use a framing protocol instead of even/odd channel

1 files changed, 167 insertions, 197 deletions

diff --git a/src/proto.rs b/src/proto.rs
index e3f9be8..d6dc35a 100644
--- a/src/proto.rs
+++ b/src/proto.rs
@@ -3,11 +3,11 @@ use std::pin::Pin;
 use std::sync::Arc;
 use std::task::{Context, Poll};
 
-use log::{trace, warn};
+use log::trace;
 
-use futures::channel::mpsc::{unbounded, UnboundedReceiver, UnboundedSender};
-use futures::Stream;
+use futures::channel::mpsc::{unbounded, UnboundedSender};
 use futures::{AsyncReadExt, AsyncWriteExt};
+use futures::{Stream, StreamExt};
 use kuska_handshake::async_std::BoxStreamWrite;
 
 use tokio::sync::mpsc;
@@ -63,39 +63,24 @@ struct SendQueueItem {
 	data: DataReader,
 }
 
-pub(crate) enum Data {
-	Full(Vec<u8>),
-	Streaming(AssociatedStream),
+#[pin_project::pin_project]
+struct DataReader {
+	#[pin]
+	reader: AssociatedStream,
+	packet: Result<Vec<u8>, u8>,
+	pos: usize,
+	buf: Vec<u8>,
+	eos: bool,
 }
 
-#[pin_project::pin_project(project = DataReaderProj)]
-enum DataReader {
-	Full {
-		#[pin]
-		data: Vec<u8>,
-		pos: usize,
-	},
-	Streaming {
-		#[pin]
-		reader: AssociatedStream,
-		packet: Result<Vec<u8>, u8>,
-		pos: usize,
-		buf: Vec<u8>,
-		eos: bool,
-	},
-}
-
-impl From<Data> for DataReader {
-	fn from(data: Data) -> DataReader {
-		match data {
-			Data::Full(data) => DataReader::Full { data, pos: 0 },
-			Data::Streaming(reader) => DataReader::Streaming {
-				reader,
-				packet: Ok(Vec::new()),
-				pos: 0,
-				buf: Vec::with_capacity(MAX_CHUNK_LENGTH as usize),
-				eos: false,
-			},
+impl From<AssociatedStream> for DataReader {
+	fn from(data: AssociatedStream) -> DataReader {
+		DataReader {
+			reader: data,
+			packet: Ok(Vec::new()),
+			pos: 0,
+			buf: Vec::with_capacity(MAX_CHUNK_LENGTH as usize),
+			eos: false,
 		}
 	}
 }
@@ -155,82 +140,60 @@ impl Stream for DataReader {
 	type Item = DataReaderItem;
 
 	fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
-		match self.project() {
-			DataReaderProj::Full { data, pos } => {
-				let len = std::cmp::min(MAX_CHUNK_LENGTH as usize, data.len() - *pos);
-				let end = *pos + len;
-
-				if len == 0 {
-					Poll::Ready(None)
-				} else {
-					let mut body = [0; MAX_CHUNK_LENGTH as usize];
-					body[..len].copy_from_slice(&data[*pos..end]);
-					*pos = end;
-					Poll::Ready(Some(DataReaderItem {
-						data: DataFrame::Data { data: body, len },
-						may_have_more: end < data.len(),
-					}))
+		let mut this = self.project();
+
+		if *this.eos {
+			// eos was reached at previous call to poll_next, where a partial packet
+			// was returned. Now return None
+			return Poll::Ready(None);
+		}
+
+		loop {
+			let packet = match this.packet {
+				Ok(v) => v,
+				Err(e) => {
+					let e = *e;
+					*this.packet = Ok(Vec::new());
+					return Poll::Ready(Some(DataReaderItem {
+						data: DataFrame::Error(e),
+						may_have_more: true,
+					}));
 				}
+			};
+			let packet_left = packet.len() - *this.pos;
+			let buf_left = MAX_CHUNK_LENGTH as usize - this.buf.len();
+			let to_read = std::cmp::min(buf_left, packet_left);
+			this.buf
+				.extend_from_slice(&packet[*this.pos..*this.pos + to_read]);
+			*this.pos += to_read;
+			if this.buf.len() == MAX_CHUNK_LENGTH as usize {
+				// we have a full buf, ready to send
+				break;
 			}
-			DataReaderProj::Streaming {
-				mut reader,
-				packet: res_packet,
-				pos,
-				buf,
-				eos,
-			} => {
-				if *eos {
-					// eos was reached at previous call to poll_next, where a partial packet
-					// was returned. Now return None
-					return Poll::Ready(None);
-				}
-				loop {
-					let packet = match res_packet {
-						Ok(v) => v,
-						Err(e) => {
-							let e = *e;
-							*res_packet = Ok(Vec::new());
-							return Poll::Ready(Some(DataReaderItem {
-								data: DataFrame::Error(e),
-								may_have_more: true,
-							}));
-						}
-					};
-					let packet_left = packet.len() - *pos;
-					let buf_left = MAX_CHUNK_LENGTH as usize - buf.len();
-					let to_read = std::cmp::min(buf_left, packet_left);
-					buf.extend_from_slice(&packet[*pos..*pos + to_read]);
-					*pos += to_read;
-					if buf.len() == MAX_CHUNK_LENGTH as usize {
-						// we have a full buf, ready to send
-						break;
-					}
 
