From f2bf1adf8b8ea784790cd74d04e173dbe9ff6139 Mon Sep 17 00:00:00 2001
From: Tim Kuehn <tikue@google.com>
Date: Fri, 16 Dec 2016 14:15:31 -0800
Subject: [PATCH] Fix bug wherein the Codec was clearing the buf after decoding
 a message. Don't do thatgit stash pop!

---
 src/framed.rs | 42 +++++++++++++++++++++++++++++-------------
 src/lib.rs    |  2 +-
 src/util.rs   | 15 +++++++++++++++
 3 files changed, 45 insertions(+), 14 deletions(-)

diff --git a/src/framed.rs b/src/framed.rs
index 502b584..3437561 100644
--- a/src/framed.rs
+++ b/src/framed.rs
@@ -12,7 +12,7 @@ use std::mem;
 use tokio_core::io::{EasyBuf, Framed, Io};
 use tokio_proto::streaming::multiplex::{self, RequestId};
 use tokio_proto::multiplex::{ClientProto, ServerProto};
-use util::Never;
+use util::{Debugger, Never};
 
 /// The type of message sent and received by the transport.
 pub type Frame<T> = multiplex::Frame<T, Never, io::Error>;
@@ -48,44 +48,60 @@ impl<Req, Resp> tokio_core::io::Codec for Codec<Req, Resp>
 
     fn encode(&mut self, (id, message): Self::Out, buf: &mut Vec<u8>) -> io::Result<()> {
         buf.write_u64::<BigEndian>(id).unwrap();
+        trace!("Encoded request id = {} as {:?}", id, buf);
         buf.write_u64::<BigEndian>(bincode::serialized_size(&message)).unwrap();
         bincode::serialize_into(buf,
                                 &message,
                                 SizeLimit::Infinite)
                  // TODO(tikue): handle err
                  .expect("In bincode::serialize_into");
+        trace!("Encoded buffer: {:?}", buf);
         Ok(())
     }
 
     fn decode(&mut self, buf: &mut EasyBuf) -> Result<Option<Self::In>, io::Error> {
         use self::CodecState::*;
+        trace!("Codec::decode: {:?}", buf.as_slice());
 
         loop {
             match self.state {
-                Id if buf.len() < mem::size_of::<u64>() => return Ok(None),
-                Id => {
-                    let id_buf = buf.drain_to(mem::size_of::<u64>());
-                    self.state = Len { id: Cursor::new(id_buf).read_u64::<BigEndian>()? };
+                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.drain_to(mem::size_of::<u64>());
+                    let id = Cursor::new(&mut id_buf).read_u64::<BigEndian>()?;
+                    trace!("--> Parsed id = {} from {:?}", id, id_buf.as_slice());
+                    self.state = Len { id: 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 { .. } if buf.len() < mem::size_of::<u64>() => return Ok(None),
                 Len { id } => {
                     let len_buf = buf.drain_to(mem::size_of::<u64>());
+                    let len = Cursor::new(len_buf).read_u64::<BigEndian>()?;
+                    trace!("--> Parsed payload length = {}, remaining buffer length = {}",
+                           len, buf.len());
                     self.state = Payload {
                         id: id,
-                        len: Cursor::new(len_buf).read_u64::<BigEndian>()?,
+                        len: len,
                     };
                 }
-                Payload { len, .. } if buf.len() < len as usize => return Ok(None),
-                Payload { id, .. } => {
-                    let mut buf = buf.get_mut();
-                    let result = bincode::deserialize_from(&mut Cursor::new(&mut *buf),
+                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.drain_to(len as usize);
+                    let result = bincode::deserialize_from(&mut Cursor::new(payload),
                                                            SizeLimit::Infinite);
-                    // Clear any unread bytes so we don't read garbage on next request.
-                    buf.clear();
                     // Reset the state machine because, either way, we're done processing this
                     // message.
                     self.state = Id;
 
+                    trace!("--> Parsed message: {:?}", Debugger(&result));
                     return Ok(Some((id, result)));
                 }
             }
diff --git a/src/lib.rs b/src/lib.rs
index 6aa202a..abc14e0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -59,7 +59,7 @@
 //! ```
 //!
 #![deny(missing_docs)]
-#![feature(plugin, conservative_impl_trait, never_type, proc_macro, unboxed_closures, fn_traits)]
+#![feature(plugin, conservative_impl_trait, never_type, proc_macro, unboxed_closures, fn_traits, specialization)]
 #![plugin(tarpc_plugins)]
 
 extern crate byteorder;
diff --git a/src/util.rs b/src/util.rs
index f6dd550..6fd9f2e 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -136,3 +136,18 @@ pub fn spawn_core() -> reactor::Remote {
     });
     rx.recv().unwrap()
 }
+
+/// A struct that will format as the contained type if the type impls Debug.
+pub struct Debugger<'a, T: 'a>(pub &'a T);
+
+impl<'a, T: fmt::Debug> fmt::Debug for Debugger<'a, T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        write!(f, "{:?}", self.0)
+    }
+}
+
+impl<'a, T> fmt::Debug for Debugger<'a, T> {
+    default fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        write!(f, "{{not debuggable}}")
+    }
+}