);
-    let num_clients = matches
-        .value_of("clients")
-        .map(&str::parse)
-        .map(Result::unwrap)
-        .unwrap_or(4);
-
-    let mut reactor = reactor::Core::new().unwrap();
-    let (handle, server) = Server::new()
-        .listen(
-            "localhost:0".first_socket_addr(),
-            &reactor.handle(),
-            server::Options::default(),
-        )
-        .unwrap();
-    reactor.handle().spawn(server);
-    info!("Server listening on {}.", handle.addr());
-
-    let clients = (0..num_clients)
-        // Spin up a couple threads to drive the clients.
-        .map(|i| (i, spawn_core()))
-        .map(|(i, remote)| {
-            info!("Client {} connecting...", i);
-            FutureClient::connect(handle.addr(), client::Options::default().remote(remote))
-                .map_err(|e| panic!(e))
-        });
-
-    let run = futures::collect(clients).and_then(|clients| run_once(clients, concurrency));
-
-    info!("Starting...");
-
-    reactor.run(run).unwrap();
-}

examples/pubsub.rs

@@ -1,160 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-#![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
-
-extern crate env_logger;
-extern crate futures;
-#[macro_use]
-extern crate tarpc;
-extern crate tokio_core;
-
-use futures::{Future, future};
-use publisher::FutureServiceExt as PublisherExt;
-use std::cell::RefCell;
-use std::collections::HashMap;
-use std::net::SocketAddr;
-use std::rc::Rc;
-use std::thread;
-use std::time::Duration;
-use subscriber::FutureServiceExt as SubscriberExt;
-use tarpc::future::{client, server};
-use tarpc::future::client::ClientExt;
-use tarpc::util::{FirstSocketAddr, Message, Never};
-use tokio_core::reactor;
-
-pub mod subscriber {
-    service! {
-        rpc receive(message: String);
-    }
-}
-
-pub mod publisher {
-    use std::net::SocketAddr;
-    use tarpc::util::Message;
-
-    service! {
-        rpc broadcast(message: String);
-        rpc subscribe(id: u32, address: SocketAddr) | Message;
-        rpc unsubscribe(id: u32);
-    }
-}
-
-#[derive(Clone, Debug)]
-struct Subscriber {
-    id: u32,
-}
-
-impl subscriber::FutureService for Subscriber {
-    type ReceiveFut = Result<(), Never>;
-
-    fn receive(&self, message: String) -> Self::ReceiveFut {
-        println!("{} received message: {}", self.id, message);
-        Ok(())
-    }
-}
-
-impl Subscriber {
-    fn listen(id: u32, handle: &reactor::Handle, options: server::Options) -> server::Handle {
-        let (server_handle, server) = Subscriber { id: id }
-            .listen("localhost:0".first_socket_addr(), handle, options)
-            .unwrap();
-        handle.spawn(server);
-        server_handle
-    }
-}
-
-#[derive(Clone, Debug)]
-struct Publisher {
-    clients: Rc<RefCell<HashMap<u32, subscriber::FutureClient>>>,
-}
-
-impl Publisher {
-    fn new() -> Publisher {
-        Publisher {
-            clients: Rc::new(RefCell::new(HashMap::new())),
-        }
-    }
-}
-
-impl publisher::FutureService for Publisher {
-    type BroadcastFut = Box<Future<Item = (), Error = Never>>;
-
-    fn broadcast(&self, message: String) -> Self::BroadcastFut {
-        let acks = self.clients
-                       .borrow()
-                       .values()
-                       .map(move |client| client.receive(message.clone())
-                           // Ignore failing subscribers. In a real pubsub,
-                           // you'd want to continually retry until subscribers
-                           // ack.
-                           .then(|_| Ok(())))
-                       // Collect to a vec to end the borrow on `self.clients`.
-                       .collect::<Vec<_>>();
-        Box::new(future::join_all(acks).map(|_| ()))
-    }
-
-    type SubscribeFut = Box<Future<Item = (), Error = Message>>;
-
-    fn subscribe(&self, id: u32, address: SocketAddr) -> Self::SubscribeFut {
-        let clients = Rc::clone(&self.clients);
-        Box::new(
-            subscriber::FutureClient::connect(address, client::Options::default())
-                .map(move |subscriber| {
-                    println!("Subscribing {}.", id);
-                    clients.borrow_mut().insert(id, subscriber);
-                    ()
-                })
-                .map_err(|e| e.to_string().into()),
-        )
-    }
-
-    type UnsubscribeFut = Box<Future<Item = (), Error = Never>>;
-
-    fn unsubscribe(&self, id: u32) -> Self::UnsubscribeFut {
-        println!("Unsubscribing {}", id);
-        self.clients.borrow_mut().remove(&id).unwrap();
-        Box::new(futures::finished(()))
-    }
-}
-
-fn main() {
-    env_logger::init();
-    let mut reactor = reactor::Core::new().unwrap();
-    let (publisher_handle, server) = Publisher::new()
-        .listen(
-            "localhost:0".first_socket_addr(),
-            &reactor.handle(),
-            server::Options::default(),
-        )
-        .unwrap();
-    reactor.handle().spawn(server);
-
-    let subscriber1 = Subscriber::listen(0, &reactor.handle(), server::Options::default());
-    let subscriber2 = Subscriber::listen(1, &reactor.handle(), server::Options::default());
-
-    let publisher = reactor
-        .run(publisher::FutureClient::connect(
-            publisher_handle.addr(),
-            client::Options::default(),
-        ))
-        .unwrap();
-    reactor
-        .run(
-            publisher
-                .subscribe(0, subscriber1.addr())
-                .and_then(|_| publisher.subscribe(1, subscriber2.addr()))
-                .map_err(|e| panic!(e))
-                .and_then(|_| {
-                    println!("Broadcasting...");
-                    publisher.broadcast("hello to all".to_string())
-                })
-                .and_then(|_| publisher.unsubscribe(1))
-                .and_then(|_| publisher.broadcast("hi again".to_string())),
-        )
-        .unwrap();
-    thread::sleep(Duration::from_millis(300));
-}

examples/readme_errors.rs

@@ -1,65 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-#![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
-
-#[macro_use]
-extern crate tarpc;
-#[macro_use]
-extern crate serde_derive;
-
-use std::error::Error;
-use std::fmt;
-use std::sync::mpsc;
-use std::thread;
-use tarpc::sync::{client, server};
-use tarpc::sync::client::ClientExt;
-
-service! {
-    rpc hello(name: String) -> String | NoNameGiven;
-}
-
-#[derive(Debug, Deserialize, Serialize)]
-pub struct NoNameGiven;
-
-impl fmt::Display for NoNameGiven {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", self.description())
-    }
-}
-
-impl Error for NoNameGiven {
-    fn description(&self) -> &str {
-        r#"The empty String, "", is not a valid argument to rpc `hello`."#
-    }
-}
-
-#[derive(Clone)]
-struct HelloServer;
-
-impl SyncService for HelloServer {
-    fn hello(&self, name: String) -> Result<String, NoNameGiven> {
-        if name == "" {
-            Err(NoNameGiven)
-        } else {
-            Ok(format!("Hello, {}!", name))
-        }
-    }
-}
-
-fn main() {
-    let (tx, rx) = mpsc::channel();
-    thread::spawn(move || {
-        let handle = HelloServer
-            .listen("localhost:10000", server::Options::default())
-            .unwrap();
-        tx.send(handle.addr()).unwrap();
-        handle.run();
-    });
-    let client = SyncClient::connect(rx.recv().unwrap(), client::Options::default()).unwrap();
-    println!("{}", client.hello("Mom".to_string()).unwrap());
-    println!("{}", client.hello("".to_string()).unwrap_err());
-}

examples/readme_futures.rs

@@ -1,55 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-#![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
-
-extern crate futures;
-#[macro_use]
-extern crate tarpc;
-extern crate tokio_core;
-
-use futures::Future;
-use tarpc::future::{client, server};
-use tarpc::future::client::ClientExt;
-use tarpc::util::{FirstSocketAddr, Never};
-use tokio_core::reactor;
-
-service! {
-    rpc hello(name: String) -> String;
-}
-
-#[derive(Clone)]
-struct HelloServer;
-
-impl FutureService for HelloServer {
-    type HelloFut = Result<String, Never>;
-
-    fn hello(&self, name: String) -> Self::HelloFut {
-        Ok(format!("Hello, {}!", name))
-    }
-}
-
-fn main() {
-    let mut reactor = reactor::Core::new().unwrap();
-    let (handle, server) = HelloServer
-        .listen(
-            "localhost:10000".first_socket_addr(),
-            &reactor.handle(),
-            server::Options::default(),
-        )
-        .unwrap();
-    reactor.handle().spawn(server);
-
-    let options = client::Options::default().handle(reactor.handle());
-    reactor
-        .run(
-            FutureClient::connect(handle.addr(), options)
-                .map_err(tarpc::Error::from)
-                .and_then(|client| client.hello("Mom".to_string()))
-                .map(|resp| println!("{}", resp)),
-        )
-        .unwrap();
-}

examples/readme_sync.rs

@@ -1,47 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-// required by `FutureClient` (not used directly in this example)
-#![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
-
-#[macro_use]
-extern crate tarpc;
-
-use std::sync::mpsc;
-use std::thread;
-use tarpc::sync::{client, server};
-use tarpc::sync::client::ClientExt;
-use tarpc::util::Never;
-
-service! {
-    rpc hello(name: String) -> String;
-}
-
-#[derive(Clone)]
-struct HelloServer;
-
-impl SyncService for HelloServer {
-    fn hello(&self, name: String) -> Result<String, Never> {
-        Ok(format!(
-            "Hello from thread {}, {}!",
-            thread::current().name().unwrap(),
-            name
-        ))
-    }
-}
-
-fn main() {
-    let (tx, rx) = mpsc::channel();
-    thread::spawn(move || {
-        let handle = HelloServer
-            .listen("localhost:0", server::Options::default())
-            .unwrap();
-        tx.send(handle.addr()).unwrap();
-        handle.run();
-    });
-    let client = SyncClient::connect(rx.recv().unwrap(), client::Options::default()).unwrap();
-    println!("{}", client.hello("Mom".to_string()).unwrap());
-}

examples/server_calling_server.rs

@@ -1,113 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-#![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
-
-extern crate env_logger;
-#[macro_use]
-extern crate tarpc;
-extern crate futures;
-extern crate tokio_core;
-
-use add::{FutureService as AddFutureService, FutureServiceExt as AddExt};
-use double::{FutureService as DoubleFutureService, FutureServiceExt as DoubleExt};
-use futures::{Future, Stream};
-use tarpc::future::{client, server};
-use tarpc::future::client::ClientExt as Fc;
-use tarpc::util::{FirstSocketAddr, Message, Never};
-use tokio_core::reactor;
-
-pub mod add {
-    service! {
-        /// Add two ints together.
-        rpc add(x: i32, y: i32) -> i32;
-    }
-}
-
-pub mod double {
-    use tarpc::util::Message;
-
-    service! {
-        /// 2 * x
-        rpc double(x: i32) -> i32 | Message;
-    }
-}
-
-#[derive(Clone)]
-struct AddServer;
-
-impl AddFutureService for AddServer {
-    type AddFut = Result<i32, Never>;
-
-    fn add(&self, x: i32, y: i32) -> Self::AddFut {
-        Ok(x + y)
-    }
-}
-
-#[derive(Clone)]
-struct DoubleServer {
-    client: add::FutureClient,
-}
-
-impl DoubleServer {
-    fn new(client: add::FutureClient) -> Self {
-        DoubleServer { client: client }
-    }
-}
-
-impl DoubleFutureService for DoubleServer {
-    type DoubleFut = Box<Future<Item=i32, Error=Message>>;
-
-    fn double(&self, x: i32) -> Self::DoubleFut {
-        Box::new(self.client
-            .add(x, x)
-            .map_err(|e| e.to_string().into()))
-    }
-}
-
-fn main() {
-    env_logger::init();
-    let mut reactor = reactor::Core::new().unwrap();
-    let (add, server) = AddServer
-        .listen(
-            "localhost:0".first_socket_addr(),
-            &reactor.handle(),
-            server::Options::default(),
-        )
-        .unwrap();
-    reactor.handle().spawn(server);
-
-    let options = client::Options::default().handle(reactor.handle());
-    let add_client = reactor
-        .run(add::FutureClient::connect(add.addr(), options))
-        .unwrap();
-
-    let (double, server) = DoubleServer::new(add_client)
-        .listen(
-            "localhost:0".first_socket_addr(),
-            &reactor.handle(),
-            server::Options::default(),
-        )
-        .unwrap();
-    reactor.handle().spawn(server);
-
-    let double_client = reactor
-        .run(double::FutureClient::connect(
-            double.addr(),
-            client::Options::default(),
-        ))
-        .unwrap();
-    reactor
-        .run(
-            futures::stream::futures_unordered((0..5).map(|i| double_client.double(i)))
-                .map_err(|e| println!("{}", e))
-                .for_each(|i| {
-                    println!("{:?}", i);
-                    Ok(())
-                }),
-        )
-        .unwrap();
-}

examples/sync_server_calling_server.rs

@@ -1,98 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-#![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
-
-extern crate env_logger;
-#[macro_use]
-extern crate tarpc;
-
-use add::{SyncService as AddSyncService, SyncServiceExt as AddExt};
-use double::{SyncService as DoubleSyncService, SyncServiceExt as DoubleExt};
-use std::sync::mpsc;
-use std::thread;
-use tarpc::sync::{client, server};
-use tarpc::sync::client::ClientExt as Fc;
-use tarpc::util::{FirstSocketAddr, Message, Never};
-
-pub mod add {
-    service! {
-        /// Add two ints together.
-        rpc add(x: i32, y: i32) -> i32;
-    }
-}
-
-pub mod double {
-    use tarpc::util::Message;
-
-    service! {
-        /// 2 * x
-        rpc double(x: i32) -> i32 | Message;
-    }
-}
-
-#[derive(Clone)]
-struct AddServer;
-
-impl AddSyncService for AddServer {
-    fn add(&self, x: i32, y: i32) -> Result<i32, Never> {
-        Ok(x + y)
-    }
-}
-
-#[derive(Clone)]
-struct DoubleServer {
-    client: add::SyncClient,
-}
-
-impl DoubleServer {
-    fn new(client: add::SyncClient) -> Self {
-        DoubleServer { client: client }
-    }
-}
-
-impl DoubleSyncService for DoubleServer {
-    fn double(&self, x: i32) -> Result<i32, Message> {
-        self.client.add(x, x).map_err(|e| e.to_string().into())
-    }
-}
-
-fn main() {
-    env_logger::init();
-    let (tx, rx) = mpsc::channel();
-    thread::spawn(move || {
-        let handle = AddServer
-            .listen(
-                "localhost:0".first_socket_addr(),
-                server::Options::default(),
-            )
-            .unwrap();
-        tx.send(handle.addr()).unwrap();
-        handle.run();
-    });
-
-
-    let add = rx.recv().unwrap();
-    let (tx, rx) = mpsc::channel();
-    thread::spawn(move || {
-        let add_client = add::SyncClient::connect(add, client::Options::default()).unwrap();
-        let handle = DoubleServer::new(add_client)
-            .listen(
-                "localhost:0".first_socket_addr(),
-                server::Options::default(),
-            )
-            .unwrap();
-        tx.send(handle.addr()).unwrap();
-        handle.run();
-    });
-    let double = rx.recv().unwrap();
-
-    let double_client = double::SyncClient::connect(double, client::Options::default()).unwrap();
-    for i in 0..5 {
-        let doubled = double_client.double(i).unwrap();
-        println!("{:?}", doubled);
-    }
-}

examples/throughput.rs

@@ -1,119 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-#![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
-
-#[macro_use]
-extern crate lazy_static;
-#[macro_use]
-extern crate tarpc;
-extern crate env_logger;
-extern crate serde_bytes;
-extern crate tokio_core;
-
-use std::io::{Read, Write, stdout};
-use std::net;
-use std::sync::mpsc;
-use std::thread;
-use std::time;
-use tarpc::future::server;
-use tarpc::sync::client::{self, ClientExt};
-use tarpc::util::{FirstSocketAddr, Never};
-use tokio_core::reactor;
-
-lazy_static! {
-    static ref BUF: serde_bytes::ByteBuf = gen_vec(CHUNK_SIZE as usize).into();
-}
-
-fn gen_vec(size: usize) -> Vec<u8> {
-    let mut vec: Vec<u8> = Vec::with_capacity(size);
-    for i in 0..size {
-        vec.push(((i % 2) << 8) as u8);
-    }
-    vec
-}
-
-service! {
-    rpc read() -> serde_bytes::ByteBuf;
-}
-
-#[derive(Clone)]
-struct Server;
-
-impl FutureService for Server {
-    type ReadFut = Result<serde_bytes::ByteBuf, Never>;
-
-    fn read(&self) -> Self::ReadFut {
-        Ok(BUF.clone())
-    }
-}
-
-const CHUNK_SIZE: u32 = 1 << 19;
-
-fn bench_tarpc(target: u64) {
-    let (tx, rx) = mpsc::channel();
-    thread::spawn(move || {
-        let mut reactor = reactor::Core::new().unwrap();
-        let (addr, server) = Server
-            .listen(
-                "localhost:0".first_socket_addr(),
-                &reactor.handle(),
-                server::Options::default(),
-            )
-            .unwrap();
-        tx.send(addr).unwrap();
-        reactor.run(server).unwrap();
-    });
-    let client =
-        SyncClient::connect(rx.recv().unwrap().addr(), client::Options::default()).unwrap();
-    let start = time::Instant::now();
-    let mut nread = 0;
-    while nread < target {
-        nread += client.read().unwrap().len() as u64;
-        print!(".");
-        stdout().flush().unwrap();
-    }
-    println!("done");
-    let duration = time::Instant::now() - start;
-    println!(
-        "TARPC: {}MB/s",
-        (target as f64 / (1024f64 * 1024f64)) /
-            (duration.as_secs() as f64 + duration.subsec_nanos() as f64 / 10E9)
-    );
-}
-
-fn bench_tcp(target: u64) {
-    let l = net::TcpListener::bind("localhost:0").unwrap();
-    let addr = l.local_addr().unwrap();
-    thread::spawn(move || {
-        let (mut stream, _) = l.accept().unwrap();
-        while let Ok(_) = stream.write_all(&*BUF) {}
-    });
-    let mut stream = net::TcpStream::connect(&addr).unwrap();
-    let mut buf = vec![0; CHUNK_SIZE as usize];
-    let start = time::Instant::now();
-    let mut nread = 0;
-    while nread < target {
-        stream.read_exact(&mut buf[..]).unwrap();
-        nread += CHUNK_SIZE as u64;
-        print!(".");
-        stdout().flush().unwrap();
-    }
-    println!("done");
-    let duration = time::Instant::now() - start;
-    println!(
-        "TCP:   {}MB/s",
-        (target as f64 / (1024f64 * 1024f64)) /
-            (duration.as_secs() as f64 + duration.subsec_nanos() as f64 / 10E9)
-    );
-}
-
-fn main() {
-    env_logger::init();
-    let _ = *BUF; // To non-lazily initialize it.
-    bench_tcp(256 << 20);
-    bench_tarpc(256 << 20);
-}

examples/two_clients.rs

@@ -1,105 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-#![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-#![plugin(tarpc_plugins)]
-
-#[macro_use]
-extern crate log;
-#[macro_use]
-extern crate tarpc;
-extern crate env_logger;
-extern crate tokio_core;
-
-use bar::FutureServiceExt as BarExt;
-use baz::FutureServiceExt as BazExt;
-use std::sync::mpsc;
-use std::thread;
-use tarpc::future::server;
-use tarpc::sync::client;
-use tarpc::sync::client::ClientExt;
-use tarpc::util::{FirstSocketAddr, Never};
-use tokio_core::reactor;
-
-mod bar {
-    service! {
-        rpc bar(i: i32) -> i32;
-    }
-}
-
-#[derive(Clone)]
-struct Bar;
-impl bar::FutureService for Bar {
-    type BarFut = Result<i32, Never>;
-
-    fn bar(&self, i: i32) -> Self::BarFut {
-        Ok(i)
-    }
-}
-
-mod baz {
-    service! {
-        rpc baz(s: String) -> String;
-    }
-}
-
-#[derive(Clone)]
-struct Baz;
-impl baz::FutureService for Baz {
-    type BazFut = Result<String, Never>;
-
-    fn baz(&self, s: String) -> Self::BazFut {
-        Ok(format!("Hello, {}!", s))
-    }
-}
-
-fn main() {
-    env_logger::init();
-    let bar_client = {
-        let (tx, rx) = mpsc::channel();
-        thread::spawn(move || {
-            let mut reactor = reactor::Core::new().unwrap();
-            let (handle, server) = Bar.listen(
-                "localhost:0".first_socket_addr(),
-                &reactor.handle(),
-                server::Options::default(),
-            ).unwrap();
-            tx.send(handle).unwrap();
-            reactor.run(server).unwrap();
-        });
-        let handle = rx.recv().unwrap();
-        bar::SyncClient::connect(handle.addr(), client::Options::default()).unwrap()
-    };
-
-    let baz_client = {
-        let (tx, rx) = mpsc::channel();
-        thread::spawn(move || {
-            let mut reactor = reactor::Core::new().unwrap();
-            let (handle, server) = Baz.listen(
-                "localhost:0".first_socket_addr(),
-                &reactor.handle(),
-                server::Options::default(),
-            ).unwrap();
-            tx.send(handle).unwrap();
-            reactor.run(server).unwrap();
-        });
-        let handle = rx.recv().unwrap();
-        baz::SyncClient::connect(handle.addr(), client::Options::default()).unwrap()
-    };
-
-
-    info!("Result: {:?}", bar_client.bar(17));
-
-    let total = 20;
-    for i in 1..(total + 1) {
-        if i % 2 == 0 {
-            info!("Result 1: {:?}", bar_client.bar(i));
-        } else {
-            info!("Result 2: {:?}", baz_client.baz(i.to_string()));
-        }
-    }
-
-    info!("Done.");
-}

hooks/pre-commit

@@ -93,10 +93,10 @@ diff=""
 for file in $(git diff --name-only --cached);
 do
 	if [ ${file: -3} == ".rs" ]; then
-        diff="$diff$(cargo fmt -- --skip-children --write-mode=diff $file)"
+        diff="$diff$(cargo fmt -- --unstable-features --skip-children --check $file)"
 	fi
 done
-if grep --quiet "^Diff at line" <<< "$diff"; then
+if grep --quiet "^[-+]" <<< "$diff"; then
     FMTRESULT=1
 fi
 

hooks/pre-push

@@ -89,13 +89,14 @@ if [ "$?" == 0 ]; then
         exit 1
     fi
 
-    try_run "Building ... " cargo build --color=always
-    try_run "Testing ... " cargo test --color=always
-    try_run "Benching ... " cargo bench --color=always
+    try_run "Building ... " cargo +stable build --color=always
+    try_run "Testing ... " cargo +stable test --color=always
+    try_run "Testing with all features enabled ... " cargo +stable test --all-features --color=always
+    for EXAMPLE in $(cargo +stable run --example 2>&1 | grep '    ' | awk '{print $1}')
+    do
+        try_run "Running example \"$EXAMPLE\" ... " cargo +stable run --example $EXAMPLE
+    done
 
-    try_run "Building with tls ... " cargo build --color=always --features tls
-    try_run "Testing with tls ... " cargo test --color=always --features tls
-    try_run "Benching with tls ... " cargo bench --color=always --features tls
 fi
 
 exit $PREPUSH_RESULT

plugins/Cargo.toml

@@ -0,0 +1,33 @@
+[package]
+name = "tarpc-plugins"
+version = "0.9.0"
+authors = ["Adam Wright <adam.austin.wright@gmail.com>", "Tim Kuehn <timothy.j.kuehn@gmail.com>"]
+edition = "2018"
+license = "MIT"
+documentation = "https://docs.rs/tarpc-plugins"
+homepage = "https://github.com/google/tarpc"
+repository = "https://github.com/google/tarpc"
+keywords = ["rpc", "network", "server", "api", "microservices"]
+categories = ["asynchronous", "network-programming"]
+readme = "../README.md"
+description = "Proc macros for tarpc."
+
+[features]
+serde1 = []
+
+[badges]
+travis-ci = { repository = "google/tarpc" }
+
+[dependencies]
+proc-macro2 = "1.0"
+quote = "1.0"
+syn = { version = "1.0", features = ["full"] }
+
+[lib]
+proc-macro = true
+
+[dev-dependencies]
+assert-type-eq = "0.1.0"
+futures = "0.3"
+serde = { version = "1.0", features = ["derive"] }
+tarpc = { path = "../tarpc" }

plugins/rustfmt.toml

@@ -0,0 +1 @@
+edition = "2018"

plugins/src/lib.rs

@@ -0,0 +1,820 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+#![recursion_limit = "512"]
+
+extern crate proc_macro;
+extern crate proc_macro2;
+extern crate quote;
+extern crate syn;
+
+use proc_macro::TokenStream;
+use proc_macro2::{Span, TokenStream as TokenStream2};
+use quote::{format_ident, quote, ToTokens};
+use syn::{
+    braced,
+    ext::IdentExt,
+    parenthesized,
+    parse::{Parse, ParseStream},
+    parse_macro_input, parse_quote, parse_str,
+    spanned::Spanned,
+    token::Comma,
+    Attribute, FnArg, Ident, ImplItem, ImplItemMethod, ImplItemType, ItemImpl, Lit, LitBool,
+    MetaNameValue, Pat, PatType, ReturnType, Token, Type, Visibility,
+};
+
+/// Accumulates multiple errors into a result.
+/// Only use this for recoverable errors, i.e. non-parse errors. Fatal errors should early exit to
+/// avoid further complications.
+macro_rules! extend_errors {
+    ($errors: ident, $e: expr) => {
+        match $errors {
+            Ok(_) => $errors = Err($e),
+            Err(ref mut errors) => errors.extend($e),
+        }
+    };
+}
+
+struct Service {
+    attrs: Vec<Attribute>,
+    vis: Visibility,
+    ident: Ident,
+    rpcs: Vec<RpcMethod>,
+}
+
+struct RpcMethod {
+    attrs: Vec<Attribute>,
+    ident: Ident,
+    args: Vec<PatType>,
+    output: ReturnType,
+}
+
+impl Parse for Service {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        let attrs = input.call(Attribute::parse_outer)?;
+        let vis = input.parse()?;
+        input.parse::<Token![trait]>()?;
+        let ident: Ident = input.parse()?;
+        let content;
+        braced!(content in input);
+        let mut rpcs = Vec::<RpcMethod>::new();
+        while !content.is_empty() {
+            rpcs.push(content.parse()?);
+        }
+        let mut ident_errors = Ok(());
+        for rpc in &rpcs {
+            if rpc.ident == "new" {
+                extend_errors!(
+                    ident_errors,
+                    syn::Error::new(
+                        rpc.ident.span(),
+                        format!(
+                            "method name conflicts with generated fn `{}Client::new`",
+                            ident.unraw()
+                        )
+                    )
+                );
+            }
+            if rpc.ident == "serve" {
+                extend_errors!(
+                    ident_errors,
+                    syn::Error::new(
+                        rpc.ident.span(),
+                        format!("method name conflicts with generated fn `{}::serve`", ident)
+                    )
+                );
+            }
+        }
+        ident_errors?;
+
+        Ok(Self {
+            attrs,
+            vis,
+            ident,
+            rpcs,
+        })
+    }
+}
+
+impl Parse for RpcMethod {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        let attrs = input.call(Attribute::parse_outer)?;
+        input.parse::<Token![async]>()?;
+        input.parse::<Token![fn]>()?;
+        let ident = input.parse()?;
+        let content;
+        parenthesized!(content in input);
+        let mut args = Vec::new();
+        let mut errors = Ok(());
+        for arg in content.parse_terminated::<FnArg, Comma>(FnArg::parse)? {
+            match arg {
+                FnArg::Typed(captured) if matches!(&*captured.pat, Pat::Ident(_)) => {
+                    args.push(captured);
+                }
+                FnArg::Typed(captured) => {
+                    extend_errors!(
+                        errors,
+                        syn::Error::new(captured.pat.span(), "patterns aren't allowed in RPC args")
+                    );
+                }
+                FnArg::Receiver(_) => {
+                    extend_errors!(
+                        errors,
+                        syn::Error::new(arg.span(), "method args cannot start with self")
+                    );
+                }
+            }
+        }
+        errors?;
+        let output = input.parse()?;
+        input.parse::<Token![;]>()?;
+
+        Ok(Self {
+            attrs,
+            ident,
+            args,
+            output,
+        })
+    }
+}
+
+// If `derive_serde` meta item is not present, defaults to cfg!(feature = "serde1").
+// `derive_serde` can only be true when serde1 is enabled.
+struct DeriveSerde(bool);
+
+impl Parse for DeriveSerde {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        let mut result = Ok(None);
+        let mut derive_serde = Vec::new();
+        let meta_items = input.parse_terminated::<MetaNameValue, Comma>(MetaNameValue::parse)?;
+        for meta in meta_items {
+            if meta.path.segments.len() != 1 {
+                extend_errors!(
+                    result,
+                    syn::Error::new(
+                        meta.span(),
+                        "tarpc::service does not support this meta item"
+                    )
+                );
+                continue;
+            }
+            let segment = meta.path.segments.first().unwrap();
+            if segment.ident != "derive_serde" {
+                extend_errors!(
+                    result,
+                    syn::Error::new(
+                        meta.span(),
+                        "tarpc::service does not support this meta item"
+                    )
+                );
+                continue;
+            }
+            match meta.lit {
+                Lit::Bool(LitBool { value: true, .. }) if cfg!(feature = "serde1") => {
+                    result = result.and(Ok(Some(true)))
+                }
+                Lit::Bool(LitBool { value: true, .. }) => {
+                    extend_errors!(
+                        result,
+                        syn::Error::new(
+                            meta.span(),
+                            "To enable serde, first enable the `serde1` feature of tarpc"
+                        )
+                    );
+                }
+                Lit::Bool(LitBool { value: false, .. }) => result = result.and(Ok(Some(false))),
+                _ => extend_errors!(
+                    result,
+                    syn::Error::new(
+                        meta.lit.span(),
+                        "`derive_serde` expects a value of type `bool`"
+                    )
+                ),
+            }
+            derive_serde.push(meta);
+        }
+        if derive_serde.len() > 1 {
+            for (i, derive_serde) in derive_serde.iter().enumerate() {
+                extend_errors!(
+                    result,
+                    syn::Error::new(
+                        derive_serde.span(),
+                        format!(
+                            "`derive_serde` appears more than once (occurrence #{})",
+                            i + 1
+                        )
+                    )
+                );
+            }
+        }
+        let derive_serde = result?.unwrap_or(cfg!(feature = "serde1"));
+        Ok(Self(derive_serde))
+    }
+}
+
+/// Generates:
+/// - derive of Debug, serde Serialize & Deserialize
+/// - serde crate annotation
+#[proc_macro_attribute]
+pub fn derive_serde(_attr: TokenStream, item: TokenStream) -> TokenStream {
+    let mut gen: proc_macro2::TokenStream = quote! {
+        #[derive(tarpc::serde::Serialize, tarpc::serde::Deserialize)]
+        #[serde(crate = "tarpc::serde")]
+    };
+    gen.extend(proc_macro2::TokenStream::from(item));
+    proc_macro::TokenStream::from(gen)
+}
+
+/// Generates:
+/// - service trait
+/// - serve fn
+/// - client stub struct
+/// - new_stub client factory fn
+/// - Request and Response enums
+/// - ResponseFut Future
+#[proc_macro_attribute]
+pub fn service(attr: TokenStream, input: TokenStream) -> TokenStream {
+    let derive_serde = parse_macro_input!(attr as DeriveSerde);
+    let unit_type: &Type = &parse_quote!(());
+    let Service {
+        ref attrs,
+        ref vis,
+        ref ident,
+        ref rpcs,
+    } = parse_macro_input!(input as Service);
+
+    let camel_case_fn_names: &Vec<_> = &rpcs
+        .iter()
+        .map(|rpc| snake_to_camel(&rpc.ident.unraw().to_string()))
+        .collect();
+    let args: &[&[PatType]] = &rpcs.iter().map(|rpc| &*rpc.args).collect::<Vec<_>>();
+    let response_fut_name = &format!("{}ResponseFut", ident.unraw());
+    let derive_serialize = if derive_serde.0 {
+        Some(
+            quote! {#[derive(tarpc::serde::Serialize, tarpc::serde::Deserialize)]
+            #[serde(crate = "tarpc::serde")]},
+        )
+    } else {
+        None
+    };
+
+    ServiceGenerator {
+        response_fut_name,
+        service_ident: ident,
+        server_ident: &format_ident!("Serve{}", ident),
+        response_fut_ident: &Ident::new(&response_fut_name, ident.span()),
+        client_ident: &format_ident!("{}Client", ident),
+        request_ident: &format_ident!("{}Request", ident),
+        response_ident: &format_ident!("{}Response", ident),
+        vis,
+        args,
+        method_attrs: &rpcs.iter().map(|rpc| &*rpc.attrs).collect::<Vec<_>>(),
+        method_idents: &rpcs.iter().map(|rpc| &rpc.ident).collect::<Vec<_>>(),
+        attrs,
+        rpcs,
+        return_types: &rpcs
+            .iter()
+            .map(|rpc| match rpc.output {
+                ReturnType::Type(_, ref ty) => ty,
+                ReturnType::Default => unit_type,
+            })
+            .collect::<Vec<_>>(),
+        arg_pats: &args
+            .iter()
+            .map(|args| args.iter().map(|arg| &*arg.pat).collect())
+            .collect::<Vec<_>>(),
+        camel_case_idents: &rpcs
+            .iter()
+            .zip(camel_case_fn_names.iter())
+            .map(|(rpc, name)| Ident::new(name, rpc.ident.span()))
+            .collect::<Vec<_>>(),
+        future_types: &camel_case_fn_names
+            .iter()
+            .map(|name| parse_str(&format!("{}Fut", name)).unwrap())
+            .collect::<Vec<_>>(),
+        derive_serialize: derive_serialize.as_ref(),
+    }
+    .into_token_stream()
+    .into()
+}
+
+/// generate an identifier consisting of the method name to CamelCase with
+/// Fut appended to it.
+fn associated_type_for_rpc(method: &ImplItemMethod) -> String {
+    snake_to_camel(&method.sig.ident.unraw().to_string()) + "Fut"
+}
+
+/// Transforms an async function into a sync one, returning a type declaration
+/// for the return type (a future).
+fn transform_method(method: &mut ImplItemMethod) -> ImplItemType {
+    method.sig.asyncness = None;
+
+    // get either the return type or ().
+    let ret = match &method.sig.output {
+        ReturnType::Default => quote!(()),
+        ReturnType::Type(_, ret) => quote!(#ret),
+    };
+
+    let fut_name = associated_type_for_rpc(method);
+    let fut_name_ident = Ident::new(&fut_name, method.sig.ident.span());
+
+    // generate the updated return signature.
+    method.sig.output = parse_quote! {
+        -> ::core::pin::Pin<Box<
+                dyn ::core::future::Future<Output = #ret> + ::core::marker::Send
+            >>
+    };
+
+    // transform the body of the method into Box::pin(async move { body }).
+    let block = method.block.clone();
+    method.block = parse_quote! [{
+        Box::pin(async move
+            #block
+        )
+    }];
+
+    // generate and return type declaration for return type.
+    let t: ImplItemType = parse_quote! {
+        type #fut_name_ident = ::core::pin::Pin<Box<dyn ::core::future::Future<Output = #ret> + ::core::marker::Send>>;
+    };
+
+    t
+}
+
+#[proc_macro_attribute]
+pub fn server(_attr: TokenStream, input: TokenStream) -> TokenStream {
+    let mut item = syn::parse_macro_input!(input as ItemImpl);
+    let span = item.span();
+
+    // the generated type declarations
+    let mut types: Vec<ImplItemType> = Vec::new();
+    let mut expected_non_async_types: Vec<(&ImplItemMethod, String)> = Vec::new();
+    let mut found_non_async_types: Vec<&ImplItemType> = Vec::new();
+
+    for inner in &mut item.items {
+        match inner {
+            ImplItem::Method(method) => {
+                if method.sig.asyncness.is_some() {
+                    // if this function is declared async, transform it into a regular function
+                    let typedecl = transform_method(method);
+                    types.push(typedecl);
+                } else {
+                    // If it's not async, keep track of all required associated types for better
+                    // error reporting.
+                    expected_non_async_types.push((method, associated_type_for_rpc(method)));
+                }
+            }
+            ImplItem::Type(typedecl) => found_non_async_types.push(typedecl),
+            _ => {}
+        }
+    }
+
+    if let Err(e) =
+        verify_types_were_provided(span, &expected_non_async_types, &found_non_async_types)
+    {
+        return TokenStream::from(e.to_compile_error());
+    }
+
+    // add the type declarations into the impl block
+    for t in types.into_iter() {
+        item.items.push(syn::ImplItem::Type(t));
+    }
+
+    TokenStream::from(quote!(#item))
+}
+
+fn verify_types_were_provided(
+    span: Span,
+    expected: &[(&ImplItemMethod, String)],
+    provided: &[&ImplItemType],
+) -> syn::Result<()> {
+    let mut result = Ok(());
+    for (method, expected) in expected {
+        if provided
+            .iter()
+            .find(|typedecl| typedecl.ident == expected)
+            .is_none()
+        {
+            let mut e = syn::Error::new(
+                span,
+                format!("not all trait items implemented, missing: `{}`", expected),
+            );
+            let fn_span = method.sig.fn_token.span();
+            e.extend(syn::Error::new(
+                fn_span.join(method.sig.ident.span()).unwrap_or(fn_span),
+                format!(
+                    "hint: `#[tarpc::server]` only rewrites async fns, and `fn {}` is not async",
+                    method.sig.ident
+                ),
+            ));
+            match result {
+                Ok(_) => result = Err(e),
+                Err(ref mut error) => error.extend(Some(e)),
+            }
+        }
+    }
+    result
+}
+
+// Things needed to generate the service items: trait, serve impl, request/response enums, and
+// the client stub.
+struct ServiceGenerator<'a> {
+    service_ident: &'a Ident,
+    server_ident: &'a Ident,
+    response_fut_ident: &'a Ident,
+    response_fut_name: &'a str,
+    client_ident: &'a Ident,
+    request_ident: &'a Ident,
+    response_ident: &'a Ident,
+    vis: &'a Visibility,
+    attrs: &'a [Attribute],
+    rpcs: &'a [RpcMethod],
+    camel_case_idents: &'a [Ident],
+    future_types: &'a [Type],
+    method_idents: &'a [&'a Ident],
+    method_attrs: &'a [&'a [Attribute]],
+    args: &'a [&'a [PatType]],
+    return_types: &'a [&'a Type],
+    arg_pats: &'a [Vec<&'a Pat>],
+    derive_serialize: Option<&'a TokenStream2>,
+}
+
+impl<'a> ServiceGenerator<'a> {
+    fn trait_service(&self) -> TokenStream2 {
+        let &Self {
+            attrs,
+            rpcs,
+            vis,
+            future_types,
+            return_types,
+            service_ident,
+            server_ident,
+            ..
+        } = self;
+
+        let types_and_fns = rpcs
+            .iter()
+            .zip(future_types.iter())
+            .zip(return_types.iter())
+            .map(
+                |(
+                    (
+                        RpcMethod {
+                            attrs, ident, args, ..
+                        },
+                        future_type,
+                    ),
+                    output,
+                )| {
+                    let ty_doc = format!("The response future returned by {}.", ident);
+                    quote! {
+                        #[doc = #ty_doc]
+                        type #future_type: std::future::Future<Output = #output>;
+
+                        #( #attrs )*
+                        fn #ident(self, context: tarpc::context::Context, #( #args ),*) -> Self::#future_type;
+                    }
+                },
+            );
+
+        quote! {
+            #( #attrs )*
+            #vis trait #service_ident: Clone {
+                #( #types_and_fns )*
+
+                /// Returns a serving function to use with [tarpc::server::Channel::respond_with].
+                fn serve(self) -> #server_ident<Self> {
+                    #server_ident { service: self }
+                }
+            }
+        }
+    }
+
+    fn struct_server(&self) -> TokenStream2 {
+        let &Self {
+            vis, server_ident, ..
+        } = self;
+
+        quote! {
+            /// A serving function to use with [tarpc::server::Channel::respond_with].
+            #[derive(Clone)]
+            #vis struct #server_ident<S> {
+                service: S,
+            }
+        }
+    }
+
+    fn impl_serve_for_server(&self) -> TokenStream2 {
+        let &Self {
+            request_ident,
+            server_ident,
+            service_ident,
+            response_ident,
+            response_fut_ident,
+            camel_case_idents,
+            arg_pats,
+            method_idents,
+            ..
+        } = self;
+
+        quote! {
+            impl<S> tarpc::server::Serve<#request_ident> for #server_ident<S>
+                where S: #service_ident
+            {
+                type Resp = #response_ident;
+                type Fut = #response_fut_ident<S>;
+
+                fn serve(self, ctx: tarpc::context::Context, req: #request_ident) -> Self::Fut {
+                    match req {
+                        #(
+                            #request_ident::#camel_case_idents{ #( #arg_pats ),* } => {
+                                #response_fut_ident::#camel_case_idents(
+                                    #service_ident::#method_idents(
+                                        self.service, ctx, #( #arg_pats ),*
+                                    )
+                                )
+                            }
+                        )*
+                    }
+                }
+            }
+        }
+    }
+
+    fn enum_request(&self) -> TokenStream2 {
+        let &Self {
+            derive_serialize,
+            vis,
+            request_ident,
+            camel_case_idents,
+            args,
+            ..
+        } = self;
+
+        quote! {
+            /// The request sent over the wire from the client to the server.
+            #[derive(Debug)]
+            #derive_serialize
+            #vis enum #request_ident {
+                #( #camel_case_idents{ #( #args ),* } ),*
+            }
+        }
+    }
+
+    fn enum_response(&self) -> TokenStream2 {
+        let &Self {
+            derive_serialize,
+            vis,
+            response_ident,
+            camel_case_idents,
+            return_types,
+            ..
+        } = self;
+
+        quote! {
+            /// The response sent over the wire from the server to the client.
+            #[derive(Debug)]
+            #derive_serialize
+            #vis enum #response_ident {
+                #( #camel_case_idents(#return_types) ),*
+            }
+        }
+    }
+
+    fn enum_response_future(&self) -> TokenStream2 {
+        let &Self {
+            vis,
+            service_ident,
+            response_fut_ident,
+            camel_case_idents,
+            future_types,
+            ..
+        } = self;
+
+        quote! {
+            /// A future resolving to a server response.
+            #vis enum #response_fut_ident<S: #service_ident> {
+                #( #camel_case_idents(<S as #service_ident>::#future_types) ),*
+            }
+        }
+    }
+
+    fn impl_debug_for_response_future(&self) -> TokenStream2 {
+        let &Self {
+            service_ident,
+            response_fut_ident,
+            response_fut_name,
+            ..
+        } = self;
+
+        quote! {
+            impl<S: #service_ident> std::fmt::Debug for #response_fut_ident<S> {
+                fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
+                    fmt.debug_struct(#response_fut_name).finish()
+                }
+            }
+        }
+    }
+
+    fn impl_future_for_response_future(&self) -> TokenStream2 {
+        let &Self {
+            service_ident,
+            response_fut_ident,
+            response_ident,
+            camel_case_idents,
+            ..
+        } = self;
+
+        quote! {
+            impl<S: #service_ident> std::future::Future for #response_fut_ident<S> {
+                type Output = #response_ident;
+
+                fn poll(self: std::pin::Pin<&mut Self>, cx: &mut std::task::Context<'_>)
+                    -> std::task::Poll<#response_ident>
+                {
+                    unsafe {
+                        match std::pin::Pin::get_unchecked_mut(self) {
+                            #(
+                                #response_fut_ident::#camel_case_idents(resp) =>
+                                    std::pin::Pin::new_unchecked(resp)
+                                        .poll(cx)
+                                        .map(#response_ident::#camel_case_idents),
+                            )*
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    fn struct_client(&self) -> TokenStream2 {
+        let &Self {
+            vis,
+            client_ident,
+            request_ident,
+            response_ident,
+            ..
+        } = self;
+
+        quote! {
+            #[allow(unused)]
+            #[derive(Clone, Debug)]
+            /// The client stub that makes RPC calls to the server. Exposes a Future interface.
+            #vis struct #client_ident<C = tarpc::client::Channel<#request_ident, #response_ident>>(C);
+        }
+    }
+
+    fn impl_from_for_client(&self) -> TokenStream2 {
+        let &Self {
+            client_ident,
+            request_ident,
+            response_ident,
+            ..
+        } = self;
+
+        quote! {
+            impl<C> From<C> for #client_ident<C>
+                where for <'a> C: tarpc::Client<'a, #request_ident, Response = #response_ident>
+            {
+                fn from(client: C) -> Self {
+                    #client_ident(client)
+                }
+            }
+        }
+    }
+
+    fn impl_client_new(&self) -> TokenStream2 {
+        let &Self {
+            client_ident,
+            vis,
+            request_ident,
+            response_ident,
+            ..
+        } = self;
+
+        quote! {
+            impl #client_ident {
+                /// Returns a new client stub that sends requests over the given transport.
+                #vis fn new<T>(config: tarpc::client::Config, transport: T)
+                    -> tarpc::client::NewClient<
+                        Self,
+                        tarpc::client::channel::RequestDispatch<#request_ident, #response_ident, T>
+                    >
+                where
+                    T: tarpc::Transport<tarpc::ClientMessage<#request_ident>, tarpc::Response<#response_ident>>
+                {
+                    let new_client = tarpc::client::new(config, transport);
+                    tarpc::client::NewClient {
+                        client: #client_ident(new_client.client),
+                        dispatch: new_client.dispatch,
+                    }
+                }
+
+            }
+        }
+    }
+
+    fn impl_client_rpc_methods(&self) -> TokenStream2 {
+        let &Self {
+            client_ident,
+            request_ident,
+            response_ident,
+            method_attrs,
+            vis,
+            method_idents,
+            args,
+            return_types,
+            arg_pats,
+            camel_case_idents,
+            ..
+        } = self;
+
+        quote! {
+            impl<C> #client_ident<C>
+                where for<'a> C: tarpc::Client<'a, #request_ident, Response = #response_ident>
+            {
+                #(
+                    #[allow(unused)]
+                    #( #method_attrs )*
+                    #vis fn #method_idents(&mut self, ctx: tarpc::context::Context, #( #args ),*)
+                        -> impl std::future::Future<Output = std::io::Result<#return_types>> + '_ {
+                        let request = #request_ident::#camel_case_idents { #( #arg_pats ),* };
+                        let resp = tarpc::Client::call(&mut self.0, ctx, request);
+                        async move {
+                            match resp.await? {
+                                #response_ident::#camel_case_idents(msg) => std::result::Result::Ok(msg),
+                                _ => unreachable!(),
+                            }
+                        }
+                    }
+                )*
+            }
+        }
+    }
+}
+
+impl<'a> ToTokens for ServiceGenerator<'a> {
+    fn to_tokens(&self, output: &mut TokenStream2) {
+        output.extend(vec![
+            self.trait_service(),
+            self.struct_server(),
+            self.impl_serve_for_server(),
+            self.enum_request(),
+            self.enum_response(),
+            self.enum_response_future(),
+            self.impl_debug_for_response_future(),
+            self.impl_future_for_response_future(),
+            self.struct_client(),
+            self.impl_from_for_client(),
+            self.impl_client_new(),
+            self.impl_client_rpc_methods(),
+        ])
+    }
+}
+
+fn snake_to_camel(ident_str: &str) -> String {
+    let mut camel_ty = String::with_capacity(ident_str.len());
+
+    let mut last_char_was_underscore = true;
+    for c in ident_str.chars() {
+        match c {
+            '_' => last_char_was_underscore = true,
+            c if last_char_was_underscore => {
+                camel_ty.extend(c.to_uppercase());
+                last_char_was_underscore = false;
+            }
+            c => camel_ty.extend(c.to_lowercase()),
+        }
+    }
+
+    camel_ty.shrink_to_fit();
+    camel_ty
+}
+
+#[test]
+fn snake_to_camel_basic() {
+    assert_eq!(snake_to_camel("abc_def"), "AbcDef");
+}
+
+#[test]
+fn snake_to_camel_underscore_suffix() {
+    assert_eq!(snake_to_camel("abc_def_"), "AbcDef");
+}
+
+#[test]
+fn snake_to_camel_underscore_prefix() {
+    assert_eq!(snake_to_camel("_abc_def"), "AbcDef");
+}
+
+#[test]
+fn snake_to_camel_underscore_consecutive() {
+    assert_eq!(snake_to_camel("abc__def"), "AbcDef");
+}
+
+#[test]
+fn snake_to_camel_capital_in_middle() {
+    assert_eq!(snake_to_camel("aBc_dEf"), "AbcDef");
+}

