Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 543 insertions, 0 deletions

diff --git a/vendor/flume/src/async.rs b/vendor/flume/src/async.rs
new file mode 100644
index 0000000..fae44d4
--- /dev/null
+++ b/vendor/flume/src/async.rs
@@ -0,0 +1,543 @@
+//! Futures and other types that allow asynchronous interaction with channels.
+
+use std::{
+    future::Future,
+    pin::Pin,
+    task::{Context, Poll, Waker},
+    any::Any,
+    ops::Deref,
+};
+use crate::*;
+use futures_core::{stream::{Stream, FusedStream}, future::FusedFuture};
+use futures_sink::Sink;
+use spin1::Mutex as Spinlock;
+
+struct AsyncSignal {
+    waker: Spinlock<Waker>,
+    woken: AtomicBool,
+    stream: bool,
+}
+
+impl AsyncSignal {
+    fn new(cx: &Context, stream: bool) -> Self {
+        AsyncSignal {
+            waker: Spinlock::new(cx.waker().clone()),
+            woken: AtomicBool::new(false),
+            stream,
+        }
+    }
+}
+
+impl Signal for AsyncSignal {
+    fn fire(&self) -> bool {
+        self.woken.store(true, Ordering::SeqCst);
+        self.waker.lock().wake_by_ref();
+        self.stream
+    }
+
+    fn as_any(&self) -> &(dyn Any + 'static) { self }
+    fn as_ptr(&self) -> *const () { self as *const _ as *const () }
+}
+
+impl<T> Hook<T, AsyncSignal> {
+    // Update the hook to point to the given Waker.
+    // Returns whether the hook has been previously awakened
+    fn update_waker(&self, cx_waker: &Waker) -> bool {
+        let mut waker = self.1.waker.lock();
+        let woken = self.1.woken.load(Ordering::SeqCst);
+        if !waker.will_wake(cx_waker) {
+            *waker = cx_waker.clone();
+
+            // Avoid the edge case where the waker was woken just before the wakers were
+            // swapped.
+            if woken {
+                cx_waker.wake_by_ref();
+            }
+        }
+        woken
+    }
+}
+
+#[derive(Clone)]
+enum OwnedOrRef<'a, T> {
+    Owned(T),
+    Ref(&'a T),
+}
+
+impl<'a, T> Deref for OwnedOrRef<'a, T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        match self {
+            OwnedOrRef::Owned(arc) => &arc,
+            OwnedOrRef::Ref(r) => r,
+        }
+    }
+}
+
+impl<T> Sender<T> {
+    /// Asynchronously send a value into the channel, returning an error if all receivers have been
+    /// dropped. If the channel is bounded and is full, the returned future will yield to the async
+    /// runtime.
+    ///
+    /// In the current implementation, the returned future will not yield to the async runtime if the
+    /// channel is unbounded. This may change in later versions.
+    pub fn send_async(&self, item: T) -> SendFut<T> {
+        SendFut {
+            sender: OwnedOrRef::Ref(&self),
+            hook: Some(SendState::NotYetSent(item)),
+        }
+    }
+
+    /// Convert this sender into a future that asynchronously sends a single message into the channel,
+    /// returning an error if all receivers have been dropped. If the channel is bounded and is full,
+    /// this future will yield to the async runtime.
+    ///
+    /// In the current implementation, the returned future will not yield to the async runtime if the
+    /// channel is unbounded. This may change in later versions.
+    pub fn into_send_async<'a>(self, item: T) -> SendFut<'a, T> {
+        SendFut {
+            sender: OwnedOrRef::Owned(self),
+            hook: Some(SendState::NotYetSent(item)),
+        }
+    }
+
+    /// Create an asynchronous sink that uses this sender to asynchronously send messages into the
+    /// channel. The sender will continue to be usable after the sink has been dropped.
+    ///
+    /// In the current implementation, the returned sink will not yield to the async runtime if the
+    /// channel is unbounded. This may change in later versions.
+    pub fn sink(&self) -> SendSink<'_, T> {
+        SendSink(SendFut {
+            sender: OwnedOrRef::Ref(&self),
+            hook: None,
+        })
+    }
+
+    /// Convert this sender into a sink that allows asynchronously sending messages into the channel.
+    ///
+    /// In the current implementation, the returned sink will not yield to the async runtime if the
+    /// channel is unbounded. This may change in later versions.
+    pub fn into_sink<'a>(self) -> SendSink<'a, T> {
+        SendSink(SendFut {
+            sender: OwnedOrRef::Owned(self),
+            hook: None,
+        })
+    }
+}
+
+enum SendState<T> {
+    NotYetSent(T),
+    QueuedItem(Arc<Hook<T, AsyncSignal>>),
+}
+
+/// A future that sends a value into a channel.