-					// we don't have a full buf, packet is empty; try receive more
-					if let Some(p) = futures::ready!(reader.as_mut().poll_next(cx)) {
-						*res_packet = p;
-						*pos = 0;
-						// if buf is empty, we will loop and return the error directly. If buf
-						// isn't empty, send it before by breaking.
-						if res_packet.is_err() && !buf.is_empty() {
-							break;
-						}
-					} else {
-						*eos = true;
-						break;
-					}
+			// we don't have a full buf, packet is empty; try receive more
+			if let Some(p) = futures::ready!(this.reader.as_mut().poll_next(cx)) {
+				*this.packet = p;
+				*this.pos = 0;
+				// if buf is empty, we will loop and return the error directly. If buf
+				// isn't empty, send it before by breaking.
+				if this.packet.is_err() && !this.buf.is_empty() {
+					break;
 				}
-
-				let mut body = [0; MAX_CHUNK_LENGTH as usize];
-				let len = buf.len();
-				body[..len].copy_from_slice(buf);
-				buf.clear();
-				Poll::Ready(Some(DataReaderItem {
-					data: DataFrame::Data { data: body, len },
-					may_have_more: !*eos,
-				}))
+			} else {
+				*this.eos = true;
+				break;
 			}
 		}
+
+		let mut body = [0; MAX_CHUNK_LENGTH as usize];
+		let len = this.buf.len();
+		body[..len].copy_from_slice(this.buf);
+		this.buf.clear();
+		Poll::Ready(Some(DataReaderItem {
+			data: DataFrame::Data { data: body, len },
+			may_have_more: !*this.eos,
+		}))
 	}
 }
 
@@ -334,7 +297,7 @@ impl<'a> futures::Future for SendQueuePollNextReady<'a> {
 pub(crate) trait SendLoop: Sync {
 	async fn send_loop<W>(
 		self: Arc<Self>,
-		mut msg_recv: mpsc::UnboundedReceiver<(RequestID, RequestPriority, Data)>,
+		mut msg_recv: mpsc::UnboundedReceiver<(RequestID, RequestPriority, AssociatedStream)>,
 		mut write: BoxStreamWrite<W>,
 	) -> Result<(), Error>
 	where
@@ -380,38 +343,82 @@ pub(crate) trait SendLoop: Sync {
 	}
 }
 
-struct ChannelPair {
-	receiver: Option<UnboundedReceiver<Vec<u8>>>,
-	sender: Option<UnboundedSender<Vec<u8>>>,
+pub(crate) struct Framing {
+	direct: Vec<u8>,
+	stream: Option<AssociatedStream>,
 }
 
-impl ChannelPair {
-	fn take_receiver(&mut self) -> Option<UnboundedReceiver<Vec<u8>>> {
-		self.receiver.take()
+impl Framing {
+	pub fn new(direct: Vec<u8>, stream: Option<AssociatedStream>) -> Self {
+		assert!(direct.len() <= u32::MAX as usize);
+		Framing { direct, stream }
 	}
 