plugins/tests/server.rs

@@ -0,0 +1,144 @@
+use assert_type_eq::assert_type_eq;
+use futures::Future;
+use std::pin::Pin;
+use tarpc::context;
+
+// these need to be out here rather than inside the function so that the
+// assert_type_eq macro can pick them up.
+#[tarpc::service]
+trait Foo {
+    async fn two_part(s: String, i: i32) -> (String, i32);
+    async fn bar(s: String) -> String;
+    async fn baz();
+}
+
+#[test]
+fn type_generation_works() {
+    #[tarpc::server]
+    impl Foo for () {
+        async fn two_part(self, _: context::Context, s: String, i: i32) -> (String, i32) {
+            (s, i)
+        }
+
+        async fn bar(self, _: context::Context, s: String) -> String {
+            s
+        }
+
+        async fn baz(self, _: context::Context) {}
+    }
+
+    // the assert_type_eq macro can only be used once per block.
+    {
+        assert_type_eq!(
+            <() as Foo>::TwoPartFut,
+            Pin<Box<dyn Future<Output = (String, i32)> + Send>>
+        );
+    }
+    {
+        assert_type_eq!(
+            <() as Foo>::BarFut,
+            Pin<Box<dyn Future<Output = String> + Send>>
+        );
+    }
+    {
+        assert_type_eq!(
+            <() as Foo>::BazFut,
+            Pin<Box<dyn Future<Output = ()> + Send>>
+        );
+    }
+}
+
+#[allow(non_camel_case_types)]
+#[test]
+fn raw_idents_work() {
+    type r#yield = String;
+
+    #[tarpc::service]
+    trait r#trait {
+        async fn r#await(r#struct: r#yield, r#enum: i32) -> (r#yield, i32);
+        async fn r#fn(r#impl: r#yield) -> r#yield;
+        async fn r#async();
+    }
+
+    #[tarpc::server]
+    impl r#trait for () {
+        async fn r#await(
+            self,
+            _: context::Context,
+            r#struct: r#yield,
+            r#enum: i32,
+        ) -> (r#yield, i32) {
+            (r#struct, r#enum)
+        }
+
+        async fn r#fn(self, _: context::Context, r#impl: r#yield) -> r#yield {
+            r#impl
+        }
+
+        async fn r#async(self, _: context::Context) {}
+    }
+}
+
+#[test]
+fn syntax() {
+    #[tarpc::service]
+    trait Syntax {
+        #[deny(warnings)]
+        #[allow(non_snake_case)]
+        async fn TestCamelCaseDoesntConflict();
+        async fn hello() -> String;
+        #[doc = "attr"]
+        async fn attr(s: String) -> String;
+        async fn no_args_no_return();
+        async fn no_args() -> ();
+        async fn one_arg(one: String) -> i32;
+        async fn two_args_no_return(one: String, two: u64);
+        async fn two_args(one: String, two: u64) -> String;
+        async fn no_args_ret_error() -> i32;
+        async fn one_arg_ret_error(one: String) -> String;
+        async fn no_arg_implicit_return_error();
+        #[doc = "attr"]
+        async fn one_arg_implicit_return_error(one: String);
+    }
+
+    #[tarpc::server]
+    impl Syntax for () {
+        #[deny(warnings)]
+        #[allow(non_snake_case)]
+        async fn TestCamelCaseDoesntConflict(self, _: context::Context) {}
+
+        async fn hello(self, _: context::Context) -> String {
+            String::new()
+        }
+
+        async fn attr(self, _: context::Context, _s: String) -> String {
+            String::new()
+        }
+
+        async fn no_args_no_return(self, _: context::Context) {}
+
+        async fn no_args(self, _: context::Context) -> () {}
+
+        async fn one_arg(self, _: context::Context, _one: String) -> i32 {
+            0
+        }
+
+        async fn two_args_no_return(self, _: context::Context, _one: String, _two: u64) {}
+
+        async fn two_args(self, _: context::Context, _one: String, _two: u64) -> String {
+            String::new()
+        }
+
+        async fn no_args_ret_error(self, _: context::Context) -> i32 {
+            0
+        }
+
+        async fn one_arg_ret_error(self, _: context::Context, _one: String) -> String {
+            String::new()
+        }
+
+        async fn no_arg_implicit_return_error(self, _: context::Context) {}
+
+        async fn one_arg_implicit_return_error(self, _: context::Context, _one: String) {}
+    }
+}

plugins/tests/service.rs

@@ -0,0 +1,85 @@
+use tarpc::context;
+
+#[test]
+fn att_service_trait() {
+    use futures::future::{ready, Ready};
+
+    #[tarpc::service]
+    trait Foo {
+        async fn two_part(s: String, i: i32) -> (String, i32);
+        async fn bar(s: String) -> String;
+        async fn baz();
+    }
+
+    impl Foo for () {
+        type TwoPartFut = Ready<(String, i32)>;
+        fn two_part(self, _: context::Context, s: String, i: i32) -> Self::TwoPartFut {
+            ready((s, i))
+        }
+
+        type BarFut = Ready<String>;
+        fn bar(self, _: context::Context, s: String) -> Self::BarFut {
+            ready(s)
+        }
+
+        type BazFut = Ready<()>;
+        fn baz(self, _: context::Context) -> Self::BazFut {
+            ready(())
+        }
+    }
+}
+
+#[allow(non_camel_case_types)]
+#[test]
+fn raw_idents() {
+    use futures::future::{ready, Ready};
+
+    type r#yield = String;
+
+    #[tarpc::service]
+    trait r#trait {
+        async fn r#await(r#struct: r#yield, r#enum: i32) -> (r#yield, i32);
+        async fn r#fn(r#impl: r#yield) -> r#yield;
+        async fn r#async();
+    }
+
+    impl r#trait for () {
+        type AwaitFut = Ready<(r#yield, i32)>;
+        fn r#await(self, _: context::Context, r#struct: r#yield, r#enum: i32) -> Self::AwaitFut {
+            ready((r#struct, r#enum))
+        }
+
+        type FnFut = Ready<r#yield>;
+        fn r#fn(self, _: context::Context, r#impl: r#yield) -> Self::FnFut {
+            ready(r#impl)
+        }
+
+        type AsyncFut = Ready<()>;
+        fn r#async(self, _: context::Context) -> Self::AsyncFut {
+            ready(())
+        }
+    }
+}
+
+#[test]
+fn syntax() {
+    #[tarpc::service]
+    trait Syntax {
+        #[deny(warnings)]
+        #[allow(non_snake_case)]
+        async fn TestCamelCaseDoesntConflict();
+        async fn hello() -> String;
+        #[doc = "attr"]
+        async fn attr(s: String) -> String;
+        async fn no_args_no_return();
+        async fn no_args() -> ();
+        async fn one_arg(one: String) -> i32;
+        async fn two_args_no_return(one: String, two: u64);
+        async fn two_args(one: String, two: u64) -> String;
+        async fn no_args_ret_error() -> i32;
+        async fn one_arg_ret_error(one: String) -> String;
+        async fn no_arg_implicit_return_error();
+        #[doc = "attr"]
+        async fn one_arg_implicit_return_error(one: String);
+    }
+}

rustfmt.toml

@@ -1 +0,0 @@
-reorder_imports = true

src/errors.rs

@@ -1,91 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-use serde::{Deserialize, Serialize};
-use std::{fmt, io};
-use std::error::Error as StdError;
-
-/// All errors that can occur during the use of tarpc.
-#[derive(Debug)]
-pub enum Error<E> {
-    /// Any IO error.
-    Io(io::Error),
-    /// Error deserializing the server response.
-    ///
-    /// Typically this indicates a faulty implementation of `serde::Serialize` or
-    /// `serde::Deserialize`.
-    ResponseDeserialize(::bincode::Error),
-    /// Error deserializing the client request.
-    ///
-    /// Typically this indicates a faulty implementation of `serde::Serialize` or
-    /// `serde::Deserialize`.
-    RequestDeserialize(String),
-    /// The server was unable to reply to the rpc for some reason.
-    ///
-    /// This is a service-specific error. Its type is individually specified in the
-    /// `service!` macro for each rpc.
-    App(E),
-}
-
-impl<'a, E: StdError + Deserialize<'a> + Serialize + Send + 'static> fmt::Display for Error<E> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match *self {
-            Error::ResponseDeserialize(ref e) => write!(f, r#"{}: "{}""#, self.description(), e),
-            Error::RequestDeserialize(ref e) => write!(f, r#"{}: "{}""#, self.description(), e),
-            Error::App(ref e) => fmt::Display::fmt(e, f),
-            Error::Io(ref e) => fmt::Display::fmt(e, f),
-        }
-    }
-}
-
-impl<'a, E: StdError + Deserialize<'a> + Serialize + Send + 'static> StdError for Error<E> {
-    fn description(&self) -> &str {
-        match *self {
-            Error::ResponseDeserialize(_) => "The client failed to deserialize the response.",
-            Error::RequestDeserialize(_) => "The server failed to deserialize the request.",
-            Error::App(ref e) => e.description(),
-            Error::Io(ref e) => e.description(),
-        }
-    }
-
-    fn cause(&self) -> Option<&StdError> {
-        match *self {
-            Error::ResponseDeserialize(ref e) => e.cause(),
-            Error::RequestDeserialize(_) | Error::App(_) => None,
-            Error::Io(ref e) => e.cause(),
-        }
-    }
-}
-
-impl<E> From<io::Error> for Error<E> {
-    fn from(err: io::Error) -> Self {
-        Error::Io(err)
-    }
-}
-
-impl<E> From<WireError<E>> for Error<E> {
-    fn from(err: WireError<E>) -> Self {
-        match err {
-            WireError::RequestDeserialize(s) => Error::RequestDeserialize(s),
-            WireError::App(e) => Error::App(e),
-        }
-    }
-}
-
-/// A serializable, server-supplied error.
-#[doc(hidden)]
-#[derive(Deserialize, Serialize, Clone, Debug)]
-pub enum WireError<E> {
-    /// Server-side error in deserializing the client request.
-    RequestDeserialize(String),
-    /// The server was unable to reply to the rpc for some reason.
-    App(E),
-}
-
-/// Convert `native_tls::Error` to `std::io::Error`
-#[cfg(feature = "tls")]
-pub fn native_to_io(e: ::native_tls::Error) -> io::Error {
-    io::Error::new(io::ErrorKind::Other, e)
-}

src/future/client.rs

@@ -1,278 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-use {REMOTE, bincode};
-use future::server::Response;
-use futures::{self, Future, future};
-use protocol::Proto;
-use serde::Serialize;
-use serde::de::DeserializeOwned;
-use std::fmt;
-use std::io;
-use std::net::SocketAddr;
-use stream_type::StreamType;
-use tokio_core::net::TcpStream;
-use tokio_core::reactor;
-use tokio_proto::BindClient as ProtoBindClient;
-use tokio_proto::multiplex::ClientService;
-use tokio_service::Service;
-
-cfg_if! {
-    if #[cfg(feature = "tls")] {
-        use errors::native_to_io;
-        use tls::client::Context;
-        use tokio_tls::TlsConnectorExt;
-    } else {}
-}
-
-/// Additional options to configure how the client connects and operates.
-#[derive(Debug)]
-pub struct Options {
-    /// Max packet size in bytes.
-    max_payload_size: u64,
-    reactor: Option<Reactor>,
-    #[cfg(feature = "tls")]
-    tls_ctx: Option<Context>,
-}
-
-impl Default for Options {
-    #[cfg(feature = "tls")]
-    fn default() -> Self {
-        Options {
-            max_payload_size: 2 << 20,
-            reactor: None,
-            tls_ctx: None,
-        }
-    }
-
-    #[cfg(not(feature = "tls"))]
-    fn default() -> Self {
-        Options {
-            max_payload_size: 2 << 20,
-            reactor: None,
-        }
-    }
-}
-
-impl Options {
-    /// Set the max payload size in bytes. The default is 2 << 20 (2 MiB).
-    pub fn max_payload_size(mut self, bytes: u64) -> Self {
-        self.max_payload_size = bytes;
-        self
-    }
-
-    /// Drive using the given reactor handle.
-    pub fn handle(mut self, handle: reactor::Handle) -> Self {
-        self.reactor = Some(Reactor::Handle(handle));
-        self
-    }
-
-    /// Drive using the given reactor remote.
-    pub fn remote(mut self, remote: reactor::Remote) -> Self {
-        self.reactor = Some(Reactor::Remote(remote));
-        self
-    }
-
-    /// Connect using the given `Context`
-    #[cfg(feature = "tls")]
-    pub fn tls(mut self, tls_ctx: Context) -> Self {
-        self.tls_ctx = Some(tls_ctx);
-        self
-    }
-}
-
-enum Reactor {
-    Handle(reactor::Handle),
-    Remote(reactor::Remote),
-}
-
-impl fmt::Debug for Reactor {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        const HANDLE: &str = "Reactor::Handle";
-        const HANDLE_INNER: &str = "Handle { .. }";
-        const REMOTE: &str = "Reactor::Remote";
-        const REMOTE_INNER: &str = "Remote { .. }";
-
-        match *self {
-            Reactor::Handle(_) => f.debug_tuple(HANDLE).field(&HANDLE_INNER).finish(),
-            Reactor::Remote(_) => f.debug_tuple(REMOTE).field(&REMOTE_INNER).finish(),
-        }
-    }
-}
-
-#[doc(hidden)]
-pub struct Client<Req, Resp, E>
-where
-    Req: Serialize + 'static,
-    Resp: DeserializeOwned + 'static,
-    E: DeserializeOwned + 'static,
-{
-    inner: ClientService<StreamType, Proto<Req, Response<Resp, E>>>,
-}
-
-impl<Req, Resp, E> Clone for Client<Req, Resp, E>
-where
-    Req: Serialize + 'static,
-    Resp: DeserializeOwned + 'static,
-    E: DeserializeOwned + 'static,
-{
-    fn clone(&self) -> Self {
-        Client {
-            inner: self.inner.clone(),
-        }
-    }
-}
-
-impl<Req, Resp, E> Service for Client<Req, Resp, E>
-where
-    Req: Serialize + Send + 'static,
-    Resp: DeserializeOwned + Send + 'static,
-    E: DeserializeOwned + Send + 'static,
-{
-    type Request = Req;
-    type Response = Resp;
-    type Error = ::Error<E>;
-    type Future = ResponseFuture<Req, Resp, E>;
-
-    fn call(&self, request: Self::Request) -> Self::Future {
-        fn identity<T>(t: T) -> T {
-            t
-        }
-        self.inner
-            .call(request)
-            .map(Self::map_err as _)
-            .map_err(::Error::from as _)
-            .and_then(identity as _)
-    }
-}
-
-impl<Req, Resp, E> Client<Req, Resp, E>
-where
-    Req: Serialize + 'static,
-    Resp: DeserializeOwned + 'static,
-    E: DeserializeOwned + 'static,
-{
-    fn bind(handle: &reactor::Handle, tcp: StreamType, max_payload_size: u64) -> Self
-    where
-        Req: Serialize + Send + 'static,
-        Resp: DeserializeOwned + Send + 'static,
-        E: DeserializeOwned + Send + 'static,
-    {
-        let inner = Proto::new(max_payload_size).bind_client(handle, tcp);
-        Client { inner }
-    }
-
-    fn map_err(resp: WireResponse<Resp, E>) -> Result<Resp, ::Error<E>> {
-        resp.map(|r| r.map_err(::Error::from))
-            .map_err(::Error::ResponseDeserialize)
-            .and_then(|r| r)
-    }
-}
-
-impl<Req, Resp, E> fmt::Debug for Client<Req, Resp, E>
-where
-    Req: Serialize + 'static,
-    Resp: DeserializeOwned + 'static,
-    E: DeserializeOwned + 'static,
-{
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        write!(f, "Client {{ .. }}")
-    }
-}
-
-/// Extension methods for clients.
-pub trait ClientExt: Sized {
-    /// The type of the future returned when calling `connect`.
-    type ConnectFut: Future<Item = Self, Error = io::Error>;
-
-    /// Connects to a server located at the given address, using the given options.
-    fn connect(addr: SocketAddr, options: Options) -> Self::ConnectFut;
-}
-
-/// A future that resolves to a `Client` or an `io::Error`.
-pub type ConnectFuture<Req, Resp, E> = futures::Flatten<
-    futures::MapErr<
-        futures::Oneshot<io::Result<Client<Req, Resp, E>>>,
-        fn(futures::Canceled) -> io::Error,
-    >,
->;
-
-impl<Req, Resp, E> ClientExt for Client<Req, Resp, E>
-where
-    Req: Serialize + Send + 'static,
-    Resp: DeserializeOwned + Send + 'static,
-    E: DeserializeOwned + Send + 'static,
-{
-    type ConnectFut = ConnectFuture<Req, Resp, E>;
-
-    fn connect(addr: SocketAddr, options: Options) -> Self::ConnectFut {
-        // we need to do this for tls because we need to avoid moving the entire `Options`
-        // struct into the `setup` closure, since `Reactor` is not `Send`.
-        #[cfg(feature = "tls")]
-        let mut options = options;
-        #[cfg(feature = "tls")]
-        let tls_ctx = options.tls_ctx.take();
-
-        let max_payload_size = options.max_payload_size;
-
-        let connect = move |handle: &reactor::Handle| {
-            let handle2 = handle.clone();
-            TcpStream::connect(&addr, handle)
-                .and_then(move |socket| {
-                    // TODO(https://github.com/tokio-rs/tokio-proto/issues/132): move this into the
-                    // ServerProto impl
-                    #[cfg(feature = "tls")]
-                    match tls_ctx {
-                        Some(tls_ctx) => {
-                            future::Either::A(
-                                tls_ctx
-                                    .tls_connector
-                                    .connect_async(&tls_ctx.domain, socket)
-                                    .map(StreamType::Tls)
-                                    .map_err(native_to_io),
-                            )
-                        }
-                        None => future::Either::B(future::ok(StreamType::Tcp(socket))),
-                    }
-                    #[cfg(not(feature = "tls"))] future::ok(StreamType::Tcp(socket))
-                })
-                .map(move |tcp| Client::bind(&handle2, tcp, max_payload_size))
-        };
-        let (tx, rx) = futures::oneshot();
-        let setup = move |handle: &reactor::Handle| {
-            connect(handle).then(move |result| {
-                // If send fails it means the client no longer cared about connecting.
-                let _ = tx.send(result);
-                Ok(())
-            })
-        };
-
-        match options.reactor {
-            Some(Reactor::Handle(handle)) => {
-                handle.spawn(setup(&handle));
-            }
-            Some(Reactor::Remote(remote)) => {
-                remote.spawn(setup);
-            }
-            None => {
-                REMOTE.spawn(setup);
-            }
-        }
-        fn panic(canceled: futures::Canceled) -> io::Error {
-            unreachable!(canceled)
-        }
-        rx.map_err(panic as _).flatten()
-    }
-}
-
-type ResponseFuture<Req, Resp, E> =
-    futures::AndThen<futures::MapErr<
-    futures::Map<<ClientService<StreamType, Proto<Req, Response<Resp, E>>> as Service>::Future,
-                 fn(WireResponse<Resp, E>) -> Result<Resp, ::Error<E>>>,
-        fn(io::Error) -> ::Error<E>>,
-                 Result<Resp, ::Error<E>>,
-                 fn(Result<Resp, ::Error<E>>) -> Result<Resp, ::Error<E>>>;
-
-type WireResponse<R, E> = Result<Response<R, E>, bincode::Error>;

src/future/mod.rs

@@ -1,4 +0,0 @@
-/// Provides the base client stubs used by the service macro.
-pub mod client;
-/// Provides the base server boilerplate used by service implementations.
-pub mod server;

src/future/server/connection.rs

@@ -1,76 +0,0 @@
-use futures::unsync;
-use std::io;
-use tokio_service::{NewService, Service};
-
-#[derive(Debug)]
-pub enum Action {
-    Increment,
-    Decrement,
-}
-
-#[derive(Clone, Debug)]
-pub struct Tracker {
-    pub tx: unsync::mpsc::UnboundedSender<Action>,
-}
-
-impl Tracker {
-    pub fn pair() -> (Self, unsync::mpsc::UnboundedReceiver<Action>) {
-        let (tx, rx) = unsync::mpsc::unbounded();
-        (Self { tx }, rx)
-    }
-
-    pub fn increment(&self) {
-        let _ = self.tx.unbounded_send(Action::Increment);
-    }
-
-    pub fn decrement(&self) {
-        debug!("Closing connection");
-        let _ = self.tx.unbounded_send(Action::Decrement);
-    }
-}
-
-#[derive(Debug)]
-pub struct TrackingService<S> {
-    pub service: S,
-    pub tracker: Tracker,
-}
-
-#[derive(Debug)]
-pub struct TrackingNewService<S> {
-    pub new_service: S,
-    pub connection_tracker: Tracker,
-}
-
-impl<S: Service> Service for TrackingService<S> {
-    type Request = S::Request;
-    type Response = S::Response;
-    type Error = S::Error;
-    type Future = S::Future;
-
-    fn call(&self, req: Self::Request) -> Self::Future {
-        trace!("Calling service.");
-        self.service.call(req)
-    }
-}
-
-impl<S> Drop for TrackingService<S> {
-    fn drop(&mut self) {
-        debug!("Dropping ConnnectionTrackingService.");
-        self.tracker.decrement();
-    }
-}
-
-impl<S: NewService> NewService for TrackingNewService<S> {
-    type Request = S::Request;
-    type Response = S::Response;
-    type Error = S::Error;
-    type Instance = TrackingService<S::Instance>;
-
-    fn new_service(&self) -> io::Result<Self::Instance> {
-        self.connection_tracker.increment();
-        Ok(TrackingService {
-            service: self.new_service.new_service()?,
-            tracker: self.connection_tracker.clone(),
-        })
-    }
-}

