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Don't leak a tokio task when using serve without graceful shutdown #3129

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Merged
merged 6 commits into from
Apr 30, 2025
Merged

Don't leak a tokio task when using serve without graceful shutdown #3129

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05da9f8
Replace futures_util::pin_mut with std::pin::pin
jplatte Apr 26, 2025
7768ee2
Move serve implementation out of WithGracefulShutdown
jplatte Apr 26, 2025
8b968e9
Stop implementing IntoFuture for Serve via with_graceful_shutdown
jplatte Apr 26, 2025
4d4750e
Simplify do_serve a bit
jplatte Apr 26, 2025
1c5b7df
Extract handle_connection out of do_serve
jplatte Apr 26, 2025
ffea2bc
Split up serve functions for Serve and WithGracefulShutdown again
jplatte Apr 26, 2025
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219 changes: 130 additions & 89 deletions axum/src/serve/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,13 +3,14 @@
use std::{
convert::Infallible,
fmt::Debug,
future::{poll_fn, Future, IntoFuture},
future::{Future, IntoFuture},
io,
marker::PhantomData,
pin::pin,
};

use axum_core::{body::Body, extract::Request, response::Response};
use futures_util::{pin_mut, FutureExt};
use futures_util::FutureExt;
use hyper::body::Incoming;
use hyper_util::rt::{TokioExecutor, TokioIo};
#[cfg(any(feature = "http1", feature = "http2"))]
Expand Down Expand Up @@ -165,6 +166,33 @@ where
}
}

#[cfg(all(feature = "tokio", any(feature = "http1", feature = "http2")))]
impl<L, M, S> Serve<L, M, S>
where
L: Listener,
L::Addr: Debug,
M: for<'a> Service<IncomingStream<'a, L>, Error = Infallible, Response = S> + Send + 'static,
for<'a> <M as Service<IncomingStream<'a, L>>>::Future: Send,
S: Service<Request, Response = Response, Error = Infallible> + Clone + Send + 'static,
S::Future: Send,
{
async fn run(self) -> ! {
let Self {
mut listener,
mut make_service,
_marker,
} = self;

let (signal_tx, _signal_rx) = watch::channel(());
let (_close_tx, close_rx) = watch::channel(());

loop {
let (io, remote_addr) = listener.accept().await;
handle_connection(&mut make_service, &signal_tx, &close_rx, io, remote_addr).await;
}
}
}

#[cfg(all(feature = "tokio", any(feature = "http1", feature = "http2")))]
impl<L, M, S> Debug for Serve<L, M, S>
where
Expand Down Expand Up @@ -200,8 +228,7 @@ where
type IntoFuture = private::ServeFuture;

fn into_future(self) -> Self::IntoFuture {
self.with_graceful_shutdown(std::future::pending())
.into_future()
private::ServeFuture(Box::pin(async move { self.run().await }))
}
}

Expand All @@ -226,6 +253,57 @@ where
}
}

#[cfg(all(feature = "tokio", any(feature = "http1", feature = "http2")))]
impl<L, M, S, F> WithGracefulShutdown<L, M, S, F>
where
L: Listener,
L::Addr: Debug,
M: for<'a> Service<IncomingStream<'a, L>, Error = Infallible, Response = S> + Send + 'static,
for<'a> <M as Service<IncomingStream<'a, L>>>::Future: Send,
S: Service<Request, Response = Response, Error = Infallible> + Clone + Send + 'static,
S::Future: Send,
F: Future<Output = ()> + Send + 'static,
{
async fn run(self) {
let Self {
mut listener,
mut make_service,
signal,
_marker,
} = self;

let (signal_tx, signal_rx) = watch::channel(());
tokio::spawn(async move {
signal.await;
trace!("received graceful shutdown signal. Telling tasks to shutdown");
drop(signal_rx);
});

let (close_tx, close_rx) = watch::channel(());

loop {
let (io, remote_addr) = tokio::select! {
conn = listener.accept() => conn,
_ = signal_tx.closed() => {
trace!("signal received, not accepting new connections");
break;
}
};

handle_connection(&mut make_service, &signal_tx, &close_rx, io, remote_addr).await;
}

drop(close_rx);
drop(listener);

trace!(
"waiting for {} task(s) to finish",
close_tx.receiver_count()
);
close_tx.closed().await;
}
}

