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codec: rewrite of codec::Framed (#2368)

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Framed was designed to encapsulate both AsyncRead and AsyncWrite so
that it could wrap two-way connections. It used Fuse to manage the pinned
io object between the FramedWrite and FramedRead structs.

I replaced the Fuse struct by isolating the state used in reading and
writing, and making the code generic over that instead. This means
the FramedImpl struct now has a parameter for the state, and contains
the logic for both directions. The Framed* structs are now simply
wrappers around this type

Hopefully removing the `Pin` handling made things easier to
understand, too.
This commit is contained in:
Plecra
2020-05-12 13:47:38 +02:00
committed by GitHub
parent 1cc0168335
commit 221f421464
6 changed files with 333 additions and 554 deletions
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tokio-util/src/codec/framed_write.rs
+21 -215
View File
@@ -1,20 +1,12 @@
use crate::codec::decoder::Decoder;
use crate::codec::encoder::Encoder;
use crate::codec::framed::{Fuse, ProjectFuse};
use crate::codec::framed_impl::{FramedImpl, WriteFrame};
use tokio::{
io::{AsyncBufRead, AsyncRead, AsyncWrite},
stream::Stream,
};
use tokio::{io::AsyncWrite, stream::Stream};
use bytes::{Buf, BytesMut};
use futures_core::ready;
use futures_sink::Sink;
use log::trace;
use pin_project_lite::pin_project;
use std::fmt;
use std::io::{self, BufRead, Read};
use std::mem::MaybeUninit;
use std::io;
use std::pin::Pin;
use std::task::{Context, Poll};
@@ -24,21 +16,10 @@ pin_project! {
/// [`Sink`]: futures_sink::Sink
pub struct FramedWrite<T, E> {
#[pin]
inner: FramedWrite2<Fuse<T, E>>,
inner: FramedImpl<T, E, WriteFrame>,
}
}
pin_project! {
pub(crate) struct FramedWrite2<T> {
#[pin]
inner: T,
buffer: BytesMut,
}
}
const INITIAL_CAPACITY: usize = 8 * 1024;
const BACKPRESSURE_BOUNDARY: usize = INITIAL_CAPACITY;
impl<T, E> FramedWrite<T, E>
where
T: AsyncWrite,
@@ -46,10 +27,11 @@ where
/// Creates a new `FramedWrite` with the given `encoder`.
pub fn new(inner: T, encoder: E) -> FramedWrite<T, E> {
FramedWrite {
inner: framed_write2(Fuse {
io: inner,
inner: FramedImpl {
inner,
codec: encoder,
}),
state: WriteFrame::default(),
},
}
}
}
@@ -62,7 +44,7 @@ impl<T, E> FramedWrite<T, E> {
/// of data coming in as it may corrupt the stream of frames otherwise
/// being worked with.
pub fn get_ref(&self) -> &T {
&self.inner.inner.io
&self.inner.inner
}
/// Returns a mutable reference to the underlying I/O stream wrapped by
@@ -72,7 +54,7 @@ impl<T, E> FramedWrite<T, E> {
/// of data coming in as it may corrupt the stream of frames otherwise
/// being worked with.
pub fn get_mut(&mut self) -> &mut T {
&mut self.inner.inner.io
&mut self.inner.inner
}
/// Consumes the `FramedWrite`, returning its underlying I/O stream.
@@ -81,21 +63,21 @@ impl<T, E> FramedWrite<T, E> {
/// of data coming in as it may corrupt the stream of frames otherwise
/// being worked with.
pub fn into_inner(self) -> T {
self.inner.inner.io
self.inner.inner
}
/// Returns a reference to the underlying decoder.
/// Returns a reference to the underlying encoder.
pub fn encoder(&self) -> &E {
&self.inner.inner.codec
&self.inner.codec
}
/// Returns a mutable reference to the underlying decoder.
/// Returns a mutable reference to the underlying encoder.
pub fn encoder_mut(&mut self) -> &mut E {
&mut self.inner.inner.codec
&mut self.inner.codec
}
}
// This impl just defers to the underlying FramedWrite2
// This impl just defers to the underlying FramedImpl
impl<T, I, E> Sink<I> for FramedWrite<T, E>
where
T: AsyncWrite,
@@ -121,6 +103,7 @@ where
}
}
// This impl just defers to the underlying T: Stream
impl<T, D> Stream for FramedWrite<T, D>
where
T: Stream,
@@ -128,13 +111,7 @@ where
type Item = T::Item;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
self.project()
.inner
.project()
.inner
.project()
.io
.poll_next(cx)
self.project().inner.project().inner.poll_next(cx)
}
}
@@ -145,180 +122,9 @@ where
