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Changed names of subscriber methods and implemented the Stream trait for it

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Dion Dokter 2022-06-16 13:48:26 +02:00
parent 03996583a1
commit 36b363a5b7
1 changed files with 43 additions and 12 deletions
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embassy/src/channel/pubsub.rs
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@ -270,14 +270,14 @@ pub struct Subscriber<'a, T: Clone> {
impl<'a, T: Clone> Subscriber<'a, T> { impl<'a, T: Clone> Subscriber<'a, T> {
/// Wait for a published message /// Wait for a published message
pub fn wait<'s>(&'s mut self) -> SubscriberWaitFuture<'s, 'a, T> { pub fn next<'s>(&'s mut self) -> SubscriberWaitFuture<'s, 'a, T> {
SubscriberWaitFuture { subscriber: self } SubscriberWaitFuture { subscriber: self }
} }
/// Try to see if there's a published message we haven't received yet. /// Try to see if there's a published message we haven't received yet.
/// ///
/// This function does not peek. The message is received if there is one. /// This function does not peek. The message is received if there is one.
pub fn check(&mut self) -> Option<WaitResult<T>> { pub fn try_next(&mut self) -> Option<WaitResult<T>> {
match self.channel.get_message(self.next_message_id) { match self.channel.get_message(self.next_message_id) {
Some(WaitResult::Lagged(amount)) => { Some(WaitResult::Lagged(amount)) => {
self.next_message_id += amount; self.next_message_id += amount;
@ -300,6 +300,37 @@ impl<'a, T: Clone> Drop for Subscriber<'a, T> {
} }
} }
impl<'a, T: Clone> futures::Stream for Subscriber<'a, T> {
type Item = WaitResult<T>;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let this = unsafe { self.get_unchecked_mut() };
// Check if we can read a message
match this.channel.get_message(this.next_message_id) {
// Yes, so we are done polling
Some(WaitResult::Message(message)) => {
this.next_message_id += 1;
Poll::Ready(Some(WaitResult::Message(message)))
}
// No, so we need to reregister our waker and sleep again
None => {
unsafe {
this
.channel
.register_subscriber_waker(this.subscriber_index, cx.waker());
}
Poll::Pending
}
// We missed a couple of messages. We must do our internal bookkeeping and return that we lagged
Some(WaitResult::Lagged(amount)) => {
this.next_message_id += amount;
Poll::Ready(Some(WaitResult::Lagged(amount)))
}
}
}
}
/// A publisher to a channel /// A publisher to a channel
/// ///
/// This instance carries a reference to the channel, but uses a trait object for it so that the channel's /// This instance carries a reference to the channel, but uses a trait object for it so that the channel's
@ -494,11 +525,11 @@ mod tests {
pub0.publish(42).await; pub0.publish(42).await;
assert_eq!(sub0.wait().await, WaitResult::Message(42)); assert_eq!(sub0.next().await, WaitResult::Message(42));
assert_eq!(sub1.wait().await, WaitResult::Message(42)); assert_eq!(sub1.next().await, WaitResult::Message(42));
assert_eq!(sub0.check(), None); assert_eq!(sub0.try_next(), None);
assert_eq!(sub1.check(), None); assert_eq!(sub1.try_next(), None);
} }
#[futures_test::test] #[futures_test::test]
@ -515,12 +546,12 @@ mod tests {
pub0.publish_immediate(46); pub0.publish_immediate(46);
pub0.publish_immediate(47); pub0.publish_immediate(47);
assert_eq!(sub0.check(), Some(WaitResult::Lagged(2))); assert_eq!(sub0.try_next(), Some(WaitResult::Lagged(2)));
assert_eq!(sub0.wait().await, WaitResult::Message(44)); assert_eq!(sub0.next().await, WaitResult::Message(44));
assert_eq!(sub0.wait().await, WaitResult::Message(45)); assert_eq!(sub0.next().await, WaitResult::Message(45));
assert_eq!(sub0.wait().await, WaitResult::Message(46)); assert_eq!(sub0.next().await, WaitResult::Message(46));
assert_eq!(sub0.wait().await, WaitResult::Message(47)); assert_eq!(sub0.next().await, WaitResult::Message(47));
assert_eq!(sub0.check(), None); assert_eq!(sub0.try_next(), None);
} }
#[test] #[test]