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fix(client): detect connection closes as pool tries to use

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Currently, if the remote closes the connection at the same time that the
pool selects it to use for a new request, the connection may actually
hang. This fix will now more allow the keep-alive read to check the
socket even when the `Conn` think it's busy.

If the connection was closed before the request write happened, returns
back an `Error::Cancel`, letting the user know they could safely retry
it.

Closes #1439
This commit is contained in:
Sean McArthur
2018-02-12 13:27:50 -08:00
parent a9413d7367
commit dc619a8fa0
6 changed files with 167 additions and 94 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
src/client/dispatch.rs
View File

@@ -85,7 +85,7 @@ impl<T, U> Drop for Receiver<T, U> {
// - Err: unreachable
while let Ok(Async::Ready(Some((_val, cb)))) = self.inner.poll() {
// maybe in future, we pass the value along with the error?
let _ = cb.send(Err(::Error::new_canceled()));
let _ = cb.send(Err(::Error::new_canceled(None)));
}
}

6
src/client/mod.rs
View File

@@ -243,11 +243,7 @@ where C: Connect,
},
Err(_) => {
error!("pooled connection was not ready, this is a hyper bug");
let err = io::Error::new(
io::ErrorKind::BrokenPipe,
"pool selected dead connection",
);
Either::B(future::err(::Error::Io(err)))
Either::B(future::err(::Error::new_canceled(None)))
}
}
});

17
src/error.rs
View File

@@ -60,9 +60,9 @@ pub enum Error {
}
impl Error {
pub(crate) fn new_canceled() -> Error {
pub(crate) fn new_canceled(cause: Option<Error>) -> Error {
Error::Cancel(Canceled {
_inner: (),
cause: cause.map(Box::new),
})
}
}
@@ -73,10 +73,9 @@ impl Error {
/// as the related connection gets closed by the remote. In that case,
/// when the connection drops, the pending response future will be
/// fulfilled with this error, signaling the `Request` was never started.
#[derive(Debug)]
pub struct Canceled {
// maybe in the future this contains an optional value of
// what was canceled?
_inner: (),
cause: Option<Box<Error>>,
}
impl Canceled {
@@ -85,13 +84,6 @@ impl Canceled {
}
}
impl fmt::Debug for Canceled {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("Canceled")
.finish()
}
}
impl fmt::Display for Canceled {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad(self.description())
@@ -142,6 +134,7 @@ impl StdError for Error {
Io(ref error) => Some(error),
Uri(ref error) => Some(error),
Utf8(ref error) => Some(error),
Cancel(ref e) => e.cause.as_ref().map(|e| &**e as &StdError),
Error::__Nonexhaustive(..) => unreachable!(),
_ => None,
}