+///
+/// Can be created via [`Sender::send_async`] or [`Sender::into_send_async`].
+#[must_use = "futures/streams/sinks do nothing unless you `.await` or poll them"]
+pub struct SendFut<'a, T> {
+    sender: OwnedOrRef<'a, Sender<T>>,
+    // Only none after dropping
+    hook: Option<SendState<T>>,
+}
+
+impl<T> std::marker::Unpin for SendFut<'_, T> {}
+
+impl<'a, T> SendFut<'a, T> {
+    /// Reset the hook, clearing it and removing it from the waiting sender's queue. This is called
+    /// on drop and just before `start_send` in the `Sink` implementation.
+    fn reset_hook(&mut self) {
+        if let Some(SendState::QueuedItem(hook)) = self.hook.take() {
+            let hook: Arc<Hook<T, dyn Signal>> = hook;
+            wait_lock(&self.sender.shared.chan).sending
+                .as_mut()
+                .unwrap().1
+                .retain(|s| s.signal().as_ptr() != hook.signal().as_ptr());
+        }
+    }
+
+    /// See [`Sender::is_disconnected`].
+    pub fn is_disconnected(&self) -> bool {
+        self.sender.is_disconnected()
+    }
+
+    /// See [`Sender::is_empty`].
+    pub fn is_empty(&self) -> bool {
+        self.sender.is_empty()
+    }
+
+    /// See [`Sender::is_full`].
+    pub fn is_full(&self) -> bool {
+        self.sender.is_full()
+    }
+
+    /// See [`Sender::len`].
+    pub fn len(&self) -> usize {
+        self.sender.len()
+    }
+
+    /// See [`Sender::capacity`].
+    pub fn capacity(&self) -> Option<usize> {
+        self.sender.capacity()
+    }
+}
+
+impl<'a, T> Drop for SendFut<'a, T> {
+    fn drop(&mut self) {
+        self.reset_hook()
+    }
+}
+
+
+impl<'a, T> Future for SendFut<'a, T> {
+    type Output = Result<(), SendError<T>>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        if let Some(SendState::QueuedItem(hook)) = self.hook.as_ref() {
+            if hook.is_empty() {
+                Poll::Ready(Ok(()))
+            } else if self.sender.shared.is_disconnected() {
+                let item = hook.try_take();
+                self.hook = None;
+                match item {
+                    Some(item) => Poll::Ready(Err(SendError(item))),
+                    None => Poll::Ready(Ok(())),
+                }
+            } else {
+                hook.update_waker(cx.waker());
+                Poll::Pending
+            }
+        } else if let Some(SendState::NotYetSent(item)) = self.hook.take() {
+            let this = self.get_mut();
+            let (shared, this_hook) = (&this.sender.shared, &mut this.hook);
+
+            shared.send(
+                // item
+                item,
+                // should_block
+                true,
+                // make_signal
+                |msg| Hook::slot(Some(msg), AsyncSignal::new(cx, false)),
+                // do_block
+                |hook| {
+                    *this_hook = Some(SendState::QueuedItem(hook));
+                    Poll::Pending
+                },
+            )
+                .map(|r| r.map_err(|err| match err {
+                    TrySendTimeoutError::Disconnected(msg) => SendError(msg),
+                    _ => unreachable!(),
+                }))
+        } else { // Nothing to do
+            Poll::Ready(Ok(()))
+        }
+    }
+}
+
+impl<'a, T> FusedFuture for SendFut<'a, T> {
+    fn is_terminated(&self) -> bool {
+        self.sender.shared.is_disconnected()
+    }
+}
+
+/// A sink that allows sending values into a channel.
+///
+/// Can be created via [`Sender::sink`] or [`Sender::into_sink`].
+pub struct SendSink<'a, T>(SendFut<'a, T>);
+
+impl<'a, T> SendSink<'a, T> {
+    /// Returns a clone of a sending half of the channel of this sink.
+    pub fn sender(&self) -> &Sender<T> {
+        &self.0.sender
+    }
+
+    /// See [`Sender::is_disconnected`].
+    pub fn is_disconnected(&self) -> bool {
+        self.0.is_disconnected()
+    }
+
+    /// See [`Sender::is_empty`].
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+
+    /// See [`Sender::is_full`].
+    pub fn is_full(&self) -> bool {
+        self.0.is_full()
+    }
+
+    /// See [`Sender::len`].
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    /// See [`Sender::capacity`].
+    pub fn capacity(&self) -> Option<usize> {
+        self.0.capacity()
+    }
+
+    /// Returns whether the SendSinks are belong to the same channel.