src/future/server/mod.rs

@@ -1,471 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-use {bincode, net2};
-use errors::WireError;
-use futures::{Async, Future, Poll, Stream, future as futures};
-use protocol::Proto;
-use serde::Serialize;
-use serde::de::DeserializeOwned;
-use std::fmt;
-use std::io;
-use std::net::SocketAddr;
-use stream_type::StreamType;
-use tokio_core::net::{Incoming, TcpListener, TcpStream};
-use tokio_core::reactor;
-use tokio_io::{AsyncRead, AsyncWrite};
-use tokio_proto::BindServer;
-use tokio_service::NewService;
-
-mod connection;
-mod shutdown;
-
-cfg_if! {
-    if #[cfg(feature = "tls")] {
-        use native_tls::{self, TlsAcceptor};
-        use tokio_tls::{AcceptAsync, TlsAcceptorExt, TlsStream};
-        use errors::native_to_io;
-    } else {}
-}
-
-pub use self::shutdown::{Shutdown, ShutdownFuture};
-
-/// A handle to a bound server.
-#[derive(Clone, Debug)]
-pub struct Handle {
-    addr: SocketAddr,
-    shutdown: Shutdown,
-}
-
-impl Handle {
-    /// Returns a hook for shutting down the server.
-    pub fn shutdown(&self) -> &Shutdown {
-        &self.shutdown
-    }
-
-    /// The socket address the server is bound to.
-    pub fn addr(&self) -> SocketAddr {
-        self.addr
-    }
-}
-
-enum Acceptor {
-    Tcp,
-    #[cfg(feature = "tls")]
-    Tls(TlsAcceptor),
-}
-
-struct Accept {
-    #[cfg(feature = "tls")]
-    inner: futures::Either<
-        futures::MapErr<
-            futures::Map<AcceptAsync<TcpStream>, fn(TlsStream<TcpStream>) -> StreamType>,
-            fn(native_tls::Error) -> io::Error,
-        >,
-        futures::FutureResult<StreamType, io::Error>,
-    >,
-    #[cfg(not(feature = "tls"))]
-    inner: futures::FutureResult<StreamType, io::Error>,
-}
-
-impl Future for Accept {
-    type Item = StreamType;
-    type Error = io::Error;
-
-    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
-        self.inner.poll()
-    }
-}
-
-impl Acceptor {
-    // TODO(https://github.com/tokio-rs/tokio-proto/issues/132): move this into the ServerProto impl
-    #[cfg(feature = "tls")]
-    fn accept(&self, socket: TcpStream) -> Accept {
-        Accept {
-            inner: match *self {
-                Acceptor::Tls(ref tls_acceptor) => {
-                    futures::Either::A(
-                        tls_acceptor
-                            .accept_async(socket)
-                            .map(StreamType::Tls as _)
-                            .map_err(native_to_io),
-                    )
-                }
-                Acceptor::Tcp => futures::Either::B(futures::ok(StreamType::Tcp(socket))),
-            },
-        }
-    }
-
-    #[cfg(not(feature = "tls"))]
-    fn accept(&self, socket: TcpStream) -> Accept {
-        Accept {
-            inner: futures::ok(StreamType::Tcp(socket)),
-        }
-    }
-}
-
-#[cfg(feature = "tls")]
-impl From<Options> for Acceptor {
-    fn from(options: Options) -> Self {
-        match options.tls_acceptor {
-            Some(tls_acceptor) => Acceptor::Tls(tls_acceptor),
-            None => Acceptor::Tcp,
-        }
-    }
-}
-
-#[cfg(not(feature = "tls"))]
-impl From<Options> for Acceptor {
-    fn from(_: Options) -> Self {
-        Acceptor::Tcp
-    }
-}
-
-impl fmt::Debug for Acceptor {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        use self::Acceptor::*;
-        #[cfg(feature = "tls")]
-        const TLS: &str = "TlsAcceptor { .. }";
-
-        match *self {
-            Tcp => fmt.debug_tuple("Acceptor::Tcp").finish(),
-            #[cfg(feature = "tls")]
-            Tls(_) => fmt.debug_tuple("Acceptor::Tls").field(&TLS).finish(),
-        }
-    }
-}
-
-impl fmt::Debug for Accept {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        fmt.debug_struct("Accept").finish()
-    }
-}
-
-#[derive(Debug)]
-struct AcceptStream<S> {
-    stream: S,
-    acceptor: Acceptor,
-    future: Option<Accept>,
-}
-
-impl<S> Stream for AcceptStream<S>
-where
-    S: Stream<Item = (TcpStream, SocketAddr), Error = io::Error>,
-{
-    type Item = <Accept as Future>::Item;
-    type Error = io::Error;
-
-    fn poll(&mut self) -> Poll<Option<Self::Item>, io::Error> {
-        if self.future.is_none() {
-            let stream = match try_ready!(self.stream.poll()) {
-                None => return Ok(Async::Ready(None)),
-                Some((stream, _)) => stream,
-            };
-            self.future = Some(self.acceptor.accept(stream));
-        }
-        assert!(self.future.is_some());
-        match self.future.as_mut().unwrap().poll() {
-            Ok(Async::Ready(e)) => {
-                self.future = None;
-                Ok(Async::Ready(Some(e)))
-            }
-            Err(e) => {
-                self.future = None;
-                Err(e)
-            }
-            Ok(Async::NotReady) => Ok(Async::NotReady),
-        }
-    }
-}
-
-/// Additional options to configure how the server operates.
-pub struct Options {
-    /// Max packet size in bytes.
-    max_payload_size: u64,
-    #[cfg(feature = "tls")]
-    tls_acceptor: Option<TlsAcceptor>,
-}
-
-impl Default for Options {
-    #[cfg(not(feature = "tls"))]
-    fn default() -> Self {
-        Options {
-            max_payload_size: 2 << 20,
-        }
-    }
-
-    #[cfg(feature = "tls")]
-    fn default() -> Self {
-        Options {
-            max_payload_size: 2 << 20,
-            tls_acceptor: None,
-        }
-    }
-}
-
-impl Options {
-    /// Set the max payload size in bytes. The default is 2 << 20 (2 MiB).
-    pub fn max_payload_size(mut self, bytes: u64) -> Self {
-        self.max_payload_size = bytes;
-        self
-    }
-
-    /// Sets the `TlsAcceptor`
-    #[cfg(feature = "tls")]
-    pub fn tls(mut self, tls_acceptor: TlsAcceptor) -> Self {
-        self.tls_acceptor = Some(tls_acceptor);
-        self
-    }
-}
-
-impl fmt::Debug for Options {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        #[cfg(feature = "tls")]
-        const SOME: &str = "Some(_)";
-        #[cfg(feature = "tls")]
-        const NONE: &str = "None";
-
-        let mut debug_struct = fmt.debug_struct("Options");
-        #[cfg(feature = "tls")]
-        debug_struct.field(
-            "tls_acceptor",
-            if self.tls_acceptor.is_some() {
-                &SOME
-            } else {
-                &NONE
-            },
-        );
-        debug_struct.finish()
-    }
-}
-
-/// A message from server to client.
-#[doc(hidden)]
-pub type Response<T, E> = Result<T, WireError<E>>;
-
-#[doc(hidden)]
-pub fn listen<S, Req, Resp, E>(new_service: S,
-                               addr: SocketAddr,
-                               handle: &reactor::Handle,
-                               options: Options)
-                               -> io::Result<(Handle, Listen<S, Req, Resp, E>)>
-    where S: NewService<Request = Result<Req, bincode::Error>,
-                        Response = Response<Resp, E>,
-                        Error = io::Error> + 'static,
-          Req: DeserializeOwned + 'static,
-          Resp: Serialize + 'static,
-          E: Serialize + 'static
-{
-    let (addr, shutdown, server) = listen_with(
-        new_service,
-        addr,
-        handle,
-        options.max_payload_size,
-        Acceptor::from(options),
-    )?;
-    Ok((
-        Handle {
-            addr: addr,
-            shutdown: shutdown,
-        },
-        server,
-    ))
-}
-
-/// Spawns a service that binds to the given address using the given handle.
-fn listen_with<S, Req, Resp, E>(new_service: S,
-                                addr: SocketAddr,
-                                handle: &reactor::Handle,
-                                max_payload_size: u64,
-                                acceptor: Acceptor)
-                                -> io::Result<(SocketAddr, Shutdown, Listen<S, Req, Resp, E>)>
-    where S: NewService<Request = Result<Req, bincode::Error>,
-                        Response = Response<Resp, E>,
-                        Error = io::Error> + 'static,
-          Req: DeserializeOwned + 'static,
-          Resp: Serialize + 'static,
-          E: Serialize + 'static
-{
-    let listener = listener(&addr, handle)?;
-    let addr = listener.local_addr()?;
-    debug!("Listening on {}.", addr);
-
-    let handle = handle.clone();
-    let (connection_tracker, shutdown, shutdown_future) = shutdown::Watcher::triple();
-    let server = BindStream {
-        handle: handle,
-        new_service: connection::TrackingNewService {
-            connection_tracker: connection_tracker,
-            new_service: new_service,
-        },
-        stream: AcceptStream {
-            stream: listener.incoming(),
-            acceptor: acceptor,
-            future: None,
-        },
-        max_payload_size: max_payload_size,
-    };
-
-    let server = AlwaysOkUnit(server.select(shutdown_future));
-    Ok((addr, shutdown, Listen { inner: server }))
-}
-
-fn listener(addr: &SocketAddr, handle: &reactor::Handle) -> io::Result<TcpListener> {
-    const PENDING_CONNECTION_BACKLOG: i32 = 1024;
-
-    let builder = match *addr {
-        SocketAddr::V4(_) => net2::TcpBuilder::new_v4(),
-        SocketAddr::V6(_) => net2::TcpBuilder::new_v6(),
-    }?;
-    configure_tcp(&builder)?;
-    builder.reuse_address(true)?;
-    builder
-        .bind(addr)?
-        .listen(PENDING_CONNECTION_BACKLOG)
-        .and_then(|l| TcpListener::from_listener(l, addr, handle))
-}
-
-#[cfg(unix)]
-fn configure_tcp(tcp: &net2::TcpBuilder) -> io::Result<()> {
-    use net2::unix::UnixTcpBuilderExt;
-    tcp.reuse_port(true)?;
-    Ok(())
-}
-
-#[cfg(windows)]
-fn configure_tcp(_tcp: &net2::TcpBuilder) -> io::Result<()> {
-    Ok(())
-}
-
-struct BindStream<S, St> {
-    handle: reactor::Handle,
-    new_service: connection::TrackingNewService<S>,
-    stream: St,
-    max_payload_size: u64,
-}
-
-impl<S, St> fmt::Debug for BindStream<S, St>
-where
-    S: fmt::Debug,
-    St: fmt::Debug,
-{
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        f.debug_struct("BindStream")
-            .field("handle", &self.handle)
-            .field("new_service", &self.new_service)
-            .field("stream", &self.stream)
-            .finish()
-    }
-}
-
-impl<S, Req, Resp, E, I, St> BindStream<S, St>
-    where S: NewService<Request = Result<Req, bincode::Error>,
-                        Response = Response<Resp, E>,
-                        Error = io::Error> + 'static,
-          Req: DeserializeOwned + 'static,
-          Resp: Serialize + 'static,
-          E: Serialize + 'static,
-          I: AsyncRead + AsyncWrite + 'static,
-          St: Stream<Item = I, Error = io::Error>
-{
-    fn bind_each(&mut self) -> Poll<(), io::Error> {
-        loop {
-            match try!(self.stream.poll()) {
-                Async::Ready(Some(socket)) => {
-                    Proto::new(self.max_payload_size).bind_server(&self.handle,
-                                                                  socket,
-                                                                  self.new_service.new_service()?);
-                }
-                Async::Ready(None) => return Ok(Async::Ready(())),
-                Async::NotReady => return Ok(Async::NotReady),
-            }
-        }
-    }
-}
-
-impl<S, Req, Resp, E, I, St> Future for BindStream<S, St>
-    where S: NewService<Request = Result<Req, bincode::Error>,
-                        Response = Response<Resp, E>,
-                        Error = io::Error> + 'static,
-          Req: DeserializeOwned + 'static,
-          Resp: Serialize + 'static,
-          E: Serialize + 'static,
-          I: AsyncRead + AsyncWrite + 'static,
-          St: Stream<Item = I, Error = io::Error>
-{
-    type Item = ();
-    type Error = ();
-
-    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
-        match self.bind_each() {
-            Ok(Async::Ready(())) => Ok(Async::Ready(())),
-            Ok(Async::NotReady) => Ok(Async::NotReady),
-            Err(e) => {
-                error!("While processing incoming connections: {}", e);
-                Err(())
-            }
-        }
-    }
-}
-
-/// The future representing a running server.
-#[doc(hidden)]
-pub struct Listen<S, Req, Resp, E>
-    where S: NewService<Request = Result<Req, bincode::Error>,
-                        Response = Response<Resp, E>,
-                        Error = io::Error> + 'static,
-          Req: DeserializeOwned + 'static,
-          Resp: Serialize + 'static,
-          E: Serialize + 'static
-{
-    inner: AlwaysOkUnit<futures::Select<BindStream<S, AcceptStream<Incoming>>, shutdown::Watcher>>,
-}
-
-impl<S, Req, Resp, E> Future for Listen<S, Req, Resp, E>
-    where S: NewService<Request = Result<Req, bincode::Error>,
-                        Response = Response<Resp, E>,
-                        Error = io::Error> + 'static,
-          Req: DeserializeOwned + 'static,
-          Resp: Serialize + 'static,
-          E: Serialize + 'static
-{
-    type Item = ();
-    type Error = ();
-
-    fn poll(&mut self) -> Poll<(), ()> {
-        self.inner.poll()
-    }
-}
-
-impl<S, Req, Resp, E> fmt::Debug for Listen<S, Req, Resp, E>
-    where S: NewService<Request = Result<Req, bincode::Error>,
-                        Response = Response<Resp, E>,
-                        Error = io::Error> + 'static,
-          Req: DeserializeOwned + 'static,
-          Resp: Serialize + 'static,
-          E: Serialize + 'static
-{
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        f.debug_struct("Listen").finish()
-    }
-}
-
-#[derive(Debug)]
-struct AlwaysOkUnit<F>(F);
-
-impl<F> Future for AlwaysOkUnit<F>
-where
-    F: Future,
-{
-    type Item = ();
-    type Error = ();
-
-    fn poll(&mut self) -> Poll<(), ()> {
-        match self.0.poll() {
-            Ok(Async::Ready(_)) | Err(_) => Ok(Async::Ready(())),
-            Ok(Async::NotReady) => Ok(Async::NotReady),
-        }
-    }
-}

src/future/server/shutdown.rs

@@ -1,182 +0,0 @@
-
-
-use super::{AlwaysOkUnit, connection};
-use futures::{Async, Future, Poll, Stream, future as futures, stream};
-use futures::sync::{mpsc, oneshot};
-use futures::unsync;
-
-/// A hook to shut down a running server.
-#[derive(Clone, Debug)]
-pub struct Shutdown {
-    tx: mpsc::UnboundedSender<oneshot::Sender<()>>,
-}
-
-/// A future that resolves when server shutdown completes.
-#[derive(Debug)]
-pub struct ShutdownFuture {
-    inner: futures::Either<futures::FutureResult<(), ()>, AlwaysOkUnit<oneshot::Receiver<()>>>,
-}
-
-impl Future for ShutdownFuture {
-    type Item = ();
-    type Error = ();
-
-    fn poll(&mut self) -> Poll<(), ()> {
-        self.inner.poll()
-    }
-}
-
-impl Shutdown {
-    /// Initiates an orderly server shutdown.
-    ///
-    /// First, the server enters lameduck mode, in which
-    /// existing connections are honored but no new connections are accepted. Then, once all
-    /// connections are closed, it initates total shutdown.
-    ///
-    /// The returned future resolves when the server is completely shut down.
-    pub fn shutdown(&self) -> ShutdownFuture {
-        let (tx, rx) = oneshot::channel();
-        let inner = if self.tx.unbounded_send(tx).is_err() {
-            trace!("Server already initiated shutdown.");
-            futures::Either::A(futures::ok(()))
-        } else {
-            futures::Either::B(AlwaysOkUnit(rx))
-        };
-        ShutdownFuture { inner: inner }
-    }
-}
-
-#[derive(Debug)]
-pub struct Watcher {
-    shutdown_rx: stream::Take<mpsc::UnboundedReceiver<oneshot::Sender<()>>>,
-    connections: unsync::mpsc::UnboundedReceiver<connection::Action>,
-    queued_error: Option<()>,
-    shutdown: Option<oneshot::Sender<()>>,
-    done: bool,
-    num_connections: u64,
-}
-
-impl Watcher {
-    pub fn triple() -> (connection::Tracker, Shutdown, Self) {
-        let (connection_tx, connections) = connection::Tracker::pair();
-        let (shutdown_tx, shutdown_rx) = mpsc::unbounded();
-        (
-            connection_tx,
-            Shutdown { tx: shutdown_tx },
-            Watcher {
-                shutdown_rx: shutdown_rx.take(1),
-                connections: connections,
-                queued_error: None,
-                shutdown: None,
-                done: false,
-                num_connections: 0,
-            },
-        )
-    }
-
-    fn process_connection(&mut self, action: connection::Action) {
-        match action {
-            connection::Action::Increment => self.num_connections += 1,
-            connection::Action::Decrement => self.num_connections -= 1,
-        }
-    }
-
-    fn poll_shutdown_requests(&mut self) -> Poll<Option<()>, ()> {
-        Ok(Async::Ready(match try_ready!(self.shutdown_rx.poll()) {
-            Some(tx) => {
-                debug!("Received shutdown request.");
-                self.shutdown = Some(tx);
-                Some(())
-            }
-            None => None,
-        }))
-    }
-
-    fn poll_connections(&mut self) -> Poll<Option<()>, ()> {
-        Ok(Async::Ready(match try_ready!(self.connections.poll()) {
-            Some(action) => {
-                self.process_connection(action);
-                Some(())
-            }
-            None => None,
-        }))
-    }
-
-    fn poll_shutdown_requests_and_connections(&mut self) -> Poll<Option<()>, ()> {
-        if let Some(e) = self.queued_error.take() {
-            return Err(e);
-        }
-
-        match try!(self.poll_shutdown_requests()) {
-            Async::NotReady => {
-                match try_ready!(self.poll_connections()) {
-                    Some(()) => Ok(Async::Ready(Some(()))),
-                    None => Ok(Async::NotReady),
-                }
-            }
-            Async::Ready(None) => {
-                match try_ready!(self.poll_connections()) {
-                    Some(()) => Ok(Async::Ready(Some(()))),
-                    None => Ok(Async::Ready(None)),
-                }
-            }
-            Async::Ready(Some(())) => {
-                match self.poll_connections() {
-                    Err(e) => {
-                        self.queued_error = Some(e);
-                        Ok(Async::Ready(Some(())))
-                    }
-                    Ok(Async::NotReady) | Ok(Async::Ready(None)) | Ok(Async::Ready(Some(()))) => {
-                        Ok(Async::Ready(Some(())))
-                    }
-                }
-            }
-        }
-    }
-
-    fn should_continue(&mut self) -> bool {
-        match self.shutdown.take() {
-            Some(shutdown) => {
-                debug!("Lameduck mode: {} open connections", self.num_connections);
-                if self.num_connections == 0 {
-                    debug!("Shutting down.");
-                    // Not required for the shutdown future to be waited on, so this
-                    // can fail (which is fine).
-                    let _ = shutdown.send(());
-                    false
-                } else {
-                    self.shutdown = Some(shutdown);
-                    true
-                }
-            }
-            None => true,
-        }
-    }
-
-    fn process_request(&mut self) -> Poll<Option<()>, ()> {
-        if self.done {
-            return Ok(Async::Ready(None));
-        }
-        if self.should_continue() {
-            self.poll_shutdown_requests_and_connections()
-        } else {
-            self.done = true;
-            Ok(Async::Ready(None))
-        }
-    }
-}
-
-impl Future for Watcher {
-    type Item = ();
-    type Error = ();
-
-    fn poll(&mut self) -> Poll<(), ()> {
-        loop {
-            match try!(self.process_request()) {
-                Async::Ready(Some(())) => continue,
-                Async::Ready(None) => return Ok(Async::Ready(())),
-                Async::NotReady => return Ok(Async::NotReady),
-            }
-        }
-    }
-}

src/lib.rs

@@ -1,213 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-//! tarpc is an RPC framework for rust with a focus on ease of use. Defining a
-//! service can be done in just a few lines of code, and most of the boilerplate of
-//! writing a server is taken care of for you.
-//!
-//! ## What is an RPC framework?
-//! "RPC" stands for "Remote Procedure Call," a function call where the work of
-//! producing the return value is being done somewhere else. When an rpc function is
-//! invoked, behind the scenes the function contacts some other process somewhere
-//! and asks them to evaluate the function instead. The original function then
-//! returns the value produced by the other process.
-//!
-//! RPC frameworks are a fundamental building block of most microservices-oriented
-//! architectures. Two well-known ones are [gRPC](http://www.grpc.io) and
-//! [Cap'n Proto](https://capnproto.org/).
-//!
-//! tarpc differentiates itself from other RPC frameworks by defining the schema in code,
-//! rather than in a separate language such as .proto. This means there's no separate compilation
-//! process, and no cognitive context switching between different languages. Additionally, it
-//! works with the community-backed library serde: any serde-serializable type can be used as
-//! arguments to tarpc fns.
-//!
-//! Example usage:
-//!
-//! ```
-//! #![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-//! #![plugin(tarpc_plugins)]
-//!
-//! #[macro_use]
-//! extern crate tarpc;
-//! extern crate tokio_core;
-//!
-//! use tarpc::sync::{client, server};
-//! use tarpc::sync::client::ClientExt;
-//! use tarpc::util::Never;
-//! use tokio_core::reactor;
-//! use std::sync::mpsc;
-//! use std::thread;
-//!
-//! service! {
-//!     rpc hello(name: String) -> String;
-//! }
-//!
-//! #[derive(Clone)]
-//! struct HelloServer;
-//!
-//! impl SyncService for HelloServer {
-//!     fn hello(&self, name: String) -> Result<String, Never> {
-//!         Ok(format!("Hello, {}!", name))
-//!     }
-//! }
-//!
-//! fn main() {
-//!     let (tx, rx) = mpsc::channel();
-//!     thread::spawn(move || {
-//!         let mut handle = HelloServer.listen("localhost:10000",
-//!             server::Options::default()).unwrap();
-//!         tx.send(handle.addr()).unwrap();
-//!         handle.run();
-//!     });
-//!     let addr = rx.recv().unwrap();
-//!     let client = SyncClient::connect(addr, client::Options::default()).unwrap();
-//!     println!("{}", client.hello("Mom".to_string()).unwrap());
-//! }
-//! ```
-//!
-//! Example usage with TLS:
-//!
-//! ```no-run
-//! #![feature(plugin, use_extern_macros, proc_macro_path_invoc)]
-//! #![plugin(tarpc_plugins)]
-//!
-//! #[macro_use]
-//! extern crate tarpc;
-//!
-//! use tarpc::sync::{client, server};
-//! use tarpc::sync::client::ClientExt;
-//! use tarpc::tls;
-//! use tarpc::util::Never;
-//! use tarpc::native_tls::{TlsAcceptor, Pkcs12};
-//!
-//! service! {
-//!     rpc hello(name: String) -> String;
-//! }
-//!
-//! #[derive(Clone)]
-//! struct HelloServer;
-//!
-//! impl SyncService for HelloServer {
-//!     fn hello(&self, name: String) -> Result<String, Never> {
-//!         Ok(format!("Hello, {}!", name))
-//!     }
-//! }
-//!
-//! fn get_acceptor() -> TlsAcceptor {
-//!      let buf = include_bytes!("test/identity.p12");
-//!      let pkcs12 = Pkcs12::from_der(buf, "password").unwrap();
-//!      TlsAcceptor::builder(pkcs12).unwrap().build().unwrap()
-//! }
-//!
-//! fn main() {
-//!     let addr = "localhost:10000";
-//!     let acceptor = get_acceptor();
-//!     let _server = HelloServer.listen(addr, server::Options::default().tls(acceptor));
-//!     let client = SyncClient::connect(addr,
-//!                                      client::Options::default()
-//!                                          .tls(tls::client::Context::new("foobar.com").unwrap()))
-//!                                          .unwrap();
-//!     println!("{}", client.hello("Mom".to_string()).unwrap());
-//! }
-//! ```
-
-#![deny(missing_docs, missing_debug_implementations)]
-#![feature(never_type)]
-#![cfg_attr(test, feature(plugin, use_extern_macros, proc_macro_path_invoc))]
-#![cfg_attr(test, plugin(tarpc_plugins))]
-
-extern crate byteorder;
-extern crate bytes;
-#[macro_use]
-extern crate cfg_if;
-#[macro_use]
-extern crate lazy_static;
-#[macro_use]
-extern crate log;
-extern crate net2;
-extern crate num_cpus;
-extern crate thread_pool;
-extern crate tokio_codec;
-extern crate tokio_io;
-
-#[doc(hidden)]
-pub extern crate bincode;
-#[doc(hidden)]
-#[macro_use]
-pub extern crate futures;
-#[doc(hidden)]
-pub extern crate serde;
-#[doc(hidden)]
-#[macro_use]
-pub extern crate serde_derive;
-#[doc(hidden)]
-pub extern crate tokio_core;
-#[doc(hidden)]
-pub extern crate tokio_proto;
-#[doc(hidden)]
-pub extern crate tokio_service;
-
-pub use errors::Error;
-#[doc(hidden)]
-pub use errors::WireError;
-
-/// Provides some utility error types, as well as a trait for spawning futures on the default event
-/// loop.
-pub mod util;
-
-/// Provides the macro used for constructing rpc services and client stubs.
-#[macro_use]
-mod macros;
-/// Synchronous version of the tarpc API
-pub mod sync;
-/// Futures-based version of the tarpc API.
-pub mod future;
-/// TLS-specific functionality.
-#[cfg(feature = "tls")]
-pub mod tls;
-/// Provides implementations of `ClientProto` and `ServerProto` that implement the tarpc protocol.
-/// The tarpc protocol is a length-delimited, bincode-serialized payload.
-mod protocol;
-/// Provides a few different error types.
-mod errors;
-/// Provides an abstraction over TLS and TCP streams.
-mod stream_type;
-
-use std::sync::mpsc;
-use std::thread;
-use tokio_core::reactor;
-
-lazy_static! {
-    /// The `Remote` for the default reactor core.
-    static ref REMOTE: reactor::Remote = {
-        spawn_core()
-    };
-}
-
-/// Spawns a `reactor::Core` running forever on a new thread.
-fn spawn_core() -> reactor::Remote {
-    let (tx, rx) = mpsc::channel();
-    thread::spawn(move || {
-        let mut core = reactor::Core::new().unwrap();
-        tx.send(core.handle().remote().clone()).unwrap();
-
-        // Run forever
-        core.run(futures::empty::<(), !>()).unwrap();
-    });
-    rx.recv().unwrap()
-}
-
-cfg_if! {
-    if #[cfg(feature = "tls")] {
-        extern crate tokio_tls;
-        extern crate native_tls as native_tls_inner;
-
-        /// Re-exported TLS-related types from the `native_tls` crate.
-        pub mod native_tls {
-            pub use native_tls_inner::{Error, Pkcs12, TlsAcceptor, TlsConnector};
-        }
-    } else {}
-}

src/plugins/Cargo.toml

@@ -1,21 +0,0 @@
-[package]
-name = "tarpc-plugins"
-version = "0.4.0"
-authors = ["Adam Wright <adam.austin.wright@gmail.com>", "Tim Kuehn <timothy.j.kuehn@gmail.com>"]
-license = "MIT"
-documentation = "https://docs.rs/tarpc"
-homepage = "https://github.com/google/tarpc"
-repository = "https://github.com/google/tarpc"
-keywords = ["rpc", "network", "server", "api", "tls"]
-categories = ["asynchronous", "network-programming"]
-readme = "../../README.md"
-description = "Plugins for tarpc, an RPC framework for Rust with a focus on ease of use."
-
-[badges]
-travis-ci = { repository = "google/tarpc" }
-
-[dependencies]
-itertools = "0.7"
-
-[lib]
-plugin = true

src/plugins/src/lib.rs

@@ -1,196 +0,0 @@
-#![feature(plugin_registrar, rustc_private)]
-
-extern crate itertools;
-extern crate rustc_plugin;
-extern crate syntax;
-
-use itertools::Itertools;
-use rustc_plugin::Registry;
-use syntax::ast::{self, Ident, TraitRef, Ty, TyKind};
-use syntax::ext::base::{ExtCtxt, MacResult, DummyResult, MacEager};
-use syntax::codemap::Span;
-use syntax::parse::{self, token, str_lit, PResult};
-use syntax::parse::parser::{Parser, PathStyle};
-use syntax::symbol::Symbol;
-use syntax::ptr::P;
-use syntax::tokenstream::{TokenTree, TokenStream};
-use syntax::util::small_vector::SmallVector;
-
-fn snake_to_camel(cx: &mut ExtCtxt, sp: Span, tts: &[TokenTree]) -> Box<MacResult + 'static> {
-    let mut parser = parse::new_parser_from_tts(cx.parse_sess(), tts.into());
-    // The `expand_expr` method is called so that any macro calls in the
-    // parsed expression are expanded.
-
-    let mut item = match parser.parse_trait_item(&mut false) {
-        Ok(s) => s,
-        Err(mut diagnostic) => {
-            diagnostic.emit();
-            return DummyResult::any(sp);
-        }
-    };
-
-    if let Err(mut diagnostic) = parser.expect(&token::Eof) {
-        diagnostic.emit();
-        return DummyResult::any(sp);
-    }
-
-    let old_ident = convert(&mut item.ident);
-
-    // As far as I know, it's not possible in macro_rules! to reference an $ident in a doc string,
-    // so this is the hacky workaround.
-    //
-    // This code looks intimidating, but it's just iterating through the trait item's attributes
-    // copying non-doc attributes, and modifying doc attributes such that replacing any {} in the
-    // doc string instead holds the original, snake_case ident.
-    let attrs: Vec<_> = item.attrs
-        .drain(..)
-        .map(|mut attr| {
-            if !attr.is_sugared_doc {
-                return attr;
-            }
-
-            // Getting at the underlying doc comment is surprisingly painful.
-            // The call-chain goes something like:
-            //
-            //  - https://github.com/rust-lang/rust/blob/9c15de4fd59bee290848b5443c7e194fd5afb02c/src/libsyntax/attr.rs#L283
-            //  - https://github.com/rust-lang/rust/blob/9c15de4fd59bee290848b5443c7e194fd5afb02c/src/libsyntax/attr.rs#L1067
-            //  - https://github.com/rust-lang/rust/blob/9c15de4fd59bee290848b5443c7e194fd5afb02c/src/libsyntax/attr.rs#L1196
-            //  - https://github.com/rust-lang/rust/blob/9c15de4fd59bee290848b5443c7e194fd5afb02c/src/libsyntax/parse/mod.rs#L399
-            //  - https://github.com/rust-lang/rust/blob/9c15de4fd59bee290848b5443c7e194fd5afb02c/src/libsyntax/parse/mod.rs#L268
-            //
-            // Note that a docstring (i.e., something with is_sugared_doc) *always* has exactly two
-            // tokens: an Eq followed by a Literal, where the Literal contains a Str_. We therefore
-            // match against that, modifying the inner Str with our modified Symbol.
-            let mut tokens = attr.tokens.clone().into_trees();
-            if let Some(tt @ TokenTree::Token(_, token::Eq)) = tokens.next() {
-                let mut docstr = tokens.next().expect("Docstrings must have literal docstring");
-                if let TokenTree::Token(_, token::Literal(token::Str_(ref mut doc), _)) = docstr {
-                    *doc = Symbol::intern(&str_lit(&doc.as_str(), None).replace("{}", &old_ident));
-                } else {
-                    unreachable!();
-                }
-                attr.tokens = TokenStream::concat(vec![tt.into(), docstr.into()]);
-            } else {
-                unreachable!();
-            }
-
-            attr
-        })
-        .collect();
-    item.attrs.extend(attrs.into_iter());
-
-    MacEager::trait_items(SmallVector::one(item))
-}
-
-fn impl_snake_to_camel(cx: &mut ExtCtxt, sp: Span, tts: &[TokenTree]) -> Box<MacResult + 'static> {
-    let mut parser = parse::new_parser_from_tts(cx.parse_sess(), tts.into());
-    // The `expand_expr` method is called so that any macro calls in the
-    // parsed expression are expanded.
-
-    let mut item = match parser.parse_impl_item(&mut false) {
-        Ok(s) => s,
-        Err(mut diagnostic) => {
-            diagnostic.emit();
-            return DummyResult::any(sp);
-        }
-    };
-
-    if let Err(mut diagnostic) = parser.expect(&token::Eof) {
-        diagnostic.emit();
-        return DummyResult::any(sp);
-    }
-
-    convert(&mut item.ident);
-    MacEager::impl_items(SmallVector::one(item))
-}
-
-fn ty_snake_to_camel(cx: &mut ExtCtxt, sp: Span, tts: &[TokenTree]) -> Box<MacResult + 'static> {
-    let mut parser = parse::new_parser_from_tts(cx.parse_sess(), tts.into());
-    // The `expand_expr` method is called so that any macro calls in the
-    // parsed expression are expanded.
-
-    let mut path = match parser.parse_path(PathStyle::Type) {
-        Ok(s) => s,
-        Err(mut diagnostic) => {
-            diagnostic.emit();
-            return DummyResult::any(sp);
-        }
-    };
-
-    if let Err(mut diagnostic) = parser.expect(&token::Eof) {
-        diagnostic.emit();
-        return DummyResult::any(sp);
-    }
-
-    // Only capitalize the final segment
-    convert(&mut path.segments
-                     .last_mut()
-                     .unwrap()
-                     .ident);
-    MacEager::ty(P(Ty {
-        id: ast::DUMMY_NODE_ID,
-        node: TyKind::Path(None, path),
-        span: sp,
-    }))
-}
-
-/// Converts an ident in-place to CamelCase and returns the previous ident.
-fn convert(ident: &mut Ident) -> String {
-    let ident_str = ident.to_string();
-    let mut camel_ty = String::new();
-
-    {
-        // Find the first non-underscore and add it capitalized.
-        let mut chars = ident_str.chars();
-
-        // Find the first non-underscore char, uppercase it, and append it.
-        // Guaranteed to succeed because all idents must have at least one non-underscore char.
-        camel_ty.extend(chars.find(|&c| c != '_').unwrap().to_uppercase());
-
-        // When we find an underscore, we remove it and capitalize the next char. To do this,
-        // we need to ensure the next char is not another underscore.
-        let mut chars = chars.coalesce(|c1, c2| {
-            if c1 == '_' && c2 == '_' {
-                Ok(c1)
-            } else {
-                Err((c1, c2))
-            }
-        });
-
-        while let Some(c) = chars.next() {
-            if c != '_' {
-                camel_ty.push(c);
-            } else if let Some(c) = chars.next() {
-                camel_ty.extend(c.to_uppercase());
-            }
-        }
-    }
-
-    // The Fut suffix is hardcoded right now; this macro isn't really meant to be general-purpose.
-    camel_ty.push_str("Fut");
-
-    *ident = Ident::with_empty_ctxt(Symbol::intern(&camel_ty));
-    ident_str
-}
-
-trait ParseTraitRef {
-    fn parse_trait_ref(&mut self) -> PResult<TraitRef>;
-}
-
-impl<'a> ParseTraitRef for Parser<'a> {
-    /// Parse a::B<String,i32>
-    fn parse_trait_ref(&mut self) -> PResult<TraitRef> {
-        Ok(TraitRef {
-            path: self.parse_path(PathStyle::Type)?,
-            ref_id: ast::DUMMY_NODE_ID,
-        })
-    }
-}
-
-#[plugin_registrar]
-#[doc(hidden)]
-pub fn plugin_registrar(reg: &mut Registry) {
-    reg.register_macro("snake_to_camel", snake_to_camel);
-    reg.register_macro("impl_snake_to_camel", impl_snake_to_camel);
-    reg.register_macro("ty_snake_to_camel", ty_snake_to_camel);
-}

src/protocol.rs

@@ -1,248 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-use bincode;
-use byteorder::{BigEndian, ByteOrder};
-use bytes::BytesMut;
-use bytes::buf::BufMut;
-use serde;
-use std::io;
-use std::marker::PhantomData;
-use std::mem;
-use tokio_io::{AsyncRead, AsyncWrite};
-use tokio_codec::{Encoder, Decoder, Framed};
-use tokio_proto::multiplex::{ClientProto, ServerProto};
-use tokio_proto::streaming::multiplex::RequestId;
-
-// `Encode` is the type that `Codec` encodes. `Decode` is the type it decodes.
-#[derive(Debug)]
-pub struct Codec<Encode, Decode> {
-    max_payload_size: u64,
-    state: CodecState,
-    _phantom_data: PhantomData<(Encode, Decode)>,
-}
-
-#[derive(Debug)]
-enum CodecState {
-    Id,
-    Len { id: u64 },
-    Payload { id: u64, len: u64 },
-}
-
-impl<Encode, Decode> Codec<Encode, Decode> {
-    fn new(max_payload_size: u64) -> Self {
-        Codec {
-            max_payload_size,
-            state: CodecState::Id,
-            _phantom_data: PhantomData,
-        }
-    }
-}
-
-fn too_big(payload_size: u64, max_payload_size: u64) -> io::Error {
-    warn!(
-        "Not sending too-big packet of size {} (max is {})",
-        payload_size,
-        max_payload_size
-    );
-    io::Error::new(
-        io::ErrorKind::InvalidData,
-        format!(
-            "Maximum payload size is {} bytes but got a payload of {}",
-            max_payload_size,
-            payload_size
-        ),
-    )
-}
-
-impl<Encode, Decode> Encoder for Codec<Encode, Decode>
-where
-    Encode: serde::Serialize,
-    Decode: serde::de::DeserializeOwned,
-{
-    type Item = (RequestId, Encode);
-    type Error = io::Error;
-
-    fn encode(&mut self, (id, message): Self::Item, buf: &mut BytesMut) -> io::Result<()> {
-        let payload_size = bincode::serialized_size(&message).map_err(|serialize_err| {
-            io::Error::new(io::ErrorKind::Other, serialize_err)
-        })?;
-        if payload_size > self.max_payload_size {
-            return Err(too_big(payload_size, self.max_payload_size));
-        }
-        let message_size = 2 * mem::size_of::<u64>() + payload_size as usize;
-        buf.reserve(message_size);
-        buf.put_u64_be(id);
-        trace!("Encoded request id = {} as {:?}", id, buf);
-        buf.put_u64_be(payload_size);
-        bincode::serialize_into(&mut buf.writer(), &message)
-            .map_err(|serialize_err| {
-                io::Error::new(io::ErrorKind::Other, serialize_err)
-            })?;
-        trace!("Encoded buffer: {:?}", buf);
-        Ok(())
-    }
-}
-
-impl<Encode, Decode> Decoder for Codec<Encode, Decode>
-where
-    Decode: serde::de::DeserializeOwned,
-{
-    type Item = (RequestId, Result<Decode, bincode::Error>);
-    type Error = io::Error;
-
-    fn decode(&mut self, buf: &mut BytesMut) -> io::Result<Option<Self::Item>> {
-        use self::CodecState::*;
-        trace!("Codec::decode: {:?}", buf);
-
-        loop {
-            match self.state {
-                Id if buf.len() < mem::size_of::<u64>() => {
-                    trace!("--> Buf len is {}; waiting for 8 to parse id.", buf.len());
-                    return Ok(None);
-                }
-                Id => {
-                    let mut id_buf = buf.split_to(mem::size_of::<u64>());
-                    let id = BigEndian::read_u64(&*id_buf);
-                    trace!("--> Parsed id = {} from {:?}", id, id_buf);
-                    self.state = Len { id };
-                }
-                Len { .. } if buf.len() < mem::size_of::<u64>() => {
-                    trace!(
-                        "--> Buf len is {}; waiting for 8 to parse packet length.",
-                        buf.len()
-                    );
-                    return Ok(None);
-                }
-                Len { id } => {
-                    let len_buf = buf.split_to(mem::size_of::<u64>());
-                    let len = BigEndian::read_u64(&*len_buf);
-                    trace!(
-                        "--> Parsed payload length = {}, remaining buffer length = {}",
-                        len,
-                        buf.len()
-                    );
-                    if len > self.max_payload_size {
-                        return Err(too_big(len, self.max_payload_size));
-                    }
-                    self.state = Payload { id, len };
-                }
-                Payload { len, .. } if buf.len() < len as usize => {
-                    trace!(
-                        "--> Buf len is {}; waiting for {} to parse payload.",
-                        buf.len(),
-                        len
-                    );
-                    return Ok(None);
-                }
-                Payload { id, len } => {
-                    let payload = buf.split_to(len as usize);
-                    let result = bincode::deserialize(&payload);
-                    // Reset the state machine because, either way, we're done processing this
-                    // message.
-                    self.state = Id;
-
-                    return Ok(Some((id, result)));
-                }
-            }
-        }
-    }
-}
-
-/// Implements the `multiplex::ServerProto` trait.
-#[derive(Debug)]
-pub struct Proto<Encode, Decode> {
-    max_payload_size: u64,
-    _phantom_data: PhantomData<(Encode, Decode)>,
-}
-
-impl<Encode, Decode> Proto<Encode, Decode> {
-    /// Returns a new `Proto`.
-    pub fn new(max_payload_size: u64) -> Self {
-        Proto {
-            max_payload_size: max_payload_size,
-            _phantom_data: PhantomData,
-        }
-    }
-}
-
-impl<T, Encode, Decode> ServerProto<T> for Proto<Encode, Decode>
-where
-    T: AsyncRead + AsyncWrite + 'static,
-    Encode: serde::Serialize + 'static,
-    Decode: serde::de::DeserializeOwned + 'static,
-{
-    type Response = Encode;
-    type Request = Result<Decode, bincode::Error>;
-    type Transport = Framed<T, Codec<Encode, Decode>>;
-    type BindTransport = Result<Self::Transport, io::Error>;
-
-    fn bind_transport(&self, io: T) -> Self::BindTransport {
-        Ok(Framed::new(io, Codec::new(self.max_payload_size)))
-    }
-}
-
-impl<T, Encode, Decode> ClientProto<T> for Proto<Encode, Decode>
-where
-    T: AsyncRead + AsyncWrite + 'static,
-    Encode: serde::Serialize + 'static,
-    Decode: serde::de::DeserializeOwned + 'static,
-{
-    type Response = Result<Decode, bincode::Error>;
-    type Request = Encode;
-    type Transport = Framed<T, Codec<Encode, Decode>>;
-    type BindTransport = Result<Self::Transport, io::Error>;
-
-    fn bind_transport(&self, io: T) -> Self::BindTransport {
-        Ok(Framed::new(io, Codec::new(self.max_payload_size)))
-    }
-}
-
-#[test]
-fn serialize() {
-    const MSG: (u64, (char, char, char)) = (4, ('a', 'b', 'c'));
-    let mut buf = BytesMut::with_capacity(10);
-
-    // Serialize twice to check for idempotence.
-    for _ in 0..2 {
-        let mut codec: Codec<(char, char, char), (char, char, char)> = Codec::new(2_000_000);
-        codec.encode(MSG, &mut buf).unwrap();
-        let actual: Result<
-            Option<(u64, Result<(char, char, char), bincode::Error>)>,
-            io::Error,
-        > = codec.decode(&mut buf);
-
-        match actual {
-            Ok(Some((id, ref v))) if id == MSG.0 && *v.as_ref().unwrap() == MSG.1 => {}
-            bad => panic!("Expected {:?}, but got {:?}", Some(MSG), bad),
-        }
-
-        assert!(buf.is_empty(), "Expected empty buf but got {:?}", buf);
-    }
-}
-
-#[test]
-fn deserialize_big() {
-    let mut codec: Codec<Vec<u8>, Vec<u8>> = Codec::new(24);
-
-    let mut buf = BytesMut::with_capacity(40);
-    assert_eq!(
-        codec
-            .encode((0, vec![0; 24]), &mut buf)
-            .err()
-            .unwrap()
-            .kind(),
-        io::ErrorKind::InvalidData
-    );
-
-    // Header
-    buf.put_slice(&mut [0u8; 8]);
-    // Len
-    buf.put_slice(&mut [0u8, 0, 0, 0, 0, 0, 0, 25]);
-    assert_eq!(
-        codec.decode(&mut buf).err().unwrap().kind(),
-        io::ErrorKind::InvalidData
-    );
-}

