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Stream now ignores lag

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This commit is contained in:
Dion Dokter 2022-06-16 14:11:41 +02:00
parent c7cdecfc93
commit 790426e2f6
1 changed files with 8 additions and 4 deletions
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12
embassy/src/channel/pubsub.rs
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@ -300,8 +300,10 @@ impl<'a, T: Clone> Drop for Subscriber<'a, T> {
} }
} }
/// Warning: The stream implementation ignores lag results and returns all messages.
/// This might miss some messages without you knowing it.
impl<'a, T: Clone> futures::Stream for Subscriber<'a, T> { impl<'a, T: Clone> futures::Stream for Subscriber<'a, T> {
type Item = WaitResult<T>; type Item = T;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let this = unsafe { self.get_unchecked_mut() }; let this = unsafe { self.get_unchecked_mut() };
@ -311,7 +313,7 @@ impl<'a, T: Clone> futures::Stream for Subscriber<'a, T> {
// Yes, so we are done polling // Yes, so we are done polling
Some(WaitResult::Message(message)) => { Some(WaitResult::Message(message)) => {
this.next_message_id += 1; this.next_message_id += 1;
Poll::Ready(Some(WaitResult::Message(message))) Poll::Ready(Some(message))
} }
// No, so we need to reregister our waker and sleep again // No, so we need to reregister our waker and sleep again
None => { None => {
@ -321,10 +323,12 @@ impl<'a, T: Clone> futures::Stream for Subscriber<'a, T> {
} }
Poll::Pending Poll::Pending
} }
// We missed a couple of messages. We must do our internal bookkeeping and return that we lagged // We missed a couple of messages. We must do our internal bookkeeping.
// This stream impl doesn't return lag results, so we just ignore and start over
Some(WaitResult::Lagged(amount)) => { Some(WaitResult::Lagged(amount)) => {
this.next_message_id += amount; this.next_message_id += amount;
Poll::Ready(Some(WaitResult::Lagged(amount))) cx.waker().wake_by_ref();
Poll::Pending
} }
} }
} }