+    pub fn same_channel(&self, other: &Self) -> bool {
+        self.sender().same_channel(other.sender())
+    }
+}
+
+impl<'a, T> Sink<T> for SendSink<'a, T> {
+    type Error = SendError<T>;
+
+    fn poll_ready(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        Pin::new(&mut self.0).poll(cx)
+    }
+
+    fn start_send(mut self: Pin<&mut Self>, item: T) -> Result<(), Self::Error> {
+        self.0.reset_hook();
+        self.0.hook = Some(SendState::NotYetSent(item));
+
+        Ok(())
+    }
+
+    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        Pin::new(&mut self.0).poll(cx) // TODO: A different strategy here?
+    }
+
+    fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+        Pin::new(&mut self.0).poll(cx) // TODO: A different strategy here?
+    }
+}
+
+impl<'a, T> Clone for SendSink<'a, T> {
+    fn clone(&self) -> SendSink<'a, T> {
+        SendSink(SendFut {
+            sender: self.0.sender.clone(),
+            hook: None,
+        })
+    }
+}
+
+impl<T> Receiver<T> {
+    /// Asynchronously receive a value from the channel, returning an error if all senders have been
+    /// dropped. If the channel is empty, the returned future will yield to the async runtime.
+    pub fn recv_async(&self) -> RecvFut<'_, T> {
+        RecvFut::new(OwnedOrRef::Ref(self))
+    }
+
+    /// Convert this receiver into a future that asynchronously receives a single message from the
+    /// channel, returning an error if all senders have been dropped. If the channel is empty, this
+    /// future will yield to the async runtime.
+    pub fn into_recv_async<'a>(self) -> RecvFut<'a, T> {
+        RecvFut::new(OwnedOrRef::Owned(self))
+    }
+
+    /// Create an asynchronous stream that uses this receiver to asynchronously receive messages
+    /// from the channel. The receiver will continue to be usable after the stream has been dropped.
+    pub fn stream(&self) -> RecvStream<'_, T> {
+        RecvStream(RecvFut::new(OwnedOrRef::Ref(self)))
+    }
+
+    /// Convert this receiver into a stream that allows asynchronously receiving messages from the channel.
+    pub fn into_stream<'a>(self) -> RecvStream<'a, T> {
+        RecvStream(RecvFut::new(OwnedOrRef::Owned(self)))
+    }
+}
+
+/// A future which allows asynchronously receiving a message.
+///
+/// Can be created via [`Receiver::recv_async`] or [`Receiver::into_recv_async`].
+#[must_use = "futures/streams/sinks do nothing unless you `.await` or poll them"]
+pub struct RecvFut<'a, T> {
+    receiver: OwnedOrRef<'a, Receiver<T>>,
+    hook: Option<Arc<Hook<T, AsyncSignal>>>,
+}
+
+impl<'a, T> RecvFut<'a, T> {
+    fn new(receiver: OwnedOrRef<'a, Receiver<T>>) -> Self {
+        Self {
+            receiver,
+            hook: None,
+        }
+    }
+
+    /// Reset the hook, clearing it and removing it from the waiting receivers queue and waking
+    /// another receiver if this receiver has been woken, so as not to cause any missed wakeups.
+    /// This is called on drop and after a new item is received in `Stream::poll_next`.
+    fn reset_hook(&mut self) {
+        if let Some(hook) = self.hook.take() {
+            let hook: Arc<Hook<T, dyn Signal>> = hook;
+            let mut chan = wait_lock(&self.receiver.shared.chan);
+            // We'd like to use `Arc::ptr_eq` here but it doesn't seem to work consistently with wide pointers?
+            chan.waiting.retain(|s| s.signal().as_ptr() != hook.signal().as_ptr());
+            if hook.signal().as_any().downcast_ref::<AsyncSignal>().unwrap().woken.load(Ordering::SeqCst) {
+                // If this signal has been fired, but we're being dropped (and so not listening to it),
+                // pass the signal on to another receiver
+                chan.try_wake_receiver_if_pending();
+            }
+        }
+    }
+
+    fn poll_inner(
+        self: Pin<&mut Self>,
+        cx: &mut Context,
+        stream: bool,
+    ) -> Poll<Result<T, RecvError>> {
+        if self.hook.is_some() {
+            match self.receiver.shared.recv_sync(None) {
+                Ok(msg) => return Poll::Ready(Ok(msg)),
+                Err(TryRecvTimeoutError::Disconnected) => {
+                    return Poll::Ready(Err(RecvError::Disconnected))
+                }
+                _ => (),
+            }
+
+            let hook = self.hook.as_ref().map(Arc::clone).unwrap();
+            if hook.update_waker(cx.waker()) {
+                // If the previous hook was awakened, we need to insert it back to the
+                // queue, otherwise, it remains valid.