src/stream_type.rs

@@ -1,94 +0,0 @@
-use bytes::{Buf, BufMut};
-use futures::Poll;
-use std::io;
-use tokio_core::net::TcpStream;
-use tokio_io::{AsyncRead, AsyncWrite};
-#[cfg(feature = "tls")]
-use tokio_tls::TlsStream;
-
-#[derive(Debug)]
-pub enum StreamType {
-    Tcp(TcpStream),
-    #[cfg(feature = "tls")]
-    Tls(TlsStream<TcpStream>),
-}
-
-impl From<TcpStream> for StreamType {
-    fn from(stream: TcpStream) -> Self {
-        StreamType::Tcp(stream)
-    }
-}
-
-#[cfg(feature = "tls")]
-impl From<TlsStream<TcpStream>> for StreamType {
-    fn from(stream: TlsStream<TcpStream>) -> Self {
-        StreamType::Tls(stream)
-    }
-}
-
-impl io::Read for StreamType {
-    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        match *self {
-            StreamType::Tcp(ref mut stream) => stream.read(buf),
-            #[cfg(feature = "tls")]
-            StreamType::Tls(ref mut stream) => stream.read(buf),
-        }
-    }
-}
-
-impl io::Write for StreamType {
-    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        match *self {
-            StreamType::Tcp(ref mut stream) => stream.write(buf),
-            #[cfg(feature = "tls")]
-            StreamType::Tls(ref mut stream) => stream.write(buf),
-        }
-    }
-
-    fn flush(&mut self) -> io::Result<()> {
-        match *self {
-            StreamType::Tcp(ref mut stream) => stream.flush(),
-            #[cfg(feature = "tls")]
-            StreamType::Tls(ref mut stream) => stream.flush(),
-        }
-    }
-}
-
-impl AsyncRead for StreamType {
-    // By overriding this fn, `StreamType` is obliged to never read the uninitialized buffer.
-    // Most sane implementations would never have a reason to, and `StreamType` does not, so
-    // this is safe.
-    unsafe fn prepare_uninitialized_buffer(&self, buf: &mut [u8]) -> bool {
-        match *self {
-            StreamType::Tcp(ref stream) => stream.prepare_uninitialized_buffer(buf),
-            #[cfg(feature = "tls")]
-            StreamType::Tls(ref stream) => stream.prepare_uninitialized_buffer(buf),
-        }
-    }
-
-    fn read_buf<B: BufMut>(&mut self, buf: &mut B) -> Poll<usize, io::Error> {
-        match *self {
-            StreamType::Tcp(ref mut stream) => stream.read_buf(buf),
-            #[cfg(feature = "tls")]
-            StreamType::Tls(ref mut stream) => stream.read_buf(buf),
-        }
-    }
-}
-
-impl AsyncWrite for StreamType {
-    fn shutdown(&mut self) -> Poll<(), io::Error> {
-        match *self {
-            StreamType::Tcp(ref mut stream) => stream.shutdown(),
-            #[cfg(feature = "tls")]
-            StreamType::Tls(ref mut stream) => stream.shutdown(),
-        }
-    }
-
-    fn write_buf<B: Buf>(&mut self, buf: &mut B) -> Poll<usize, io::Error> {
-        match *self {
-            StreamType::Tcp(ref mut stream) => stream.write_buf(buf),
-            #[cfg(feature = "tls")]
-            StreamType::Tls(ref mut stream) => stream.write_buf(buf),
-        }
-    }
-}

src/sync/client.rs

@@ -1,253 +0,0 @@
-use future::client::{Client as FutureClient, ClientExt as FutureClientExt,
-                     Options as FutureOptions};
-use futures::{Future, Stream};
-use serde::Serialize;
-use serde::de::DeserializeOwned;
-use std::fmt;
-use std::io;
-use std::net::{SocketAddr, ToSocketAddrs};
-use std::sync::mpsc;
-use std::thread;
-#[cfg(feature = "tls")]
-use tls::client::Context;
-use tokio_core::reactor;
-use tokio_proto::util::client_proxy::{ClientProxy, Receiver, pair};
-use tokio_service::Service;
-use util::FirstSocketAddr;
-
-#[doc(hidden)]
-pub struct Client<Req, Resp, E> {
-    proxy: ClientProxy<Req, Resp, ::Error<E>>,
-}
-
-impl<Req, Resp, E> Clone for Client<Req, Resp, E> {
-    fn clone(&self) -> Self {
-        Client {
-            proxy: self.proxy.clone(),
-        }
-    }
-}
-
-impl<Req, Resp, E> fmt::Debug for Client<Req, Resp, E> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        const PROXY: &str = "ClientProxy { .. }";
-        f.debug_struct("Client").field("proxy", &PROXY).finish()
-    }
-}
-
-impl<Req, Resp, E> Client<Req, Resp, E>
-where
-    Req: Serialize + Send + 'static,
-    Resp: DeserializeOwned + Send + 'static,
-    E: DeserializeOwned + Send + 'static,
-{
-    /// Drives an RPC call for the given request.
-    pub fn call(&self, request: Req) -> Result<Resp, ::Error<E>> {
-        // Must call wait here to block on the response.
-        // The request handler relies on this fact to safely unwrap the
-        // oneshot send.
-        self.proxy.call(request).wait()
-    }
-}
-
-/// Additional options to configure how the client connects and operates.
-pub struct Options {
-    /// Max packet size in bytes.
-    max_payload_size: u64,
-    #[cfg(feature = "tls")]
-    tls_ctx: Option<Context>,
-}
-
-impl Default for Options {
-    #[cfg(not(feature = "tls"))]
-    fn default() -> Self {
-        Options {
-            max_payload_size: 2_000_000,
-        }
-    }
-
-    #[cfg(feature = "tls")]
-    fn default() -> Self {
-        Options {
-            max_payload_size: 2_000_000,
-            tls_ctx: None,
-        }
-    }
-}
-
-impl Options {
-    /// Set the max payload size in bytes. The default is 2,000,000 (2 MB).
-    pub fn max_payload_size(mut self, bytes: u64) -> Self {
-        self.max_payload_size = bytes;
-        self
-    }
-
-    /// Connect using the given `Context`
-    #[cfg(feature = "tls")]
-    pub fn tls(mut self, ctx: Context) -> Self {
-        self.tls_ctx = Some(ctx);
-        self
-    }
-}
-
-impl fmt::Debug for Options {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        #[cfg(feature = "tls")]
-        const SOME: &str = "Some(_)";
-        #[cfg(feature = "tls")]
-        const NONE: &str = "None";
-        let mut f = f.debug_struct("Options");
-        #[cfg(feature = "tls")] f.field("tls_ctx", if self.tls_ctx.is_some() { &SOME } else { &NONE });
-        f.finish()
-    }
-}
-
-impl Into<FutureOptions> for (reactor::Handle, Options) {
-    #[cfg(feature = "tls")]
-    fn into(self) -> FutureOptions {
-        let (handle, options) = self;
-        let mut opts = FutureOptions::default().handle(handle);
-        if let Some(tls_ctx) = options.tls_ctx {
-            opts = opts.tls(tls_ctx);
-        }
-        opts
-    }
-
-    #[cfg(not(feature = "tls"))]
-    fn into(self) -> FutureOptions {
-        let (handle, _) = self;
-        FutureOptions::default().handle(handle)
-    }
-}
-
-/// Extension methods for Clients.
-pub trait ClientExt: Sized {
-    /// Connects to a server located at the given address.
-    fn connect<A>(addr: A, options: Options) -> io::Result<Self>
-    where
-        A: ToSocketAddrs;
-}
-
-impl<Req, Resp, E> ClientExt for Client<Req, Resp, E>
-where
-    Req: Serialize + Send + 'static,
-    Resp: DeserializeOwned + Send + 'static,
-    E: DeserializeOwned + Send + 'static,
-{
-    fn connect<A>(addr: A, options: Options) -> io::Result<Self>
-    where
-        A: ToSocketAddrs,
-    {
-        let addr = addr.try_first_socket_addr()?;
-        let (connect_tx, connect_rx) = mpsc::channel();
-        thread::spawn(move || match RequestHandler::connect(addr, options) {
-            Ok((proxy, mut handler)) => {
-                connect_tx.send(Ok(proxy)).unwrap();
-                handler.handle_requests();
-            }
-            Err(e) => connect_tx.send(Err(e)).unwrap(),
-        });
-        Ok(connect_rx.recv().unwrap()?)
-    }
-}
-
-/// Forwards incoming requests of type `Req`
-/// with expected response `Result<Resp, ::Error<E>>`
-/// to service `S`.
-struct RequestHandler<Req, Resp, E, S> {
-    reactor: reactor::Core,
-    client: S,
-    requests: Receiver<Req, Resp, ::Error<E>>,
-}
-
-impl<Req, Resp, E> RequestHandler<Req, Resp, E, FutureClient<Req, Resp, E>>
-where
-    Req: Serialize + Send + 'static,
-    Resp: DeserializeOwned + Send + 'static,
-    E: DeserializeOwned + Send + 'static,
-{
-    /// Creates a new `RequestHandler` by connecting a `FutureClient` to the given address
-    /// using the given options.
-    fn connect(addr: SocketAddr, options: Options) -> io::Result<(Client<Req, Resp, E>, Self)> {
-        let mut reactor = reactor::Core::new()?;
-        let options = (reactor.handle(), options).into();
-        let client = reactor.run(FutureClient::connect(addr, options))?;
-        let (proxy, requests) = pair();
-        Ok((
-            Client { proxy },
-            RequestHandler {
-                reactor,
-                client,
-                requests,
-            },
-        ))
-    }
-}
-
-impl<Req, Resp, E, S> RequestHandler<Req, Resp, E, S>
-where
-    Req: Serialize + 'static,
-    Resp: DeserializeOwned + 'static,
-    E: DeserializeOwned + 'static,
-    S: Service<Request = Req, Response = Resp, Error = ::Error<E>>,
-    S::Future: 'static,
-{
-    fn handle_requests(&mut self) {
-        let RequestHandler {
-            ref mut reactor,
-            ref mut requests,
-            ref mut client,
-        } = *self;
-        let handle = reactor.handle();
-        let requests = requests
-            .map(|result| {
-                match result {
-                    Ok(req) => req,
-                    // The ClientProxy never sends Err currently
-                    Err(e) => panic!("Unimplemented error handling in RequestHandler: {}", e),
-                }
-            })
-            .for_each(|(request, response_tx)| {
-                let request = client.call(request).then(move |response| {
-                    // Safe to unwrap because clients always block on the response future.
-                    response_tx
-                        .send(response)
-                        .map_err(|_| ())
-                        .expect("Client should block on response");
-                    Ok(())
-                });
-                handle.spawn(request);
-                Ok(())
-            });
-        reactor.run(requests).unwrap();
-    }
-}
-
-#[test]
-fn handle_requests() {
-    use futures::future;
-
-    struct Client;
-    impl Service for Client {
-        type Request = i32;
-        type Response = i32;
-        type Error = ::Error<()>;
-        type Future = future::FutureResult<i32, ::Error<()>>;
-
-        fn call(&self, req: i32) -> Self::Future {
-            future::ok(req)
-        }
-    }
-
-    let (request, requests) = ::futures::sync::mpsc::unbounded();
-    let reactor = reactor::Core::new().unwrap();
-    let client = Client;
-    let mut request_handler = RequestHandler {
-        reactor,
-        client,
-        requests,
-    };
-    // Test that `handle_requests` returns when all request senders are dropped.
-    drop(request);
-    request_handler.handle_requests();
-}

src/sync/mod.rs

@@ -1,4 +0,0 @@
-/// Provides the base client stubs used by the service macro.
-pub mod client;
-/// Provides the base server boilerplate used by service implementations.
-pub mod server;

src/sync/server.rs

@@ -1,249 +0,0 @@
-use {bincode, future, num_cpus};
-use future::server::{Response, Shutdown};
-use futures::{Future, future as futures};
-use futures::sync::oneshot;
-#[cfg(feature = "tls")]
-use native_tls_inner::TlsAcceptor;
-use serde::Serialize;
-use serde::de::DeserializeOwned;
-use std::fmt;
-use std::io;
-use std::net::SocketAddr;
-use std::time::Duration;
-use std::usize;
-use thread_pool::{self, Sender, Task, ThreadPool};
-use tokio_core::reactor;
-use tokio_service::{NewService, Service};
-
-/// Additional options to configure how the server operates.
-#[derive(Debug)]
-pub struct Options {
-    thread_pool: thread_pool::Builder,
-    opts: future::server::Options,
-}
-
-impl Default for Options {
-    fn default() -> Self {
-        let num_cpus = num_cpus::get();
-        Options {
-            thread_pool: thread_pool::Builder::new()
-                .keep_alive(Duration::from_secs(60))
-                .max_pool_size(num_cpus * 100)
-                .core_pool_size(num_cpus)
-                .work_queue_capacity(usize::MAX)
-                .name_prefix("request-thread-"),
-            opts: future::server::Options::default(),
-        }
-    }
-}
-
-impl Options {
-    /// Set the max payload size in bytes. The default is 2,000,000 (2 MB).
-    pub fn max_payload_size(mut self, bytes: u64) -> Self {
-        self.opts = self.opts.max_payload_size(bytes);
-        self
-    }
-
-    /// Sets the thread pool builder to use when creating the server's thread pool.
-    pub fn thread_pool(mut self, builder: thread_pool::Builder) -> Self {
-        self.thread_pool = builder;
-        self
-    }
-
-    /// Set the `TlsAcceptor`
-    #[cfg(feature = "tls")]
-    pub fn tls(mut self, tls_acceptor: TlsAcceptor) -> Self {
-        self.opts = self.opts.tls(tls_acceptor);
-        self
-    }
-}
-
-/// A handle to a bound server. Must be run to start serving requests.
-#[must_use = "A server does nothing until `run` is called."]
-pub struct Handle {
-    reactor: reactor::Core,
-    handle: future::server::Handle,
-    server: Box<Future<Item = (), Error = ()>>,
-}
-
-impl Handle {
-    /// Runs the server on the current thread, blocking indefinitely.
-    pub fn run(mut self) {
-        trace!("Running...");
-        match self.reactor.run(self.server) {
-            Ok(()) => debug!("Server successfully shutdown."),
-            Err(()) => debug!("Server shutdown due to error."),
-        }
-    }
-
-    /// Returns a hook for shutting down the server.
-    pub fn shutdown(&self) -> Shutdown {
-        self.handle.shutdown().clone()
-    }
-
-    /// The socket address the server is bound to.
-    pub fn addr(&self) -> SocketAddr {
-        self.handle.addr()
-    }
-}
-
-impl fmt::Debug for Handle {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        const SERVER: &str = "Box<Future<Item = (), Error = ()>>";
-
-        f.debug_struct("Handle")
-            .field("reactor", &self.reactor)
-            .field("handle", &self.handle)
-            .field("server", &SERVER)
-            .finish()
-    }
-}
-
-#[doc(hidden)]
-pub fn listen<S, Req, Resp, E>(new_service: S,
-                               addr: SocketAddr,
-                               options: Options)
-                               -> io::Result<Handle>
-    where S: NewService<Request = Result<Req, bincode::Error>,
-                        Response = Response<Resp, E>,
-                        Error = io::Error> + 'static,
-          <S::Instance as Service>::Future: Send + 'static,
-          S::Response: Send,
-          S::Error: Send,
-          Req: DeserializeOwned + 'static,
-          Resp: Serialize + 'static,
-          E: Serialize + 'static
-{
-    let new_service = NewThreadService::new(new_service, options.thread_pool);
-    let reactor = reactor::Core::new()?;
-    let (handle, server) =
-        future::server::listen(new_service, addr, &reactor.handle(), options.opts)?;
-    let server = Box::new(server);
-    Ok(Handle {
-        reactor: reactor,
-        handle: handle,
-        server: server,
-    })
-}
-
-/// A service that uses a thread pool.
-struct NewThreadService<S>
-where
-    S: NewService,
-{
-    new_service: S,
-    sender: Sender<ServiceTask<<S::Instance as Service>::Future>>,
-    _pool: ThreadPool<ServiceTask<<S::Instance as Service>::Future>>,
-}
-
-/// A service that runs by executing request handlers in a thread pool.
-struct ThreadService<S>
-where
-    S: Service,
-{
-    service: S,
-    sender: Sender<ServiceTask<S::Future>>,
-}
-
-/// A task that handles a single request.
-struct ServiceTask<F>
-where
-    F: Future,
-{
-    future: F,
-    tx: oneshot::Sender<Result<F::Item, F::Error>>,
-}
-
-impl<S> NewThreadService<S>
-where
-    S: NewService,
-    <S::Instance as Service>::Future: Send + 'static,
-    S::Response: Send,
-    S::Error: Send,
-{
-    /// Create a NewThreadService by wrapping another service.
-    fn new(new_service: S, pool: thread_pool::Builder) -> Self {
-        let (sender, _pool) = pool.build();
-        NewThreadService {
-            new_service,
-            sender,
-            _pool,
-        }
-    }
-}
-
-impl<S> NewService for NewThreadService<S>
-where
-    S: NewService,
-    <S::Instance as Service>::Future: Send + 'static,
-    S::Response: Send,
-    S::Error: Send,
-{
-    type Request = S::Request;
-    type Response = S::Response;
-    type Error = S::Error;
-    type Instance = ThreadService<S::Instance>;
-
-    fn new_service(&self) -> io::Result<Self::Instance> {
-        Ok(ThreadService {
-            service: self.new_service.new_service()?,
-            sender: self.sender.clone(),
-        })
-    }
-}
-
-impl<F> Task for ServiceTask<F>
-where
-    F: Future + Send + 'static,
-    F::Item: Send,
-    F::Error: Send,
-{
-    fn run(self) {
-        // Don't care if sending fails. It just means the request is no longer
-        // being handled (I think).
-        let _ = self.tx.send(self.future.wait());
-    }
-}
-
-impl<S> Service for ThreadService<S>
-where
-    S: Service,
-    S::Future: Send + 'static,
-    S::Response: Send,
-    S::Error: Send,
-{
-    type Request = S::Request;
-    type Response = S::Response;
-    type Error = S::Error;
-    type Future = futures::AndThen<
-        futures::MapErr<
-            oneshot::Receiver<Result<Self::Response, Self::Error>>,
-            fn(oneshot::Canceled) -> Self::Error,
-        >,
-        Result<Self::Response, Self::Error>,
-        fn(Result<Self::Response, Self::Error>)
-            -> Result<Self::Response, Self::Error>,
-    >;
-
-    fn call(&self, request: Self::Request) -> Self::Future {
-        let (tx, rx) = oneshot::channel();
-        self.sender
-            .send(ServiceTask {
-                future: self.service.call(request),
-                tx: tx,
-            })
-            .unwrap();
-        rx.map_err(unreachable as _).and_then(ident)
-    }
-}
-
-fn unreachable<T, U>(t: T) -> U
-where
-    T: fmt::Display,
-{
-    unreachable!(t)
-}
-
-fn ident<T>(t: T) -> T {
-    t
-}

src/tls.rs

@@ -1,50 +0,0 @@
-/// TLS-specific functionality for clients.
-pub mod client {
-    use native_tls::{Error, TlsConnector};
-    use std::fmt;
-
-    /// TLS context for client
-    pub struct Context {
-        /// Domain to connect to
-        pub domain: String,
-        /// TLS connector
-        pub tls_connector: TlsConnector,
-    }
-
-    impl Context {
-        /// Try to construct a new `Context`.
-        ///
-        /// The provided domain will be used for both
-        /// [SNI](https://en.wikipedia.org/wiki/Server_Name_Indication) and certificate hostname
-        /// validation.
-        pub fn new<S: Into<String>>(domain: S) -> Result<Self, Error> {
-            Ok(Context {
-                domain: domain.into(),
-                tls_connector: TlsConnector::builder()?.build()?,
-            })
-        }
-
-        /// Construct a new `Context` using the provided domain and `TlsConnector`
-        ///
-        /// The domain will be used for both
-        /// [SNI](https://en.wikipedia.org/wiki/Server_Name_Indication) and certificate hostname
-        /// validation.
-        pub fn from_connector<S: Into<String>>(domain: S, tls_connector: TlsConnector) -> Self {
-            Context {
-                domain: domain.into(),
-                tls_connector: tls_connector,
-            }
-        }
-    }
-
-    impl fmt::Debug for Context {
-        fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-            const TLS_CONNECTOR: &str = "TlsConnector { .. }";
-            f.debug_struct("Context")
-                .field("domain", &self.domain)
-                .field("tls_connector", &TLS_CONNECTOR)
-                .finish()
-        }
-    }
-
-}

src/util.rs

@@ -1,185 +0,0 @@
-// Copyright 2016 Google Inc. All Rights Reserved.
-//
-// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
-// This file may not be copied, modified, or distributed except according to those terms.
-
-use futures::{Future, IntoFuture, Poll};
-use futures::stream::Stream;
-use serde::{Deserialize, Deserializer, Serialize, Serializer};
-use std::{fmt, io, mem};
-use std::error::Error;
-use std::net::{SocketAddr, ToSocketAddrs};
-
-/// A bottom type that impls `Error`, `Serialize`, and `Deserialize`. It is impossible to
-/// instantiate this type.
-#[allow(unreachable_code)]
-pub struct Never(!);
-
-impl fmt::Debug for Never {
-    fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
-        self.0
-    }
-}
-
-impl Error for Never {
-    fn description(&self) -> &str {
-        self.0
-    }
-}
-
-impl fmt::Display for Never {
-    fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
-        self.0
-    }
-}
-
-impl Future for Never {
-    type Item = Never;
-    type Error = Never;
-
-    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
-        self.0
-    }
-}
-
-impl Stream for Never {
-    type Item = Never;
-    type Error = Never;
-
-    fn poll(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
-        self.0
-    }
-}
-
-impl Serialize for Never {
-    fn serialize<S>(&self, _: S) -> Result<S::Ok, S::Error>
-    where
-        S: Serializer,
-    {
-        self.0
-    }
-}
-
-// Please don't try to deserialize this. :(
-impl<'a> Deserialize<'a> for Never {
-    fn deserialize<D>(_: D) -> Result<Self, D::Error>
-    where
-        D: Deserializer<'a>,
-    {
-        panic!("Never cannot be instantiated!");
-    }
-}
-
-/// A `String` that impls `std::error::Error`. Useful for quick-and-dirty error propagation.
-#[derive(Debug, Serialize, Deserialize)]
-pub struct Message(pub String);
-
-impl Error for Message {
-    fn description(&self) -> &str {
-        &self.0
-    }
-}
-
-impl fmt::Display for Message {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Display::fmt(&self.0, f)
-    }
-}
-
-impl<S: Into<String>> From<S> for Message {
-    fn from(s: S) -> Self {
-        Message(s.into())
-    }
-}
-
-
-/// Provides a utility method for more ergonomically parsing a `SocketAddr` when only one is
-/// needed.
-pub trait FirstSocketAddr: ToSocketAddrs {
-    /// Returns the first resolved `SocketAddr`, if one exists.
-    fn try_first_socket_addr(&self) -> io::Result<SocketAddr> {
-        if let Some(a) = self.to_socket_addrs()?.next() {
-            Ok(a)
-        } else {
-            Err(io::Error::new(
-                io::ErrorKind::AddrNotAvailable,
-                "`ToSocketAddrs::to_socket_addrs` returned an empty iterator.",
-            ))
-        }
-    }
-
-    /// Returns the first resolved `SocketAddr` or panics otherwise.
-    fn first_socket_addr(&self) -> SocketAddr {
-        self.try_first_socket_addr().unwrap()
-    }
-}
-
-impl<A: ToSocketAddrs> FirstSocketAddr for A {}
-
-/// Creates a new future which will eventually be the same as the one created
-/// by calling the closure provided with the arguments provided.
-///
-/// The provided closure is only run once the future has a callback scheduled
-/// on it, otherwise the callback never runs. Once run, however, this future is
-/// the same as the one the closure creates.
-pub fn lazy<F, A, R>(f: F, args: A) -> Lazy<F, A, R>
-where
-    F: FnOnce(A) -> R,
-    R: IntoFuture,
-{
-    Lazy {
-        inner: _Lazy::First(f, args),
-    }
-}
-
-/// A future which defers creation of the actual future until a callback is
-/// scheduled.
-///
-/// This is created by the `lazy` function.
-#[derive(Debug)]
-#[must_use = "futures do nothing unless polled"]
-pub struct Lazy<F, A, R: IntoFuture> {
-    inner: _Lazy<F, A, R::Future>,
-}
-
-#[derive(Debug)]
-enum _Lazy<F, A, R> {
-    First(F, A),
-    Second(R),
-    Moved,
-}
-
-impl<F, A, R> Lazy<F, A, R>
-where
-    F: FnOnce(A) -> R,
-    R: IntoFuture,
-{
-    fn get(&mut self) -> &mut R::Future {
-        match self.inner {
-            _Lazy::First(..) => {}
-            _Lazy::Second(ref mut f) => return f,
-            _Lazy::Moved => panic!(), // can only happen if `f()` panics
-        }
-        match mem::replace(&mut self.inner, _Lazy::Moved) {
-            _Lazy::First(f, args) => self.inner = _Lazy::Second(f(args).into_future()),
-            _ => panic!(), // we already found First
-        }
-        match self.inner {
-            _Lazy::Second(ref mut f) => f,
-            _ => panic!(), // we just stored Second
-        }
-    }
-}
-
-impl<F, A, R> Future for Lazy<F, A, R>
-where
-    F: FnOnce(A) -> R,
-    R: IntoFuture,
-{
-    type Item = R::Item;
-    type Error = R::Error;
-
-    fn poll(&mut self) -> Poll<R::Item, R::Error> {
-        self.get().poll()
-    }
-}

tarpc/Cargo.toml

@@ -0,0 +1,86 @@
+[package]
+name = "tarpc"
+version = "0.24.1"
+authors = ["Adam Wright <adam.austin.wright@gmail.com>", "Tim Kuehn <timothy.j.kuehn@gmail.com>"]
+edition = "2018"
+license = "MIT"
+documentation = "https://docs.rs/tarpc"
+homepage = "https://github.com/google/tarpc"
+repository = "https://github.com/google/tarpc"
+keywords = ["rpc", "network", "server", "api", "microservices"]
+categories = ["asynchronous", "network-programming"]
+readme = "../README.md"
+description = "An RPC framework for Rust with a focus on ease of use."
+
+[features]
+default = []
+
+serde1 = ["tarpc-plugins/serde1", "serde", "serde/derive"]
+tokio1 = ["tokio/rt-multi-thread"]
+serde-transport = ["serde1", "tokio1", "tokio-serde/json", "tokio-util/codec"]
+tcp = ["tokio/net"]
+
+full = ["serde1", "tokio1", "serde-transport", "tcp"]
+
+[badges]
+travis-ci = { repository = "google/tarpc" }
+
+[dependencies]
+anyhow = "1.0"
+fnv = "1.0"
+futures = "0.3"
+humantime = "2.0"
+log = "0.4"
+pin-project = "1.0"
+rand = "0.7"
+serde = { optional = true, version = "1.0", features = ["derive"] }
+static_assertions = "1.1.0"
+tarpc-plugins = { path = "../plugins", version = "0.9" }
+tokio = { version = "1", features = ["time"] }
+tokio-util = { optional = true, version = "0.6" }
+tokio-serde = { optional = true, version = "0.8" }
+
+[dev-dependencies]
+assert_matches = "1.4"
+bincode = "1.3"
+bytes = { version = "1", features = ["serde"] }
+env_logger = "0.8"
+flate2 = "1.0"
+log = "0.4"
+pin-utils = "0.1.0-alpha"
+serde_bytes = "0.11"
+tokio = { version = "1", features = ["full"] }
+tokio-serde = { version = "0.8", features = ["json", "bincode"] }
+trybuild = "1.0"
+
+[package.metadata.docs.rs]
+all-features = true
+rustdoc-args = ["--cfg", "docsrs"]
+
+[[example]]
+name = "compression"
+required-features = ["serde-transport", "tcp"]
+
+[[example]]
+name = "server_calling_server"
+required-features = ["full"]
+
+[[example]]
+name = "readme"
+required-features = ["full"]
+
+[[example]]
+name = "pubsub"
+required-features = ["full"]
+
+[[example]]
+name = "custom_transport"
+required-features = ["serde1", "tokio1", "serde-transport"]
+
+[[test]]
+name = "service_functional"
+required-features = ["serde-transport"]
+
+[[test]]
+name = "dataservice"
+required-features = ["serde-transport", "tcp"]

tarpc/README.md

@@ -0,0 +1 @@
+../README.md

tarpc/examples/compression.rs

@@ -0,0 +1,130 @@
+use flate2::{read::DeflateDecoder, write::DeflateEncoder, Compression};
+use futures::{Sink, SinkExt, Stream, StreamExt, TryStreamExt};
+use serde::{Deserialize, Serialize};
+use serde_bytes::ByteBuf;
+use std::{io, io::Read, io::Write};
+use tarpc::{
+    client, context,
+    serde_transport::tcp,
+    server::{BaseChannel, Channel},
+};
+use tokio_serde::formats::Bincode;
+
+/// Type of compression that should be enabled on the request. The transport is free to ignore this.
+#[derive(Debug, PartialEq, Eq, Clone, Copy, Deserialize, Serialize)]
+pub enum CompressionAlgorithm {
+    Deflate,
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+pub enum CompressedMessage<T> {
+    Uncompressed(T),
+    Compressed {
+        algorithm: CompressionAlgorithm,
+        payload: ByteBuf,
+    },
+}
+
+#[derive(Deserialize, Serialize)]
+enum CompressionType {
+    Uncompressed,
+    Compressed,
+}
+
+async fn compress<T>(message: T) -> io::Result<CompressedMessage<T>>
+where
+    T: Serialize,
+{
+    let message = serialize(message)?;
+    let mut encoder = DeflateEncoder::new(Vec::new(), Compression::default());
+    encoder.write_all(&message).unwrap();
+    let compressed = encoder.finish()?;
+    Ok(CompressedMessage::Compressed {
+        algorithm: CompressionAlgorithm::Deflate,
+        payload: ByteBuf::from(compressed),
+    })
+}
+
+async fn decompress<T>(message: CompressedMessage<T>) -> io::Result<T>
+where
+    for<'a> T: Deserialize<'a>,
+{
+    match message {
+        CompressedMessage::Compressed { algorithm, payload } => {
+            if algorithm != CompressionAlgorithm::Deflate {
+                return Err(io::Error::new(
+                    io::ErrorKind::InvalidData,
+                    format!("Compression algorithm {:?} not supported", algorithm),
+                ));
+            }
+            let mut deflater = DeflateDecoder::new(payload.as_slice());
+            let mut payload = ByteBuf::new();
+            deflater.read_to_end(&mut payload)?;
+            let message = deserialize(payload)?;
+            Ok(message)
+        }
+        CompressedMessage::Uncompressed(message) => Ok(message),
+    }
+}
+
+fn serialize<T: Serialize>(t: T) -> io::Result<ByteBuf> {
+    bincode::serialize(&t)
+        .map(ByteBuf::from)
+        .map_err(|e| io::Error::new(io::ErrorKind::Other, e))
+}
+
+fn deserialize<D>(message: ByteBuf) -> io::Result<D>
+where
+    for<'a> D: Deserialize<'a>,
+{
+    bincode::deserialize(message.as_ref()).map_err(|e| io::Error::new(io::ErrorKind::Other, e))
+}
+
+fn add_compression<In, Out>(
+    transport: impl Stream<Item = io::Result<CompressedMessage<In>>>
+        + Sink<CompressedMessage<Out>, Error = io::Error>,
+) -> impl Stream<Item = io::Result<In>> + Sink<Out, Error = io::Error>
+where
+    Out: Serialize,
+    for<'a> In: Deserialize<'a>,
+{
+    transport.with(compress).and_then(decompress)
+}
+
+#[tarpc::service]
+pub trait World {
+    async fn hello(name: String) -> String;
+}
+
+#[derive(Clone, Debug)]
+struct HelloServer;
+
+#[tarpc::server]
+impl World for HelloServer {
+    async fn hello(self, _: context::Context, name: String) -> String {
+        format!("Hey, {}!", name)
+    }
+}
+
+#[tokio::main]
+async fn main() -> anyhow::Result<()> {
+    let mut incoming = tcp::listen("localhost:0", Bincode::default).await?;
+    let addr = incoming.local_addr();
+    tokio::spawn(async move {
+        let transport = incoming.next().await.unwrap().unwrap();
+        BaseChannel::with_defaults(add_compression(transport))
+            .respond_with(HelloServer.serve())
+            .execute()
+            .await;
+    });
+
+    let transport = tcp::connect(addr, Bincode::default).await?;
+    let mut client =
+        WorldClient::new(client::Config::default(), add_compression(transport)).spawn()?;
+
+    println!(
+        "{}",
+        client.hello(context::current(), "friend".into()).await?
+    );
+    Ok(())
+}

tarpc/examples/custom_transport.rs

@@ -0,0 +1,52 @@
+use futures::future;
+use tarpc::context::Context;
+use tarpc::serde_transport as transport;
+use tarpc::server::{BaseChannel, Channel};
+use tokio::net::{UnixListener, UnixStream};
+use tokio_serde::formats::Bincode;
+use tokio_util::codec::length_delimited::LengthDelimitedCodec;
+
+#[tarpc::service]
+pub trait PingService {
+    async fn ping();
+}
+
+#[derive(Clone)]
+struct Service;
+
+impl PingService for Service {
+    type PingFut = future::Ready<()>;
+
+    fn ping(self, _: Context) -> Self::PingFut {
+        future::ready(())
+    }
+}
+
+#[tokio::main]
+async fn main() -> std::io::Result<()> {
+    let bind_addr = "/tmp/tarpc_on_unix_example.sock";
+
+    let _ = std::fs::remove_file(bind_addr);
+
+    let listener = UnixListener::bind(bind_addr).unwrap();
+    let codec_builder = LengthDelimitedCodec::builder();
+    tokio::spawn(async move {
+        loop {
+            let (conn, _addr) = listener.accept().await.unwrap();
+            let framed = codec_builder.new_framed(conn);
+            let transport = transport::new(framed, Bincode::default());
+
+            let fut = BaseChannel::with_defaults(transport)
+                .respond_with(Service.serve())
+                .execute();
+            tokio::spawn(fut);
+        }
+    });
+
+    let conn = UnixStream::connect(bind_addr).await?;
+    let transport = transport::new(codec_builder.new_framed(conn), Bincode::default());
+    PingServiceClient::new(Default::default(), transport)
+        .spawn()?
+        .ping(tarpc::context::current())
+        .await
+}

