feat: re-export used packages (#371)

## Problem
Library users might get stuck with or ran into issues while using tarpc because of incompatible third party libraries. in particular, tokio_serde and tokio_util.

## Solution
This PR does the following:

1. re-export tokio_serde as part of feature serde-transport, because the end user imports it to use some serde-transport APIs.
2. Update third library packages to latest release and fix resulting issues from that.

## Important Notes
tokio_util 7.3 DelayQueue::poll_expired API changed [0] therefore, InFlightRequests::poll_expired now returns Poll<Option<u64>>

[0] https://docs.rs/tokio-util/latest/tokio_util/time/delay_queue/struct.DelayQueue.html#method.poll_expired

example-service/Cargo.toml

@@ -18,14 +18,14 @@ anyhow = "1.0"
 clap = { version = "3.0.0-rc.9", features = ["derive"] }
 log = "0.4"
 futures = "0.3"
-opentelemetry = { version = "0.16", features = ["rt-tokio"] }
-opentelemetry-jaeger = { version = "0.15", features = ["rt-tokio"] }
+opentelemetry = { version = "0.17", features = ["rt-tokio"] }
+opentelemetry-jaeger = { version = "0.16", features = ["rt-tokio"] }
 rand = "0.8"
 tarpc = { version = "0.29", path = "../tarpc", features = ["full"] }
 tokio = { version = "1", features = ["macros", "net", "rt-multi-thread"] }
 tracing = { version = "0.1" }
-tracing-opentelemetry = "0.15"
-tracing-subscriber = "0.2"
+tracing-opentelemetry = "0.17"
+tracing-subscriber = {version = "0.3", features = ["env-filter"]}
 
 [lib]
 name = "service"

tarpc/Cargo.toml

@@ -50,7 +50,7 @@ static_assertions = "1.1.0"
 tarpc-plugins = { path = "../plugins", version = "0.12" }
 thiserror = "1.0"
 tokio = { version = "1", features = ["time"] }
-tokio-util = { version = "0.6.9", features = ["time"] }
+tokio-util = { version = "0.7.3", features = ["time"] }
 tokio-serde = { optional = true, version = "0.8" }
 tracing = { version = "0.1", default-features = false, features = [
     "attributes",

tarpc/examples/custom_transport.rs

@@ -1,8 +1,9 @@
+use tarpc::context::Context;
 use tarpc::serde_transport as transport;
 use tarpc::server::{BaseChannel, Channel};
-use tarpc::{context::Context, tokio_serde::formats::Bincode};
+use tarpc::tokio_serde::formats::Bincode;
+use tarpc::tokio_util::codec::length_delimited::LengthDelimitedCodec;
 use tokio::net::{UnixListener, UnixStream};
-use tokio_util::codec::length_delimited::LengthDelimitedCodec;
 
 #[tarpc::service]
 pub trait PingService {

tarpc/examples/pubsub.rs

@@ -52,9 +52,9 @@ use tarpc::{
     client, context,
     serde_transport::tcp,
     server::{self, Channel},
+    tokio_serde::formats::Json,
 };
 use tokio::net::ToSocketAddrs;
-use tokio_serde::formats::Json;
 use tracing::info;
 use tracing_subscriber::prelude::*;
 

tarpc/examples/tracing.rs

@@ -9,8 +9,8 @@ use futures::{future, prelude::*};
 use tarpc::{
     client, context,
     server::{incoming::Incoming, BaseChannel},
+    tokio_serde::formats::Json,
 };
-use tokio_serde::formats::Json;
 use tracing_subscriber::prelude::*;
 
 pub mod add {

tarpc/src/client.rs

@@ -395,11 +395,7 @@ where
         // Receiving Poll::Ready(None) when polling expired requests never indicates "Closed",
         // because there can temporarily be zero in-flight rquests. Therefore, there is no need to
         // track the status like is done with pending and cancelled requests.
-        if let Poll::Ready(Some(_)) = self
-            .in_flight_requests()
-            .poll_expired(cx)
-            .map_err(ChannelError::Timer)?
-        {
+        if let Poll::Ready(Some(_)) = self.in_flight_requests().poll_expired(cx) {
             // Expired requests are considered complete; there is no compelling reason to send a
             // cancellation message to the server, since it will have already exhausted its
             // allotted processing time.