+                wait_lock(&self.receiver.shared.chan)
+                    .waiting
+                    .push_back(hook);
+            }
+            // To avoid a missed wakeup, re-check disconnect status here because the channel might have
+            // gotten shut down before we had a chance to push our hook
+            if self.receiver.shared.is_disconnected() {
+                // And now, to avoid a race condition between the first recv attempt and the disconnect check we
+                // just performed, attempt to recv again just in case we missed something.
+                Poll::Ready(
+                    self.receiver
+                        .shared
+                        .recv_sync(None)
+                        .map(Ok)
+                        .unwrap_or(Err(RecvError::Disconnected)),
+                )
+            } else {
+                Poll::Pending
+            }
+        } else {
+            let mut_self = self.get_mut();
+            let (shared, this_hook) = (&mut_self.receiver.shared, &mut mut_self.hook);
+
+            shared.recv(
+                // should_block
+                true,
+                // make_signal
+                || Hook::trigger(AsyncSignal::new(cx, stream)),
+                // do_block
+                |hook| {
+                    *this_hook = Some(hook);
+                    Poll::Pending
+                },
+            )
+                .map(|r| r.map_err(|err| match err {
+                    TryRecvTimeoutError::Disconnected => RecvError::Disconnected,
+                    _ => unreachable!(),
+                }))
+        }
+    }
+
+    /// See [`Receiver::is_disconnected`].
+    pub fn is_disconnected(&self) -> bool {
+        self.receiver.is_disconnected()
+    }
+
+    /// See [`Receiver::is_empty`].
+    pub fn is_empty(&self) -> bool {
+        self.receiver.is_empty()
+    }
+
+    /// See [`Receiver::is_full`].
+    pub fn is_full(&self) -> bool {
+        self.receiver.is_full()
+    }
+
+    /// See [`Receiver::len`].
+    pub fn len(&self) -> usize {
+        self.receiver.len()
+    }
+
+    /// See [`Receiver::capacity`].
+    pub fn capacity(&self) -> Option<usize> {
+        self.receiver.capacity()
+    }
+}
+
+impl<'a, T> Drop for RecvFut<'a, T> {
+    fn drop(&mut self) {
+        self.reset_hook();
+    }
+}
+
+impl<'a, T> Future for RecvFut<'a, T> {
+    type Output = Result<T, RecvError>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        self.poll_inner(cx, false) // stream = false
+    }
+}
+
+impl<'a, T> FusedFuture for RecvFut<'a, T> {
+    fn is_terminated(&self) -> bool {
+        self.receiver.shared.is_disconnected() && self.receiver.shared.is_empty()
+    }
+}
+
+/// A stream which allows asynchronously receiving messages.
+///
+/// Can be created via [`Receiver::stream`] or [`Receiver::into_stream`].
+pub struct RecvStream<'a, T>(RecvFut<'a, T>);
+
+impl<'a, T> RecvStream<'a, T> {
+    /// See [`Receiver::is_disconnected`].
+    pub fn is_disconnected(&self) -> bool {
+        self.0.is_disconnected()
+    }
+
+    /// See [`Receiver::is_empty`].
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+
+    /// See [`Receiver::is_full`].
+    pub fn is_full(&self) -> bool {
+        self.0.is_full()
+    }
+
+    /// See [`Receiver::len`].
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    /// See [`Receiver::capacity`].
+    pub fn capacity(&self) -> Option<usize> {
+        self.0.capacity()
+    }
+
+    /// Returns whether the SendSinks are belong to the same channel.
+    pub fn same_channel(&self, other: &Self) -> bool {
+        self.0.receiver.same_channel(&*other.0.receiver)
+    }
+}
+
+impl<'a, T> Clone for RecvStream<'a, T> {
+    fn clone(&self) -> RecvStream<'a, T> {
+        RecvStream(RecvFut::new(self.0.receiver.clone()))
+    }
+}
+
+impl<'a, T> Stream for RecvStream<'a, T> {
+    type Item = T;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        match Pin::new(&mut self.0).poll_inner(cx, true) { // stream = true
+            Poll::Pending => Poll::Pending,
+            Poll::Ready(item) => {
+                self.0.reset_hook();
+                Poll::Ready(item.ok())
+            }
+        }
+    }
+}
+
+impl<'a, T> FusedStream for RecvStream<'a, T> {
+    fn is_terminated(&self) -> bool {
+        self.0.is_terminated()
+    }
+}