tarpc/examples/pubsub.rs

@@ -0,0 +1,344 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+/// - The PubSub server sets up TCP listeners on 2 ports, the "subscriber" port and the "publisher"
+///   port. Because both publishers and subscribers initiate their connections to the PubSub
+///   server, the server requires no prior knowledge of either publishers or subscribers.
+///
+/// - Subscribers connect to the server on the server's "subscriber" port. Once a connection is
+///   established, the server acts as the client of the Subscriber service, initially requesting
+///   the topics the subscriber is interested in, and subsequently sending topical messages to the
+///   subscriber.
+///
+/// - Publishers connect to the server on the "publisher" port and, once connected, they send
+///   topical messages via Publisher service to the server. The server then broadcasts each
+///   messages to all clients subscribed to the topic of that message.
+///
+///       Subscriber                        Publisher                       PubSub Server
+/// T1        |                                 |                                 |
+/// T2        |-----Connect------------------------------------------------------>|
+/// T3        |                                 |                                 |
+/// T2        |<-------------------------------------------------------Topics-----|
+/// T2        |-----(OK) Topics-------------------------------------------------->|
+/// T3        |                                 |                                 |
+/// T4        |                                 |-----Connect-------------------->|
+/// T5        |                                 |                                 |
+/// T6        |                                 |-----Publish-------------------->|
+/// T7        |                                 |                                 |
+/// T8        |<------------------------------------------------------Receive-----|
+/// T9        |-----(OK) Receive------------------------------------------------->|
+/// T10       |                                 |                                 |
+/// T11       |                                 |<--------------(OK) Publish------|
+use anyhow::anyhow;
+use futures::{
+    channel::oneshot,
+    future::{self, AbortHandle},
+    prelude::*,
+};
+use log::info;
+use publisher::Publisher as _;
+use std::{
+    collections::HashMap,
+    io,
+    net::SocketAddr,
+    sync::{Arc, Mutex, RwLock},
+};
+use subscriber::Subscriber as _;
+use tarpc::{
+    client, context,
+    serde_transport::tcp,
+    server::{self, Channel},
+};
+use tokio::net::ToSocketAddrs;
+use tokio_serde::formats::Json;
+
+pub mod subscriber {
+    #[tarpc::service]
+    pub trait Subscriber {
+        async fn topics() -> Vec<String>;
+        async fn receive(topic: String, message: String);
+    }
+}
+
+pub mod publisher {
+    #[tarpc::service]
+    pub trait Publisher {
+        async fn publish(topic: String, message: String);
+    }
+}
+
+#[derive(Clone, Debug)]
+struct Subscriber {
+    local_addr: SocketAddr,
+    topics: Vec<String>,
+}
+
+#[tarpc::server]
+impl subscriber::Subscriber for Subscriber {
+    async fn topics(self, _: context::Context) -> Vec<String> {
+        self.topics.clone()
+    }
+
+    async fn receive(self, _: context::Context, topic: String, message: String) {
+        info!(
+            "[{}] received message on topic '{}': {}",
+            self.local_addr, topic, message
+        );
+    }
+}
+
+struct SubscriberHandle(AbortHandle);
+
+impl Drop for SubscriberHandle {
+    fn drop(&mut self) {
+        self.0.abort();
+    }
+}
+
+impl Subscriber {
+    async fn connect(
+        publisher_addr: impl ToSocketAddrs,
+        topics: Vec<String>,
+    ) -> anyhow::Result<SubscriberHandle> {
+        let publisher = tcp::connect(publisher_addr, Json::default).await?;
+        let local_addr = publisher.local_addr()?;
+        let mut handler = server::BaseChannel::with_defaults(publisher)
+            .respond_with(Subscriber { local_addr, topics }.serve());
+        // The first request is for the topics being subscriibed to.
+        match handler.next().await {
+            Some(init_topics) => init_topics?.await,
+            None => {
+                return Err(anyhow!(
+                    "[{}] Server never initialized the subscriber.",
+                    local_addr
+                ))
+            }
+        };
+        let (handler, abort_handle) = future::abortable(handler.execute());
+        tokio::spawn(async move {
+            match handler.await {
+                Ok(()) | Err(future::Aborted) => info!("[{}] subscriber shutdown.", local_addr),
+            }
+        });
+        Ok(SubscriberHandle(abort_handle))
+    }
+}
+
+#[derive(Debug)]
+struct Subscription {
+    subscriber: subscriber::SubscriberClient,
+    topics: Vec<String>,
+}
+
+#[derive(Clone, Debug)]
+struct Publisher {
+    clients: Arc<Mutex<HashMap<SocketAddr, Subscription>>>,
+    subscriptions: Arc<RwLock<HashMap<String, HashMap<SocketAddr, subscriber::SubscriberClient>>>>,
+}
+
+struct PublisherAddrs {
+    publisher: SocketAddr,
+    subscriptions: SocketAddr,
+}
+
+impl Publisher {
+    async fn start(self) -> io::Result<PublisherAddrs> {
+        let mut connecting_publishers = tcp::listen("localhost:0", Json::default).await?;
+
+        let publisher_addrs = PublisherAddrs {
+            publisher: connecting_publishers.local_addr(),
+            subscriptions: self.clone().start_subscription_manager().await?,
+        };
+
+        info!("[{}] listening for publishers.", publisher_addrs.publisher);
+        tokio::spawn(async move {
+            // Because this is just an example, we know there will only be one publisher. In more
+            // realistic code, this would be a loop to continually accept new publisher
+            // connections.
+            let publisher = connecting_publishers.next().await.unwrap().unwrap();
+            info!("[{}] publisher connected.", publisher.peer_addr().unwrap());
+
+            server::BaseChannel::with_defaults(publisher)
+                .respond_with(self.serve())
+                .execute()
+                .await
+        });
+
+        Ok(publisher_addrs)
+    }
+
+    async fn start_subscription_manager(mut self) -> io::Result<SocketAddr> {
+        let mut connecting_subscribers = tcp::listen("localhost:0", Json::default)
+            .await?
+            .filter_map(|r| future::ready(r.ok()));
+        let new_subscriber_addr = connecting_subscribers.get_ref().local_addr();
+        info!("[{}] listening for subscribers.", new_subscriber_addr);
+
+        tokio::spawn(async move {
+            while let Some(conn) = connecting_subscribers.next().await {
+                let subscriber_addr = conn.peer_addr().unwrap();
+
+                let tarpc::client::NewClient {
+                    client: subscriber,
+                    dispatch,
+                } = subscriber::SubscriberClient::new(client::Config::default(), conn);
+                let (ready_tx, ready) = oneshot::channel();
+                self.clone()
+                    .start_subscriber_gc(subscriber_addr, dispatch, ready);
+
+                // Populate the topics
+                self.initialize_subscription(subscriber_addr, subscriber)
+                    .await;
+
+                // Signal that initialization is done.
+                ready_tx.send(()).unwrap();
+            }
+        });
+
+        Ok(new_subscriber_addr)
+    }
+
+    async fn initialize_subscription(
+        &mut self,
+        subscriber_addr: SocketAddr,
+        mut subscriber: subscriber::SubscriberClient,
+    ) {
+        // Populate the topics
+        if let Ok(topics) = subscriber.topics(context::current()).await {
+            self.clients.lock().unwrap().insert(
+                subscriber_addr,
+                Subscription {
+                    subscriber: subscriber.clone(),
+                    topics: topics.clone(),
+                },
+            );
+
+            info!("[{}] subscribed to topics: {:?}", subscriber_addr, topics);
+            let mut subscriptions = self.subscriptions.write().unwrap();
+            for topic in topics {
+                subscriptions
+                    .entry(topic)
+                    .or_insert_with(HashMap::new)
+                    .insert(subscriber_addr, subscriber.clone());
+            }
+        }
+    }
+
+    fn start_subscriber_gc(
+        self,
+        subscriber_addr: SocketAddr,
+        client_dispatch: impl Future<Output = anyhow::Result<()>> + Send + 'static,
+        subscriber_ready: oneshot::Receiver<()>,
+    ) {
+        tokio::spawn(async move {
+            if let Err(e) = client_dispatch.await {
+                info!(
+                    "[{}] subscriber connection broken: {:?}",
+                    subscriber_addr, e
+                )
+            }
+            // Don't clean up the subscriber until initialization is done.
+            let _ = subscriber_ready.await;
+            if let Some(subscription) = self.clients.lock().unwrap().remove(&subscriber_addr) {
+                info!(
+                    "[{} unsubscribing from topics: {:?}",
+                    subscriber_addr, subscription.topics
+                );
+                let mut subscriptions = self.subscriptions.write().unwrap();
+                for topic in subscription.topics {
+                    let subscribers = subscriptions.get_mut(&topic).unwrap();
+                    subscribers.remove(&subscriber_addr);
+                    if subscribers.is_empty() {
+                        subscriptions.remove(&topic);
+                    }
+                }
+            }
+        });
+    }
+}
+
+#[tarpc::server]
+impl publisher::Publisher for Publisher {
+    async fn publish(self, _: context::Context, topic: String, message: String) {
+        info!("received message to publish.");
+        let mut subscribers = match self.subscriptions.read().unwrap().get(&topic) {
+            None => return,
+            Some(subscriptions) => subscriptions.clone(),
+        };
+        let mut publications = Vec::new();
+        for client in subscribers.values_mut() {
+            publications.push(client.receive(context::current(), topic.clone(), message.clone()));
+        }
+        // Ignore failing subscribers. In a real pubsub, you'd want to continually retry until
+        // subscribers ack. Of course, a lot would be different in a real pubsub :)
+        for response in future::join_all(publications).await {
+            if let Err(e) = response {
+                info!("failed to broadcast to subscriber: {}", e);
+            }
+        }
+    }
+}
+
+#[tokio::main]
+async fn main() -> anyhow::Result<()> {
+    env_logger::init();
+
+    let clients = Arc::new(Mutex::new(HashMap::new()));
+    let addrs = Publisher {
+        clients,
+        subscriptions: Arc::new(RwLock::new(HashMap::new())),
+    }
+    .start()
+    .await?;
+
+    let _subscriber0 = Subscriber::connect(
+        addrs.subscriptions,
+        vec!["calculus".into(), "cool shorts".into()],
+    )
+    .await?;
+
+    let _subscriber1 = Subscriber::connect(
+        addrs.subscriptions,
+        vec!["cool shorts".into(), "history".into()],
+    )
+    .await?;
+
+    let mut publisher = publisher::PublisherClient::new(
+        client::Config::default(),
+        tcp::connect(addrs.publisher, Json::default).await?,
+    )
+    .spawn()?;
+
+    publisher
+        .publish(context::current(), "calculus".into(), "sqrt(2)".into())
+        .await?;
+
+    publisher
+        .publish(
+            context::current(),
+            "cool shorts".into(),
+            "hello to all".into(),
+        )
+        .await?;
+
+    publisher
+        .publish(context::current(), "history".into(), "napoleon".to_string())
+        .await?;
+
+    drop(_subscriber0);
+
+    publisher
+        .publish(
+            context::current(),
+            "cool shorts".into(),
+            "hello to who?".into(),
+        )
+        .await?;
+
+    info!("done.");
+
+    Ok(())
+}

tarpc/examples/readme.rs

@@ -0,0 +1,79 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+use futures::{
+    future::{self, Ready},
+    prelude::*,
+};
+use std::io;
+use tarpc::{
+    client, context,
+    server::{BaseChannel, Channel},
+};
+use tokio_serde::formats::Json;
+
+/// This is the service definition. It looks a lot like a trait definition.
+/// It defines one RPC, hello, which takes one arg, name, and returns a String.
+#[tarpc::service]
+pub trait World {
+    async fn hello(name: String) -> String;
+}
+
+/// This is the type that implements the generated World trait. It is the business logic
+/// and is used to start the server.
+#[derive(Clone)]
+struct HelloServer;
+
+impl World for HelloServer {
+    // Each defined rpc generates two items in the trait, a fn that serves the RPC, and
+    // an associated type representing the future output by the fn.
+
+    type HelloFut = Ready<String>;
+
+    fn hello(self, _: context::Context, name: String) -> Self::HelloFut {
+        future::ready(format!("Hello, {}!", name))
+    }
+}
+
+#[tokio::main]
+async fn main() -> io::Result<()> {
+    // tarpc_json_transport is provided by the associated crate json_transport. It makes it
+    // easy to start up a serde-powered JSON serialization strategy over TCP.
+    let mut transport = tarpc::serde_transport::tcp::listen("localhost:0", Json::default).await?;
+    let addr = transport.local_addr();
+
+    let server = async move {
+        // For this example, we're just going to wait for one connection.
+        let client = transport.next().await.unwrap().unwrap();
+
+        // `Channel` is a trait representing a server-side connection. It is a trait to allow
+        // for some channels to be instrumented: for example, to track the number of open connections.
+        // BaseChannel is the most basic channel, simply wrapping a transport with no added
+        // functionality.
+        BaseChannel::with_defaults(client)
+            // serve_world is generated by the tarpc::service attribute. It takes as input any type
+            // implementing the generated World trait.
+            .respond_with(HelloServer.serve())
+            .execute()
+            .await;
+    };
+    tokio::spawn(server);
+
+    let transport = tarpc::serde_transport::tcp::connect(addr, Json::default).await?;
+
+    // WorldClient is generated by the tarpc::service attribute. It has a constructor `new` that
+    // takes a config and any Transport as input.
+    let mut client = WorldClient::new(client::Config::default(), transport).spawn()?;
+
+    // The client has an RPC method for each RPC defined in the annotated trait. It takes the same
+    // args as defined, with the addition of a Context, which is always the first arg. The Context
+    // specifies a deadline and trace information which can be helpful in debugging requests.
+    let hello = client.hello(context::current(), "Stim".to_string()).await?;
+
+    eprintln!("{}", hello);
+
+    Ok(())
+}

tarpc/examples/server_calling_server.rs

@@ -0,0 +1,92 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+use crate::{add::Add as AddService, double::Double as DoubleService};
+use futures::{future, prelude::*};
+use std::io;
+use tarpc::{
+    client, context,
+    server::{Handler, Server},
+};
+use tokio_serde::formats::Json;
+
+pub mod add {
+    #[tarpc::service]
+    pub trait Add {
+        /// Add two ints together.
+        async fn add(x: i32, y: i32) -> i32;
+    }
+}
+
+pub mod double {
+    #[tarpc::service]
+    pub trait Double {
+        /// 2 * x
+        async fn double(x: i32) -> Result<i32, String>;
+    }
+}
+
+#[derive(Clone)]
+struct AddServer;
+
+#[tarpc::server]
+impl AddService for AddServer {
+    async fn add(self, _: context::Context, x: i32, y: i32) -> i32 {
+        x + y
+    }
+}
+
+#[derive(Clone)]
+struct DoubleServer {
+    add_client: add::AddClient,
+}
+
+#[tarpc::server]
+impl DoubleService for DoubleServer {
+    async fn double(mut self, _: context::Context, x: i32) -> Result<i32, String> {
+        self.add_client
+            .add(context::current(), x, x)
+            .await
+            .map_err(|e| e.to_string())
+    }
+}
+
+#[tokio::main]
+async fn main() -> io::Result<()> {
+    env_logger::init();
+
+    let add_listener = tarpc::serde_transport::tcp::listen("localhost:0", Json::default)
+        .await?
+        .filter_map(|r| future::ready(r.ok()));
+    let addr = add_listener.get_ref().local_addr();
+    let add_server = Server::default()
+        .incoming(add_listener)
+        .take(1)
+        .respond_with(AddServer.serve());
+    tokio::spawn(add_server);
+
+    let to_add_server = tarpc::serde_transport::tcp::connect(addr, Json::default).await?;
+    let add_client = add::AddClient::new(client::Config::default(), to_add_server).spawn()?;
+
+    let double_listener = tarpc::serde_transport::tcp::listen("localhost:0", Json::default)
+        .await?
+        .filter_map(|r| future::ready(r.ok()));
+    let addr = double_listener.get_ref().local_addr();
+    let double_server = tarpc::Server::default()
+        .incoming(double_listener)
+        .take(1)
+        .respond_with(DoubleServer { add_client }.serve());
+    tokio::spawn(double_server);
+
+    let to_double_server = tarpc::serde_transport::tcp::connect(addr, Json::default).await?;
+    let mut double_client =
+        double::DoubleClient::new(client::Config::default(), to_double_server).spawn()?;
+
+    for i in 1..=5 {
+        eprintln!("{:?}", double_client.double(context::current(), i).await?);
+    }
+    Ok(())
+}

tarpc/rustfmt.toml

@@ -0,0 +1 @@
+edition = "2018"

tarpc/src/lib.rs

@@ -0,0 +1,302 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+//! *Disclaimer*: This is not an official Google product.
+//!
+//! tarpc is an RPC framework for rust with a focus on ease of use. Defining a
+//! service can be done in just a few lines of code, and most of the boilerplate of
+//! writing a server is taken care of for you.
+//!
+//! [Documentation](https://docs.rs/crate/tarpc/)
+//!
+//! ## What is an RPC framework?
+//! "RPC" stands for "Remote Procedure Call," a function call where the work of
+//! producing the return value is being done somewhere else. When an rpc function is
+//! invoked, behind the scenes the function contacts some other process somewhere
+//! and asks them to evaluate the function instead. The original function then
+//! returns the value produced by the other process.
+//!
+//! RPC frameworks are a fundamental building block of most microservices-oriented
+//! architectures. Two well-known ones are [gRPC](http://www.grpc.io) and
+//! [Cap'n Proto](https://capnproto.org/).
+//!
+//! tarpc differentiates itself from other RPC frameworks by defining the schema in code,
+//! rather than in a separate language such as .proto. This means there's no separate compilation
+//! process, and no context switching between different languages.
+//!
+//! Some other features of tarpc:
+//! - Pluggable transport: any type impling `Stream<Item = Request> + Sink<Response>` can be
+//!   used as a transport to connect the client and server.
+//! - `Send + 'static` optional: if the transport doesn't require it, neither does tarpc!
+//! - Cascading cancellation: dropping a request will send a cancellation message to the server.
+//!   The server will cease any unfinished work on the request, subsequently cancelling any of its
+//!   own requests, repeating for the entire chain of transitive dependencies.
+//! - Configurable deadlines and deadline propagation: request deadlines default to 10s if
+//!   unspecified. The server will automatically cease work when the deadline has passed. Any
+//!   requests sent by the server that use the request context will propagate the request deadline.
+//!   For example, if a server is handling a request with a 10s deadline, does 2s of work, then
+//!   sends a request to another server, that server will see an 8s deadline.
+//! - Serde serialization: enabling the `serde1` Cargo feature will make service requests and
+//!   responses `Serialize + Deserialize`. It's entirely optional, though: in-memory transports can
+//!   be used, as well, so the price of serialization doesn't have to be paid when it's not needed.
+//!
+//! ## Usage
+//! Add to your `Cargo.toml` dependencies:
+//!
+//! ```toml
+//! tarpc = "0.24"
+//! ```
+//!
+//! The `tarpc::service` attribute expands to a collection of items that form an rpc service.
+//! These generated types make it easy and ergonomic to write servers with less boilerplate.
+//! Simply implement the generated service trait, and you're off to the races!
+//!
+//! ## Example
+//!
+//! This example uses [tokio](https://tokio.rs), so add the following dependencies to
+//! your `Cargo.toml`:
+//!
+//! ```toml
+//! futures = "1.0"
+//! tarpc = { version = "0.24", features = ["tokio1"] }
+//! tokio = { version = "1.0", features = ["macros"] }
+//! ```
+//!
+//! In the following example, we use an in-process channel for communication between
+//! client and server. In real code, you will likely communicate over the network.
+//! For a more real-world example, see [example-service](example-service).
+//!
+//! First, let's set up the dependencies and service definition.
+//!
+//! ```rust
+//! # extern crate futures;
+//!
+//! use futures::{
+//!     future::{self, Ready},
+//!     prelude::*,
+//! };
+//! use tarpc::{
+//!     client, context,
+//!     server::{self, Handler},
+//! };
+//! use std::io;
+//!
+//! // This is the service definition. It looks a lot like a trait definition.
+//! // It defines one RPC, hello, which takes one arg, name, and returns a String.
+//! #[tarpc::service]
+//! trait World {
+//!     /// Returns a greeting for name.
+//!     async fn hello(name: String) -> String;
+//! }
+//! ```
+//!
+//! This service definition generates a trait called `World`. Next we need to
+//! implement it for our Server struct.
+//!
+//! ```rust
+//! # extern crate futures;
+//! # use futures::{
+//! #     future::{self, Ready},
+//! #     prelude::*,
+//! # };
+//! # use tarpc::{
+//! #     client, context,
+//! #     server::{self, Handler},
+//! # };
+//! # use std::io;
+//! # // This is the service definition. It looks a lot like a trait definition.
+//! # // It defines one RPC, hello, which takes one arg, name, and returns a String.
+//! # #[tarpc::service]
+//! # trait World {
+//! #     /// Returns a greeting for name.
+//! #     async fn hello(name: String) -> String;
+//! # }
+//! // This is the type that implements the generated World trait. It is the business logic
+//! // and is used to start the server.
+//! #[derive(Clone)]
+//! struct HelloServer;
+//!
+//! impl World for HelloServer {
+//!     // Each defined rpc generates two items in the trait, a fn that serves the RPC, and
+//!     // an associated type representing the future output by the fn.
+//!
+//!     type HelloFut = Ready<String>;
+//!
+//!     fn hello(self, _: context::Context, name: String) -> Self::HelloFut {
+//!         future::ready(format!("Hello, {}!", name))
+//!     }
+//! }
+//! ```
+//!
+//! Lastly let's write our `main` that will start the server. While this example uses an
+//! [in-process channel](rpc::transport::channel), tarpc also ships a generic [`serde_transport`]
+//! behind the `serde-transport` feature, with additional [TCP](serde_transport::tcp) functionality
+//! available behind the `tcp` feature.
+//!
+//! ```rust
+//! # extern crate futures;
+//! # use futures::{
+//! #     future::{self, Ready},
+//! #     prelude::*,
+//! # };
+//! # use tarpc::{
+//! #     client, context,
+//! #     server::{self, Handler},
+//! # };
+//! # use std::io;
+//! # // This is the service definition. It looks a lot like a trait definition.
+//! # // It defines one RPC, hello, which takes one arg, name, and returns a String.
+//! # #[tarpc::service]
+//! # trait World {
+//! #     /// Returns a greeting for name.
+//! #     async fn hello(name: String) -> String;
+//! # }
+//! # // This is the type that implements the generated World trait. It is the business logic
+//! # // and is used to start the server.
+//! # #[derive(Clone)]
+//! # struct HelloServer;
+//! # impl World for HelloServer {
+//! #     // Each defined rpc generates two items in the trait, a fn that serves the RPC, and
+//! #     // an associated type representing the future output by the fn.
+//! #     type HelloFut = Ready<String>;
+//! #     fn hello(self, _: context::Context, name: String) -> Self::HelloFut {
+//! #         future::ready(format!("Hello, {}!", name))
+//! #     }
+//! # }
+//! # #[cfg(not(feature = "tokio1"))]
+//! # fn main() {}
+//! # #[cfg(feature = "tokio1")]
+//! #[tokio::main]
+//! async fn main() -> io::Result<()> {
+//!     let (client_transport, server_transport) = tarpc::transport::channel::unbounded();
+//!
+//!     let server = server::new(server::Config::default())
+//!         // incoming() takes a stream of transports such as would be returned by
+//!         // TcpListener::incoming (but a stream instead of an iterator).
+//!         .incoming(stream::once(future::ready(server_transport)))
+//!         .respond_with(HelloServer.serve());
+//!
+//!     tokio::spawn(server);
+//!
+//!     // WorldClient is generated by the macro. It has a constructor `new` that takes a config and
+//!     // any Transport as input
+//!     let mut client = WorldClient::new(client::Config::default(), client_transport).spawn()?;
+//!
+//!     // The client has an RPC method for each RPC defined in the annotated trait. It takes the same
+//!     // args as defined, with the addition of a Context, which is always the first arg. The Context
+//!     // specifies a deadline and trace information which can be helpful in debugging requests.
+//!     let hello = client.hello(context::current(), "Stim".to_string()).await?;
+//!
+//!     println!("{}", hello);
+//!
+//!     Ok(())
+//! }
+//! ```
+//!
+//! ## Service Documentation
+//!
+//! Use `cargo doc` as you normally would to see the documentation created for all
+//! items expanded by a `service!` invocation.
+#![deny(missing_docs)]
+#![allow(clippy::type_complexity)]
+#![cfg_attr(docsrs, feature(doc_cfg))]
+
+pub mod rpc;
+pub use rpc::*;
+
+#[cfg(feature = "serde1")]
+pub use serde;
+
+#[cfg(feature = "serde-transport")]
+pub use tokio_serde;
+
+#[cfg(feature = "serde-transport")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde-transport")))]
+pub mod serde_transport;
+
+pub mod trace;
+
+#[cfg(feature = "serde1")]
+pub use tarpc_plugins::derive_serde;
+
+/// The main macro that creates RPC services.
+///
+/// Rpc methods are specified, mirroring trait syntax:
+///
+/// ```
+/// #[tarpc::service]
+/// trait Service {
+/// /// Say hello
+/// async fn hello(name: String) -> String;
+/// }
+/// ```
+///
+/// Attributes can be attached to each rpc. These attributes
+/// will then be attached to the generated service traits'
+/// corresponding `fn`s, as well as to the client stubs' RPCs.
+///
+/// The following items are expanded in the enclosing module:
+///
+/// * `trait Service` -- defines the RPC service.
+///   * `fn serve` -- turns a service impl into a request handler.
+/// * `Client` -- a client stub with a fn for each RPC.
+///   * `fn new_stub` -- creates a new Client stub.
+pub use tarpc_plugins::service;
+
+/// A utility macro that can be used for RPC server implementations.
+///
+/// Syntactic sugar to make using async functions in the server implementation
+/// easier. It does this by rewriting code like this, which would normally not
+/// compile because async functions are disallowed in trait implementations:
+///
+/// ```rust
+/// # use tarpc::context;
+/// # use std::net::SocketAddr;
+/// #[tarpc::service]
+/// trait World {
+///     async fn hello(name: String) -> String;
+/// }
+///
+/// #[derive(Clone)]
+/// struct HelloServer(SocketAddr);
+///
+/// #[tarpc::server]
+/// impl World for HelloServer {
+///     async fn hello(self, _: context::Context, name: String) -> String {
+///         format!("Hello, {}! You are connected from {:?}.", name, self.0)
+///     }
+/// }
+/// ```
+///
+/// Into code like this, which matches the service trait definition:
+///
+/// ```rust
+/// # use tarpc::context;
+/// # use std::pin::Pin;
+/// # use futures::Future;
+/// # use std::net::SocketAddr;
+/// #[derive(Clone)]
+/// struct HelloServer(SocketAddr);
+///
+/// #[tarpc::service]
+/// trait World {
+///     async fn hello(name: String) -> String;
+/// }
+///
+/// impl World for HelloServer {
+///     type HelloFut = Pin<Box<dyn Future<Output = String> + Send>>;
+///
+///     fn hello(self, _: context::Context, name: String) -> Pin<Box<dyn Future<Output = String>
+///     + Send>> {
+///         Box::pin(async move {
+///             format!("Hello, {}! You are connected from {:?}.", name, self.0)
+///         })
+///     }
+/// }
+/// ```
+///
+/// Note that this won't touch functions unless they have been annotated with
+/// `async`, meaning that this should not break existing code.
+pub use tarpc_plugins::server;

tarpc/src/rpc.rs

@@ -0,0 +1,148 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+#![deny(missing_docs, missing_debug_implementations)]
+
+//! An RPC framework providing client and server.
+//!
+//! Features:
+//! * RPC deadlines, both client- and server-side.
+//! * Cascading cancellation (works with multiple hops).
+//! * Configurable limits
+//!    * In-flight requests, both client and server-side.
+//!        * Server-side limit is per-connection.
+//!        * When the server reaches the in-flight request maximum, it returns a throttled error
+//!          to the client.
+//!        * When the client reaches the in-flight request max, messages are buffered up to a
+//!          configurable maximum, beyond which the requests are back-pressured.
+//!    * Server connections.
+//!        * Total and per-IP limits.
+//!        * When an incoming connection is accepted, if already at maximum, the connection is
+//!          dropped.
+//! * Transport agnostic.
+
+pub mod client;
+pub mod context;
+pub mod server;
+pub mod transport;
+pub(crate) mod util;
+
+pub use crate::{client::Client, server::Server, trace, transport::sealed::Transport};
+
+use anyhow::Context as _;
+use futures::task::*;
+use std::{fmt::Display, io, time::SystemTime};
+
+/// A message from a client to a server.
+#[derive(Debug)]
+#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
+#[non_exhaustive]
+pub enum ClientMessage<T> {
+    /// A request initiated by a user. The server responds to a request by invoking a
+    /// service-provided request handler.  The handler completes with a [`response`](Response), which
+    /// the server sends back to the client.
+    Request(Request<T>),
+    /// A command to cancel an in-flight request, automatically sent by the client when a response
+    /// future is dropped.
+    ///
+    /// When received, the server will immediately cancel the main task (top-level future) of the
+    /// request handler for the associated request. Any tasks spawned by the request handler will
+    /// not be canceled, because the framework layer does not
+    /// know about them.
+    Cancel {
+        /// The trace context associates the message with a specific chain of causally-related actions,
+        /// possibly orchestrated across many distributed systems.
+        #[cfg_attr(feature = "serde1", serde(default))]
+        trace_context: trace::Context,
+        /// The ID of the request to cancel.
+        request_id: u64,
+    },
+}
+
+/// A request from a client to a server.
+#[derive(Clone, Copy, Debug)]
+#[non_exhaustive]
+#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
+pub struct Request<T> {
+    /// Trace context, deadline, and other cross-cutting concerns.
+    pub context: context::Context,
+    /// Uniquely identifies the request across all requests sent over a single channel.
+    pub id: u64,
+    /// The request body.
+    pub message: T,
+}
+
+/// A response from a server to a client.
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+#[non_exhaustive]
+#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
+pub struct Response<T> {
+    /// The ID of the request being responded to.
+    pub request_id: u64,
+    /// The response body, or an error if the request failed.
+    pub message: Result<T, ServerError>,
+}
+
+/// An error response from a server to a client.
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+#[non_exhaustive]
+#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
+pub struct ServerError {
+    #[cfg_attr(
+        feature = "serde1",
+        serde(serialize_with = "util::serde::serialize_io_error_kind_as_u32")
+    )]
+    #[cfg_attr(
+        feature = "serde1",
+        serde(deserialize_with = "util::serde::deserialize_io_error_kind_from_u32")
+    )]
+    /// The type of error that occurred to fail the request.
+    pub kind: io::ErrorKind,
+    /// A message describing more detail about the error that occurred.
+    pub detail: Option<String>,
+}
+
+impl From<ServerError> for io::Error {
+    fn from(e: ServerError) -> io::Error {
+        io::Error::new(e.kind, e.detail.unwrap_or_default())
+    }
+}
+
+impl<T> Request<T> {
+    /// Returns the deadline for this request.
+    pub fn deadline(&self) -> &SystemTime {
+        &self.context.deadline
+    }
+}
+
+pub(crate) type PollIo<T> = Poll<Option<io::Result<T>>>;
+pub(crate) trait PollContext<T> {
+    fn context<C>(self, context: C) -> Poll<Option<anyhow::Result<T>>>
+    where
+        C: Display + Send + Sync + 'static;
+
+    fn with_context<C, F>(self, f: F) -> Poll<Option<anyhow::Result<T>>>
+    where
+        C: Display + Send + Sync + 'static,
+        F: FnOnce() -> C;
+}
+
+impl<T> PollContext<T> for PollIo<T> {
+    fn context<C>(self, context: C) -> Poll<Option<anyhow::Result<T>>>
+    where
+        C: Display + Send + Sync + 'static,
+    {
+        self.map(|o| o.map(|r| r.context(context)))
+    }
+
+    fn with_context<C, F>(self, f: F) -> Poll<Option<anyhow::Result<T>>>
+    where
+        C: Display + Send + Sync + 'static,
+        F: FnOnce() -> C,
+    {
+        self.map(|o| o.map(|r| r.with_context(f)))
+    }
+}

tarpc/src/rpc/client.rs

@@ -0,0 +1,161 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+//! Provides a client that connects to a server and sends multiplexed requests.
+
+use crate::context;
+use futures::prelude::*;
+use std::fmt;
+use std::io;
+
+/// Provides a [`Client`] backed by a transport.
+pub mod channel;
+pub use channel::{new, Channel};
+
+/// Sends multiplexed requests to, and receives responses from, a server.
+pub trait Client<'a, Req> {
+    /// The response type.
+    type Response;
+
+    /// The future response.
+    type Future: Future<Output = io::Result<Self::Response>> + 'a;
+
+    /// Initiates a request, sending it to the dispatch task.
+    ///
+    /// Returns a [`Future`] that resolves to this client and the future response
+    /// once the request is successfully enqueued.
+    ///
+    /// [`Future`]: futures::Future
+    fn call(&'a mut self, ctx: context::Context, request: Req) -> Self::Future;
+
+    /// Returns a Client that applies a post-processing function to the returned response.
+    fn map_response<F, R>(self, f: F) -> MapResponse<Self, F>
+    where
+        F: FnMut(Self::Response) -> R,
+        Self: Sized,
+    {
+        MapResponse { inner: self, f }
+    }
+
+    /// Returns a Client that applies a pre-processing function to the request.
+    fn with_request<F, Req2>(self, f: F) -> WithRequest<Self, F>
+    where
+        F: FnMut(Req2) -> Req,
+        Self: Sized,
+    {
+        WithRequest { inner: self, f }
+    }
+}
+
+/// A Client that applies a function to the returned response.
+#[derive(Clone, Debug)]
+pub struct MapResponse<C, F> {
+    inner: C,
+    f: F,
+}
+
+impl<'a, C, F, Req, Resp, Resp2> Client<'a, Req> for MapResponse<C, F>
+where
+    C: Client<'a, Req, Response = Resp>,
+    F: FnMut(Resp) -> Resp2 + 'a,
+{
+    type Response = Resp2;
+    type Future = futures::future::MapOk<<C as Client<'a, Req>>::Future, &'a mut F>;
+
+    fn call(&'a mut self, ctx: context::Context, request: Req) -> Self::Future {
+        self.inner.call(ctx, request).map_ok(&mut self.f)
+    }
+}
+
+/// A Client that applies a pre-processing function to the request.
+#[derive(Clone, Debug)]
+pub struct WithRequest<C, F> {
+    inner: C,
+    f: F,
+}
+
+impl<'a, C, F, Req, Req2, Resp> Client<'a, Req2> for WithRequest<C, F>
+where
+    C: Client<'a, Req, Response = Resp>,
+    F: FnMut(Req2) -> Req,
+{
+    type Response = Resp;
+    type Future = <C as Client<'a, Req>>::Future;
+
+    fn call(&'a mut self, ctx: context::Context, request: Req2) -> Self::Future {
+        self.inner.call(ctx, (self.f)(request))
+    }
+}
+
+impl<'a, Req, Resp> Client<'a, Req> for Channel<Req, Resp>
+where
+    Req: 'a,
+    Resp: 'a,
+{
+    type Response = Resp;
+    type Future = channel::Call<'a, Req, Resp>;
+
+    fn call(&'a mut self, ctx: context::Context, request: Req) -> channel::Call<'a, Req, Resp> {
+        self.call(ctx, request)
+    }
+}
+
+/// Settings that control the behavior of the client.
+#[derive(Clone, Debug)]
+#[non_exhaustive]
+pub struct Config {
+    /// The number of requests that can be in flight at once.
+    /// `max_in_flight_requests` controls the size of the map used by the client
+    /// for storing pending requests.
+    pub max_in_flight_requests: usize,
+    /// The number of requests that can be buffered client-side before being sent.
+    /// `pending_requests_buffer` controls the size of the channel clients use
+    /// to communicate with the request dispatch task.
+    pub pending_request_buffer: usize,
+}
+
+impl Default for Config {
+    fn default() -> Self {
+        Config {
+            max_in_flight_requests: 1_000,
+            pending_request_buffer: 100,
+        }
+    }
+}
+
+/// A channel and dispatch pair. The dispatch drives the sending and receiving of requests
+/// and must be polled continuously or spawned.
+pub struct NewClient<C, D> {
+    /// The new client.
+    pub client: C,
+    /// The client's dispatch.
+    pub dispatch: D,
+}
+
+impl<C, D, E> NewClient<C, D>
+where
+    D: Future<Output = Result<(), E>> + Send + 'static,
+    E: std::fmt::Display,
+{
+    /// Helper method to spawn the dispatch on the default executor.
+    #[cfg(feature = "tokio1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "tokio1")))]
+    pub fn spawn(self) -> io::Result<C> {
+        use log::error;
+
+        let dispatch = self
+            .dispatch
+            .unwrap_or_else(move |e| error!("Connection broken: {}", e));
+        tokio::spawn(dispatch);
+        Ok(self.client)
+    }
+}
+
+impl<C, D> fmt::Debug for NewClient<C, D> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(fmt, "NewClient")
+    }
+}

