mirror of https://github.com/smol-rs/smol
912 lines
26 KiB
Rust
912 lines
26 KiB
Rust
use std::cell::UnsafeCell;
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use std::fmt;
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use std::future::Future;
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use std::isize;
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use std::marker::PhantomData;
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use std::mem;
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use std::pin::Pin;
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use std::process;
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use std::ptr;
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use std::sync::atomic::{self, AtomicUsize, Ordering};
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use std::sync::Arc;
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use std::task::{Context, Poll};
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use crossbeam_utils::Backoff;
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use futures::future;
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use futures::stream::Stream;
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use crate::signal::{Signal, SignalListener};
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/// Creates a bounded multi-producer multi-consumer channel.
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///
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/// This channel has a buffer that can hold at most `cap` messages at a time.
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///
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/// Senders and receivers can be cloned. When all senders associated with a channel get dropped, it
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/// becomes closed. Receive operations on a closed and empty channel return `None` instead of
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/// trying to await a message.
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///
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/// # Panics
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///
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/// If `cap` is zero, this function will panic.
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// #
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/// use std::time::Duration;
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///
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/// use async_std::sync::channel;
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/// use async_std::task;
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///
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/// let (s, r) = channel(1);
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///
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/// // This call returns immediately because there is enough space in the channel.
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/// s.send(1).await;
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///
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/// task::spawn(async move {
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/// // This call will have to wait because the channel is full.
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/// // It will be able to complete only after the first message is received.
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/// s.send(2).await;
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/// });
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///
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/// task::sleep(Duration::from_secs(1)).await;
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/// assert_eq!(r.recv().await, Some(1));
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/// assert_eq!(r.recv().await, Some(2));
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/// #
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/// # })
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/// ```
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pub fn chan<T>(cap: usize) -> (Sender<T>, Receiver<T>) {
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let channel = Arc::new(Channel::with_capacity(cap));
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let s = Sender {
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channel: channel.clone(),
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};
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let r = Receiver {
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channel,
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next_listener: None,
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};
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(s, r)
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}
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/// The sending side of a channel.
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///
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/// This struct is created by the [`chan`] function. See its documentation for more.
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///
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/// [`chan`]: fn.chan.html
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// #
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/// use async_std::sync::channel;
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/// use async_std::task;
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///
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/// let (s1, r) = channel(100);
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/// let s2 = s1.clone();
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///
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/// task::spawn(async move { s1.send(1).await });
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/// task::spawn(async move { s2.send(2).await });
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///
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/// let msg1 = r.recv().await.unwrap();
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/// let msg2 = r.recv().await.unwrap();
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///
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/// assert_eq!(msg1 + msg2, 3);
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/// #
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/// # })
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/// ```
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pub struct Sender<T> {
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/// The inner channel.
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channel: Arc<Channel<T>>,
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}
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impl<T> Sender<T> {
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/// Sends a message into the channel.
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///
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/// If the channel is full, this method will wait until there is space in the channel.
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// #
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/// use async_std::sync::channel;
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/// use async_std::task;
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///
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/// let (s, r) = channel(1);
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///
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/// task::spawn(async move {
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/// s.send(1).await;
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/// s.send(2).await;
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/// });
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///
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/// assert_eq!(r.recv().await, Some(1));
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/// assert_eq!(r.recv().await, Some(2));
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/// assert_eq!(r.recv().await, None);
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/// #
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/// # })
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/// ```
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pub async fn send(&self, msg: T) {
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self.channel.send(msg).await
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}
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/// Returns the channel capacity.
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///
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/// # Examples
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///
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/// ```
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/// use async_std::sync::channel;
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///
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/// let (s, _) = channel::<i32>(5);
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/// assert_eq!(s.capacity(), 5);
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/// ```
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pub fn capacity(&self) -> usize {
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if self.channel.handoff.is_some() {
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0
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} else {
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self.channel.cap
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}
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}
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/// Returns `true` if the channel is empty.
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// #
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/// use async_std::sync::channel;
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///
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/// let (s, r) = channel(1);
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///
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/// assert!(s.is_empty());
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/// s.send(0).await;
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/// assert!(!s.is_empty());
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/// #
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/// # })
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/// ```
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pub fn is_empty(&self) -> bool {
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self.channel.is_empty()
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}
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/// Returns `true` if the channel is full.
