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fix: Encoder state machine (Nullus157#308)
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@aatifsyed
aatifsyed committed Nov 1, 2024
1 parent e259060 commit 8af0baa
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Showing 2 changed files with 50 additions and 118 deletions.
151 changes: 42 additions & 109 deletions src/tokio/write/generic/encoder.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,20 +13,13 @@ use futures_core::ready;
use pin_project_lite::pin_project;
use tokio::io::{AsyncBufRead, AsyncRead, AsyncWrite, ReadBuf};

#[derive(Debug)]
enum State {
Encoding,
Finishing,
Done,
}

pin_project! {
#[derive(Debug)]
pub struct Encoder<W, E> {
#[pin]
writer: BufWriter<W>,
encoder: E,
state: State,
finished: bool
}
}

Expand All @@ -35,7 +28,7 @@ impl<W: AsyncWrite, E: Encode> Encoder<W, E> {
Self {
writer: BufWriter::new(writer),
encoder,
state: State::Encoding,
finished: false,
}
}
}
Expand All @@ -62,97 +55,6 @@ impl<W, E> Encoder<W, E> {
}
}

impl<W: AsyncWrite, E: Encode> Encoder<W, E> {
fn do_poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
input: &mut PartialBuffer<&[u8]>,
) -> Poll<io::Result<()>> {
let mut this = self.project();

loop {
let output = ready!(this.writer.as_mut().poll_partial_flush_buf(cx))?;
let mut output = PartialBuffer::new(output);

*this.state = match this.state {
State::Encoding => {
this.encoder.encode(input, &mut output)?;
State::Encoding
}

State::Finishing | State::Done => {
return Poll::Ready(Err(io::Error::new(
io::ErrorKind::Other,
"Write after shutdown",
)))
}
};

let produced = output.written().len();
this.writer.as_mut().produce(produced);

if input.unwritten().is_empty() {
return Poll::Ready(Ok(()));
}
}
}

fn do_poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
let mut this = self.project();

loop {
let output = ready!(this.writer.as_mut().poll_partial_flush_buf(cx))?;
let mut output = PartialBuffer::new(output);

let done = match this.state {
State::Encoding => this.encoder.flush(&mut output)?,

State::Finishing | State::Done => {
return Poll::Ready(Err(io::Error::new(
io::ErrorKind::Other,
"Flush after shutdown",
)))
}
};

let produced = output.written().len();
this.writer.as_mut().produce(produced);

if done {
return Poll::Ready(Ok(()));
}
}
}

fn do_poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
let mut this = self.project();

loop {
let output = ready!(this.writer.as_mut().poll_partial_flush_buf(cx))?;
let mut output = PartialBuffer::new(output);

*this.state = match this.state {
State::Encoding | State::Finishing => {
if this.encoder.finish(&mut output)? {
State::Done
} else {
State::Finishing
}
}

State::Done => State::Done,
};

let produced = output.written().len();
this.writer.as_mut().produce(produced);

if let State::Done = this.state {
return Poll::Ready(Ok(()));
}
}
}
}

impl<W: AsyncWrite, E: Encode> AsyncWrite for Encoder<W, E> {
fn poll_write(
self: Pin<&mut Self>,
Expand All @@ -163,24 +65,55 @@ impl<W: AsyncWrite, E: Encode> AsyncWrite for Encoder<W, E> {
return Poll::Ready(Ok(0));
}

let mut input = PartialBuffer::new(buf);
let mut this = self.project();

let mut encodeme = PartialBuffer::new(buf);

match self.do_poll_write(cx, &mut input)? {
Poll::Pending if input.written().is_empty() => Poll::Pending,
_ => Poll::Ready(Ok(input.written().len())),
loop {
let mut space =
PartialBuffer::new(ready!(this.writer.as_mut().poll_partial_flush_buf(cx))?);
this.encoder.encode(&mut encodeme, &mut space)?;
let bytes_encoded = space.written().len();
this.writer.as_mut().produce(bytes_encoded);
if encodeme.unwritten().is_empty() {
break;
}
}