tarpc/src/rpc/client/channel.rs

@@ -0,0 +1,907 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+use crate::{
+    context,
+    trace::SpanId,
+    util::{Compact, TimeUntil},
+    ClientMessage, PollContext, PollIo, Request, Response, Transport,
+};
+use fnv::FnvHashMap;
+use futures::{
+    channel::{mpsc, oneshot},
+    prelude::*,
+    ready,
+    stream::Fuse,
+    task::*,
+};
+use log::{debug, info, trace};
+use pin_project::{pin_project, pinned_drop};
+use std::{
+    io,
+    pin::Pin,
+    sync::{
+        atomic::{AtomicU64, Ordering},
+        Arc,
+    },
+};
+
+use super::{Config, NewClient};
+
+/// Handles communication from the client to request dispatch.
+#[derive(Debug)]
+pub struct Channel<Req, Resp> {
+    to_dispatch: mpsc::Sender<DispatchRequest<Req, Resp>>,
+    /// Channel to send a cancel message to the dispatcher.
+    cancellation: RequestCancellation,
+    /// The ID to use for the next request to stage.
+    next_request_id: Arc<AtomicU64>,
+}
+
+impl<Req, Resp> Clone for Channel<Req, Resp> {
+    fn clone(&self) -> Self {
+        Self {
+            to_dispatch: self.to_dispatch.clone(),
+            cancellation: self.cancellation.clone(),
+            next_request_id: self.next_request_id.clone(),
+        }
+    }
+}
+
+/// A future returned by [`Channel::send`] that resolves to a server response.
+#[pin_project]
+#[derive(Debug)]
+#[must_use = "futures do nothing unless polled"]
+struct Send<'a, Req, Resp> {
+    #[pin]
+    fut: MapOkDispatchResponse<SendMapErrConnectionReset<'a, Req, Resp>, Resp>,
+}
+
+type SendMapErrConnectionReset<'a, Req, Resp> = MapErrConnectionReset<
+    futures::sink::Send<'a, mpsc::Sender<DispatchRequest<Req, Resp>>, DispatchRequest<Req, Resp>>,
+>;
+
+impl<'a, Req, Resp> Future for Send<'a, Req, Resp> {
+    type Output = io::Result<DispatchResponse<Resp>>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        self.as_mut().project().fut.poll(cx)
+    }
+}
+
+/// A future returned by [`Channel::call`] that resolves to a server response.
+#[pin_project]
+#[derive(Debug)]
+#[must_use = "futures do nothing unless polled"]
+pub struct Call<'a, Req, Resp> {
+    #[pin]
+    fut: tokio::time::Timeout<AndThenIdent<Send<'a, Req, Resp>, DispatchResponse<Resp>>>,
+}
+
+impl<'a, Req, Resp> Future for Call<'a, Req, Resp> {
+    type Output = io::Result<Resp>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let resp = ready!(self.as_mut().project().fut.poll(cx));
+        Poll::Ready(match resp {
+            Ok(resp) => resp,
+            Err(tokio::time::error::Elapsed { .. }) => Err(io::Error::new(
+                io::ErrorKind::TimedOut,
+                "Client dropped expired request.".to_string(),
+            )),
+        })
+    }
+}
+
+impl<Req, Resp> Channel<Req, Resp> {
+    /// Sends a request to the dispatch task to forward to the server, returning a [`Future`] that
+    /// resolves when the request is sent (not when the response is received).
+    fn send(&mut self, mut ctx: context::Context, request: Req) -> Send<Req, Resp> {
+        // Convert the context to the call context.
+        ctx.trace_context.parent_id = Some(ctx.trace_context.span_id);
+        ctx.trace_context.span_id = SpanId::random(&mut rand::thread_rng());
+
+        let (response_completion, response) = oneshot::channel();
+        let cancellation = self.cancellation.clone();
+        let request_id = self.next_request_id.fetch_add(1, Ordering::Relaxed);
+        Send {
+            fut: MapOkDispatchResponse::new(
+                MapErrConnectionReset::new(self.to_dispatch.send(DispatchRequest {
+                    ctx,
+                    request_id,
+                    request,
+                    response_completion,
+                })),
+                DispatchResponse {
+                    response,
+                    complete: false,
+                    request_id,
+                    cancellation,
+                    ctx,
+                },
+            ),
+        }
+    }
+
+    /// Sends a request to the dispatch task to forward to the server, returning a [`Future`] that
+    /// resolves to the response.
+    pub fn call(&mut self, ctx: context::Context, request: Req) -> Call<Req, Resp> {
+        let timeout = ctx.deadline.time_until();
+        trace!(
+            "[{}] Queuing request with timeout {:?}.",
+            ctx.trace_id(),
+            timeout,
+        );
+
+        Call {
+            fut: tokio::time::timeout(timeout, AndThenIdent::new(self.send(ctx, request))),
+        }
+    }
+}
+
+/// A server response that is completed by request dispatch when the corresponding response
+/// arrives off the wire.
+#[pin_project(PinnedDrop)]
+#[derive(Debug)]
+struct DispatchResponse<Resp> {
+    response: oneshot::Receiver<Response<Resp>>,
+    ctx: context::Context,
+    complete: bool,
+    cancellation: RequestCancellation,
+    request_id: u64,
+}
+
+impl<Resp> Future for DispatchResponse<Resp> {
+    type Output = io::Result<Resp>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<Resp>> {
+        let resp = ready!(self.response.poll_unpin(cx));
+        self.complete = true;
+        Poll::Ready(match resp {
+            Ok(resp) => Ok(resp.message?),
+            Err(oneshot::Canceled) => {
+                // The oneshot is Canceled when the dispatch task ends. In that case,
+                // there's nothing listening on the other side, so there's no point in
+                // propagating cancellation.
+                Err(io::Error::from(io::ErrorKind::ConnectionReset))
+            }
+        })
+    }
+}
+
+// Cancels the request when dropped, if not already complete.
+#[pinned_drop]
+impl<Resp> PinnedDrop for DispatchResponse<Resp> {
+    fn drop(mut self: Pin<&mut Self>) {
+        if !self.complete {
+            // The receiver needs to be closed to handle the edge case that the request has not
+            // yet been received by the dispatch task. It is possible for the cancel message to
+            // arrive before the request itself, in which case the request could get stuck in the
+            // dispatch map forever if the server never responds (e.g. if the server dies while
+            // responding). Even if the server does respond, it will have unnecessarily done work
+            // for a client no longer waiting for a response. To avoid this, the dispatch task
+            // checks if the receiver is closed before inserting the request in the map. By
+            // closing the receiver before sending the cancel message, it is guaranteed that if the
+            // dispatch task misses an early-arriving cancellation message, then it will see the
+            // receiver as closed.
+            self.response.close();
+            let request_id = self.request_id;
+            self.cancellation.cancel(request_id);
+        }
+    }
+}
+
+/// Returns a channel and dispatcher that manages the lifecycle of requests initiated by the
+/// channel.
+pub fn new<Req, Resp, C>(
+    config: Config,
+    transport: C,
+) -> NewClient<Channel<Req, Resp>, RequestDispatch<Req, Resp, C>>
+where
+    C: Transport<ClientMessage<Req>, Response<Resp>>,
+{
+    let (to_dispatch, pending_requests) = mpsc::channel(config.pending_request_buffer);
+    let (cancellation, canceled_requests) = cancellations();
+    let canceled_requests = canceled_requests.fuse();
+
+    NewClient {
+        client: Channel {
+            to_dispatch,
+            cancellation,
+            next_request_id: Arc::new(AtomicU64::new(0)),
+        },
+        dispatch: RequestDispatch {
+            config,
+            canceled_requests,
+            transport: transport.fuse(),
+            in_flight_requests: FnvHashMap::default(),
+            pending_requests: pending_requests.fuse(),
+        },
+    }
+}
+
+/// Handles the lifecycle of requests, writing requests to the wire, managing cancellations,
+/// and dispatching responses to the appropriate channel.
+#[pin_project]
+#[derive(Debug)]
+pub struct RequestDispatch<Req, Resp, C> {
+    /// Writes requests to the wire and reads responses off the wire.
+    #[pin]
+    transport: Fuse<C>,
+    /// Requests waiting to be written to the wire.
+    #[pin]
+    pending_requests: Fuse<mpsc::Receiver<DispatchRequest<Req, Resp>>>,
+    /// Requests that were dropped.
+    #[pin]
+    canceled_requests: Fuse<CanceledRequests>,
+    /// Requests already written to the wire that haven't yet received responses.
+    in_flight_requests: FnvHashMap<u64, InFlightData<Resp>>,
+    /// Configures limits to prevent unlimited resource usage.
+    config: Config,
+}
+
+impl<Req, Resp, C> RequestDispatch<Req, Resp, C>
+where
+    C: Transport<ClientMessage<Req>, Response<Resp>>,
+{
+    fn pump_read(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> PollIo<()> {
+        Poll::Ready(
+            match ready!(self.as_mut().project().transport.poll_next(cx)?) {
+                Some(response) => {
+                    self.complete(response);
+                    Some(Ok(()))
+                }
+                None => None,
+            },
+        )
+    }
+
+    fn pump_write(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> PollIo<()> {
+        enum ReceiverStatus {
+            NotReady,
+            Closed,
+        }
+
+        let pending_requests_status = match self.as_mut().poll_next_request(cx)? {
+            Poll::Ready(Some(dispatch_request)) => {
+                self.as_mut().write_request(dispatch_request)?;
+                return Poll::Ready(Some(Ok(())));
+            }
+            Poll::Ready(None) => ReceiverStatus::Closed,
+            Poll::Pending => ReceiverStatus::NotReady,
+        };
+
+        let canceled_requests_status = match self.as_mut().poll_next_cancellation(cx)? {
+            Poll::Ready(Some((context, request_id))) => {
+                self.as_mut().write_cancel(context, request_id)?;
+                return Poll::Ready(Some(Ok(())));
+            }
+            Poll::Ready(None) => ReceiverStatus::Closed,
+            Poll::Pending => ReceiverStatus::NotReady,
+        };
+
+        match (pending_requests_status, canceled_requests_status) {
+            (ReceiverStatus::Closed, ReceiverStatus::Closed) => {
+                ready!(self.as_mut().project().transport.poll_flush(cx)?);
+                Poll::Ready(None)
+            }
+            (ReceiverStatus::NotReady, _) | (_, ReceiverStatus::NotReady) => {
+                // No more messages to process, so flush any messages buffered in the transport.
+                ready!(self.as_mut().project().transport.poll_flush(cx)?);
+
+                // Even if we fully-flush, we return Pending, because we have no more requests
+                // or cancellations right now.
+                Poll::Pending
+            }
+        }
+    }
+
+    /// Yields the next pending request, if one is ready to be sent.
+    fn poll_next_request(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> PollIo<DispatchRequest<Req, Resp>> {
+        if self.as_mut().project().in_flight_requests.len() >= self.config.max_in_flight_requests {
+            info!(
+                "At in-flight request capacity ({}/{}).",
+                self.as_mut().project().in_flight_requests.len(),
+                self.config.max_in_flight_requests
+            );
+
+            // No need to schedule a wakeup, because timers and responses are responsible
+            // for clearing out in-flight requests.
+            return Poll::Pending;
+        }
+
+        while let Poll::Pending = self.as_mut().project().transport.poll_ready(cx)? {
+            // We can't yield a request-to-be-sent before the transport is capable of buffering it.
+            ready!(self.as_mut().project().transport.poll_flush(cx)?);
+        }
+
+        loop {
+            match ready!(self.as_mut().project().pending_requests.poll_next_unpin(cx)) {
+                Some(request) => {
+                    if request.response_completion.is_canceled() {
+                        trace!(
+                            "[{}] Request canceled before being sent.",
+                            request.ctx.trace_id()
+                        );
+                        continue;
+                    }
+
+                    return Poll::Ready(Some(Ok(request)));
+                }
+                None => return Poll::Ready(None),
+            }
+        }
+    }
+
+    /// Yields the next pending cancellation, and, if one is ready, cancels the associated request.
+    fn poll_next_cancellation(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> PollIo<(context::Context, u64)> {
+        while let Poll::Pending = self.as_mut().project().transport.poll_ready(cx)? {
+            ready!(self.as_mut().project().transport.poll_flush(cx)?);
+        }
+
+        loop {
+            let cancellation = self
+                .as_mut()
+                .project()
+                .canceled_requests
+                .poll_next_unpin(cx);
+            match ready!(cancellation) {
+                Some(request_id) => {
+                    if let Some(in_flight_data) = self
+                        .as_mut()
+                        .project()
+                        .in_flight_requests
+                        .remove(&request_id)
+                    {
+                        self.as_mut().project().in_flight_requests.compact(0.1);
+                        debug!("[{}] Removed request.", in_flight_data.ctx.trace_id());
+                        return Poll::Ready(Some(Ok((in_flight_data.ctx, request_id))));
+                    }
+                }
+                None => return Poll::Ready(None),
+            }
+        }
+    }
+
+    fn write_request(
+        mut self: Pin<&mut Self>,
+        dispatch_request: DispatchRequest<Req, Resp>,
+    ) -> io::Result<()> {
+        let request_id = dispatch_request.request_id;
+        let request = ClientMessage::Request(Request {
+            id: request_id,
+            message: dispatch_request.request,
+            context: context::Context {
+                deadline: dispatch_request.ctx.deadline,
+                trace_context: dispatch_request.ctx.trace_context,
+            },
+        });
+        self.as_mut().project().transport.start_send(request)?;
+        self.as_mut().project().in_flight_requests.insert(
+            request_id,
+            InFlightData {
+                ctx: dispatch_request.ctx,
+                response_completion: dispatch_request.response_completion,
+            },
+        );
+        Ok(())
+    }
+
+    fn write_cancel(
+        mut self: Pin<&mut Self>,
+        context: context::Context,
+        request_id: u64,
+    ) -> io::Result<()> {
+        let trace_id = *context.trace_id();
+        let cancel = ClientMessage::Cancel {
+            trace_context: context.trace_context,
+            request_id,
+        };
+        self.as_mut().project().transport.start_send(cancel)?;
+        trace!("[{}] Cancel message sent.", trace_id);
+        Ok(())
+    }
+
+    /// Sends a server response to the client task that initiated the associated request.
+    fn complete(mut self: Pin<&mut Self>, response: Response<Resp>) -> bool {
+        if let Some(in_flight_data) = self
+            .as_mut()
+            .project()
+            .in_flight_requests
+            .remove(&response.request_id)
+        {
+            self.as_mut().project().in_flight_requests.compact(0.1);
+
+            trace!("[{}] Received response.", in_flight_data.ctx.trace_id());
+            let _ = in_flight_data.response_completion.send(response);
+            return true;
+        }
+
+        debug!(
+            "No in-flight request found for request_id = {}.",
+            response.request_id
+        );
+
+        // If the response completion was absent, then the request was already canceled.
+        false
+    }
+}
+
+impl<Req, Resp, C> Future for RequestDispatch<Req, Resp, C>
+where
+    C: Transport<ClientMessage<Req>, Response<Resp>>,
+{
+    type Output = anyhow::Result<()>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<anyhow::Result<()>> {
+        loop {
+            match (
+                self.as_mut()
+                    .pump_read(cx)
+                    .context("failed to read from transport")?,
+                self.as_mut()
+                    .pump_write(cx)
+                    .context("failed to write to transport")?,
+            ) {
+                (Poll::Ready(None), _) => {
+                    info!("Shutdown: read half closed, so shutting down.");
+                    return Poll::Ready(Ok(()));
+                }
+                (read, Poll::Ready(None)) => {
+                    if self.as_mut().project().in_flight_requests.is_empty() {
+                        info!("Shutdown: write half closed, and no requests in flight.");
+                        return Poll::Ready(Ok(()));
+                    }
+                    info!(
+                        "Shutdown: write half closed, and {} requests in flight.",
+                        self.as_mut().project().in_flight_requests.len()
+                    );
+                    match read {
+                        Poll::Ready(Some(())) => continue,
+                        _ => return Poll::Pending,
+                    }
+                }
+                (Poll::Ready(Some(())), _) | (_, Poll::Ready(Some(()))) => {}
+                _ => return Poll::Pending,
+            }
+        }
+    }
+}
+
+/// A server-bound request sent from a [`Channel`] to request dispatch, which will then manage
+/// the lifecycle of the request.
+#[derive(Debug)]
+struct DispatchRequest<Req, Resp> {
+    ctx: context::Context,
+    request_id: u64,
+    request: Req,
+    response_completion: oneshot::Sender<Response<Resp>>,
+}
+
+#[derive(Debug)]
+struct InFlightData<Resp> {
+    ctx: context::Context,
+    response_completion: oneshot::Sender<Response<Resp>>,
+}
+
+/// Sends request cancellation signals.
+#[derive(Debug, Clone)]
+struct RequestCancellation(mpsc::UnboundedSender<u64>);
+
+/// A stream of IDs of requests that have been canceled.
+#[derive(Debug)]
+struct CanceledRequests(mpsc::UnboundedReceiver<u64>);
+
+/// Returns a channel to send request cancellation messages.
+fn cancellations() -> (RequestCancellation, CanceledRequests) {
+    // Unbounded because messages are sent in the drop fn. This is fine, because it's still
+    // bounded by the number of in-flight requests. Additionally, each request has a clone
+    // of the sender, so the bounded channel would have the same behavior,
+    // since it guarantees a slot.
+    let (tx, rx) = mpsc::unbounded();
+    (RequestCancellation(tx), CanceledRequests(rx))
+}
+
+impl RequestCancellation {
+    /// Cancels the request with ID `request_id`.
+    fn cancel(&mut self, request_id: u64) {
+        let _ = self.0.unbounded_send(request_id);
+    }
+}
+
+impl Stream for CanceledRequests {
+    type Item = u64;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<u64>> {
+        self.0.poll_next_unpin(cx)
+    }
+}
+
+#[pin_project]
+#[derive(Debug)]
+#[must_use = "futures do nothing unless polled"]
+struct MapErrConnectionReset<Fut> {
+    #[pin]
+    future: Fut,
+    finished: Option<()>,
+}
+
+impl<Fut> MapErrConnectionReset<Fut> {
+    fn new(future: Fut) -> MapErrConnectionReset<Fut> {
+        MapErrConnectionReset {
+            future,
+            finished: Some(()),
+        }
+    }
+}
+
+impl<Fut> Future for MapErrConnectionReset<Fut>
+where
+    Fut: TryFuture,
+{
+    type Output = io::Result<Fut::Ok>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        match self.as_mut().project().future.try_poll(cx) {
+            Poll::Pending => Poll::Pending,
+            Poll::Ready(result) => {
+                self.project().finished.take().expect(
+                    "MapErrConnectionReset must not be polled after it returned `Poll::Ready`",
+                );
+                Poll::Ready(result.map_err(|_| io::Error::from(io::ErrorKind::ConnectionReset)))
+            }
+        }
+    }
+}
+
+#[pin_project]
+#[derive(Debug)]
+#[must_use = "futures do nothing unless polled"]
+struct MapOkDispatchResponse<Fut, Resp> {
+    #[pin]
+    future: Fut,
+    response: Option<DispatchResponse<Resp>>,
+}
+
+impl<Fut, Resp> MapOkDispatchResponse<Fut, Resp> {
+    fn new(future: Fut, response: DispatchResponse<Resp>) -> MapOkDispatchResponse<Fut, Resp> {
+        MapOkDispatchResponse {
+            future,
+            response: Some(response),
+        }
+    }
+}
+
+impl<Fut, Resp> Future for MapOkDispatchResponse<Fut, Resp>
+where
+    Fut: TryFuture,
+{
+    type Output = Result<DispatchResponse<Resp>, Fut::Error>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        match self.as_mut().project().future.try_poll(cx) {
+            Poll::Pending => Poll::Pending,
+            Poll::Ready(result) => {
+                let response = self
+                    .as_mut()
+                    .project()
+                    .response
+                    .take()
+                    .expect("MapOk must not be polled after it returned `Poll::Ready`");
+                Poll::Ready(result.map(|_| response))
+            }
+        }
+    }
+}
+
+#[pin_project]
+#[derive(Debug)]
+#[must_use = "futures do nothing unless polled"]
+struct AndThenIdent<Fut1, Fut2> {
+    #[pin]
+    try_chain: TryChain<Fut1, Fut2>,
+}
+
+impl<Fut1, Fut2> AndThenIdent<Fut1, Fut2>
+where
+    Fut1: TryFuture<Ok = Fut2>,
+    Fut2: TryFuture,
+{
+    /// Creates a new `Then`.
+    fn new(future: Fut1) -> AndThenIdent<Fut1, Fut2> {
+        AndThenIdent {
+            try_chain: TryChain::new(future),
+        }
+    }
+}
+
+impl<Fut1, Fut2> Future for AndThenIdent<Fut1, Fut2>
+where
+    Fut1: TryFuture<Ok = Fut2>,
+    Fut2: TryFuture<Error = Fut1::Error>,
+{
+    type Output = Result<Fut2::Ok, Fut2::Error>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        self.project().try_chain.poll(cx, |result| match result {
+            Ok(ok) => TryChainAction::Future(ok),
+            Err(err) => TryChainAction::Output(Err(err)),
+        })
+    }
+}
+
+#[pin_project(project = TryChainProj)]
+#[must_use = "futures do nothing unless polled"]
+#[derive(Debug)]
+enum TryChain<Fut1, Fut2> {
+    First(#[pin] Fut1),
+    Second(#[pin] Fut2),
+    Empty,
+}
+
+enum TryChainAction<Fut2>
+where
+    Fut2: TryFuture,
+{
+    Future(Fut2),
+    Output(Result<Fut2::Ok, Fut2::Error>),
+}
+
+impl<Fut1, Fut2> TryChain<Fut1, Fut2>
+where
+    Fut1: TryFuture<Ok = Fut2>,
+    Fut2: TryFuture,
+{
+    fn new(fut1: Fut1) -> TryChain<Fut1, Fut2> {
+        TryChain::First(fut1)
+    }
+
+    fn poll<F>(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        f: F,
+    ) -> Poll<Result<Fut2::Ok, Fut2::Error>>
+    where
+        F: FnOnce(Result<Fut1::Ok, Fut1::Error>) -> TryChainAction<Fut2>,
+    {
+        let mut f = Some(f);
+
+        loop {
+            let output = match self.as_mut().project() {
+                TryChainProj::First(fut1) => {
+                    // Poll the first future
+                    match fut1.try_poll(cx) {
+                        Poll::Pending => return Poll::Pending,
+                        Poll::Ready(output) => output,
+                    }
+                }
+                TryChainProj::Second(fut2) => {
+                    // Poll the second future
+                    return fut2.try_poll(cx);
+                }
+                TryChainProj::Empty => {
+                    panic!("future must not be polled after it returned `Poll::Ready`");
+                }
+            };
+
+            self.set(TryChain::Empty); // Drop fut1
+            let f = f.take().unwrap();
+            match f(output) {
+                TryChainAction::Future(fut2) => self.set(TryChain::Second(fut2)),
+                TryChainAction::Output(output) => return Poll::Ready(output),
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{
+        cancellations, CanceledRequests, Channel, DispatchResponse, RequestCancellation,
+        RequestDispatch,
+    };
+    use crate::{
+        client::Config,
+        context,
+        transport::{self, channel::UnboundedChannel},
+        ClientMessage, Response,
+    };
+    use fnv::FnvHashMap;
+    use futures::{
+        channel::{mpsc, oneshot},
+        prelude::*,
+        task::*,
+    };
+    use std::{pin::Pin, sync::atomic::AtomicU64, sync::Arc};
+
+    #[tokio::test]
+    async fn dispatch_response_cancels_on_drop() {
+        let (cancellation, mut canceled_requests) = cancellations();
+        let (_, response) = oneshot::channel();
+        drop(DispatchResponse::<u32> {
+            response,
+            cancellation,
+            complete: false,
+            request_id: 3,
+            ctx: context::current(),
+        });
+        // resp's drop() is run, which should send a cancel message.
+        assert_eq!(canceled_requests.0.try_next().unwrap(), Some(3));
+    }
+
+    #[tokio::test]
+    async fn stage_request() {
+        let (mut dispatch, mut channel, _server_channel) = set_up();
+        let dispatch = Pin::new(&mut dispatch);
+        let cx = &mut Context::from_waker(&noop_waker_ref());
+
+        let _resp = send_request(&mut channel, "hi").await;
+
+        let req = dispatch.poll_next_request(cx).ready();
+        assert!(req.is_some());
+
+        let req = req.unwrap();
+        assert_eq!(req.request_id, 0);
+        assert_eq!(req.request, "hi".to_string());
+    }
+
+    // Regression test for  https://github.com/google/tarpc/issues/220
+    #[tokio::test]
+    async fn stage_request_channel_dropped_doesnt_panic() {
+        let (mut dispatch, mut channel, mut server_channel) = set_up();
+        let mut dispatch = Pin::new(&mut dispatch);
+        let cx = &mut Context::from_waker(&noop_waker_ref());
+
+        let _ = send_request(&mut channel, "hi").await;
+        drop(channel);
+
+        assert!(dispatch.as_mut().poll(cx).is_ready());
+        send_response(
+            &mut server_channel,
+            Response {
+                request_id: 0,
+                message: Ok("hello".into()),
+            },
+        )
+        .await;
+        dispatch.await.unwrap();
+    }
+
+    #[tokio::test]
+    async fn stage_request_response_future_dropped_is_canceled_before_sending() {
+        let (mut dispatch, mut channel, _server_channel) = set_up();
+        let dispatch = Pin::new(&mut dispatch);
+        let cx = &mut Context::from_waker(&noop_waker_ref());
+
+        let _ = send_request(&mut channel, "hi").await;
+
+        // Drop the channel so polling returns none if no requests are currently ready.
+        drop(channel);
+        // Test that a request future dropped before it's processed by dispatch will cause the request
+        // to not be added to the in-flight request map.
+        assert!(dispatch.poll_next_request(cx).ready().is_none());
+    }
+
+    #[tokio::test]
+    async fn stage_request_response_future_dropped_is_canceled_after_sending() {
+        let (mut dispatch, mut channel, _server_channel) = set_up();
+        let cx = &mut Context::from_waker(&noop_waker_ref());
+        let mut dispatch = Pin::new(&mut dispatch);
+
+        let req = send_request(&mut channel, "hi").await;
+
+        assert!(dispatch.as_mut().pump_write(cx).ready().is_some());
+        assert!(!dispatch.as_mut().project().in_flight_requests.is_empty());
+
+        // Test that a request future dropped after it's processed by dispatch will cause the request
+        // to be removed from the in-flight request map.
+        drop(req);
+        if let Poll::Ready(Some(_)) = dispatch.as_mut().poll_next_cancellation(cx).unwrap() {
+            // ok
+        } else {
+            panic!("Expected request to be cancelled")
+        };
+        assert!(dispatch.project().in_flight_requests.is_empty());
+    }
+
+    #[tokio::test]
+    async fn stage_request_response_closed_skipped() {
+        let (mut dispatch, mut channel, _server_channel) = set_up();
+        let dispatch = Pin::new(&mut dispatch);
+        let cx = &mut Context::from_waker(&noop_waker_ref());
+
+        // Test that a request future that's closed its receiver but not yet canceled its request --
+        // i.e. still in `drop fn` -- will cause the request to not be added to the in-flight request
+        // map.
+        let mut resp = send_request(&mut channel, "hi").await;
+        resp.response.close();
+
+        assert!(dispatch.poll_next_request(cx).is_pending());
+    }
+
+    fn set_up() -> (
+        RequestDispatch<String, String, UnboundedChannel<Response<String>, ClientMessage<String>>>,
+        Channel<String, String>,
+        UnboundedChannel<ClientMessage<String>, Response<String>>,
+    ) {
+        let _ = env_logger::try_init();
+
+        let (to_dispatch, pending_requests) = mpsc::channel(1);
+        let (cancel_tx, canceled_requests) = mpsc::unbounded();
+        let (client_channel, server_channel) = transport::channel::unbounded();
+
+        let dispatch = RequestDispatch::<String, String, _> {
+            transport: client_channel.fuse(),
+            pending_requests: pending_requests.fuse(),
+            canceled_requests: CanceledRequests(canceled_requests).fuse(),
+            in_flight_requests: FnvHashMap::default(),
+            config: Config::default(),
+        };
+
+        let cancellation = RequestCancellation(cancel_tx);
+        let channel = Channel {
+            to_dispatch,
+            cancellation,
+            next_request_id: Arc::new(AtomicU64::new(0)),
+        };
+
+        (dispatch, channel, server_channel)
+    }
+
+    async fn send_request(
+        channel: &mut Channel<String, String>,
+        request: &str,
+    ) -> DispatchResponse<String> {
+        channel
+            .send(context::current(), request.to_string())
+            .await
+            .unwrap()
+    }
+
+    async fn send_response(
+        channel: &mut UnboundedChannel<ClientMessage<String>, Response<String>>,
+        response: Response<String>,
+    ) {
+        channel.send(response).await.unwrap();
+    }
+
+    trait PollTest {
+        type T;
+        fn unwrap(self) -> Poll<Self::T>;
+        fn ready(self) -> Self::T;
+    }
+
+    impl<T, E> PollTest for Poll<Option<Result<T, E>>>
+    where
+        E: ::std::fmt::Display,
+    {
+        type T = Option<T>;
+
+        fn unwrap(self) -> Poll<Option<T>> {
+            match self {
+                Poll::Ready(Some(Ok(t))) => Poll::Ready(Some(t)),
+                Poll::Ready(None) => Poll::Ready(None),
+                Poll::Ready(Some(Err(e))) => panic!(e.to_string()),
+                Poll::Pending => Poll::Pending,
+            }
+        }
+
+        fn ready(self) -> Option<T> {
+            match self {
+                Poll::Ready(Some(Ok(t))) => Some(t),
+                Poll::Ready(None) => None,
+                Poll::Ready(Some(Err(e))) => panic!(e.to_string()),
+                Poll::Pending => panic!("Pending"),
+            }
+        }
+    }
+}

tarpc/src/rpc/context.rs

@@ -0,0 +1,63 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+//! Provides a request context that carries a deadline and trace context. This context is sent from
+//! client to server and is used by the server to enforce response deadlines.
+
+use crate::trace::{self, TraceId};
+use static_assertions::assert_impl_all;
+use std::time::{Duration, SystemTime};
+
+/// A request context that carries request-scoped information like deadlines and trace information.
+/// It is sent from client to server and is used by the server to enforce response deadlines.
+///
+/// The context should not be stored directly in a server implementation, because the context will
+/// be different for each request in scope.
+#[derive(Clone, Copy, Debug)]
+#[non_exhaustive]
+#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
+pub struct Context {
+    /// When the client expects the request to be complete by. The server should cancel the request
+    /// if it is not complete by this time.
+    #[cfg_attr(
+        feature = "serde1",
+        serde(serialize_with = "crate::util::serde::serialize_epoch_secs")
+    )]
+    #[cfg_attr(
+        feature = "serde1",
+        serde(deserialize_with = "crate::util::serde::deserialize_epoch_secs")
+    )]
+    #[cfg_attr(feature = "serde1", serde(default = "ten_seconds_from_now"))]
+    pub deadline: SystemTime,
+    /// Uniquely identifies requests originating from the same source.
+    /// When a service handles a request by making requests itself, those requests should
+    /// include the same `trace_id` as that included on the original request. This way,
+    /// users can trace related actions across a distributed system.
+    pub trace_context: trace::Context,
+}
+
+assert_impl_all!(Context: Send, Sync);
+
+#[cfg(feature = "serde1")]
+fn ten_seconds_from_now() -> SystemTime {
+    SystemTime::now() + Duration::from_secs(10)
+}
+
+/// Returns the context for the current request, or a default Context if no request is active.
+// TODO: populate Context with request-scoped data, with default fallbacks.
+pub fn current() -> Context {
+    Context {
+        deadline: SystemTime::now() + Duration::from_secs(10),
+        trace_context: trace::Context::new_root(),
+    }
+}
+
+impl Context {
+    /// Returns the ID of the request-scoped trace.
+    pub fn trace_id(&self) -> &TraceId {
+        &self.trace_context.trace_id
+    }
+}

