Simplify send.rs

1 files changed, 50 insertions, 155 deletions

diff --git a/src/send.rs b/src/send.rs
index 59805cf..a8cf966 100644
--- a/src/send.rs
+++ b/src/send.rs
@@ -8,7 +8,6 @@ use bytes::Bytes;
 use log::trace;
 
 use futures::AsyncWriteExt;
-use futures::Stream;
 use kuska_handshake::async_std::BoxStreamWrite;
 use tokio::sync::mpsc;
 
@@ -30,152 +29,14 @@ pub(crate) const MAX_CHUNK_LENGTH: ChunkLength = 0x3FF0;
 pub(crate) const ERROR_MARKER: ChunkLength = 0x4000;
 pub(crate) const CHUNK_HAS_CONTINUATION: ChunkLength = 0x8000;
 
+struct SendQueue {
+	items: VecDeque<(u8, VecDeque<SendQueueItem>)>,
+}
+
 struct SendQueueItem {
 	id: RequestID,
 	prio: RequestPriority,
-	data: DataReader,
-}
-
-#[pin_project::pin_project]
-struct DataReader {
-	#[pin]
-	reader: ByteStream,
-	packet: Packet,
-	pos: usize,
-	buf: Vec<u8>,
-	eos: bool,
-}
-
-impl From<ByteStream> for DataReader {
-	fn from(data: ByteStream) -> DataReader {
-		DataReader {
-			reader: data,
-			packet: Ok(Bytes::new()),
-			pos: 0,
-			buf: Vec::with_capacity(MAX_CHUNK_LENGTH as usize),
-			eos: false,
-		}
-	}
-}
-
-enum DataFrame {
-	Data {
-		/// a fixed size buffer containing some data, possibly padded with 0s
-		data: [u8; MAX_CHUNK_LENGTH as usize],
-		/// actual lenght of data
-		len: usize,
-		/// whethere there may be more data comming from this stream. Can be used for some
-		/// optimization. It's an error to set it to false if there is more data, but it is correct
-		/// (albeit sub-optimal) to set it to true if there is nothing coming after
-		may_have_more: bool,
-	},
-	/// An error code automatically signals the end of the stream
-	Error(u8),
-}
-
-impl DataFrame {
-	fn empty_last() -> Self {
-		DataFrame::Data {
-			data: [0; MAX_CHUNK_LENGTH as usize],
-			len: 0,
-			may_have_more: false,
-		}
-	}
-
-	fn header(&self) -> [u8; 2] {
-		let header_u16 = match self {
-			DataFrame::Data {
-				len,
-				may_have_more: false,
-				..
-			} => *len as u16,
-			DataFrame::Data {
-				len,
-				may_have_more: true,
-				..
-			} => *len as u16 | CHUNK_HAS_CONTINUATION,
-			DataFrame::Error(e) => *e as u16 | ERROR_MARKER,
-		};
-		ChunkLength::to_be_bytes(header_u16)
-	}
-
-	fn data(&self) -> &[u8] {
-		match self {
-			DataFrame::Data { ref data, len, .. } => &data[..*len],
-			DataFrame::Error(_) => &[],
-		}
-	}
-
-	fn may_have_more(&self) -> bool {
-		match self {
-			DataFrame::Data { may_have_more, .. } => *may_have_more,
-			DataFrame::Error(_) => false,
-		}
-	}
-}
-
-impl Stream for DataReader {
-	type Item = DataFrame;
-
-	fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
-		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(Bytes::new());
-					*this.eos = true;
-					return Poll::Ready(Some(DataFrame::Error(e)));
-				}
-			};
-			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;
-			}
-
-			// 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;
-				}
-			} 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(DataFrame::Data {
-			data: body,
-			len,
-			may_have_more: !*this.eos,
-		}))
-	}
-}
-
-struct SendQueue {
-	items: VecDeque<(u8, VecDeque<SendQueueItem>)>,
+	data: ByteStreamReader,
 }
 
 impl SendQueue {
@@ -232,35 +93,69 @@ impl<'a> futures::Future for SendQueuePollNextReady<'a> {
 
 			let mut ready_item = None;
 			for (j, item) in items_at_prio.iter_mut().enumerate() {
-				match Pin::new(&mut item.data).poll_next(ctx) {
+				let mut item_reader = item.data.read_exact_or_eos(MAX_CHUNK_LENGTH as usize);
+				match Pin::new(&mut item_reader).poll(ctx) {
 					Poll::Pending => (),
 					Poll::Ready(ready_v) => {
-						ready_item = Some((j, ready_v));
+						ready_item = Some((j, ready_v, item.data.eos()));
 						break;
 					}
 				}
 			}
 
-			if let Some((j, ready_v)) = ready_item {
+			if let Some((j, bytes_or_err, eos)) = ready_item {
+				let data_frame = match bytes_or_err {
+					Ok(bytes) => DataFrame::Data(bytes, !eos),
+					Err(e) => DataFrame::Error(match e {
+						ReadExactError::Stream(code) => code,
+						_ => unreachable!(),
+					}),
+				};
 				let item = items_at_prio.remove(j).unwrap();
 				let id = item.id;
-				if ready_v
-					.as_ref()
-					.map(|data| data.may_have_more())
-					.unwrap_or(false)
-				{
+				if !eos {
 					items_at_prio.push_back(item);
 				} else if items_at_prio.is_empty() {
 					self.queue.items.remove(i);
 				}
-				return Poll::Ready((id, ready_v.unwrap_or_else(DataFrame::empty_last)));
+				return Poll::Ready((id, data_frame));
 			}
 		}
-		// TODO what do we do if self.queue is empty? We won't get scheduled again.
+		// If the queue is empty, this futures is eternally pending.
+		// This is ok because we use it in a select with another future
+		// that can interrupt it.
 		Poll::Pending
 	}
 }
 
+enum DataFrame {
+	/// a fixed size buffer containing some data + a boolean indicating whether
+	/// there may be more data comming from this stream. Can be used for some
+	/// optimization. It's an error to set it to false if there is more data, but it is correct
+	/// (albeit sub-optimal) to set it to true if there is nothing coming after
+	Data(Bytes, bool),
+	/// An error code automatically signals the end of the stream
+	Error(u8),
+}
+
+impl DataFrame {
+	fn header(&self) -> [u8; 2] {
+		let header_u16 = match self {
+			DataFrame::Data(data, false) => data.len() as u16,
+			DataFrame::Data(data, true) => data.len() as u16 | CHUNK_HAS_CONTINUATION,
+			DataFrame::Error(e) => *e as u16 | ERROR_MARKER,
+		};
+		ChunkLength::to_be_bytes(header_u16)
+	}
+
+	fn data(&self) -> &[u8] {
+		match self {
+			DataFrame::Data(ref data, _) => &data[..],
+			DataFrame::Error(_) => &[],
+		}
+	}
+}
+
 /// The SendLoop trait, which is implemented both by the client and the server
 /// connection objects (ServerConna and ClientConn) adds a method `.send_loop()`
 /// that takes a channel of messages to send and an asynchronous writer,
@@ -295,7 +190,7 @@ pub(crate) trait SendLoop: Sync {
 						sending.push(SendQueueItem {
 							id,
 							prio,
-							data: data.into(),
+							data: ByteStreamReader::new(data),
 						});
 					} else {
 						should_exit = true;