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("FramedWrite")
.field("inner", &self.inner.get_ref().io)
.field("encoder", &self.inner.get_ref().codec)
.field("buffer", &self.inner.buffer)
.field("inner", &self.get_ref())
.field("encoder", &self.encoder())
.field("buffer", &self.inner.state.buffer)
.finish()
}
}
// ===== impl FramedWrite2 =====
pub(crate) fn framed_write2<T>(inner: T) -> FramedWrite2<T> {
FramedWrite2 {
inner,
buffer: BytesMut::with_capacity(INITIAL_CAPACITY),
}
}
pub(crate) fn framed_write2_with_buffer<T>(inner: T, mut buf: BytesMut) -> FramedWrite2<T> {
if buf.capacity() < INITIAL_CAPACITY {
let bytes_to_reserve = INITIAL_CAPACITY - buf.capacity();
buf.reserve(bytes_to_reserve);
}
FramedWrite2 { inner, buffer: buf }
}
impl<T> FramedWrite2<T> {
pub(crate) fn get_ref(&self) -> &T {
&self.inner
}
pub(crate) fn into_inner(self) -> T {
self.inner
}
pub(crate) fn into_parts(self) -> (T, BytesMut) {
(self.inner, self.buffer)
}
pub(crate) fn get_mut(&mut self) -> &mut T {
&mut self.inner
}
}
impl<I, T> Sink<I> for FramedWrite2<T>
where
T: ProjectFuse + AsyncWrite,
T::Codec: Encoder<I>,
{
type Error = <T::Codec as Encoder<I>>::Error;
fn poll_ready(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
// If the buffer is already over 8KiB, then attempt to flush it. If after flushing it's
// *still* over 8KiB, then apply backpressure (reject the send).
if self.buffer.len() >= BACKPRESSURE_BOUNDARY {
match self.as_mut().poll_flush(cx) {
Poll::Pending => return Poll::Pending,
Poll::Ready(Err(e)) => return Poll::Ready(Err(e)),
Poll::Ready(Ok(())) => (),
};
if self.buffer.len() >= BACKPRESSURE_BOUNDARY {
return Poll::Pending;
}
}
Poll::Ready(Ok(()))
}
fn start_send(self: Pin<&mut Self>, item: I) -> Result<(), Self::Error> {
let mut pinned = self.project();
pinned
.inner
.project()
.codec
.encode(item, &mut pinned.buffer)?;
Ok(())
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
trace!("flushing framed transport");
let mut pinned = self.project();
while !pinned.buffer.is_empty() {
trace!("writing; remaining={}", pinned.buffer.len());
let buf = &pinned.buffer;
let n = ready!(pinned.inner.as_mut().poll_write(cx, &buf))?;
if n == 0 {
return Poll::Ready(Err(io::Error::new(
io::ErrorKind::WriteZero,
"failed to \
write frame to transport",
)
.into()));
}
pinned.buffer.advance(n);
}
// Try flushing the underlying IO
ready!(pinned.inner.poll_flush(cx))?;
trace!("framed transport flushed");
Poll::Ready(Ok(()))
}
fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
ready!(self.as_mut().poll_flush(cx))?;
ready!(self.project().inner.poll_shutdown(cx))?;
Poll::Ready(Ok(()))
}
}
impl<T: Decoder> Decoder for FramedWrite2<T> {
type Item = T::Item;
type Error = T::Error;
fn decode(&mut self, src: &mut BytesMut) -> Result<Option<T::Item>, T::Error> {
self.inner.decode(src)
}
fn decode_eof(&mut self, src: &mut BytesMut) -> Result<Option<T::Item>, T::Error> {
self.inner.decode_eof(src)
}
}
impl<T: Read> Read for FramedWrite2<T> {
fn read(&mut self, dst: &mut [u8]) -> io::Result<usize> {
self.inner.read(dst)
}
}
impl<T: BufRead> BufRead for FramedWrite2<T> {
fn fill_buf(&mut self) -> io::Result<&[u8]> {
self.inner.fill_buf()
}
fn consume(&mut self, amt: usize) {
self.inner.consume(amt)
}
}
impl<T: AsyncRead> AsyncRead for FramedWrite2<T> {
unsafe fn prepare_uninitialized_buffer(&self, buf: &mut [MaybeUninit<u8>]) -> bool {
self.inner.prepare_uninitialized_buffer(buf)
}
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<Result<usize, io::Error>> {
self.project().inner.poll_read(cx, buf)
}
}
impl<T: AsyncBufRead> AsyncBufRead for FramedWrite2<T> {
fn poll_fill_buf(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<&[u8]>> {
self.project().inner.poll_fill_buf(cx)
}
fn consume(self: Pin<&mut Self>, amt: usize) {
self.project().inner.consume(amt)
}
}
impl<T> ProjectFuse for FramedWrite2<T>
where
T: ProjectFuse,
{
type Io = T::Io;
type Codec = T::Codec;
fn project(self: Pin<&mut Self>) -> Fuse<Pin<&mut Self::Io>, &mut Self::Codec> {
self.project().inner.project()
}
}