#[cfg(all(feature = "tokio", any(feature = "http1", feature = "http2")))]
impl<L, M, S, F> Debug for WithGracefulShutdown<L, M, S, F>
where
Expand Down Expand Up @@ -272,106 +350,69 @@ where
}
}

#[cfg(all(feature = "tokio", any(feature = "http1", feature = "http2")))]
impl<L, M, S, F> WithGracefulShutdown<L, M, S, F>
where
async fn handle_connection<L, M, S>(
make_service: &mut M,
signal_tx: &watch::Sender<()>,
close_rx: &watch::Receiver<()>,
io: <L as Listener>::Io,
remote_addr: <L as Listener>::Addr,
) where
L: Listener,
L::Addr: Debug,
M: for<'a> Service<IncomingStream<'a, L>, Error = Infallible, Response = S> + Send + 'static,
for<'a> <M as Service<IncomingStream<'a, L>>>::Future: Send,
S: Service<Request, Response = Response, Error = Infallible> + Clone + Send + 'static,
S::Future: Send,
F: Future<Output = ()> + Send + 'static,
{
async fn run(self) {
let Self {
mut listener,
mut make_service,
signal,
_marker: _,
} = self;

let (signal_tx, signal_rx) = watch::channel(());
tokio::spawn(async move {
signal.await;
trace!("received graceful shutdown signal. Telling tasks to shutdown");
drop(signal_rx);
});

let (close_tx, close_rx) = watch::channel(());
let io = TokioIo::new(io);

trace!("connection {remote_addr:?} accepted");

make_service
.ready()
.await
.unwrap_or_else(|err| match err {});

let tower_service = make_service
.call(IncomingStream {
io: &io,
remote_addr,
})
.await
.unwrap_or_else(|err| match err {})
.map_request(|req: Request<Incoming>| req.map(Body::new));

let hyper_service = TowerToHyperService::new(tower_service);
let signal_tx = signal_tx.clone();
let close_rx = close_rx.clone();

tokio::spawn(async move {
#[allow(unused_mut)]
let mut builder = Builder::new(TokioExecutor::new());
// CONNECT protocol needed for HTTP/2 websockets
#[cfg(feature = "http2")]
builder.http2().enable_connect_protocol();

let mut conn = pin!(builder.serve_connection_with_upgrades(io, hyper_service));
let mut signal_closed = pin!(signal_tx.closed().fuse());

loop {
let (io, remote_addr) = tokio::select! {
conn = listener.accept() => conn,
_ = signal_tx.closed() => {
trace!("signal received, not accepting new connections");
tokio::select! {
result = conn.as_mut() => {
if let Err(_err) = result {
trace!("failed to serve connection: {_err:#}");
}
break;
}
};

let io = TokioIo::new(io);

trace!("connection {remote_addr:?} accepted");

poll_fn(|cx| make_service.poll_ready(cx))
.await
.unwrap_or_else(|err| match err {});

let tower_service = make_service
.call(IncomingStream {
io: &io,
remote_addr,
})
.await
.unwrap_or_else(|err| match err {})
.map_request(|req: Request<Incoming>| req.map(Body::new));

let hyper_service = TowerToHyperService::new(tower_service);

let signal_tx = signal_tx.clone();

let close_rx = close_rx.clone();

tokio::spawn(async move {
#[allow(unused_mut)]
let mut builder = Builder::new(TokioExecutor::new());
// CONNECT protocol needed for HTTP/2 websockets
#[cfg(feature = "http2")]
builder.http2().enable_connect_protocol();
let conn = builder.serve_connection_with_upgrades(io, hyper_service);
pin_mut!(conn);

let signal_closed = signal_tx.closed().fuse();
pin_mut!(signal_closed);

loop {
tokio::select! {
result = conn.as_mut() => {
if let Err(_err) = result {
trace!("failed to serve connection: {_err:#}");
}
break;
}
_ = &mut signal_closed => {
trace!("signal received in task, starting graceful shutdown");
conn.as_mut().graceful_shutdown();
}
}
_ = &mut signal_closed => {
trace!("signal received in task, starting graceful shutdown");
conn.as_mut().graceful_shutdown();
}

drop(close_rx);
});
}
}

drop(close_rx);
drop(listener);

trace!(
"waiting for {} task(s) to finish",
close_tx.receiver_count()
);
close_tx.closed().await;
}
});
}

/// An incoming stream.
Expand Down