tarpc/src/rpc/server.rs

@@ -0,0 +1,731 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+//! Provides a server that concurrently handles many connections sending multiplexed requests.
+
+use crate::{
+    context, trace, util::Compact, util::TimeUntil, ClientMessage, PollIo, Request, Response,
+    ServerError, Transport,
+};
+use fnv::FnvHashMap;
+use futures::{
+    channel::mpsc,
+    future::{AbortHandle, AbortRegistration, Abortable},
+    prelude::*,
+    ready,
+    stream::Fuse,
+    task::*,
+};
+use humantime::format_rfc3339;
+use log::{debug, trace};
+use pin_project::pin_project;
+use std::{fmt, hash::Hash, io, marker::PhantomData, pin::Pin, time::SystemTime};
+use tokio::time::Timeout;
+
+mod filter;
+#[cfg(test)]
+mod testing;
+mod throttle;
+
+pub use self::{
+    filter::ChannelFilter,
+    throttle::{Throttler, ThrottlerStream},
+};
+
+/// Manages clients, serving multiplexed requests over each connection.
+pub struct Server<Req, Resp> {
+    config: Config,
+    ghost: PhantomData<(Req, Resp)>,
+}
+
+impl<Req, Resp> Default for Server<Req, Resp> {
+    fn default() -> Self {
+        new(Config::default())
+    }
+}
+
+impl<Req, Resp> fmt::Debug for Server<Req, Resp> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(fmt, "Server")
+    }
+}
+
+/// Settings that control the behavior of the server.
+#[derive(Clone, Debug)]
+pub struct Config {
+    /// The number of responses per client that can be buffered server-side before being sent.
+    /// `pending_response_buffer` controls the buffer size of the channel that a server's
+    /// response tasks use to send responses to the client handler task.
+    pub pending_response_buffer: usize,
+}
+
+impl Default for Config {
+    fn default() -> Self {
+        Config {
+            pending_response_buffer: 100,
+        }
+    }
+}
+
+impl Config {
+    /// Returns a channel backed by `transport` and configured with `self`.
+    pub fn channel<Req, Resp, T>(self, transport: T) -> BaseChannel<Req, Resp, T>
+    where
+        T: Transport<Response<Resp>, ClientMessage<Req>>,
+    {
+        BaseChannel::new(self, transport)
+    }
+}
+
+/// Returns a new server with configuration specified `config`.
+pub fn new<Req, Resp>(config: Config) -> Server<Req, Resp> {
+    Server {
+        config,
+        ghost: PhantomData,
+    }
+}
+
+impl<Req, Resp> Server<Req, Resp> {
+    /// Returns the config for this server.
+    pub fn config(&self) -> &Config {
+        &self.config
+    }
+
+    /// Returns a stream of server channels.
+    pub fn incoming<S, T>(self, listener: S) -> impl Stream<Item = BaseChannel<Req, Resp, T>>
+    where
+        S: Stream<Item = T>,
+        T: Transport<Response<Resp>, ClientMessage<Req>>,
+    {
+        listener.map(move |t| BaseChannel::new(self.config.clone(), t))
+    }
+}
+
+/// Basically a Fn(Req) -> impl Future<Output = Resp>;
+pub trait Serve<Req>: Sized + Clone {
+    /// Type of response.
+    type Resp;
+
+    /// Type of response future.
+    type Fut: Future<Output = Self::Resp>;
+
+    /// Responds to a single request.
+    fn serve(self, ctx: context::Context, req: Req) -> Self::Fut;
+}
+
+impl<Req, Resp, Fut, F> Serve<Req> for F
+where
+    F: FnOnce(context::Context, Req) -> Fut + Clone,
+    Fut: Future<Output = Resp>,
+{
+    type Resp = Resp;
+    type Fut = Fut;
+
+    fn serve(self, ctx: context::Context, req: Req) -> Self::Fut {
+        self(ctx, req)
+    }
+}
+
+/// A utility trait enabling a stream to fluently chain a request handler.
+pub trait Handler<C>
+where
+    Self: Sized + Stream<Item = C>,
+    C: Channel,
+{
+    /// Enforces channel per-key limits.
+    fn max_channels_per_key<K, KF>(self, n: u32, keymaker: KF) -> filter::ChannelFilter<Self, K, KF>
+    where
+        K: fmt::Display + Eq + Hash + Clone + Unpin,
+        KF: Fn(&C) -> K,
+    {
+        ChannelFilter::new(self, n, keymaker)
+    }
+
+    /// Caps the number of concurrent requests per channel.
+    fn max_concurrent_requests_per_channel(self, n: usize) -> ThrottlerStream<Self> {
+        ThrottlerStream::new(self, n)
+    }
+
+    /// Responds to all requests with [`server::serve`](Serve).
+    #[cfg(feature = "tokio1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "tokio1")))]
+    fn respond_with<S>(self, server: S) -> Running<Self, S>
+    where
+        S: Serve<C::Req, Resp = C::Resp>,
+    {
+        Running {
+            incoming: self,
+            server,
+        }
+    }
+}
+
+impl<S, C> Handler<C> for S
+where
+    S: Sized + Stream<Item = C>,
+    C: Channel,
+{
+}
+
+/// BaseChannel lifts a Transport to a Channel by tracking in-flight requests.
+#[pin_project]
+pub struct BaseChannel<Req, Resp, T> {
+    config: Config,
+    /// Writes responses to the wire and reads requests off the wire.
+    #[pin]
+    transport: Fuse<T>,
+    /// Number of requests currently being responded to.
+    in_flight_requests: FnvHashMap<u64, AbortHandle>,
+    /// Types the request and response.
+    ghost: PhantomData<(Req, Resp)>,
+}
+
+impl<Req, Resp, T> BaseChannel<Req, Resp, T>
+where
+    T: Transport<Response<Resp>, ClientMessage<Req>>,
+{
+    /// Creates a new channel backed by `transport` and configured with `config`.
+    pub fn new(config: Config, transport: T) -> Self {
+        BaseChannel {
+            config,
+            transport: transport.fuse(),
+            in_flight_requests: FnvHashMap::default(),
+            ghost: PhantomData,
+        }
+    }
+
+    /// Creates a new channel backed by `transport` and configured with the defaults.
+    pub fn with_defaults(transport: T) -> Self {
+        Self::new(Config::default(), transport)
+    }
+
+    /// Returns the inner transport over which messages are sent and received.
+    pub fn get_ref(&self) -> &T {
+        self.transport.get_ref()
+    }
+
+    /// Returns the inner transport over which messages are sent and received.
+    pub fn get_pin_ref(self: Pin<&mut Self>) -> Pin<&mut T> {
+        self.project().transport.get_pin_mut()
+    }
+
+    fn cancel_request(mut self: Pin<&mut Self>, trace_context: &trace::Context, request_id: u64) {
+        // It's possible the request was already completed, so it's fine
+        // if this is None.
+        if let Some(cancel_handle) = self
+            .as_mut()
+            .project()
+            .in_flight_requests
+            .remove(&request_id)
+        {
+            self.as_mut().project().in_flight_requests.compact(0.1);
+
+            cancel_handle.abort();
+            let remaining = self.as_mut().project().in_flight_requests.len();
+            trace!(
+                "[{}] Request canceled. In-flight requests = {}",
+                trace_context.trace_id,
+                remaining,
+            );
+        } else {
+            trace!(
+                "[{}] Received cancellation, but response handler \
+                 is already complete.",
+                trace_context.trace_id,
+            );
+        }
+    }
+}
+
+impl<Req, Resp, T> fmt::Debug for BaseChannel<Req, Resp, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "BaseChannel")
+    }
+}
+
+/// The server end of an open connection with a client, streaming in requests from, and sinking
+/// responses to, the client.
+///
+/// Channels are free to somewhat rely on the assumption that all in-flight requests are eventually
+/// either [cancelled](BaseChannel::cancel_request) or [responded to](Sink::start_send). Safety cannot
+/// rely on this assumption, but it is best for `Channel` users to always account for all outstanding
+/// requests.
+pub trait Channel
+where
+    Self: Transport<Response<<Self as Channel>::Resp>, Request<<Self as Channel>::Req>>,
+{
+    /// Type of request item.
+    type Req;
+
+    /// Type of response sink item.
+    type Resp;
+
+    /// Configuration of the channel.
+    fn config(&self) -> &Config;
+
+    /// Returns the number of in-flight requests over this channel.
+    fn in_flight_requests(self: Pin<&mut Self>) -> usize;
+
+    /// Caps the number of concurrent requests.
+    fn max_concurrent_requests(self, n: usize) -> Throttler<Self>
+    where
+        Self: Sized,
+    {
+        Throttler::new(self, n)
+    }
+
+    /// Tells the Channel that request with ID `request_id` is being handled.
+    /// The request will be tracked until a response with the same ID is sent
+    /// to the Channel.
+    fn start_request(self: Pin<&mut Self>, request_id: u64) -> AbortRegistration;
+
+    /// Respond to requests coming over the channel with `f`. Returns a future that drives the
+    /// responses and resolves when the connection is closed.
+    fn respond_with<S>(self, server: S) -> ClientHandler<Self, S>
+    where
+        S: Serve<Self::Req, Resp = Self::Resp>,
+        Self: Sized,
+    {
+        let (responses_tx, responses) = mpsc::channel(self.config().pending_response_buffer);
+        let responses = responses.fuse();
+
+        ClientHandler {
+            channel: self,
+            server,
+            pending_responses: responses,
+            responses_tx,
+        }
+    }
+}
+
+impl<Req, Resp, T> Stream for BaseChannel<Req, Resp, T>
+where
+    T: Transport<Response<Resp>, ClientMessage<Req>>,
+{
+    type Item = io::Result<Request<Req>>;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> {
+        loop {
+            match ready!(self.as_mut().project().transport.poll_next(cx)?) {
+                Some(message) => match message {
+                    ClientMessage::Request(request) => {
+                        return Poll::Ready(Some(Ok(request)));
+                    }
+                    ClientMessage::Cancel {
+                        trace_context,
+                        request_id,
+                    } => {
+                        self.as_mut().cancel_request(&trace_context, request_id);
+                    }
+                },
+                None => return Poll::Ready(None),
+            }
+        }
+    }
+}
+
+impl<Req, Resp, T> Sink<Response<Resp>> for BaseChannel<Req, Resp, T>
+where
+    T: Transport<Response<Resp>, ClientMessage<Req>>,
+{
+    type Error = io::Error;
+
+    fn poll_ready(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        self.project().transport.poll_ready(cx)
+    }
+
+    fn start_send(mut self: Pin<&mut Self>, response: Response<Resp>) -> Result<(), Self::Error> {
+        if self
+            .as_mut()
+            .project()
+            .in_flight_requests
+            .remove(&response.request_id)
+            .is_some()
+        {
+            self.as_mut().project().in_flight_requests.compact(0.1);
+        }
+
+        self.project().transport.start_send(response)
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        self.project().transport.poll_flush(cx)
+    }
+
+    fn poll_close(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        self.project().transport.poll_close(cx)
+    }
+}
+
+impl<Req, Resp, T> AsRef<T> for BaseChannel<Req, Resp, T> {
+    fn as_ref(&self) -> &T {
+        self.transport.get_ref()
+    }
+}
+
+impl<Req, Resp, T> Channel for BaseChannel<Req, Resp, T>
+where
+    T: Transport<Response<Resp>, ClientMessage<Req>>,
+{
+    type Req = Req;
+    type Resp = Resp;
+
+    fn config(&self) -> &Config {
+        &self.config
+    }
+
+    fn in_flight_requests(mut self: Pin<&mut Self>) -> usize {
+        self.as_mut().project().in_flight_requests.len()
+    }
+
+    fn start_request(self: Pin<&mut Self>, request_id: u64) -> AbortRegistration {
+        let (abort_handle, abort_registration) = AbortHandle::new_pair();
+        assert!(self
+            .project()
+            .in_flight_requests
+            .insert(request_id, abort_handle)
+            .is_none());
+        abort_registration
+    }
+}
+
+/// A running handler serving all requests coming over a channel.
+#[pin_project]
+pub struct ClientHandler<C, S>
+where
+    C: Channel,
+{
+    #[pin]
+    channel: C,
+    /// Responses waiting to be written to the wire.
+    #[pin]
+    pending_responses: Fuse<mpsc::Receiver<(context::Context, Response<C::Resp>)>>,
+    /// Handed out to request handlers to fan in responses.
+    #[pin]
+    responses_tx: mpsc::Sender<(context::Context, Response<C::Resp>)>,
+    /// Server
+    server: S,
+}
+
+impl<C, S> ClientHandler<C, S>
+where
+    C: Channel,
+    S: Serve<C::Req, Resp = C::Resp>,
+{
+    /// Returns the inner channel over which messages are sent and received.
+    pub fn get_pin_channel(self: Pin<&mut Self>) -> Pin<&mut C> {
+        self.project().channel
+    }
+
+    fn pump_read(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> PollIo<RequestHandler<S::Fut, C::Resp>> {
+        match ready!(self.as_mut().project().channel.poll_next(cx)?) {
+            Some(request) => Poll::Ready(Some(Ok(self.handle_request(request)))),
+            None => Poll::Ready(None),
+        }
+    }
+
+    fn pump_write(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        read_half_closed: bool,
+    ) -> PollIo<()> {
+        match self.as_mut().poll_next_response(cx)? {
+            Poll::Ready(Some((ctx, response))) => {
+                trace!(
+                    "[{}] Staging response. In-flight requests = {}.",
+                    ctx.trace_id(),
+                    self.as_mut().project().channel.in_flight_requests(),
+                );
+                self.as_mut().project().channel.start_send(response)?;
+                Poll::Ready(Some(Ok(())))
+            }
+            Poll::Ready(None) => {
+                // Shutdown can't be done before we finish pumping out remaining responses.
+                ready!(self.as_mut().project().channel.poll_flush(cx)?);
+                Poll::Ready(None)
+            }
+            Poll::Pending => {
+                // No more requests to process, so flush any requests buffered in the transport.
+                ready!(self.as_mut().project().channel.poll_flush(cx)?);
+
+                // Being here means there are no staged requests and all written responses are
+                // fully flushed. So, if the read half is closed and there are no in-flight
+                // requests, then we can close the write half.
+                if read_half_closed && self.as_mut().project().channel.in_flight_requests() == 0 {
+                    Poll::Ready(None)
+                } else {
+                    Poll::Pending
+                }
+            }
+        }
+    }
+
+    fn poll_next_response(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> PollIo<(context::Context, Response<C::Resp>)> {
+        // Ensure there's room to write a response.
+        while let Poll::Pending = self.as_mut().project().channel.poll_ready(cx)? {
+            ready!(self.as_mut().project().channel.poll_flush(cx)?);
+        }
+
+        match ready!(self.as_mut().project().pending_responses.poll_next(cx)) {
+            Some((ctx, response)) => Poll::Ready(Some(Ok((ctx, response)))),
+            None => {
+                // This branch likely won't happen, since the ClientHandler is holding a Sender.
+                Poll::Ready(None)
+            }
+        }
+    }
+
+    fn handle_request(
+        mut self: Pin<&mut Self>,
+        request: Request<C::Req>,
+    ) -> RequestHandler<S::Fut, C::Resp> {
+        let request_id = request.id;
+        let deadline = request.context.deadline;
+        let timeout = deadline.time_until();
+        trace!(
+            "[{}] Received request with deadline {} (timeout {:?}).",
+            request.context.trace_id(),
+            format_rfc3339(deadline),
+            timeout,
+        );
+        let ctx = request.context;
+        let request = request.message;
+
+        let response = self.as_mut().project().server.clone().serve(ctx, request);
+        let response = Resp {
+            state: RespState::PollResp,
+            request_id,
+            ctx,
+            deadline,
+            f: tokio::time::timeout(timeout, response),
+            response: None,
+            response_tx: self.as_mut().project().responses_tx.clone(),
+        };
+        let abort_registration = self.as_mut().project().channel.start_request(request_id);
+        RequestHandler {
+            resp: Abortable::new(response, abort_registration),
+        }
+    }
+}
+
+impl<C, S> fmt::Debug for ClientHandler<C, S>
+where
+    C: Channel,
+{
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(fmt, "ClientHandler")
+    }
+}
+
+/// A future fulfilling a single client request.
+#[pin_project]
+pub struct RequestHandler<F, R> {
+    #[pin]
+    resp: Abortable<Resp<F, R>>,
+}
+
+impl<F, R> Future for RequestHandler<F, R>
+where
+    F: Future<Output = R>,
+{
+    type Output = ();
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
+        let _ = ready!(self.project().resp.poll(cx));
+        Poll::Ready(())
+    }
+}
+
+impl<F, R> fmt::Debug for RequestHandler<F, R> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(fmt, "RequestHandler")
+    }
+}
+
+#[pin_project]
+struct Resp<F, R> {
+    state: RespState,
+    request_id: u64,
+    ctx: context::Context,
+    deadline: SystemTime,
+    #[pin]
+    f: Timeout<F>,
+    response: Option<Response<R>>,
+    #[pin]
+    response_tx: mpsc::Sender<(context::Context, Response<R>)>,
+}
+
+#[derive(Debug)]
+#[allow(clippy::enum_variant_names)]
+enum RespState {
+    PollResp,
+    PollReady,
+    PollFlush,
+}
+
+impl<F, R> Future for Resp<F, R>
+where
+    F: Future<Output = R>,
+{
+    type Output = ();
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
+        loop {
+            match self.as_mut().project().state {
+                RespState::PollResp => {
+                    let result = ready!(self.as_mut().project().f.poll(cx));
+                    *self.as_mut().project().response = Some(Response {
+                        request_id: self.request_id,
+                        message: match result {
+                            Ok(message) => Ok(message),
+                            Err(tokio::time::error::Elapsed { .. }) => {
+                                debug!(
+                                    "[{}] Response did not complete before deadline of {}s.",
+                                    self.ctx.trace_id(),
+                                    format_rfc3339(self.deadline)
+                                );
+                                // No point in responding, since the client will have dropped the
+                                // request.
+                                Err(ServerError {
+                                    kind: io::ErrorKind::TimedOut,
+                                    detail: Some(format!(
+                                        "Response did not complete before deadline of {}s.",
+                                        format_rfc3339(self.deadline)
+                                    )),
+                                })
+                            }
+                        },
+                    });
+                    *self.as_mut().project().state = RespState::PollReady;
+                }
+                RespState::PollReady => {
+                    let ready = ready!(self.as_mut().project().response_tx.poll_ready(cx));
+                    if ready.is_err() {
+                        return Poll::Ready(());
+                    }
+                    let resp = (self.ctx, self.as_mut().project().response.take().unwrap());
+                    if self
+                        .as_mut()
+                        .project()
+                        .response_tx
+                        .start_send(resp)
+                        .is_err()
+                    {
+                        return Poll::Ready(());
+                    }
+                    *self.as_mut().project().state = RespState::PollFlush;
+                }
+                RespState::PollFlush => {
+                    let ready = ready!(self.as_mut().project().response_tx.poll_flush(cx));
+                    if ready.is_err() {
+                        return Poll::Ready(());
+                    }
+                    return Poll::Ready(());
+                }
+            }
+        }
+    }
+}
+
+impl<F, R> fmt::Debug for Resp<F, R> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(fmt, "Resp")
+    }
+}
+
+impl<C, S> Stream for ClientHandler<C, S>
+where
+    C: Channel,
+    S: Serve<C::Req, Resp = C::Resp>,
+{
+    type Item = io::Result<RequestHandler<S::Fut, C::Resp>>;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        loop {
+            let read = self.as_mut().pump_read(cx)?;
+            let read_closed = matches!(read, Poll::Ready(None));
+            match (read, self.as_mut().pump_write(cx, read_closed)?) {
+                (Poll::Ready(None), Poll::Ready(None)) => {
+                    return Poll::Ready(None);
+                }
+                (Poll::Ready(Some(request_handler)), _) => {
+                    return Poll::Ready(Some(Ok(request_handler)));
+                }
+                (_, Poll::Ready(Some(()))) => {}
+                _ => {
+                    return Poll::Pending;
+                }
+            }
+        }
+    }
+}
+
+// Send + 'static execution helper methods.
+
+impl<C, S> ClientHandler<C, S>
+where
+    C: Channel + 'static,
+    C::Req: Send + 'static,
+    C::Resp: Send + 'static,
+    S: Serve<C::Req, Resp = C::Resp> + Send + 'static,
+    S::Fut: Send + 'static,
+{
+    /// Runs the client handler until completion by [spawning](tokio::spawn) each
+    /// request handler onto the default executor.
+    #[cfg(feature = "tokio1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "tokio1")))]
+    pub fn execute(self) -> impl Future<Output = ()> {
+        self.try_for_each(|request_handler| async {
+            tokio::spawn(request_handler);
+            Ok(())
+        })
+        .map_ok(|()| log::info!("ClientHandler finished."))
+        .unwrap_or_else(|e| log::info!("ClientHandler errored out: {}", e))
+    }
+}
+
+/// A future that drives the server by [spawning](tokio::spawn) channels and request handlers on the default
+/// executor.
+#[pin_project]
+#[derive(Debug)]
+#[cfg(feature = "tokio1")]
+#[cfg_attr(docsrs, doc(cfg(feature = "tokio1")))]
+pub struct Running<St, Se> {
+    #[pin]
+    incoming: St,
+    server: Se,
+}
+
+#[cfg(feature = "tokio1")]
+impl<St, C, Se> Future for Running<St, Se>
+where
+    St: Sized + Stream<Item = C>,
+    C: Channel + Send + 'static,
+    C::Req: Send + 'static,
+    C::Resp: Send + 'static,
+    Se: Serve<C::Req, Resp = C::Resp> + Send + 'static + Clone,
+    Se::Fut: Send + 'static,
+{
+    type Output = ();
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
+        while let Some(channel) = ready!(self.as_mut().project().incoming.poll_next(cx)) {
+            tokio::spawn(
+                channel
+                    .respond_with(self.as_mut().project().server.clone())
+                    .execute(),
+            );
+        }
+        log::info!("Server shutting down.");
+        Poll::Ready(())
+    }
+}

tarpc/src/rpc/server/filter.rs

@@ -0,0 +1,471 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+use crate::{
+    server::{self, Channel},
+    util::Compact,
+};
+use fnv::FnvHashMap;
+use futures::{channel::mpsc, future::AbortRegistration, prelude::*, ready, stream::Fuse, task::*};
+use log::{debug, info, trace};
+use pin_project::pin_project;
+use std::sync::{Arc, Weak};
+use std::{
+    collections::hash_map::Entry, convert::TryInto, fmt, hash::Hash, marker::Unpin, pin::Pin,
+};
+
+/// A single-threaded filter that drops channels based on per-key limits.
+#[pin_project]
+#[derive(Debug)]
+pub struct ChannelFilter<S, K, F>
+where
+    K: Eq + Hash,
+{
+    #[pin]
+    listener: Fuse<S>,
+    channels_per_key: u32,
+    #[pin]
+    dropped_keys: mpsc::UnboundedReceiver<K>,
+    #[pin]
+    dropped_keys_tx: mpsc::UnboundedSender<K>,
+    key_counts: FnvHashMap<K, Weak<Tracker<K>>>,
+    keymaker: F,
+}
+
+/// A channel that is tracked by a ChannelFilter.
+#[pin_project]
+#[derive(Debug)]
+pub struct TrackedChannel<C, K> {
+    #[pin]
+    inner: C,
+    tracker: Arc<Tracker<K>>,
+}
+
+#[derive(Debug)]
+struct Tracker<K> {
+    key: Option<K>,
+    dropped_keys: mpsc::UnboundedSender<K>,
+}
+
+impl<K> Drop for Tracker<K> {
+    fn drop(&mut self) {
+        // Don't care if the listener is dropped.
+        let _ = self.dropped_keys.unbounded_send(self.key.take().unwrap());
+    }
+}
+
+impl<C, K> Stream for TrackedChannel<C, K>
+where
+    C: Stream,
+{
+    type Item = <C as Stream>::Item;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> {
+        self.channel().poll_next(cx)
+    }
+}
+
+impl<C, I, K> Sink<I> for TrackedChannel<C, K>
+where
+    C: Sink<I>,
+{
+    type Error = C::Error;
+
+    fn poll_ready(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        self.channel().poll_ready(cx)
+    }
+
+    fn start_send(self: Pin<&mut Self>, item: I) -> Result<(), Self::Error> {
+        self.channel().start_send(item)
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        self.channel().poll_flush(cx)
+    }
+
+    fn poll_close(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        self.channel().poll_close(cx)
+    }
+}
+
+impl<C, K> AsRef<C> for TrackedChannel<C, K> {
+    fn as_ref(&self) -> &C {
+        &self.inner
+    }
+}
+
+impl<C, K> Channel for TrackedChannel<C, K>
+where
+    C: Channel,
+{
+    type Req = C::Req;
+    type Resp = C::Resp;
+
+    fn config(&self) -> &server::Config {
+        self.inner.config()
+    }
+
+    fn in_flight_requests(self: Pin<&mut Self>) -> usize {
+        self.project().inner.in_flight_requests()
+    }
+
+    fn start_request(self: Pin<&mut Self>, request_id: u64) -> AbortRegistration {
+        self.project().inner.start_request(request_id)
+    }
+}
+
+impl<C, K> TrackedChannel<C, K> {
+    /// Returns the inner channel.
+    pub fn get_ref(&self) -> &C {
+        &self.inner
+    }
+
+    /// Returns the pinned inner channel.
+    fn channel<'a>(self: Pin<&'a mut Self>) -> Pin<&'a mut C> {
+        self.project().inner
+    }
+}
+
+impl<S, K, F> ChannelFilter<S, K, F>
+where
+    K: Eq + Hash,
+    S: Stream,
+    F: Fn(&S::Item) -> K,
+{
+    /// Sheds new channels to stay under configured limits.
+    pub(crate) fn new(listener: S, channels_per_key: u32, keymaker: F) -> Self {
+        let (dropped_keys_tx, dropped_keys) = mpsc::unbounded();
+        ChannelFilter {
+            listener: listener.fuse(),
+            channels_per_key,
+            dropped_keys,
+            dropped_keys_tx,
+            key_counts: FnvHashMap::default(),
+            keymaker,
+        }
+    }
+}
+
+impl<S, K, F> ChannelFilter<S, K, F>
+where
+    S: Stream,
+    K: fmt::Display + Eq + Hash + Clone + Unpin,
+    F: Fn(&S::Item) -> K,
+{
+    fn handle_new_channel(
+        mut self: Pin<&mut Self>,
+        stream: S::Item,
+    ) -> Result<TrackedChannel<S::Item, K>, K> {
+        let key = (self.as_mut().keymaker)(&stream);
+        let tracker = self.as_mut().increment_channels_for_key(key.clone())?;
+
+        trace!(
+            "[{}] Opening channel ({}/{}) channels for key.",
+            key,
+            Arc::strong_count(&tracker),
+            self.as_mut().project().channels_per_key
+        );
+
+        Ok(TrackedChannel {
+            tracker,
+            inner: stream,
+        })
+    }
+
+    fn increment_channels_for_key(mut self: Pin<&mut Self>, key: K) -> Result<Arc<Tracker<K>>, K> {
+        let channels_per_key = self.channels_per_key;
+        let dropped_keys = self.dropped_keys_tx.clone();
+        let key_counts = &mut self.as_mut().project().key_counts;
+        match key_counts.entry(key.clone()) {
+            Entry::Vacant(vacant) => {
+                let tracker = Arc::new(Tracker {
+                    key: Some(key),
+                    dropped_keys,
+                });
+
+                vacant.insert(Arc::downgrade(&tracker));
+                Ok(tracker)
+            }
+            Entry::Occupied(mut o) => {
+                let count = o.get().strong_count();
+                if count >= channels_per_key.try_into().unwrap() {
+                    info!(
+                        "[{}] Opened max channels from key ({}/{}).",
+                        key, count, channels_per_key
+                    );
+                    Err(key)
+                } else {
+                    Ok(o.get().upgrade().unwrap_or_else(|| {
+                        let tracker = Arc::new(Tracker {
+                            key: Some(key),
+                            dropped_keys,
+                        });
+
+                        *o.get_mut() = Arc::downgrade(&tracker);
+                        tracker
+                    }))
+                }
+            }
+        }
+    }
+
+    fn poll_listener(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Option<Result<TrackedChannel<S::Item, K>, K>>> {
+        match ready!(self.as_mut().project().listener.poll_next_unpin(cx)) {
+            Some(codec) => Poll::Ready(Some(self.handle_new_channel(codec))),
+            None => Poll::Ready(None),
+        }
+    }
+
+    fn poll_closed_channels(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
+        match ready!(self.as_mut().project().dropped_keys.poll_next_unpin(cx)) {
+            Some(key) => {
+                debug!("All channels dropped for key [{}]", key);
+                self.as_mut().project().key_counts.remove(&key);
+                self.as_mut().project().key_counts.compact(0.1);
+                Poll::Ready(())
+            }
+            None => unreachable!("Holding a copy of closed_channels and didn't close it."),
+        }
+    }
+}
+
+impl<S, K, F> Stream for ChannelFilter<S, K, F>
+where
+    S: Stream,
+    K: fmt::Display + Eq + Hash + Clone + Unpin,
+    F: Fn(&S::Item) -> K,
+{
+    type Item = TrackedChannel<S::Item, K>;
+
+    fn poll_next(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Option<TrackedChannel<S::Item, K>>> {
+        loop {
+            match (
+                self.as_mut().poll_listener(cx),
+                self.as_mut().poll_closed_channels(cx),
+            ) {
+                (Poll::Ready(Some(Ok(channel))), _) => {
+                    return Poll::Ready(Some(channel));
+                }
+                (Poll::Ready(Some(Err(_))), _) => {
+                    continue;
+                }
+                (_, Poll::Ready(())) => continue,
+                (Poll::Pending, Poll::Pending) => return Poll::Pending,
+                (Poll::Ready(None), Poll::Pending) => {
+                    trace!("Shutting down listener.");
+                    return Poll::Ready(None);
+                }
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+fn ctx() -> Context<'static> {
+    use futures::task::*;
+
+    Context::from_waker(&noop_waker_ref())
+}
+
+#[test]
+fn tracker_drop() {
+    use assert_matches::assert_matches;
+
+    let (tx, mut rx) = mpsc::unbounded();
+    Tracker {
+        key: Some(1),
+        dropped_keys: tx,
+    };
+    assert_matches!(rx.try_next(), Ok(Some(1)));
+}
+
+#[test]
+fn tracked_channel_stream() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    let (chan_tx, chan) = mpsc::unbounded();
+    let (dropped_keys, _) = mpsc::unbounded();
+    let channel = TrackedChannel {
+        inner: chan,
+        tracker: Arc::new(Tracker {
+            key: Some(1),
+            dropped_keys,
+        }),
+    };
+
+    chan_tx.unbounded_send("test").unwrap();
+    pin_mut!(channel);
+    assert_matches!(channel.poll_next(&mut ctx()), Poll::Ready(Some("test")));
+}
+
+#[test]
+fn tracked_channel_sink() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    let (chan, mut chan_rx) = mpsc::unbounded();
+    let (dropped_keys, _) = mpsc::unbounded();
+    let channel = TrackedChannel {
+        inner: chan,
+        tracker: Arc::new(Tracker {
+            key: Some(1),
+            dropped_keys,
+        }),
+    };
+
+    pin_mut!(channel);
+    assert_matches!(channel.as_mut().poll_ready(&mut ctx()), Poll::Ready(Ok(())));
+    assert_matches!(channel.as_mut().start_send("test"), Ok(()));
+    assert_matches!(channel.as_mut().poll_flush(&mut ctx()), Poll::Ready(Ok(())));
+    assert_matches!(chan_rx.try_next(), Ok(Some("test")));
+}
+
+#[test]
+fn channel_filter_increment_channels_for_key() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    struct TestChannel {
+        key: &'static str,
+    }
+    let (_, listener) = mpsc::unbounded();
+    let filter = ChannelFilter::new(listener, 2, |chan: &TestChannel| chan.key);
+    pin_mut!(filter);
+    let tracker1 = filter.as_mut().increment_channels_for_key("key").unwrap();
+    assert_eq!(Arc::strong_count(&tracker1), 1);
+    let tracker2 = filter.as_mut().increment_channels_for_key("key").unwrap();
+    assert_eq!(Arc::strong_count(&tracker1), 2);
+    assert_matches!(filter.increment_channels_for_key("key"), Err("key"));
+    drop(tracker2);
+    assert_eq!(Arc::strong_count(&tracker1), 1);
+}
+
+#[test]
+fn channel_filter_handle_new_channel() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    #[derive(Debug)]
+    struct TestChannel {
+        key: &'static str,
+    }
+    let (_, listener) = mpsc::unbounded();
+    let filter = ChannelFilter::new(listener, 2, |chan: &TestChannel| chan.key);
+    pin_mut!(filter);
+    let channel1 = filter
+        .as_mut()
+        .handle_new_channel(TestChannel { key: "key" })
+        .unwrap();
+    assert_eq!(Arc::strong_count(&channel1.tracker), 1);
+
+    let channel2 = filter
+        .as_mut()
+        .handle_new_channel(TestChannel { key: "key" })
+        .unwrap();
+    assert_eq!(Arc::strong_count(&channel1.tracker), 2);
+
+    assert_matches!(
+        filter.handle_new_channel(TestChannel { key: "key" }),
+        Err("key")
+    );
+    drop(channel2);
+    assert_eq!(Arc::strong_count(&channel1.tracker), 1);
+}
+
+#[test]
+fn channel_filter_poll_listener() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    #[derive(Debug)]
+    struct TestChannel {
+        key: &'static str,
+    }
+    let (new_channels, listener) = mpsc::unbounded();
+    let filter = ChannelFilter::new(listener, 2, |chan: &TestChannel| chan.key);
+    pin_mut!(filter);
+
+    new_channels
+        .unbounded_send(TestChannel { key: "key" })
+        .unwrap();
+    let channel1 =
+        assert_matches!(filter.as_mut().poll_listener(&mut ctx()), Poll::Ready(Some(Ok(c))) => c);
+    assert_eq!(Arc::strong_count(&channel1.tracker), 1);
+
+    new_channels
+        .unbounded_send(TestChannel { key: "key" })
+        .unwrap();
+    let _channel2 =
+        assert_matches!(filter.as_mut().poll_listener(&mut ctx()), Poll::Ready(Some(Ok(c))) => c);
+    assert_eq!(Arc::strong_count(&channel1.tracker), 2);
+
+    new_channels
+        .unbounded_send(TestChannel { key: "key" })
+        .unwrap();
+    let key =
+        assert_matches!(filter.as_mut().poll_listener(&mut ctx()), Poll::Ready(Some(Err(k))) => k);
+    assert_eq!(key, "key");
+    assert_eq!(Arc::strong_count(&channel1.tracker), 2);
+}
+
+#[test]
+fn channel_filter_poll_closed_channels() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    #[derive(Debug)]
+    struct TestChannel {
+        key: &'static str,
+    }
+    let (new_channels, listener) = mpsc::unbounded();
+    let filter = ChannelFilter::new(listener, 2, |chan: &TestChannel| chan.key);
+    pin_mut!(filter);
+
+    new_channels
+        .unbounded_send(TestChannel { key: "key" })
+        .unwrap();
+    let channel =
+        assert_matches!(filter.as_mut().poll_listener(&mut ctx()), Poll::Ready(Some(Ok(c))) => c);
+    assert_eq!(filter.key_counts.len(), 1);
+
+    drop(channel);
+    assert_matches!(
+        filter.as_mut().poll_closed_channels(&mut ctx()),
+        Poll::Ready(())
+    );
+    assert!(filter.key_counts.is_empty());
+}
+
+#[test]
+fn channel_filter_stream() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    #[derive(Debug)]
+    struct TestChannel {
+        key: &'static str,
+    }
+    let (new_channels, listener) = mpsc::unbounded();
+    let filter = ChannelFilter::new(listener, 2, |chan: &TestChannel| chan.key);
+    pin_mut!(filter);
+
+    new_channels
+        .unbounded_send(TestChannel { key: "key" })
+        .unwrap();
+    let channel = assert_matches!(filter.as_mut().poll_next(&mut ctx()), Poll::Ready(Some(c)) => c);
+    assert_eq!(filter.key_counts.len(), 1);
+
+    drop(channel);
+    assert_matches!(filter.as_mut().poll_next(&mut ctx()), Poll::Pending);
+    assert!(filter.key_counts.is_empty());
+}

tarpc/src/rpc/server/testing.rs

@@ -0,0 +1,126 @@
+// Copyright 2020 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+use crate::server::{Channel, Config};
+use crate::{context, Request, Response};
+use fnv::FnvHashSet;
+use futures::{
+    future::{AbortHandle, AbortRegistration},
+    task::*,
+    Sink, Stream,
+};
+use pin_project::pin_project;
+use std::collections::VecDeque;
+use std::io;
+use std::pin::Pin;
+use std::time::SystemTime;
+
+#[pin_project]
+pub(crate) struct FakeChannel<In, Out> {
+    #[pin]
+    pub stream: VecDeque<In>,
+    #[pin]
+    pub sink: VecDeque<Out>,
+    pub config: Config,
+    pub in_flight_requests: FnvHashSet<u64>,
+}
+
+impl<In, Out> Stream for FakeChannel<In, Out>
+where
+    In: Unpin,
+{
+    type Item = In;
+
+    fn poll_next(self: Pin<&mut Self>, _cx: &mut Context) -> Poll<Option<Self::Item>> {
+        Poll::Ready(self.project().stream.pop_front())
+    }
+}
+
+impl<In, Resp> Sink<Response<Resp>> for FakeChannel<In, Response<Resp>> {
+    type Error = io::Error;
+
+    fn poll_ready(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        self.project().sink.poll_ready(cx).map_err(|e| match e {})
+    }
+
+    fn start_send(mut self: Pin<&mut Self>, response: Response<Resp>) -> Result<(), Self::Error> {
+        self.as_mut()
+            .project()
+            .in_flight_requests
+            .remove(&response.request_id);
+        self.project()
+            .sink
+            .start_send(response)
+            .map_err(|e| match e {})
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        self.project().sink.poll_flush(cx).map_err(|e| match e {})
+    }
+
+    fn poll_close(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        self.project().sink.poll_close(cx).map_err(|e| match e {})
+    }
+}
+
+impl<Req, Resp> Channel for FakeChannel<io::Result<Request<Req>>, Response<Resp>>
+where
+    Req: Unpin,
+{
+    type Req = Req;
+    type Resp = Resp;
+
+    fn config(&self) -> &Config {
+        &self.config
+    }
+
+    fn in_flight_requests(self: Pin<&mut Self>) -> usize {
+        self.in_flight_requests.len()
+    }
+
+    fn start_request(self: Pin<&mut Self>, id: u64) -> AbortRegistration {
+        self.project().in_flight_requests.insert(id);
+        AbortHandle::new_pair().1
+    }
+}
+
+impl<Req, Resp> FakeChannel<io::Result<Request<Req>>, Response<Resp>> {
+    pub fn push_req(&mut self, id: u64, message: Req) {
+        self.stream.push_back(Ok(Request {
+            context: context::Context {
+                deadline: SystemTime::UNIX_EPOCH,
+                trace_context: Default::default(),
+            },
+            id,
+            message,
+        }));
+    }
+}
+
+impl FakeChannel<(), ()> {
+    pub fn default<Req, Resp>() -> FakeChannel<io::Result<Request<Req>>, Response<Resp>> {
+        FakeChannel {
+            stream: Default::default(),
+            sink: Default::default(),
+            config: Default::default(),
+            in_flight_requests: Default::default(),
+        }
+    }
+}
+
+pub trait PollExt {
+    fn is_done(&self) -> bool;
+}
+
+impl<T> PollExt for Poll<Option<T>> {
+    fn is_done(&self) -> bool {
+        matches!(self, Poll::Ready(None))
+    }
+}
+
+pub fn cx() -> Context<'static> {
+    Context::from_waker(&noop_waker_ref())
+}

tarpc/src/rpc/server/throttle.rs

@@ -0,0 +1,328 @@
+// Copyright 2020 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+use super::{Channel, Config};
+use crate::{Response, ServerError};
+use futures::{future::AbortRegistration, prelude::*, ready, task::*};
+use log::debug;
+use pin_project::pin_project;
+use std::{io, pin::Pin};
+
+/// A [`Channel`] that limits the number of concurrent
+/// requests by throttling.
+#[pin_project]
+#[derive(Debug)]
+pub struct Throttler<C> {
+    max_in_flight_requests: usize,
+    #[pin]
+    inner: C,
+}
+
+impl<C> Throttler<C> {
+    /// Returns the inner channel.
+    pub fn get_ref(&self) -> &C {
+        &self.inner
+    }
+}
+
+impl<C> Throttler<C>
+where
+    C: Channel,
+{
+    /// Returns a new `Throttler` that wraps the given channel and limits concurrent requests to
+    /// `max_in_flight_requests`.
+    pub fn new(inner: C, max_in_flight_requests: usize) -> Self {
+        Throttler {
+            inner,
+            max_in_flight_requests,
+        }
+    }
+}
+
+impl<C> Stream for Throttler<C>
+where
+    C: Channel,
+{
+    type Item = <C as Stream>::Item;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> {
+        while self.as_mut().in_flight_requests() >= *self.as_mut().project().max_in_flight_requests
+        {
+            ready!(self.as_mut().project().inner.poll_ready(cx)?);
+
+            match ready!(self.as_mut().project().inner.poll_next(cx)?) {
+                Some(request) => {
+                    debug!(
+                        "[{}] Client has reached in-flight request limit ({}/{}).",
+                        request.context.trace_id(),
+                        self.as_mut().in_flight_requests(),
+                        self.as_mut().project().max_in_flight_requests,
+                    );
+
+                    self.as_mut().start_send(Response {
+                        request_id: request.id,
+                        message: Err(ServerError {
+                            kind: io::ErrorKind::WouldBlock,
+                            detail: Some("Server throttled the request.".into()),
+                        }),
+                    })?;
+                }
+                None => return Poll::Ready(None),
+            }
+        }
+        self.project().inner.poll_next(cx)
+    }
+}
+
+impl<C> Sink<Response<<C as Channel>::Resp>> for Throttler<C>
+where
+    C: Channel,
+{
+    type Error = io::Error;
+
+    fn poll_ready(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        self.project().inner.poll_ready(cx)
+    }
+
+    fn start_send(self: Pin<&mut Self>, item: Response<<C as Channel>::Resp>) -> io::Result<()> {
+        self.project().inner.start_send(item)
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context) -> Poll<io::Result<()>> {
+        self.project().inner.poll_flush(cx)
+    }
+
+    fn poll_close(self: Pin<&mut Self>, cx: &mut Context) -> Poll<io::Result<()>> {
+        self.project().inner.poll_close(cx)
+    }
+}
+
+impl<C> AsRef<C> for Throttler<C> {
+    fn as_ref(&self) -> &C {
+        &self.inner
+    }
+}
+
+impl<C> Channel for Throttler<C>
+where
+    C: Channel,
+{
+    type Req = <C as Channel>::Req;
+    type Resp = <C as Channel>::Resp;
+
+    fn in_flight_requests(self: Pin<&mut Self>) -> usize {
+        self.project().inner.in_flight_requests()
+    }
+
+    fn config(&self) -> &Config {
+        self.inner.config()
+    }
+
+    fn start_request(self: Pin<&mut Self>, request_id: u64) -> AbortRegistration {
+        self.project().inner.start_request(request_id)
+    }
+}
+
+/// A stream of throttling channels.
+#[pin_project]
+#[derive(Debug)]
+pub struct ThrottlerStream<S> {
+    #[pin]
+    inner: S,
+    max_in_flight_requests: usize,
+}
+
+impl<S> ThrottlerStream<S>
+where
+    S: Stream,
+    <S as Stream>::Item: Channel,
+{
+    pub(crate) fn new(inner: S, max_in_flight_requests: usize) -> Self {
+        Self {
+            inner,
+            max_in_flight_requests,
+        }
+    }
+}
+
+impl<S> Stream for ThrottlerStream<S>
+where
+    S: Stream,
+    <S as Stream>::Item: Channel,
+{
+    type Item = Throttler<<S as Stream>::Item>;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> {
+        match ready!(self.as_mut().project().inner.poll_next(cx)) {
+            Some(channel) => Poll::Ready(Some(Throttler::new(
+                channel,
+                *self.project().max_in_flight_requests,
+            ))),
+            None => Poll::Ready(None),
+        }
+    }
+}
+
+#[cfg(test)]
+use super::testing::{self, FakeChannel, PollExt};
+#[cfg(test)]
+use crate::Request;
+#[cfg(test)]
+use pin_utils::pin_mut;
+#[cfg(test)]
+use std::marker::PhantomData;
+
+#[test]
+fn throttler_in_flight_requests() {
+    let throttler = Throttler {
+        max_in_flight_requests: 0,
+        inner: FakeChannel::default::<isize, isize>(),
+    };
+
+    pin_mut!(throttler);
+    for i in 0..5 {
+        throttler.inner.in_flight_requests.insert(i);
+    }
+    assert_eq!(throttler.as_mut().in_flight_requests(), 5);
+}
+
+#[test]
+fn throttler_start_request() {
+    let throttler = Throttler {
+        max_in_flight_requests: 0,
+        inner: FakeChannel::default::<isize, isize>(),
+    };
+
+    pin_mut!(throttler);
+    throttler.as_mut().start_request(1);
+    assert_eq!(throttler.inner.in_flight_requests.len(), 1);
+}
+
+#[test]
+fn throttler_poll_next_done() {
+    let throttler = Throttler {
+        max_in_flight_requests: 0,
+        inner: FakeChannel::default::<isize, isize>(),
+    };
+
+    pin_mut!(throttler);
+    assert!(throttler.as_mut().poll_next(&mut testing::cx()).is_done());
+}
+
+#[test]
+fn throttler_poll_next_some() -> io::Result<()> {
+    let throttler = Throttler {
+        max_in_flight_requests: 1,
+        inner: FakeChannel::default::<isize, isize>(),
+    };
+
+    pin_mut!(throttler);
+    throttler.inner.push_req(0, 1);
+    assert!(throttler.as_mut().poll_ready(&mut testing::cx()).is_ready());
+    assert_eq!(
+        throttler
+            .as_mut()
+            .poll_next(&mut testing::cx())?
+            .map(|r| r.map(|r| (r.id, r.message))),
+        Poll::Ready(Some((0, 1)))
+    );
+    Ok(())
+}
+
+#[test]
+fn throttler_poll_next_throttled() {
+    let throttler = Throttler {
+        max_in_flight_requests: 0,
+        inner: FakeChannel::default::<isize, isize>(),
+    };
+
+    pin_mut!(throttler);
+    throttler.inner.push_req(1, 1);
+    assert!(throttler.as_mut().poll_next(&mut testing::cx()).is_done());
+    assert_eq!(throttler.inner.sink.len(), 1);
+    let resp = throttler.inner.sink.get(0).unwrap();
+    assert_eq!(resp.request_id, 1);
+    assert!(resp.message.is_err());
+}
+
+#[test]
+fn throttler_poll_next_throttled_sink_not_ready() {
+    let throttler = Throttler {
+        max_in_flight_requests: 0,
+        inner: PendingSink::default::<isize, isize>(),
+    };
+    pin_mut!(throttler);
+    assert!(throttler.poll_next(&mut testing::cx()).is_pending());
+
+    struct PendingSink<In, Out> {
+        ghost: PhantomData<fn(Out) -> In>,
+    }
+    impl PendingSink<(), ()> {
+        pub fn default<Req, Resp>() -> PendingSink<io::Result<Request<Req>>, Response<Resp>> {
+            PendingSink { ghost: PhantomData }
+        }
+    }
+    impl<In, Out> Stream for PendingSink<In, Out> {
+        type Item = In;
+        fn poll_next(self: Pin<&mut Self>, _: &mut Context) -> Poll<Option<Self::Item>> {
+            unimplemented!()
+        }
+    }
+    impl<In, Out> Sink<Out> for PendingSink<In, Out> {
+        type Error = io::Error;
+        fn poll_ready(self: Pin<&mut Self>, _: &mut Context) -> Poll<Result<(), Self::Error>> {
+            Poll::Pending
+        }
+        fn start_send(self: Pin<&mut Self>, _: Out) -> Result<(), Self::Error> {
+            Err(io::Error::from(io::ErrorKind::WouldBlock))
+        }
+        fn poll_flush(self: Pin<&mut Self>, _: &mut Context) -> Poll<Result<(), Self::Error>> {
+            Poll::Pending
+        }
+        fn poll_close(self: Pin<&mut Self>, _: &mut Context) -> Poll<Result<(), Self::Error>> {
+            Poll::Pending
+        }
+    }
+    impl<Req, Resp> Channel for PendingSink<io::Result<Request<Req>>, Response<Resp>> {
+        type Req = Req;
+        type Resp = Resp;
+        fn config(&self) -> &Config {
+            unimplemented!()
+        }
+        fn in_flight_requests(self: Pin<&mut Self>) -> usize {
+            0
+        }
+        fn start_request(self: Pin<&mut Self>, _: u64) -> AbortRegistration {
+            unimplemented!()
+        }
+    }
+}
+
+#[test]
+fn throttler_start_send() {
+    let throttler = Throttler {
+        max_in_flight_requests: 0,
+        inner: FakeChannel::default::<isize, isize>(),
+    };
+
+    pin_mut!(throttler);
+    throttler.inner.in_flight_requests.insert(0);
+    throttler
+        .as_mut()
+        .start_send(Response {
+            request_id: 0,
+            message: Ok(1),
+        })
+        .unwrap();
+    assert!(throttler.inner.in_flight_requests.is_empty());
+    assert_eq!(
+        throttler.inner.sink.get(0),
+        Some(&Response {
+            request_id: 0,
+            message: Ok(1),
+        })
+    );
+}

