Sindbad~EG File Manager
//! 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 pin_project::{pin_project, pinned_drop};
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(self, item: T) -> SendFut<'static, 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(self) -> SendSink<'static, 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"]
#[pin_project(PinnedDrop)]
pub struct SendFut<'a, T> {
sender: OwnedOrRef<'a, Sender<T>>,
// Only none after dropping
hook: Option<SendState<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()
}
}
#[allow(clippy::needless_lifetimes)] // False positive, see https://github.com/rust-lang/rust-clippy/issues/5787
#[pinned_drop]
impl<'a, T> PinnedDrop for SendFut<'a, T> {
fn drop(mut self: Pin<&mut Self>) {
self.reset_hook()
}
}
// 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() {
match self.hook.take().unwrap() {
SendState::NotYetSent(item) => Poll::Ready(Err(SendError(item))),
SendState::QueuedItem(hook) => match hook.try_take() {
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(_)) = self.hook {
let mut mut_self = self.project();
let (shared, this_hook) = (&mut_self.sender.shared, &mut mut_self.hook);
shared.send(
// item
match this_hook.take().unwrap() {
SendState::NotYetSent(item) => item,
SendState::QueuedItem(_) => return Poll::Ready(Ok(())),
},
// 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()
}
}
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(self) -> RecvFut<'static, 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(self) -> RecvStream<'static, 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() {
if let Ok(msg) = self.receiver.shared.recv_sync(None) {
Poll::Ready(Ok(msg))
} else if self.receiver.shared.is_disconnected() {
Poll::Ready(Err(RecvError::Disconnected))
} else {
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()
}
}
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()
}
}
Sindbad File Manager Version 1.0, Coded By Sindbad EG ~ The Terrorists