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// #
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/// use async_std::sync::channel;
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///
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/// let (s, r) = channel(1);
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///
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/// assert!(!s.is_full());
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/// s.send(0).await;
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/// assert!(s.is_full());
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/// #
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/// # })
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/// ```
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pub fn is_full(&self) -> bool {
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self.channel.is_full()
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}
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/// Returns the number of messages in the channel.
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// #
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/// use async_std::sync::channel;
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///
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/// let (s, r) = channel(2);
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/// assert_eq!(s.len(), 0);
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///
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/// s.send(1).await;
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/// s.send(2).await;
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/// assert_eq!(s.len(), 2);
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/// #
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/// # })
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/// ```
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pub fn len(&self) -> usize {
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self.channel.len()
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}
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}
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impl<T> Drop for Sender<T> {
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fn drop(&mut self) {
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// Decrement the sender count and disconnect the channel if it drops down to zero.
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if self.channel.sender_count.fetch_sub(1, Ordering::AcqRel) == 1 {
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self.channel.disconnect();
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}
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}
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}
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impl<T> Clone for Sender<T> {
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fn clone(&self) -> Sender<T> {
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let count = self.channel.sender_count.fetch_add(1, Ordering::Relaxed);
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// Make sure the count never overflows, even if lots of sender clones are leaked.
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if count > isize::MAX as usize {
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process::abort();
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}
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Sender {
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channel: self.channel.clone(),
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}
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}
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}
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impl<T> fmt::Debug for Sender<T> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.pad("Sender { .. }")
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}
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}
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/// The receiving side of a channel.
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///
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/// This type receives messages by calling `recv`. But it also implements the [`Stream`] trait,
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/// which means it can act as an asynchronous iterator. This struct is created by the [`chan`]
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/// function. See its documentation for more.
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///
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/// [`chan`]: fn.chan.html
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/// [`Stream`]: ../stream/trait.Stream.html
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// #
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/// use std::time::Duration;
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///
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/// use async_std::sync::channel;
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/// use async_std::task;
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///
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/// let (s, r) = channel(100);
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///
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/// task::spawn(async move {
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/// s.send(1).await;
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/// task::sleep(Duration::from_secs(1)).await;
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/// s.send(2).await;
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/// });
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///
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/// assert_eq!(r.recv().await, Some(1)); // Received immediately.
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/// assert_eq!(r.recv().await, Some(2)); // Received after 1 second.
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/// #
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/// # })
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/// ```
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pub struct Receiver<T> {
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/// The inner channel.
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channel: Arc<Channel<T>>,
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/// The key for this receiver in the `channel.next_ops` set. TODO
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next_listener: Option<SignalListener>,
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}
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impl<T> Receiver<T> {
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/// TODO
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pub fn try_recv(&self) -> Option<T> {
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self.channel.try_recv().ok()
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}
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/// Receives a message from the channel.
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///
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/// If the channel is empty and still has senders, this method will wait until a message is
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/// sent into the channel or until all senders get dropped.
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// #
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/// use async_std::sync::channel;
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/// use async_std::task;
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///
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/// let (s, r) = channel(1);
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///
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/// task::spawn(async move {
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/// s.send(1).await;
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/// s.send(2).await;
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/// });
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///
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/// assert_eq!(r.recv().await, Some(1));
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/// assert_eq!(r.recv().await, Some(2));
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/// assert_eq!(r.recv().await, None);
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/// #
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/// # })
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/// ```
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pub async fn recv(&self) -> Option<T> {
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self.channel.recv().await
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}
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/// Returns the channel capacity.
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///
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/// # Examples
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///
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/// ```
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/// use async_std::sync::channel;
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///
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/// let (_, r) = channel::<i32>(5);
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/// assert_eq!(r.capacity(), 5);
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/// ```
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pub fn capacity(&self) -> usize {
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if self.channel.handoff.is_some() {
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0
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} else {
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self.channel.cap
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}
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}
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/// Returns `true` if the channel is empty.
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// #
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/// use async_std::sync::channel;
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///
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/// let (s, r) = channel(1);
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///
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/// assert!(r.is_empty());
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/// s.send(0).await;
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/// assert!(!r.is_empty());
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/// #
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/// # })
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/// ```
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pub fn is_empty(&self) -> bool {
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self.channel.is_empty()
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}
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/// Returns `true` if the channel is full.
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// #
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/// use async_std::sync::channel;
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///
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/// let (s, r) = channel(1);
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///
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/// assert!(!r.is_full());
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/// s.send(0).await;
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/// assert!(r.is_full());
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/// #
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/// # })
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/// ```
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pub fn is_full(&self) -> bool {
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self.channel.is_full()
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}
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/// Returns the number of messages in the channel.