-	fn take_sender(&mut self) -> Option<UnboundedSender<Vec<u8>>> {
-		self.sender.take()
-	}
+	pub fn into_stream(self) -> AssociatedStream {
+		use futures::stream;
+		let len = self.direct.len() as u32;
+		// required because otherwise the borrow-checker complains
+		let Framing { direct, stream } = self;
 
-	fn ref_sender(&mut self) -> Option<&UnboundedSender<Vec<u8>>> {
-		self.sender.as_ref().take()
-	}
+		let res = stream::once(async move { Ok(u32::to_be_bytes(len).to_vec()) })
+			.chain(stream::once(async move { Ok(direct) }));
 
-	fn insert_into(self, map: &mut HashMap<RequestID, ChannelPair>, index: RequestID) {
-		if self.receiver.is_some() || self.sender.is_some() {
-			map.insert(index, self);
+		if let Some(stream) = stream {
+			Box::pin(res.chain(stream))
+		} else {
+			Box::pin(res)
 		}
 	}
-}
 
-impl Default for ChannelPair {
-	fn default() -> Self {
-		let (send, recv) = unbounded();
-		ChannelPair {
-			receiver: Some(recv),
-			sender: Some(send),
+	pub async fn from_stream<S: Stream<Item = Result<Vec<u8>, u8>> + Unpin + Send + 'static>(
+		mut stream: S,
+	) -> Result<Self, Error> {
+		let mut packet = stream
+			.next()
+			.await
+			.ok_or(Error::Framing)?
+			.map_err(|_| Error::Framing)?;
+		if packet.len() < 4 {
+			return Err(Error::Framing);
+		}
+
+		let mut len = [0; 4];
+		len.copy_from_slice(&packet[..4]);
+		let len = u32::from_be_bytes(len);
+		packet.drain(..4);
+
+		let mut buffer = Vec::new();
+		let len = len as usize;
+		loop {
+			let max_cp = std::cmp::min(len - buffer.len(), packet.len());
+
+			buffer.extend_from_slice(&packet[..max_cp]);
+			if buffer.len() == len {
+				packet.drain(..max_cp);
+				break;
+			}
+			packet = stream
+				.next()
+				.await
+				.ok_or(Error::Framing)?
+				.map_err(|_| Error::Framing)?;
 		}
+
+		let stream: AssociatedStream = if packet.is_empty() {
+			Box::pin(stream)
+		} else {
+			Box::pin(futures::stream::once(async move { Ok(packet) }).chain(stream))
+		};
+
+		Ok(Framing {
+			direct: buffer,
+			stream: Some(stream),
+		})
+	}
+
+	pub fn into_parts(self) -> (Vec<u8>, AssociatedStream) {
+		let Framing { direct, stream } = self;
+		(direct, stream.unwrap_or(Box::pin(futures::stream::empty())))
 	}
 }
 
@@ -424,14 +431,13 @@ impl Default for ChannelPair {
 /// the full message is passed to the receive handler.
 #[async_trait]
 pub(crate) trait RecvLoop: Sync + 'static {
-	fn recv_handler(self: &Arc<Self>, id: RequestID, msg: Vec<u8>, stream: AssociatedStream);
+	fn recv_handler(self: &Arc<Self>, id: RequestID, stream: AssociatedStream);
 
 	async fn recv_loop<R>(self: Arc<Self>, mut read: R) -> Result<(), Error>
 	where
 		R: AsyncReadExt + Unpin + Send + Sync,
 	{
-		let mut receiving: HashMap<RequestID, Vec<u8>> = HashMap::new();
-		let mut streams: HashMap<RequestID, ChannelPair> = HashMap::new();
+		let mut streams: HashMap<RequestID, UnboundedSender<Result<Vec<u8>, u8>>> = HashMap::new();
 		loop {
 			trace!("recv_loop: reading packet");
 			let mut header_id = [0u8; RequestID::BITS as usize / 8];
@@ -450,55 +456,30 @@ pub(crate) trait RecvLoop: Sync + 'static {
 