88
src/proto/h1/conn.rs
View File

@@ -119,7 +119,7 @@ where I: AsyncRead + AsyncWrite,
} else {
trace!("poll when on keep-alive");
if !T::should_read_first() {
self.try_empty_read()?;
self.require_empty_read()?;
if self.is_read_closed() {
return Ok(Async::Ready(None));
}
@@ -281,17 +281,23 @@ where I: AsyncRead + AsyncWrite,
pub fn read_keep_alive(&mut self) -> Result<(), ::Error> {
debug_assert!(!self.can_read_head() && !self.can_read_body());
trace!("Conn::read_keep_alive");
trace!("read_keep_alive; is_mid_message={}", self.is_mid_message());
if T::should_read_first() || !self.state.is_idle() {
if self.is_mid_message() {
self.maybe_park_read();
} else {
self.try_empty_read()?;
self.require_empty_read()?;
}
Ok(())
}
fn is_mid_message(&self) -> bool {
match (&self.state.reading, &self.state.writing) {
(&Reading::Init, &Writing::Init) => false,
_ => true,
}
}
fn maybe_park_read(&mut self) {
if !self.io.is_read_blocked() {
// the Io object is ready to read, which means it will never alert
@@ -312,40 +318,68 @@ where I: AsyncRead + AsyncWrite,
//
// This should only be called for Clients wanting to enter the idle
// state.
fn try_empty_read(&mut self) -> io::Result<()> {
fn require_empty_read(&mut self) -> io::Result<()> {
assert!(!self.can_read_head() && !self.can_read_body());
if !self.io.read_buf().is_empty() {
debug!("received an unexpected {} bytes", self.io.read_buf().len());
Err(io::Error::new(io::ErrorKind::InvalidData, "unexpected bytes after message ended"))
} else {
match self.io.read_from_io() {
Ok(Async::Ready(0)) => {
trace!("try_empty_read; found EOF on connection: {:?}", self.state);
let must_error = self.should_error_on_eof();
// order is important: must_error needs state BEFORE close_read
self.state.close_read();
if must_error {
Err(io::Error::new(io::ErrorKind::UnexpectedEof, "unexpected EOF waiting for response"))
} else {
Ok(())
}
},
Ok(Async::Ready(n)) => {
debug!("received {} bytes on an idle connection", n);
Err(io::Error::new(io::ErrorKind::InvalidData, "unexpected bytes after message ended"))
},
Ok(Async::NotReady) => {
match self.try_io_read()? {
Async::Ready(0) => {
// case handled in try_io_read
Ok(())
},
Async::Ready(n) => {
debug!("received {} bytes on an idle connection", n);
let desc = if self.state.is_idle() {
"unexpected bytes after message ended"
} else {
"unexpected bytes before writing message"
};
Err(io::Error::new(io::ErrorKind::InvalidData, desc))
},
Async::NotReady => {
Ok(())
},
Err(e) => {
self.state.close();
Err(e)
}
}
}
}
fn try_io_read(&mut self) -> Poll<usize, io::Error> {
match self.io.read_from_io() {
Ok(Async::Ready(0)) => {
trace!("try_io_read; found EOF on connection: {:?}", self.state);
let must_error = self.should_error_on_eof();
let ret = if must_error {
let desc = if self.is_mid_message() {
"unexpected EOF waiting for response"
} else {
"unexpected EOF before writing message"
};
Err(io::Error::new(io::ErrorKind::UnexpectedEof, desc))
} else {
Ok(Async::Ready(0))
};
// order is important: must_error needs state BEFORE close_read
self.state.close_read();
ret
},
Ok(Async::Ready(n)) => {
Ok(Async::Ready(n))
},
Ok(Async::NotReady) => {
Ok(Async::NotReady)
},
Err(e) => {
self.state.close();
Err(e)
}
}
}
fn maybe_notify(&mut self) {
// its possible that we returned NotReady from poll() without having
// exhausted the underlying Io. We would have done this when we

22
src/proto/h1/dispatch.rs
View File

@@ -401,7 +401,9 @@ where
let _ = cb.send(Err(err));
Ok(())
} else if let Ok(Async::Ready(Some((_, cb)))) = self.rx.poll() {
let _ = cb.send(Err(err));
// in this case, the message was never even started, so it's safe to tell
// the user that the request was completely canceled
let _ = cb.send(Err(::Error::new_canceled(Some(err))));
Ok(())
} else {
Err(err)
@@ -431,13 +433,14 @@ where
#[cfg(test)]
mod tests {
extern crate pretty_env_logger;
use super::*;
use mock::AsyncIo;
use proto::ClientTransaction;
#[test]
fn client_read_response_before_writing_request() {
extern crate pretty_env_logger;
fn client_read_bytes_before_writing_request() {
let _ = pretty_env_logger::try_init();
::futures::lazy(|| {
let io = AsyncIo::new_buf(b"HTTP/1.1 200 OK\r\n\r\n".to_vec(), 100);
@@ -452,11 +455,16 @@ mod tests {
};
let res_rx = tx.send((req, None::<::Body>)).unwrap();
dispatcher.poll().expect("dispatcher poll 1");
dispatcher.poll().expect("dispatcher poll 2");
let _res = res_rx.wait()
let a1 = dispatcher.poll().expect("error should be sent on channel");
assert!(a1.is_ready(), "dispatcher should be closed");
let err = res_rx.wait()
.expect("callback poll")
.expect("callback response");
.expect_err("callback response");
match err {
::Error::Cancel(_) => (),
other => panic!("expected Cancel(_), got {:?}", other),
}
Ok::<(), ()>(())
}).wait().unwrap();
}