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// #
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/// use async_std::sync::channel;
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///
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/// let (s, r) = channel(2);
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/// assert_eq!(r.len(), 0);
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///
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/// s.send(1).await;
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/// s.send(2).await;
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/// assert_eq!(r.len(), 2);
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/// #
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/// # })
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/// ```
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pub fn len(&self) -> usize {
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self.channel.len()
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}
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}
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impl<T> Drop for Receiver<T> {
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fn drop(&mut self) {
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// Decrement the receiver count and disconnect the channel if it drops down to zero.
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if self.channel.receiver_count.fetch_sub(1, Ordering::AcqRel) == 1 {
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self.channel.disconnect();
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}
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}
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}
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impl<T> Clone for Receiver<T> {
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fn clone(&self) -> Receiver<T> {
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let count = self.channel.receiver_count.fetch_add(1, Ordering::Relaxed);
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// Make sure the count never overflows, even if lots of receiver clones are leaked.
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if count > isize::MAX as usize {
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process::abort();
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}
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Receiver {
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channel: self.channel.clone(),
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next_listener: None,
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}
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}
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}
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impl<T> Stream for Receiver<T> {
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type Item = T;
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fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
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let poll = loop {
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match self.channel.try_recv() {
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Ok(msg) => break Poll::Ready(Some(msg)),
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Err(TryRecvError::Disconnected) => break Poll::Ready(None),
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Err(TryRecvError::Empty) => {}
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}
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self.next_listener = Some(self.channel.next_ops.listen());
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match self.channel.try_recv() {
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Ok(msg) => break Poll::Ready(Some(msg)),
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Err(TryRecvError::Disconnected) => break Poll::Ready(None),
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Err(TryRecvError::Empty) => {}
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}
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match Pin::new(self.next_listener.as_mut().unwrap()).poll(cx) {
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Poll::Ready(()) => {}
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Poll::Pending => return Poll::Pending,
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}
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};
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if self.next_listener.take().is_some() {
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self.channel.next_ops.notify_all();
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}
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poll
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}
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}
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impl<T> fmt::Debug for Receiver<T> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.pad("Receiver { .. }")
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}
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}
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/// A slot in a channel.
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struct Slot<T> {
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/// The current stamp.
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stamp: AtomicUsize,
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/// The message in this slot.
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msg: UnsafeCell<T>,
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}
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/// Bounded channel based on a preallocated array.
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struct Channel<T> {
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/// The head of the channel.
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///
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/// This value is a "stamp" consisting of an index into the buffer, a mark bit, and a lap, but
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/// packed into a single `usize`. The lower bits represent the index, while the upper bits
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/// represent the lap. The mark bit in the head is always zero.
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///
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/// Messages are popped from the head of the channel.
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head: AtomicUsize,
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/// The tail of the channel.
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///
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/// This value is a "stamp" consisting of an index into the buffer, a mark bit, and a lap, but
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/// packed into a single `usize`. The lower bits represent the index, while the upper bits
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/// represent the lap. The mark bit indicates that the channel is disconnected.
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///
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/// Messages are pushed into the tail of the channel.
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tail: AtomicUsize,
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/// The buffer holding slots.
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buffer: *mut Slot<T>,
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/// The channel capacity.
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cap: usize,
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/// A stamp with the value of `{ lap: 1, mark: 0, index: 0 }`.
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one_lap: usize,
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/// If this bit is set in the tail, that means either all senders were dropped or all receivers
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/// were dropped.
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mark_bit: usize,
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/// Send operations waiting while the channel is full.
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send_ops: Signal,
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/// TODO
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handoff: Option<Signal>,
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/// Receive operations waiting while the channel is empty and not disconnected.
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recv_ops: Signal,
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/// Stream operations while the channel is empty and not disconnected.
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next_ops: Signal,
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/// The number of currently active `Sender`s.
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sender_count: AtomicUsize,
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/// The number of currently active `Receivers`s.
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receiver_count: AtomicUsize,
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/// Indicates that dropping a `Channel<T>` may drop values of type `T`.
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_marker: PhantomData<T>,
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}
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unsafe impl<T: Send> Send for Channel<T> {}
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unsafe impl<T: Send> Sync for Channel<T> {}
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impl<T> Unpin for Channel<T> {}
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impl<T> Channel<T> {
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/// Creates a bounded channel of capacity `cap`.