 			let has_cont = (size & CHUNK_HAS_CONTINUATION) != 0;
 			let is_error = (size & ERROR_MARKER) != 0;
-			let size = if !is_error {
-				size & !CHUNK_HAS_CONTINUATION
+			let packet = if is_error {
+				Err(size as u8)
 			} else {
-				0
+				let size = size & !CHUNK_HAS_CONTINUATION;
+				let mut next_slice = vec![0; size as usize];
+				read.read_exact(&mut next_slice[..]).await?;
+				trace!("recv_loop: read {} bytes", next_slice.len());
+				Ok(next_slice)
 			};
-			// TODO propagate errors
-
-			let mut next_slice = vec![0; size as usize];
-			read.read_exact(&mut next_slice[..]).await?;
-			trace!("recv_loop: read {} bytes", next_slice.len());
-
-			if id & 1 == 0 {
-				// main stream
-				let mut msg_bytes = receiving.remove(&id).unwrap_or_default();
-				msg_bytes.extend_from_slice(&next_slice[..]);
-
-				if has_cont {
-					receiving.insert(id, msg_bytes);
-				} else {
-					let mut channel_pair = streams.remove(&(id | 1)).unwrap_or_default();
-
-					if let Some(receiver) = channel_pair.take_receiver() {
-						use futures::StreamExt;
-						self.recv_handler(id, msg_bytes, Box::pin(receiver.map(|v| Ok(v))));
-					} else {
-						warn!("Couldn't take receiver part of stream")
-					}
 
-					channel_pair.insert_into(&mut streams, id | 1);
-				}
+			let sender = if let Some(send) = streams.remove(&(id)) {
+				send
 			} else {
-				// associated stream
-				let mut channel_pair = streams.remove(&(id)).unwrap_or_default();
-
-				// if we get an error, the receiving end is disconnected. We still need to
-				// reach eos before dropping this sender
-				if !next_slice.is_empty() {
-					if let Some(sender) = channel_pair.ref_sender() {
-						let _ = sender.unbounded_send(next_slice);
-					} else {
-						warn!("Couldn't take sending part of stream")
-					}
-				}
+				let (send, recv) = unbounded();
+				self.recv_handler(id, Box::pin(recv));
+				send
+			};
 
-				if !has_cont {
-					channel_pair.take_sender();
-				}
+			// if we get an error, the receiving end is disconnected. We still need to
+			// reach eos before dropping this sender
+			let _ = sender.unbounded_send(packet);
 
-				channel_pair.insert_into(&mut streams, id);
+			if has_cont {
+				streams.insert(id, sender);
 			}
 		}
 		Ok(())
@@ -509,55 +490,44 @@ pub(crate) trait RecvLoop: Sync + 'static {
 mod test {
 	use super::*;
 
+	fn empty_data() -> DataReader {
+		type Item = Result<Vec<u8>, u8>;
+		let stream: Pin<Box<dyn futures::Stream<Item = Item> + Send + 'static>> =
+			Box::pin(futures::stream::empty::<Result<Vec<u8>, u8>>());
+		stream.into()
+	}
+
 	#[test]
 	fn test_priority_queue() {
 		let i1 = SendQueueItem {
 			id: 1,
 			prio: PRIO_NORMAL,
-			data: DataReader::Full {
-				data: vec![],
-				pos: 0,
-			},
+			data: empty_data(),
 		};
 		let i2 = SendQueueItem {
 			id: 2,
 			prio: PRIO_HIGH,
-			data: DataReader::Full {
-				data: vec![],
-				pos: 0,
-			},
+			data: empty_data(),
 		};
 		let i2bis = SendQueueItem {
 			id: 20,
 			prio: PRIO_HIGH,
-			data: DataReader::Full {
-				data: vec![],
-				pos: 0,
-			},
+			data: empty_data(),
 		};
 		let i3 = SendQueueItem {
 			id: 3,
 			prio: PRIO_HIGH | PRIO_SECONDARY,
-			data: DataReader::Full {
-				data: vec![],
-				pos: 0,
-			},
+			data: empty_data(),
 		};
 		let i4 = SendQueueItem {
 			id: 4,
 			prio: PRIO_BACKGROUND | PRIO_SECONDARY,
-			data: DataReader::Full {
-				data: vec![],
-				pos: 0,
-			},
+			data: empty_data(),
 		};
 		let i5 = SendQueueItem {
 			id: 5,
 			prio: PRIO_BACKGROUND | PRIO_PRIMARY,
-			data: DataReader::Full {
-				data: vec![],
-				pos: 0,
-			},
+			data: empty_data(),
 		};
 
 		let mut q = SendQueue::new();