Poll::Ready(Ok(encodeme.written().len()))
}

fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
ready!(self.as_mut().do_poll_flush(cx))?;
ready!(self.project().writer.as_mut().poll_flush(cx))?;
let mut this = self.project();
loop {
let mut space =
PartialBuffer::new(ready!(this.writer.as_mut().poll_partial_flush_buf(cx))?);
let flushed = this.encoder.flush(&mut space)?;
let bytes_encoded = space.written().len();
this.writer.as_mut().produce(bytes_encoded);
if flushed {
break;
}
}
Poll::Ready(Ok(()))
}

fn poll_shutdown(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
ready!(self.as_mut().do_poll_shutdown(cx))?;
ready!(self.project().writer.as_mut().poll_shutdown(cx))?;
Poll::Ready(Ok(()))
let mut this = self.project();
if !*this.finished {
loop {
let mut space =
PartialBuffer::new(ready!(this.writer.as_mut().poll_partial_flush_buf(cx))?);
let finished = this.encoder.finish(&mut space)?;
let bytes_encoded = space.written().len();
this.writer.as_mut().produce(bytes_encoded);
if finished {
*this.finished = true;
break;
}
}
}
this.writer.poll_shutdown(cx)
}
}

Expand Down
17 changes: 8 additions & 9 deletions tests/issues.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,6 @@ use tracing_subscriber::fmt::format::FmtSpan;
/// [`tokio_util::codec`](https://docs.rs/tokio-util/latest/tokio_util/codec)
/// [`poll_shutdown`](AsyncWrite::poll_shutdown)
/// [`poll_flush`](AsyncWrite::poll_flush)
#[should_panic = "Flush after shutdown"] // TODO: this should be removed when the bug is fixed
#[test]
fn issue_246() {
tracing_subscriber::fmt()
Expand All @@ -34,26 +33,26 @@ fn issue_246() {
.with_target(false)
.with_span_events(FmtSpan::NEW)
.init();
let mut zstd_encoder =
Transparent::new(Trace::new(ZstdEncoder::new(DelayedShutdown::default())));
let mut zstd_encoder = Wrapper::new(Trace::new(ZstdEncoder::new(DelayedShutdown::default())));
futures::executor::block_on(zstd_encoder.shutdown()).unwrap();
}

pin_project_lite::pin_project! {
/// A simple wrapper struct that follows the [`AsyncWrite`] protocol.
struct Transparent<T> {
/// This is a stand-in for combinators like `tokio_util::codec`s
struct Wrapper<T> {
#[pin] inner: T
}
}

impl<T> Transparent<T> {
impl<T> Wrapper<T> {
fn new(inner: T) -> Self {
Self { inner }
}
}

impl<T: AsyncWrite> AsyncWrite for Transparent<T> {
#[tracing::instrument(name = "Transparent::poll_write", skip_all, ret)]
impl<T: AsyncWrite> AsyncWrite for Wrapper<T> {
#[tracing::instrument(name = "Wrapper::poll_write", skip_all, ret)]
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
Expand All @@ -62,7 +61,7 @@ impl<T: AsyncWrite> AsyncWrite for Transparent<T> {
self.project().inner.poll_write(cx, buf)
}

#[tracing::instrument(name = "Transparent::poll_flush", skip_all, ret)]
#[tracing::instrument(name = "Wrapper::poll_flush", skip_all, ret)]
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
self.project().inner.poll_flush(cx)
}
Expand All @@ -72,7 +71,7 @@ impl<T: AsyncWrite> AsyncWrite for Transparent<T> {
/// > Once this method returns Ready it implies that a flush successfully happened before the shutdown happened.
/// > That is, callers don't need to call flush before calling shutdown.
/// > They can rely that by calling shutdown any pending buffered data will be written out.
#[tracing::instrument(name = "Transparent::poll_shutdown", skip_all, ret)]
#[tracing::instrument(name = "Wrapper::poll_shutdown", skip_all, ret)]
fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
let mut this = self.project();
ready!(this.inner.as_mut().poll_flush(cx))?;
Expand Down

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