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fn with_capacity(cap: usize) -> Self {
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let handoff = if cap == 0 { Some(Signal::new()) } else { None };
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let cap = cap.max(1);
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// Compute constants `mark_bit` and `one_lap`.
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let mark_bit = (cap + 1).next_power_of_two();
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let one_lap = mark_bit * 2;
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// Head is initialized to `{ lap: 0, mark: 0, index: 0 }`.
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let head = 0;
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// Tail is initialized to `{ lap: 0, mark: 0, index: 0 }`.
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let tail = 0;
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// Allocate a buffer of `cap` slots.
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let buffer = {
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let mut v = Vec::<Slot<T>>::with_capacity(cap);
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let ptr = v.as_mut_ptr();
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mem::forget(v);
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ptr
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};
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// Initialize stamps in the slots.
|
|
for i in 0..cap {
|
|
unsafe {
|
|
// Set the stamp to `{ lap: 0, mark: 0, index: i }`.
|
|
let slot = buffer.add(i);
|
|
ptr::write(&mut (*slot).stamp, AtomicUsize::new(i));
|
|
}
|
|
}
|
|
|
|
Channel {
|
|
buffer,
|
|
cap,
|
|
one_lap,
|
|
mark_bit,
|
|
head: AtomicUsize::new(head),
|
|
tail: AtomicUsize::new(tail),
|
|
send_ops: Signal::new(),
|
|
handoff,
|
|
recv_ops: Signal::new(),
|
|
next_ops: Signal::new(),
|
|
sender_count: AtomicUsize::new(1),
|
|
receiver_count: AtomicUsize::new(1),
|
|
_marker: PhantomData,
|
|
}
|
|
}
|
|
|
|
/// Attempts to send a message.
|
|
fn try_send(&self, msg: T) -> Result<usize, TrySendError<T>> {
|
|
let backoff = Backoff::new();
|
|
let mut tail = self.tail.load(Ordering::Relaxed);
|
|
|
|
loop {
|
|
// Extract mark bit from the tail and unset it.
|
|
//
|
|
// If the mark bit was set (which means all receivers have been dropped), we will still
|
|
// send the message into the channel if there is enough capacity. The message will get
|
|
// dropped when the channel is dropped (which means when all senders are also dropped).
|
|
let mark_bit = tail & self.mark_bit;
|
|
tail ^= mark_bit;
|
|
|
|
// Deconstruct the tail.
|
|
let index = tail & (self.mark_bit - 1);
|
|
let lap = tail & !(self.one_lap - 1);
|
|
|
|
// Inspect the corresponding slot.
|
|
let slot = unsafe { &*self.buffer.add(index) };
|
|
let stamp = slot.stamp.load(Ordering::Acquire);
|
|
|
|
// If the tail and the stamp match, we may attempt to push.
|
|
if tail == stamp {
|
|
let new_tail = if index + 1 < self.cap {
|
|
// Same lap, incremented index.
|
|
// Set to `{ lap: lap, mark: 0, index: index + 1 }`.
|
|
tail + 1
|
|
} else {
|
|
// One lap forward, index wraps around to zero.
|
|
// Set to `{ lap: lap.wrapping_add(1), mark: 0, index: 0 }`.
|
|
lap.wrapping_add(self.one_lap)
|
|
};
|
|
|
|
// Try moving the tail.
|
|
match self.tail.compare_exchange_weak(
|
|
tail | mark_bit,
|
|
new_tail | mark_bit,
|
|
Ordering::SeqCst,
|
|
Ordering::Relaxed,
|
|
) {
|
|
Ok(_) => {
|
|
// Write the message into the slot and update the stamp.
|
|
unsafe { slot.msg.get().write(msg) };
|
|
let stamp = tail + 1;
|
|
slot.stamp.store(stamp, Ordering::Release);
|
|
|
|
// Wake a blocked receive operation.
|
|
self.recv_ops.notify_one();
|
|
|
|
// Wake all blocked streams.
|
|
self.next_ops.notify_all();
|
|
|
|
return Ok(stamp);
|
|
}
|
|
Err(t) => {
|
|
tail = t;
|
|
backoff.spin();
|
|
}
|
|
}
|
|
} else if stamp.wrapping_add(self.one_lap) == tail + 1 {
|
|
atomic::fence(Ordering::SeqCst);
|
|
let head = self.head.load(Ordering::Relaxed);
|
|
|
|
// If the head lags one lap behind the tail as well...
