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Use a smart pipe that keeps connection status for passing data to the…
… network writer
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,163 @@ | ||
| use core::{ | ||
| cell::RefCell, | ||
| future::Future, | ||
| pin::Pin, | ||
| task::{Context, Poll, Waker}, | ||
| }; | ||
|
|
||
| use embassy_sync::blocking_mutex::{raw::RawMutex, Mutex}; | ||
| use pin_project::pin_project; | ||
|
|
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| struct PipeData<T, const N: usize> { | ||
| connect_count: usize, | ||
| receiver_waker: Option<Waker>, | ||
| sender_waker: Option<Waker>, | ||
| pending: Option<T>, | ||
| } | ||
|
|
||
| fn swap_wakers(waker: &mut Option<Waker>, new_waker: &Waker) { | ||
| if let Some(old_waker) = waker.take() { | ||
| if old_waker.will_wake(new_waker) { | ||
| *waker = Some(old_waker) | ||
| } else { | ||
| if !new_waker.will_wake(&old_waker) { | ||
| old_waker.wake(); | ||
| } | ||
|
|
||
| *waker = Some(new_waker.clone()); | ||
| } | ||
| } else { | ||
| *waker = Some(new_waker.clone()) | ||
| } | ||
| } | ||
|
|
||
| pub(crate) struct ReceiveFuture<'a, M: RawMutex, T, const N: usize> { | ||
| pipe: &'a ConnectedPipe<M, T, N>, | ||
| } | ||
|
|
||
| impl<M: RawMutex, T, const N: usize> Future for ReceiveFuture<'_, M, T, N> { | ||
| type Output = T; | ||
|
|
||
| fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { | ||
| self.pipe.inner.lock(|cell| { | ||
| let mut inner = cell.borrow_mut(); | ||
|
|
||
| if let Some(waker) = inner.sender_waker.take() { | ||
| waker.wake(); | ||
| } | ||
|
|
||
| if let Some(item) = inner.pending.take() { | ||
| if let Some(old_waker) = inner.receiver_waker.take() { | ||
| old_waker.wake(); | ||
| } | ||
|
|
||
| Poll::Ready(item) | ||
| } else { | ||
| swap_wakers(&mut inner.receiver_waker, cx.waker()); | ||
| Poll::Pending | ||
| } | ||
| }) | ||
| } | ||
| } | ||
|
|
||
| pub(crate) struct PipeReader<'a, M: RawMutex, T, const N: usize> { | ||
| pipe: &'a ConnectedPipe<M, T, N>, | ||
| } | ||
|
|
||
| impl<M: RawMutex, T, const N: usize> PipeReader<'_, M, T, N> { | ||
| #[must_use] | ||
| pub(crate) fn receive(&self) -> ReceiveFuture<'_, M, T, N> { | ||
| ReceiveFuture { pipe: self.pipe } | ||
| } | ||
| } | ||
|
|
||
| impl<M: RawMutex, T, const N: usize> Drop for PipeReader<'_, M, T, N> { | ||
| fn drop(&mut self) { | ||
| self.pipe.inner.lock(|cell| { | ||
| let mut inner = cell.borrow_mut(); | ||
| inner.connect_count -= 1; | ||
|
|
||
| if inner.connect_count == 0 { | ||
| inner.pending = None; | ||
| } | ||
|
|
||
| if let Some(waker) = inner.sender_waker.take() { | ||
| waker.wake(); | ||
| } | ||
| }) | ||
| } | ||
| } | ||
|
|
||
| #[pin_project] | ||
| pub(crate) struct PushFuture<'a, M: RawMutex, T, const N: usize> { | ||
| data: Option<T>, | ||
| pipe: &'a ConnectedPipe<M, T, N>, | ||
| } | ||
|
|
||
| impl<M: RawMutex, T, const N: usize> Future for PushFuture<'_, M, T, N> { | ||
| type Output = (); | ||
|
|
||
| fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { | ||
| self.pipe.inner.lock(|cell| { | ||
| let project = self.project(); | ||
| let mut inner = cell.borrow_mut(); | ||
|
|
||
| if let Some(receiver) = inner.receiver_waker.take() { | ||
| receiver.wake(); | ||
| } | ||
|
|
||
| if project.data.is_none() || inner.connect_count == 0 { | ||
| trace!("Dropping packet"); | ||
| Poll::Ready(()) | ||
| } else if inner.pending.is_some() { | ||
| swap_wakers(&mut inner.sender_waker, cx.waker()); | ||
| Poll::Pending | ||
| } else { | ||
| trace!("Pushed packet to receiver"); | ||
| inner.pending = project.data.take(); | ||
|
|
||
| Poll::Ready(()) | ||
| } | ||
| }) | ||
| } | ||
| } | ||
|
|
||
| /// A pipe that knows whether a receiver is connected. If so pushing to the | ||
| /// queue waits until there is space in the queue, otherwise data is simply | ||
| /// dropped. | ||
| pub(crate) struct ConnectedPipe<M: RawMutex, T, const N: usize> { | ||
| inner: Mutex<M, RefCell<PipeData<T, N>>>, | ||
| } | ||
|
|
||
| impl<M: RawMutex, T, const N: usize> ConnectedPipe<M, T, N> { | ||
| pub(crate) const fn new() -> Self { | ||
| Self { | ||
| inner: Mutex::new(RefCell::new(PipeData { | ||
| connect_count: 0, | ||
| receiver_waker: None, | ||
| sender_waker: None, | ||
| pending: None, | ||
| })), | ||
| } | ||
| } | ||
|
|
||
| /// A future that waits for a new item to be available. | ||
| pub(crate) fn reader(&self) -> PipeReader<'_, M, T, N> { | ||
| self.inner.lock(|cell| { | ||
| let mut inner = cell.borrow_mut(); | ||
| inner.connect_count += 1; | ||
|
|
||
| PipeReader { pipe: self } | ||
| }) | ||
| } | ||
|
|
||
| /// Pushes an item to the reader, waiting for a slot to become available if | ||
| /// connected. | ||
| #[must_use] | ||
| pub(crate) fn push(&self, data: T) -> PushFuture<'_, M, T, N> { | ||
| PushFuture { | ||
| data: Some(data), | ||
| pipe: self, | ||
| } | ||
| } | ||
| } |
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