tarpc/src/client/in_flight_requests.rs

@@ -117,12 +117,9 @@ impl<Resp> InFlightRequests<Resp> {
 
     /// Yields a request that has expired, completing it with a TimedOut error.
     /// The caller should send cancellation messages for any yielded request ID.
-    pub fn poll_expired(
-        &mut self,
-        cx: &mut Context,
-    ) -> Poll<Option<Result<u64, tokio::time::error::Error>>> {
-        self.deadlines.poll_expired(cx).map_ok(|expired| {
-            let request_id = expired.into_inner();
+    pub fn poll_expired(&mut self, cx: &mut Context) -> Poll<Option<u64>> {
+        self.deadlines.poll_expired(cx).map(|expired| {
+            let request_id = expired?.into_inner();
             if let Some(request_data) = self.request_data.remove(&request_id) {
                 let _entered = request_data.span.enter();
                 tracing::error!("DeadlineExceeded");
@@ -131,7 +128,7 @@ impl<Resp> InFlightRequests<Resp> {
                     .response_completion
                     .send(Err(DeadlineExceededError));
             }
-            request_id
+            Some(request_id)
         })
     }
 }

tarpc/src/lib.rs

@@ -209,7 +209,7 @@
 pub use serde;
 
 #[cfg(feature = "serde-transport")]
-pub use tokio_serde;
+pub use {tokio_serde, tokio_util};
 
 #[cfg(feature = "serde-transport")]
 #[cfg_attr(docsrs, doc(cfg(feature = "serde-transport")))]

tarpc/src/server.rs

@@ -393,11 +393,7 @@ where
                 Poll::Pending | Poll::Ready(None) => Closed,
             };
 
-            let expiration_status = match self
-                .in_flight_requests_mut()
-                .poll_expired(cx)
-                .map_err(ChannelError::Timer)?
-            {
+            let expiration_status = match self.in_flight_requests_mut().poll_expired(cx) {
                 // No need to send a response, since the client wouldn't be waiting for one
                 // anymore.
                 Poll::Ready(Some(_)) => Ready,

tarpc/src/server/in_flight_requests.rs

@@ -94,16 +94,14 @@ impl InFlightRequests {
     }
 
     /// Yields a request that has expired, aborting any ongoing processing of that request.
-    pub fn poll_expired(
-        &mut self,
-        cx: &mut Context,
-    ) -> Poll<Option<Result<u64, tokio::time::error::Error>>> {
+    pub fn poll_expired(&mut self, cx: &mut Context) -> Poll<Option<u64>> {
         if self.deadlines.is_empty() {
             // TODO(https://github.com/tokio-rs/tokio/issues/4161)
             // This is a workaround for DelayQueue not always treating this case correctly.
             return Poll::Ready(None);
         }
-        self.deadlines.poll_expired(cx).map_ok(|expired| {
+        self.deadlines.poll_expired(cx).map(|expired| {
+            let expired = expired?;
             if let Some(RequestData {
                 abort_handle, span, ..
             }) = self.request_data.remove(expired.get_ref())
@@ -113,7 +111,7 @@ impl InFlightRequests {
                 abort_handle.abort();
                 tracing::error!("DeadlineExceeded");
             }
-            expired.into_inner()
+            Some(expired.into_inner())
         })
     }
 }
@@ -161,7 +159,7 @@ mod tests {
 
         assert_matches!(
             in_flight_requests.poll_expired(&mut noop_context()),
-            Poll::Ready(Some(Ok(_)))
+            Poll::Ready(Some(_))
         );
         assert_matches!(
             abortable_future.poll_unpin(&mut noop_context()),