|
|
if head.wrapping_add(self.one_lap) == tail {
|
|
// ...then the channel is full.
|
|
|
|
// Check if the channel is disconnected.
|
|
if mark_bit != 0 {
|
|
return Err(TrySendError::Disconnected(msg));
|
|
} else {
|
|
return Err(TrySendError::Full(msg));
|
|
}
|
|
}
|
|
|
|
backoff.spin();
|
|
tail = self.tail.load(Ordering::Relaxed);
|
|
} else {
|
|
// Snooze because we need to wait for the stamp to get updated.
|
|
backoff.snooze();
|
|
tail = self.tail.load(Ordering::Relaxed);
|
|
}
|
|
}
|
|
}
|
|
|
|
async fn send(&self, mut msg: T) {
|
|
let mut listener = None;
|
|
|
|
let stamp = loop {
|
|
match self.try_send(msg) {
|
|
Ok(stamp) => break stamp,
|
|
Err(TrySendError::Disconnected(_)) => return future::pending().await,
|
|
Err(TrySendError::Full(m)) => msg = m,
|
|
}
|
|
|
|
match listener.take() {
|
|
None => listener = Some(self.send_ops.listen()),
|
|
Some(w) => {
|
|
w.await;
|
|
if self.cap > 1 {
|
|
self.send_ops.notify_one();
|
|
}
|
|
}
|
|
}
|
|
};
|
|
|
|
if let Some(h) = &self.handoff {
|
|
let mut listener = None;
|
|
|
|
while unsafe { &*self.buffer }.stamp.load(Ordering::SeqCst) != stamp {
|
|
match listener.take() {
|
|
None => listener = Some(h.listen()),
|
|
Some(w) => w.await,
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Attempts to receive a message.
|
|
fn try_recv(&self) -> Result<T, TryRecvError> {
|
|
let backoff = Backoff::new();
|
|
let mut head = self.head.load(Ordering::Relaxed);
|
|
|
|
loop {
|
|
// Deconstruct the head.
|
|
let index = head & (self.mark_bit - 1);
|
|
let lap = head & !(self.one_lap - 1);
|
|
|
|
// Inspect the corresponding slot.
|
|
let slot = unsafe { &*self.buffer.add(index) };
|
|
let stamp = slot.stamp.load(Ordering::Acquire);
|
|
|
|
// If the the stamp is ahead of the head by 1, we may attempt to pop.
|
|
if head + 1 == stamp {
|
|
let new = if index + 1 < self.cap {
|
|
// Same lap, incremented index.
|
|
// Set to `{ lap: lap, mark: 0, index: index + 1 }`.
|
|
head + 1
|
|
} else {
|
|
// One lap forward, index wraps around to zero.
|
|
// Set to `{ lap: lap.wrapping_add(1), mark: 0, index: 0 }`.
|
|
lap.wrapping_add(self.one_lap)
|
|
};
|
|
|
|
// Try moving the head.
|
|
match self.head.compare_exchange_weak(
|
|
head,
|
|
new,
|
|
Ordering::SeqCst,
|
|
Ordering::Relaxed,
|
|
) {
|
|
Ok(_) => {
|
|
// Read the message from the slot and update the stamp.
|
|
let msg = unsafe { slot.msg.get().read() };
|
|
let stamp = head.wrapping_add(self.one_lap);
|
|
slot.stamp.store(stamp, Ordering::Release);
|
|
|
|
// Wake a blocked send operation.
|
|
self.send_ops.notify_one();
|
|
|
|
// Notify a send operation waiting for handoff.
|
|
if let Some(h) = &self.handoff {
|
|
h.notify_all();
|
|
}
|
|
|
|
return Ok(msg);
|
|
}
|
|
Err(h) => {
|
|
head = h;
|
|
backoff.spin();
|
|
}
|
|
}
|
|
} else if stamp == head {
|
|
atomic::fence(Ordering::SeqCst);
|
|
let tail = self.tail.load(Ordering::Relaxed);
|
|
|
|
// If the tail equals the head, that means the channel is empty.
|
|
if (tail & !self.mark_bit) == head {
|
|
// If the channel is disconnected...
|
|
if tail & self.mark_bit != 0 {
|
|
return Err(TryRecvError::Disconnected);
|
|
} else {
|
|
// Otherwise, the receive operation is not ready.
|
|
return Err(TryRecvError::Empty);
|
|
}
|
|
}
|
|
|
|
backoff.spin();
|
|
head = self.head.load(Ordering::Relaxed);
|
|
} else {
|
|
// Snooze because we need to wait for the stamp to get updated.