tarpc/src/rpc/transport.rs

@@ -0,0 +1,30 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+//! Provides a [`Transport`](sealed::Transport) trait as well as implementations.
+//!
+//! The rpc crate is transport- and protocol-agnostic. Any transport that impls [`Transport`](sealed::Transport)
+//! can be plugged in, using whatever protocol it wants.
+
+use futures::prelude::*;
+use std::io;
+
+pub mod channel;
+
+pub(crate) mod sealed {
+    use super::*;
+
+    /// A bidirectional stream ([`Sink`] + [`Stream`]) of messages.
+    pub trait Transport<SinkItem, Item>:
+        Stream<Item = io::Result<Item>> + Sink<SinkItem, Error = io::Error>
+    {
+    }
+
+    impl<T, SinkItem, Item> Transport<SinkItem, Item> for T where
+        T: Stream<Item = io::Result<Item>> + Sink<SinkItem, Error = io::Error> + ?Sized
+    {
+    }
+}

tarpc/src/rpc/transport/channel.rs

@@ -0,0 +1,123 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+//! Transports backed by in-memory channels.
+
+use crate::PollIo;
+use futures::{channel::mpsc, task::*, Sink, Stream};
+use pin_project::pin_project;
+use std::io;
+use std::pin::Pin;
+
+/// Returns two unbounded channel peers. Each [`Stream`] yields items sent through the other's
+/// [`Sink`].
+pub fn unbounded<SinkItem, Item>() -> (
+    UnboundedChannel<SinkItem, Item>,
+    UnboundedChannel<Item, SinkItem>,
+) {
+    let (tx1, rx2) = mpsc::unbounded();
+    let (tx2, rx1) = mpsc::unbounded();
+    (
+        UnboundedChannel { tx: tx1, rx: rx1 },
+        UnboundedChannel { tx: tx2, rx: rx2 },
+    )
+}
+
+/// A bi-directional channel backed by an [`UnboundedSender`](mpsc::UnboundedSender)
+/// and [`UnboundedReceiver`](mpsc::UnboundedReceiver).
+#[pin_project]
+#[derive(Debug)]
+pub struct UnboundedChannel<Item, SinkItem> {
+    #[pin]
+    rx: mpsc::UnboundedReceiver<Item>,
+    #[pin]
+    tx: mpsc::UnboundedSender<SinkItem>,
+}
+
+impl<Item, SinkItem> Stream for UnboundedChannel<Item, SinkItem> {
+    type Item = Result<Item, io::Error>;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> PollIo<Item> {
+        self.project().rx.poll_next(cx).map(|option| option.map(Ok))
+    }
+}
+
+impl<Item, SinkItem> Sink<SinkItem> for UnboundedChannel<Item, SinkItem> {
+    type Error = io::Error;
+
+    fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.project()
+            .tx
+            .poll_ready(cx)
+            .map_err(|_| io::Error::from(io::ErrorKind::NotConnected))
+    }
+
+    fn start_send(self: Pin<&mut Self>, item: SinkItem) -> io::Result<()> {
+        self.project()
+            .tx
+            .start_send(item)
+            .map_err(|_| io::Error::from(io::ErrorKind::NotConnected))
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.project()
+            .tx
+            .poll_flush(cx)
+            .map_err(|_| io::Error::from(io::ErrorKind::NotConnected))
+    }
+
+    fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        self.project()
+            .tx
+            .poll_close(cx)
+            .map_err(|_| io::Error::from(io::ErrorKind::NotConnected))
+    }
+}
+
+#[cfg(test)]
+#[cfg(feature = "tokio1")]
+mod tests {
+    use crate::{
+        client, context,
+        server::{Handler, Server},
+        transport,
+    };
+    use assert_matches::assert_matches;
+    use futures::{prelude::*, stream};
+    use log::trace;
+    use std::io;
+
+    #[tokio::test]
+    async fn integration() -> io::Result<()> {
+        let _ = env_logger::try_init();
+
+        let (client_channel, server_channel) = transport::channel::unbounded();
+        tokio::spawn(
+            Server::default()
+                .incoming(stream::once(future::ready(server_channel)))
+                .respond_with(|_ctx, request: String| {
+                    future::ready(request.parse::<u64>().map_err(|_| {
+                        io::Error::new(
+                            io::ErrorKind::InvalidInput,
+                            format!("{:?} is not an int", request),
+                        )
+                    }))
+                }),
+        );
+
+        let mut client = client::new(client::Config::default(), client_channel).spawn()?;
+
+        let response1 = client.call(context::current(), "123".into()).await?;
+        let response2 = client.call(context::current(), "abc".into()).await?;
+
+        trace!("response1: {:?}, response2: {:?}", response1, response2);
+
+        assert_matches!(response1, Ok(123));
+        assert_matches!(response2, Err(ref e) if e.kind() == io::ErrorKind::InvalidInput);
+
+        Ok(())
+    }
+}

tarpc/src/rpc/util.rs

@@ -0,0 +1,48 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+use std::{
+    collections::HashMap,
+    hash::{BuildHasher, Hash},
+    time::{Duration, SystemTime},
+};
+
+#[cfg(feature = "serde1")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde1")))]
+pub mod serde;
+
+/// Extension trait for [SystemTimes](SystemTime) in the future, i.e. deadlines.
+pub trait TimeUntil {
+    /// How much time from now until this time is reached.
+    fn time_until(&self) -> Duration;
+}
+
+impl TimeUntil for SystemTime {
+    fn time_until(&self) -> Duration {
+        self.duration_since(SystemTime::now()).unwrap_or_default()
+    }
+}
+
+/// Collection compaction; configurable `shrink_to_fit`.
+pub trait Compact {
+    /// Compacts space if the ratio of length : capacity is less than `usage_ratio_threshold`.
+    fn compact(&mut self, usage_ratio_threshold: f64);
+}
+
+impl<K, V, H> Compact for HashMap<K, V, H>
+where
+    K: Eq + Hash,
+    H: BuildHasher,
+{
+    fn compact(&mut self, usage_ratio_threshold: f64) {
+        if self.capacity() > 1000 {
+            let usage_ratio = self.len() as f64 / self.capacity() as f64;
+            if usage_ratio < usage_ratio_threshold {
+                self.shrink_to_fit();
+            }
+        }
+    }
+}

tarpc/src/rpc/util/serde.rs

@@ -0,0 +1,97 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+use std::{
+    io,
+    time::{Duration, SystemTime},
+};
+
+/// Serializes `system_time` as a `u64` equal to the number of seconds since the epoch.
+pub fn serialize_epoch_secs<S>(system_time: &SystemTime, serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+{
+    const ZERO_SECS: Duration = Duration::from_secs(0);
+    system_time
+        .duration_since(SystemTime::UNIX_EPOCH)
+        .unwrap_or(ZERO_SECS)
+        .as_secs() // Only care about second precision
+        .serialize(serializer)
+}
+
+/// Deserializes [`SystemTime`] from a `u64` equal to the number of seconds since the epoch.
+pub fn deserialize_epoch_secs<'de, D>(deserializer: D) -> Result<SystemTime, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    Ok(SystemTime::UNIX_EPOCH + Duration::from_secs(u64::deserialize(deserializer)?))
+}
+
+/// Serializes [`io::ErrorKind`] as a `u32`.
+#[allow(clippy::trivially_copy_pass_by_ref)] // Exact fn signature required by serde derive
+pub fn serialize_io_error_kind_as_u32<S>(
+    kind: &io::ErrorKind,
+    serializer: S,
+) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+{
+    use std::io::ErrorKind::*;
+    match *kind {
+        NotFound => 0,
+        PermissionDenied => 1,
+        ConnectionRefused => 2,
+        ConnectionReset => 3,
+        ConnectionAborted => 4,
+        NotConnected => 5,
+        AddrInUse => 6,
+        AddrNotAvailable => 7,
+        BrokenPipe => 8,
+        AlreadyExists => 9,
+        WouldBlock => 10,
+        InvalidInput => 11,
+        InvalidData => 12,
+        TimedOut => 13,
+        WriteZero => 14,
+        Interrupted => 15,
+        Other => 16,
+        UnexpectedEof => 17,
+        _ => 16,
+    }
+    .serialize(serializer)
+}
+
+/// Deserializes [`io::ErrorKind`] from a `u32`.
+pub fn deserialize_io_error_kind_from_u32<'de, D>(
+    deserializer: D,
+) -> Result<io::ErrorKind, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    use std::io::ErrorKind::*;
+    Ok(match u32::deserialize(deserializer)? {
+        0 => NotFound,
+        1 => PermissionDenied,
+        2 => ConnectionRefused,
+        3 => ConnectionReset,
+        4 => ConnectionAborted,
+        5 => NotConnected,
+        6 => AddrInUse,
+        7 => AddrNotAvailable,
+        8 => BrokenPipe,
+        9 => AlreadyExists,
+        10 => WouldBlock,
+        11 => InvalidInput,
+        12 => InvalidData,
+        13 => TimedOut,
+        14 => WriteZero,
+        15 => Interrupted,
+        16 => Other,
+        17 => UnexpectedEof,
+        _ => Other,
+    })
+}

tarpc/src/serde_transport.rs

@@ -0,0 +1,394 @@
+// Copyright 2019 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+//! A generic Serde-based `Transport` that can serialize anything supported by `tokio-serde` via any medium that implements `AsyncRead` and `AsyncWrite`.
+
+#![deny(missing_docs)]
+
+use futures::{prelude::*, task::*};
+use pin_project::pin_project;
+use serde::{Deserialize, Serialize};
+use std::{error::Error, io, pin::Pin};
+use tokio::io::{AsyncRead, AsyncWrite};
+use tokio_serde::{Framed as SerdeFramed, *};
+use tokio_util::codec::{length_delimited::LengthDelimitedCodec, Framed};
+
+/// A transport that serializes to, and deserializes from, a byte stream.
+#[pin_project]
+pub struct Transport<S, Item, SinkItem, Codec> {
+    #[pin]
+    inner: SerdeFramed<Framed<S, LengthDelimitedCodec>, Item, SinkItem, Codec>,
+}
+
+impl<S, Item, SinkItem, Codec> Transport<S, Item, SinkItem, Codec> {
+    /// Returns the inner transport over which messages are sent and received.
+    pub fn get_ref(&self) -> &S {
+        self.inner.get_ref().get_ref()
+    }
+}
+
+impl<S, Item, SinkItem, Codec, CodecError> Stream for Transport<S, Item, SinkItem, Codec>
+where
+    S: AsyncWrite + AsyncRead,
+    Item: for<'a> Deserialize<'a>,
+    Codec: Deserializer<Item>,
+    CodecError: Into<Box<dyn std::error::Error + Send + Sync>>,
+    SerdeFramed<Framed<S, LengthDelimitedCodec>, Item, SinkItem, Codec>:
+        Stream<Item = Result<Item, CodecError>>,
+{
+    type Item = io::Result<Item>;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<io::Result<Item>>> {
+        match self.project().inner.poll_next(cx) {
+            Poll::Pending => Poll::Pending,
+            Poll::Ready(None) => Poll::Ready(None),
+            Poll::Ready(Some(Ok::<_, CodecError>(next))) => Poll::Ready(Some(Ok(next))),
+            Poll::Ready(Some(Err::<_, CodecError>(e))) => {
+                Poll::Ready(Some(Err(io::Error::new(io::ErrorKind::Other, e))))
+            }
+        }
+    }
+}
+
+impl<S, Item, SinkItem, Codec, CodecError> Sink<SinkItem> for Transport<S, Item, SinkItem, Codec>
+where
+    S: AsyncWrite,
+    SinkItem: Serialize,
+    Codec: Serializer<SinkItem>,
+    CodecError: Into<Box<dyn Error + Send + Sync>>,
+    SerdeFramed<Framed<S, LengthDelimitedCodec>, Item, SinkItem, Codec>:
+        Sink<SinkItem, Error = CodecError>,
+{
+    type Error = io::Error;
+
+    fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        convert(self.project().inner.poll_ready(cx))
+    }
+
+    fn start_send(self: Pin<&mut Self>, item: SinkItem) -> io::Result<()> {
+        self.project()
+            .inner
+            .start_send(item)
+            .map_err(|e| io::Error::new(io::ErrorKind::Other, e))
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        convert(self.project().inner.poll_flush(cx))
+    }
+
+    fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        convert(self.project().inner.poll_close(cx))
+    }
+}
+
+fn convert<E: Into<Box<dyn Error + Send + Sync>>>(
+    poll: Poll<Result<(), E>>,
+) -> Poll<io::Result<()>> {
+    poll.map(|ready| ready.map_err(|e| io::Error::new(io::ErrorKind::Other, e)))
+}
+
+/// Constructs a new transport from a framed transport and a serialization codec.
+pub fn new<S, Item, SinkItem, Codec>(
+    framed_io: Framed<S, LengthDelimitedCodec>,
+    codec: Codec,
+) -> Transport<S, Item, SinkItem, Codec>
+where
+    S: AsyncWrite + AsyncRead,
+    Item: for<'de> Deserialize<'de>,
+    SinkItem: Serialize,
+    Codec: Serializer<SinkItem> + Deserializer<Item>,
+{
+    Transport {
+        inner: SerdeFramed::new(framed_io, codec),
+    }
+}
+
+impl<S, Item, SinkItem, Codec> From<(S, Codec)> for Transport<S, Item, SinkItem, Codec>
+where
+    S: AsyncWrite + AsyncRead,
+    Item: for<'de> Deserialize<'de>,
+    SinkItem: Serialize,
+    Codec: Serializer<SinkItem> + Deserializer<Item>,
+{
+    fn from((io, codec): (S, Codec)) -> Self {
+        new(Framed::new(io, LengthDelimitedCodec::new()), codec)
+    }
+}
+
+#[cfg(feature = "tcp")]
+#[cfg_attr(docsrs, doc(cfg(feature = "tcp")))]
+/// TCP support for generic transport using Tokio.
+pub mod tcp {
+    use {
+        super::*,
+        futures::ready,
+        std::{marker::PhantomData, net::SocketAddr},
+        tokio::net::{TcpListener, TcpStream, ToSocketAddrs},
+        tokio_util::codec::length_delimited,
+    };
+
+    mod private {
+        use super::*;
+
+        pub trait Sealed {}
+
+        impl<Item, SinkItem, Codec> Sealed for Transport<TcpStream, Item, SinkItem, Codec> {}
+    }
+
+    impl<Item, SinkItem, Codec> Transport<TcpStream, Item, SinkItem, Codec> {
+        /// Returns the peer address of the underlying TcpStream.
+        pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+            self.inner.get_ref().get_ref().peer_addr()
+        }
+        /// Returns the local address of the underlying TcpStream.
+        pub fn local_addr(&self) -> io::Result<SocketAddr> {
+            self.inner.get_ref().get_ref().local_addr()
+        }
+    }
+
+    /// A connection Future that also exposes the length-delimited framing config.
+    #[pin_project]
+    pub struct Connect<T, Item, SinkItem, CodecFn> {
+        #[pin]
+        inner: T,
+        codec_fn: CodecFn,
+        config: length_delimited::Builder,
+        ghost: PhantomData<(fn(SinkItem), fn() -> Item)>,
+    }
+
+    impl<T, Item, SinkItem, Codec, CodecFn> Future for Connect<T, Item, SinkItem, CodecFn>
+    where
+        T: Future<Output = io::Result<TcpStream>>,
+        Item: for<'de> Deserialize<'de>,
+        SinkItem: Serialize,
+        Codec: Serializer<SinkItem> + Deserializer<Item>,
+        CodecFn: Fn() -> Codec,
+    {
+        type Output = io::Result<Transport<TcpStream, Item, SinkItem, Codec>>;
+
+        fn poll(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
+            let io = ready!(self.as_mut().project().inner.poll(cx))?;
+            Poll::Ready(Ok(new(self.config.new_framed(io), (self.codec_fn)())))
+        }
+    }
+
+    impl<T, Item, SinkItem, CodecFn> Connect<T, Item, SinkItem, CodecFn> {
+        /// Returns an immutable reference to the length-delimited codec's config.
+        pub fn config(&self) -> &length_delimited::Builder {
+            &self.config
+        }
+
+        /// Returns a mutable reference to the length-delimited codec's config.
+        pub fn config_mut(&mut self) -> &mut length_delimited::Builder {
+            &mut self.config
+        }
+    }
+
+    /// Connects to `addr`, wrapping the connection in a TCP transport.
+    pub fn connect<A, Item, SinkItem, Codec, CodecFn>(
+        addr: A,
+        codec_fn: CodecFn,
+    ) -> Connect<impl Future<Output = io::Result<TcpStream>>, Item, SinkItem, CodecFn>
+    where
+        A: ToSocketAddrs,
+        Item: for<'de> Deserialize<'de>,
+        SinkItem: Serialize,
+        Codec: Serializer<SinkItem> + Deserializer<Item>,
+        CodecFn: Fn() -> Codec,
+    {
+        Connect {
+            inner: TcpStream::connect(addr),
+            codec_fn,
+            config: LengthDelimitedCodec::builder(),
+            ghost: PhantomData,
+        }
+    }
+
+    /// Listens on `addr`, wrapping accepted connections in TCP transports.
+    pub async fn listen<A, Item, SinkItem, Codec, CodecFn>(
+        addr: A,
+        codec_fn: CodecFn,
+    ) -> io::Result<Incoming<Item, SinkItem, Codec, CodecFn>>
+    where
+        A: ToSocketAddrs,
+        Item: for<'de> Deserialize<'de>,
+        Codec: Serializer<SinkItem> + Deserializer<Item>,
+        CodecFn: Fn() -> Codec,
+    {
+        let listener = TcpListener::bind(addr).await?;
+        let local_addr = listener.local_addr()?;
+        Ok(Incoming {
+            listener,
+            codec_fn,
+            local_addr,
+            config: LengthDelimitedCodec::builder(),
+            ghost: PhantomData,
+        })
+    }
+
+    /// A [`TcpListener`] that wraps connections in [transports](Transport).
+    #[pin_project]
+    #[derive(Debug)]
+    pub struct Incoming<Item, SinkItem, Codec, CodecFn> {
+        listener: TcpListener,
+        local_addr: SocketAddr,
+        codec_fn: CodecFn,
+        config: length_delimited::Builder,
+        ghost: PhantomData<(fn() -> Item, fn(SinkItem), Codec)>,
+    }
+
+    impl<Item, SinkItem, Codec, CodecFn> Incoming<Item, SinkItem, Codec, CodecFn> {
+        /// Returns the address being listened on.
+        pub fn local_addr(&self) -> SocketAddr {
+            self.local_addr
+        }
+
+        /// Returns an immutable reference to the length-delimited codec's config.
+        pub fn config(&self) -> &length_delimited::Builder {
+            &self.config
+        }
+
+        /// Returns a mutable reference to the length-delimited codec's config.
+        pub fn config_mut(&mut self) -> &mut length_delimited::Builder {
+            &mut self.config
+        }
+    }
+
+    impl<Item, SinkItem, Codec, CodecFn> Stream for Incoming<Item, SinkItem, Codec, CodecFn>
+    where
+        Item: for<'de> Deserialize<'de>,
+        SinkItem: Serialize,
+        Codec: Serializer<SinkItem> + Deserializer<Item>,
+        CodecFn: Fn() -> Codec,
+    {
+        type Item = io::Result<Transport<TcpStream, Item, SinkItem, Codec>>;
+
+        fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+            let conn: TcpStream =
+                ready!(Pin::new(&mut self.as_mut().project().listener).poll_accept(cx)?).0;
+            Poll::Ready(Some(Ok(new(
+                self.config.new_framed(conn),
+                (self.codec_fn)(),
+            ))))
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Transport;
+    use assert_matches::assert_matches;
+    use futures::{task::*, Sink, Stream};
+    use pin_utils::pin_mut;
+    use std::{
+        io::{self, Cursor},
+        pin::Pin,
+    };
+    use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
+    use tokio_serde::formats::SymmetricalJson;
+
+    fn ctx() -> Context<'static> {
+        Context::from_waker(&noop_waker_ref())
+    }
+
+    #[test]
+    fn test_stream() {
+        struct TestIo(Cursor<&'static [u8]>);
+
+        impl AsyncRead for TestIo {
+            fn poll_read(
+                mut self: Pin<&mut Self>,
+                cx: &mut Context<'_>,
+                buf: &mut ReadBuf<'_>,
+            ) -> Poll<io::Result<()>> {
+                AsyncRead::poll_read(Pin::new(self.0.get_mut()), cx, buf)
+            }
+        }
+
+        impl AsyncWrite for TestIo {
+            fn poll_write(
+                self: Pin<&mut Self>,
+                _cx: &mut Context<'_>,
+                _buf: &[u8],
+            ) -> Poll<io::Result<usize>> {
+                unreachable!()
+            }
+
+            fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+                unreachable!()
+            }
+
+            fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+                unreachable!()
+            }
+        }
+
+        let data = b"\x00\x00\x00\x18\"Test one, check check.\"";
+        let transport = Transport::from((
+            TestIo(Cursor::new(data)),
+            SymmetricalJson::<String>::default(),
+        ));
+        pin_mut!(transport);
+
+        assert_matches!(
+            transport.poll_next(&mut ctx()),
+            Poll::Ready(Some(Ok(ref s))) if s == "Test one, check check.");
+    }
+
+    #[test]
+    fn test_sink() {
+        struct TestIo<'a>(&'a mut Vec<u8>);
+
+        impl<'a> AsyncRead for TestIo<'a> {
+            fn poll_read(
+                self: Pin<&mut Self>,
+                _cx: &mut Context<'_>,
+                _buf: &mut ReadBuf<'_>,
+            ) -> Poll<io::Result<()>> {
+                unreachable!()
+            }
+        }
+
+        impl<'a> AsyncWrite for TestIo<'a> {
+            fn poll_write(
+                mut self: Pin<&mut Self>,
+                cx: &mut Context<'_>,
+                buf: &[u8],
+            ) -> Poll<io::Result<usize>> {
+                AsyncWrite::poll_write(Pin::new(&mut *self.0), cx, buf)
+            }
+
+            fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+                AsyncWrite::poll_flush(Pin::new(&mut *self.0), cx)
+            }
+
+            fn poll_shutdown(
+                mut self: Pin<&mut Self>,
+                cx: &mut Context<'_>,
+            ) -> Poll<io::Result<()>> {
+                AsyncWrite::poll_shutdown(Pin::new(&mut *self.0), cx)
+            }
+        }
+
+        let mut writer = vec![];
+        let transport =
+            Transport::from((TestIo(&mut writer), SymmetricalJson::<String>::default()));
+        pin_mut!(transport);
+
+        assert_matches!(
+            transport.as_mut().poll_ready(&mut ctx()),
+            Poll::Ready(Ok(()))
+        );
+        assert_matches!(
+            transport
+                .as_mut()
+                .start_send("Test one, check check.".into()),
+            Ok(())
+        );
+        assert_matches!(transport.poll_flush(&mut ctx()), Poll::Ready(Ok(())));
+        assert_eq!(writer, b"\x00\x00\x00\x18\"Test one, check check.\"");
+    }
+}

tarpc/src/trace.rs

@@ -0,0 +1,97 @@
+// Copyright 2018 Google LLC
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+#![deny(missing_docs, missing_debug_implementations)]
+
+//! Provides building blocks for tracing distributed programs.
+//!
+//! A trace is logically a tree of causally-related events called spans. Traces are tracked via a
+//! [context](Context) that identifies the current trace, span, and parent of the current span.  In
+//! distributed systems, a context can be sent from client to server to connect events occurring on
+//! either side.
+//!
+//! This crate's design is based on [opencensus
+//! tracing](https://opencensus.io/core-concepts/tracing/).
+
+use rand::Rng;
+use std::{
+    fmt::{self, Formatter},
+    mem,
+};
+
+/// A context for tracing the execution of processes, distributed or otherwise.
+///
+/// Consists of a span identifying an event, an optional parent span identifying a causal event
+/// that triggered the current span, and a trace with which all related spans are associated.
+#[derive(Debug, Default, PartialEq, Eq, Hash, Clone, Copy)]
+#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
+pub struct Context {
+    /// An identifier of the trace associated with the current context. A trace ID is typically
+    /// created at a root span and passed along through all causal events.
+    pub trace_id: TraceId,
+    /// An identifier of the current span. In typical RPC usage, a span is created by a client
+    /// before making an RPC, and the span ID is sent to the server. The server is free to create
+    /// its own spans, for which it sets the client's span as the parent span.
+    pub span_id: SpanId,
+    /// An identifier of the span that originated the current span. For example, if a server sends
+    /// an RPC in response to a client request that included a span, the server would create a span
+    /// for the RPC and set its parent to the span_id in the incoming request's context.
+    ///
+    /// If `parent_id` is `None`, then this is a root context.
+    pub parent_id: Option<SpanId>,
+}
+
+/// A 128-bit UUID identifying a trace. All spans caused by the same originating span share the
+/// same trace ID.
+#[derive(Debug, Default, PartialEq, Eq, Hash, Clone, Copy)]
+#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
+pub struct TraceId(u128);
+
+/// A 64-bit identifier of a span within a trace. The identifier is unique within the span's trace.
+#[derive(Debug, Default, PartialEq, Eq, Hash, Clone, Copy)]
+#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
+pub struct SpanId(u64);
+
+impl Context {
+    /// Constructs a new root context. A root context is one with no parent span.
+    pub fn new_root() -> Self {
+        let rng = &mut rand::thread_rng();
+        Context {
+            trace_id: TraceId::random(rng),
+            span_id: SpanId::random(rng),
+            parent_id: None,
+        }
+    }
+}
+
+impl TraceId {
+    /// Returns a random trace ID that can be assumed to be globally unique if `rng` generates
+    /// actually-random numbers.
+    pub fn random<R: Rng>(rng: &mut R) -> Self {
+        TraceId(u128::from(rng.next_u64()) << mem::size_of::<u64>() | u128::from(rng.next_u64()))
+    }
+}
+
+impl SpanId {
+    /// Returns a random span ID that can be assumed to be unique within a single trace.
+    pub fn random<R: Rng>(rng: &mut R) -> Self {
+        SpanId(rng.next_u64())
+    }
+}
+
+impl fmt::Display for TraceId {
+    fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> {
+        write!(f, "{:02x}", self.0)?;
+        Ok(())
+    }
+}
+
+impl fmt::Display for SpanId {
+    fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> {
+        write!(f, "{:02x}", self.0)?;
+        Ok(())
+    }
+}

tarpc/tests/compile_fail.rs

@@ -0,0 +1,5 @@
+#[test]
+fn ui() {
+    let t = trybuild::TestCases::new();
+    t.compile_fail("tests/compile_fail/*.rs");
+}

tarpc/tests/compile_fail/tarpc_server_missing_async.rs

@@ -0,0 +1,15 @@
+#[tarpc::service(derive_serde = false)]
+trait World {
+    async fn hello(name: String) -> String;
+}
+
+struct HelloServer;
+
+#[tarpc::server]
+impl World for HelloServer {
+    fn hello(name: String) ->  String {
+        format!("Hello, {}!", name)
+    }
+}
+
+fn main() {}

tarpc/tests/compile_fail/tarpc_server_missing_async.stderr

@@ -0,0 +1,11 @@
+error: not all trait items implemented, missing: `HelloFut`
+ --> $DIR/tarpc_server_missing_async.rs:9:1
+  |
+9 | impl World for HelloServer {
+  | ^^^^
+
+error: hint: `#[tarpc::server]` only rewrites async fns, and `fn hello` is not async
+  --> $DIR/tarpc_server_missing_async.rs:10:5
+   |
+10 |     fn hello(name: String) ->  String {
+   |     ^^

tarpc/tests/compile_fail/tarpc_service_arg_pat.rs

@@ -0,0 +1,6 @@
+#[tarpc::service]
+trait World {
+    async fn pat((a, b): (u8, u32));
+}
+
+fn main() {}

tarpc/tests/compile_fail/tarpc_service_arg_pat.stderr

@@ -0,0 +1,5 @@
+error: patterns aren't allowed in RPC args
+ --> $DIR/tarpc_service_arg_pat.rs:3:18
+  |
+3 |     async fn pat((a, b): (u8, u32));
+  |                  ^^^^^^

tarpc/tests/compile_fail/tarpc_service_fn_new.rs

@@ -0,0 +1,6 @@
+#[tarpc::service]
+trait World {
+    async fn new();
+}
+
+fn main() {}

tarpc/tests/compile_fail/tarpc_service_fn_new.stderr

@@ -0,0 +1,5 @@
+error: method name conflicts with generated fn `WorldClient::new`
+ --> $DIR/tarpc_service_fn_new.rs:3:14
+  |
+3 |     async fn new();
+  |              ^^^

tarpc/tests/compile_fail/tarpc_service_fn_serve.rs

@@ -0,0 +1,6 @@
+#[tarpc::service]
+trait World {
+    async fn serve();
+}
+
+fn main() {}

tarpc/tests/compile_fail/tarpc_service_fn_serve.stderr

@@ -0,0 +1,5 @@
+error: method name conflicts with generated fn `World::serve`
+ --> $DIR/tarpc_service_fn_serve.rs:3:14
+  |
+3 |     async fn serve();
+  |              ^^^^^

tarpc/tests/dataservice.rs

@@ -0,0 +1,51 @@
+use futures::prelude::*;
+use std::io;
+use tarpc::serde_transport;
+use tarpc::{client, context, server::Handler};
+use tokio_serde::formats::Json;
+
+#[tarpc::derive_serde]
+#[derive(Debug, PartialEq)]
+pub enum TestData {
+    Black,
+    White,
+}
+
+#[tarpc::service]
+pub trait ColorProtocol {
+    async fn get_opposite_color(color: TestData) -> TestData;
+}
+
+#[derive(Clone)]
+struct ColorServer;
+
+#[tarpc::server]
+impl ColorProtocol for ColorServer {
+    async fn get_opposite_color(self, _: context::Context, color: TestData) -> TestData {
+        match color {
+            TestData::White => TestData::Black,
+            TestData::Black => TestData::White,
+        }
+    }
+}
+
+#[tokio::test]
+async fn test_call() -> io::Result<()> {
+    let transport = tarpc::serde_transport::tcp::listen("localhost:56797", Json::default).await?;
+    let addr = transport.local_addr();
+    tokio::spawn(
+        tarpc::Server::default()
+            .incoming(transport.take(1).filter_map(|r| async { r.ok() }))
+            .respond_with(ColorServer.serve()),
+    );
+
+    let transport = serde_transport::tcp::connect(addr, Json::default).await?;
+    let mut client = ColorProtocolClient::new(client::Config::default(), transport).spawn()?;
+
+    let color = client
+        .get_opposite_color(context::current(), TestData::White)
+        .await?;
+    assert_eq!(color, TestData::Black);
+
+    Ok(())
+}

tarpc/tests/service_functional.rs

@@ -0,0 +1,171 @@
+use assert_matches::assert_matches;
+use futures::{
+    future::{join_all, ready, Ready},
+    prelude::*,
+};
+use std::io;
+use tarpc::{
+    client::{self},
+    context,
+    server::{self, BaseChannel, Channel, Handler},
+    transport::channel,
+};
+use tokio::join;
+
+#[tarpc_plugins::service]
+trait Service {
+    async fn add(x: i32, y: i32) -> i32;
+    async fn hey(name: String) -> String;
+}
+
+#[derive(Clone)]
+struct Server;
+
+impl Service for Server {
+    type AddFut = Ready<i32>;
+
+    fn add(self, _: context::Context, x: i32, y: i32) -> Self::AddFut {
+        ready(x + y)
+    }
+
+    type HeyFut = Ready<String>;
+
+    fn hey(self, _: context::Context, name: String) -> Self::HeyFut {
+        ready(format!("Hey, {}.", name))
+    }
+}
+
+#[tokio::test]
+async fn sequential() -> io::Result<()> {
+    let _ = env_logger::try_init();
+
+    let (tx, rx) = channel::unbounded();
+
+    tokio::spawn(
+        BaseChannel::new(server::Config::default(), rx)
+            .respond_with(Server.serve())
+            .execute(),
+    );
+
+    let mut client = ServiceClient::new(client::Config::default(), tx).spawn()?;
+
+    assert_matches!(client.add(context::current(), 1, 2).await, Ok(3));
+    assert_matches!(
+        client.hey(context::current(), "Tim".into()).await,
+        Ok(ref s) if s == "Hey, Tim.");
+
+    Ok(())
+}
+
+#[cfg(all(feature = "serde-transport", feature = "tcp"))]
+#[tokio::test]
+async fn serde() -> io::Result<()> {
+    use tarpc::serde_transport;
+    use tokio_serde::formats::Json;
+
+    let _ = env_logger::try_init();
+
+    let transport = tarpc::serde_transport::tcp::listen("localhost:56789", Json::default).await?;
+    let addr = transport.local_addr();
+    tokio::spawn(
+        tarpc::Server::default()
+            .incoming(transport.take(1).filter_map(|r| async { r.ok() }))
+            .respond_with(Server.serve()),
+    );
+
+    let transport = serde_transport::tcp::connect(addr, Json::default).await?;
+    let mut client = ServiceClient::new(client::Config::default(), transport).spawn()?;
+
+    assert_matches!(client.add(context::current(), 1, 2).await, Ok(3));
+    assert_matches!(
+        client.hey(context::current(), "Tim".to_string()).await,
+        Ok(ref s) if s == "Hey, Tim."
+    );
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn concurrent() -> io::Result<()> {
+    let _ = env_logger::try_init();
+
+    let (tx, rx) = channel::unbounded();
+    tokio::spawn(
+        tarpc::Server::default()
+            .incoming(stream::once(ready(rx)))
+            .respond_with(Server.serve()),
+    );
+
+    let client = ServiceClient::new(client::Config::default(), tx).spawn()?;
+
+    let mut c = client.clone();
+    let req1 = c.add(context::current(), 1, 2);
+
+    let mut c = client.clone();
+    let req2 = c.add(context::current(), 3, 4);
+
+    let mut c = client.clone();
+    let req3 = c.hey(context::current(), "Tim".to_string());
+
+    assert_matches!(req1.await, Ok(3));
+    assert_matches!(req2.await, Ok(7));
+    assert_matches!(req3.await, Ok(ref s) if s == "Hey, Tim.");
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn concurrent_join() -> io::Result<()> {
+    let _ = env_logger::try_init();
+
+    let (tx, rx) = channel::unbounded();
+    tokio::spawn(
+        tarpc::Server::default()
+            .incoming(stream::once(ready(rx)))
+            .respond_with(Server.serve()),
+    );
+
+    let client = ServiceClient::new(client::Config::default(), tx).spawn()?;
+
+    let mut c = client.clone();
+    let req1 = c.add(context::current(), 1, 2);
+
+    let mut c = client.clone();
+    let req2 = c.add(context::current(), 3, 4);
+
+    let mut c = client.clone();
+    let req3 = c.hey(context::current(), "Tim".to_string());
+
+    let (resp1, resp2, resp3) = join!(req1, req2, req3);
+    assert_matches!(resp1, Ok(3));
+    assert_matches!(resp2, Ok(7));
+    assert_matches!(resp3, Ok(ref s) if s == "Hey, Tim.");
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn concurrent_join_all() -> io::Result<()> {
+    let _ = env_logger::try_init();
+
+    let (tx, rx) = channel::unbounded();
+    tokio::spawn(
+        tarpc::Server::default()
+            .incoming(stream::once(ready(rx)))
+            .respond_with(Server.serve()),
+    );
+
+    let client = ServiceClient::new(client::Config::default(), tx).spawn()?;
+
+    let mut c1 = client.clone();
+    let mut c2 = client.clone();
+
+    let req1 = c1.add(context::current(), 1, 2);
+    let req2 = c2.add(context::current(), 3, 4);
+
+    let responses = join_all(vec![req1, req2]).await;
+    assert_matches!(responses[0], Ok(3));
+    assert_matches!(responses[1], Ok(7));
+
+    Ok(())
+}

test/root-ca.pem

@@ -1,21 +0,0 @@
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