|
|
backoff.snooze();
|
|
head = self.head.load(Ordering::Relaxed);
|
|
}
|
|
}
|
|
}
|
|
|
|
async fn recv(&self) -> Option<T> {
|
|
let mut listener = None;
|
|
|
|
loop {
|
|
match self.try_recv() {
|
|
Ok(msg) => return Some(msg),
|
|
Err(TryRecvError::Disconnected) => return None,
|
|
Err(TryRecvError::Empty) => {}
|
|
}
|
|
|
|
match listener.take() {
|
|
None => listener = Some(self.recv_ops.listen()),
|
|
Some(w) => {
|
|
w.await;
|
|
if self.cap > 1 {
|
|
self.recv_ops.notify_one();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Returns the current number of messages inside the channel.
|
|
fn len(&self) -> usize {
|
|
loop {
|
|
// Load the tail, then load the head.
|
|
let tail = self.tail.load(Ordering::SeqCst);
|
|
let head = self.head.load(Ordering::SeqCst);
|
|
|
|
// If the tail didn't change, we've got consistent values to work with.
|
|
if self.tail.load(Ordering::SeqCst) == tail {
|
|
let hix = head & (self.mark_bit - 1);
|
|
let tix = tail & (self.mark_bit - 1);
|
|
|
|
return if hix < tix {
|
|
tix - hix
|
|
} else if hix > tix {
|
|
self.cap - hix + tix
|
|
} else if (tail & !self.mark_bit) == head {
|
|
0
|
|
} else {
|
|
self.cap
|
|
};
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Returns `true` if the channel is empty.
|
|
fn is_empty(&self) -> bool {
|
|
let head = self.head.load(Ordering::SeqCst);
|
|
let tail = self.tail.load(Ordering::SeqCst);
|
|
|
|
// Is the tail equal to the head?
|
|
//
|
|
// Note: If the head changes just before we load the tail, that means there was a moment
|
|
// when the channel was not empty, so it is safe to just return `false`.
|
|
(tail & !self.mark_bit) == head
|
|
}
|
|
|
|
/// Returns `true` if the channel is full.
|
|
fn is_full(&self) -> bool {
|
|
let tail = self.tail.load(Ordering::SeqCst);
|
|
let head = self.head.load(Ordering::SeqCst);
|
|
|
|
// Is the head lagging one lap behind tail?
|
|
//
|
|
// Note: If the tail changes just before we load the head, that means there was a moment
|
|
// when the channel was not full, so it is safe to just return `false`.
|
|
head.wrapping_add(self.one_lap) == tail & !self.mark_bit
|
|
}
|
|
|
|
/// Disconnects the channel and wakes up all blocked operations.
|
|
fn disconnect(&self) {
|
|
let tail = self.tail.fetch_or(self.mark_bit, Ordering::SeqCst);
|
|
|
|
if tail & self.mark_bit == 0 {
|
|
// Notify everyone blocked on this channel.
|
|
self.send_ops.notify_all();
|
|
self.recv_ops.notify_all();
|
|
self.next_ops.notify_all();
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<T> Drop for Channel<T> {
|
|
fn drop(&mut self) {
|
|
// Get the index of the head.
|
|
let hix = self.head.load(Ordering::Relaxed) & (self.mark_bit - 1);
|
|
|
|
// Loop over all slots that hold a message and drop them.
|
|
for i in 0..self.len() {
|
|
// Compute the index of the next slot holding a message.
|
|
let index = if hix + i < self.cap {
|
|
hix + i
|
|
} else {
|
|
hix + i - self.cap
|
|
};
|
|
|
|
unsafe {
|
|
self.buffer.add(index).drop_in_place();
|
|
}
|
|
}
|
|
|
|
// Finally, deallocate the buffer, but don't run any destructors.
|
|
unsafe {
|
|
Vec::from_raw_parts(self.buffer, 0, self.cap);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// An error returned from the `try_send()` method.
|
|
enum TrySendError<T> {
|
|
/// The channel is full but not disconnected.
|
|
Full(T),
|
|
|
|
/// The channel is full and disconnected.
|
|
Disconnected(T),
|
|
}
|
|
|
|
/// An error returned from the `try_recv()` method.
|
|
enum TryRecvError {
|
|
/// The channel is empty but not disconnected.
|
|
Empty,
|
|
|
|
/// The channel is empty and disconnected.
|
|
Disconnected,
|
|
}
|