| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-channel-0.3.28/src/mpsc/mod.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>mod.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../futures_channel/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../futures_channel/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="doccomment">//! A multi-producer, single-consumer queue for sending values across |
| //! asynchronous tasks. |
| //! |
| //! Similarly to the `std`, channel creation provides [`Receiver`] and |
| //! [`Sender`] handles. [`Receiver`] implements [`Stream`] and allows a task to |
| //! read values out of the channel. If there is no message to read from the |
| //! channel, the current task will be notified when a new value is sent. |
| //! [`Sender`] implements the `Sink` trait and allows a task to send messages into |
| //! the channel. If the channel is at capacity, the send will be rejected and |
| //! the task will be notified when additional capacity is available. In other |
| //! words, the channel provides backpressure. |
| //! |
| //! Unbounded channels are also available using the `unbounded` constructor. |
| //! |
| //! # Disconnection |
| //! |
| //! When all [`Sender`] handles have been dropped, it is no longer |
| //! possible to send values into the channel. This is considered the termination |
| //! event of the stream. As such, [`Receiver::poll_next`] |
| //! will return `Ok(Ready(None))`. |
| //! |
| //! If the [`Receiver`] handle is dropped, then messages can no longer |
| //! be read out of the channel. In this case, all further attempts to send will |
| //! result in an error. |
| //! |
| //! # Clean Shutdown |
| //! |
| //! If the [`Receiver`] is simply dropped, then it is possible for |
| //! there to be messages still in the channel that will not be processed. As |
| //! such, it is usually desirable to perform a "clean" shutdown. To do this, the |
| //! receiver will first call `close`, which will prevent any further messages to |
| //! be sent into the channel. Then, the receiver consumes the channel to |
| //! completion, at which point the receiver can be dropped. |
| //! |
| //! [`Sender`]: struct.Sender.html |
| //! [`Receiver`]: struct.Receiver.html |
| //! [`Stream`]: ../../futures_core/stream/trait.Stream.html |
| //! [`Receiver::poll_next`]: |
| //! ../../futures_core/stream/trait.Stream.html#tymethod.poll_next |
| |
| </span><span class="comment">// At the core, the channel uses an atomic FIFO queue for message passing. This |
| // queue is used as the primary coordination primitive. In order to enforce |
| // capacity limits and handle back pressure, a secondary FIFO queue is used to |
| // send parked task handles. |
| // |
| // The general idea is that the channel is created with a `buffer` size of `n`. |
| // The channel capacity is `n + num-senders`. Each sender gets one "guaranteed" |
| // slot to hold a message. This allows `Sender` to know for a fact that a send |
| // will succeed *before* starting to do the actual work of sending the value. |
| // Since most of this work is lock-free, once the work starts, it is impossible |
| // to safely revert. |
| // |
| // If the sender is unable to process a send operation, then the current |
| // task is parked and the handle is sent on the parked task queue. |
| // |
| // Note that the implementation guarantees that the channel capacity will never |
| // exceed the configured limit, however there is no *strict* guarantee that the |
| // receiver will wake up a parked task *immediately* when a slot becomes |
| // available. However, it will almost always unpark a task when a slot becomes |
| // available and it is *guaranteed* that a sender will be unparked when the |
| // message that caused the sender to become parked is read out of the channel. |
| // |
| // The steps for sending a message are roughly: |
| // |
| // 1) Increment the channel message count |
| // 2) If the channel is at capacity, push the task handle onto the wait queue |
| // 3) Push the message onto the message queue. |
| // |
| // The steps for receiving a message are roughly: |
| // |
| // 1) Pop a message from the message queue |
| // 2) Pop a task handle from the wait queue |
| // 3) Decrement the channel message count. |
| // |
| // It's important for the order of operations on lock-free structures to happen |
| // in reverse order between the sender and receiver. This makes the message |
| // queue the primary coordination structure and establishes the necessary |
| // happens-before semantics required for the acquire / release semantics used |
| // by the queue structure. |
| |
| </span><span class="kw">use </span>futures_core::stream::{FusedStream, Stream}; |
| <span class="kw">use </span>futures_core::task::__internal::AtomicWaker; |
| <span class="kw">use </span>futures_core::task::{Context, Poll, Waker}; |
| <span class="kw">use </span>std::fmt; |
| <span class="kw">use </span>std::pin::Pin; |
| <span class="kw">use </span>std::sync::atomic::AtomicUsize; |
| <span class="kw">use </span>std::sync::atomic::Ordering::SeqCst; |
| <span class="kw">use </span>std::sync::{Arc, Mutex}; |
| <span class="kw">use </span>std::thread; |
| |
| <span class="kw">use </span><span class="kw">crate</span>::mpsc::queue::Queue; |
| |
| <span class="kw">mod </span>queue; |
| <span class="attribute">#[cfg(feature = <span class="string">"sink"</span>)] |
| </span><span class="kw">mod </span>sink_impl; |
| |
| <span class="kw">struct </span>UnboundedSenderInner<T> { |
| <span class="comment">// Channel state shared between the sender and receiver. |
| </span>inner: Arc<UnboundedInner<T>>, |
| } |
| |
| <span class="kw">struct </span>BoundedSenderInner<T> { |
| <span class="comment">// Channel state shared between the sender and receiver. |
| </span>inner: Arc<BoundedInner<T>>, |
| |
| <span class="comment">// Handle to the task that is blocked on this sender. This handle is sent |
| // to the receiver half in order to be notified when the sender becomes |
| // unblocked. |
| </span>sender_task: Arc<Mutex<SenderTask>>, |
| |
| <span class="comment">// `true` if the sender might be blocked. This is an optimization to avoid |
| // having to lock the mutex most of the time. |
| </span>maybe_parked: bool, |
| } |
| |
| <span class="comment">// We never project Pin<&mut SenderInner> to `Pin<&mut T>` |
| </span><span class="kw">impl</span><T> Unpin <span class="kw">for </span>UnboundedSenderInner<T> {} |
| <span class="kw">impl</span><T> Unpin <span class="kw">for </span>BoundedSenderInner<T> {} |
| |
| <span class="doccomment">/// The transmission end of a bounded mpsc channel. |
| /// |
| /// This value is created by the [`channel`](channel) function. |
| </span><span class="kw">pub struct </span>Sender<T>(<span class="prelude-ty">Option</span><BoundedSenderInner<T>>); |
| |
| <span class="doccomment">/// The transmission end of an unbounded mpsc channel. |
| /// |
| /// This value is created by the [`unbounded`](unbounded) function. |
| </span><span class="kw">pub struct </span>UnboundedSender<T>(<span class="prelude-ty">Option</span><UnboundedSenderInner<T>>); |
| |
| <span class="kw">trait </span>AssertKinds: Send + Sync + Clone {} |
| <span class="kw">impl </span>AssertKinds <span class="kw">for </span>UnboundedSender<u32> {} |
| |
| <span class="doccomment">/// The receiving end of a bounded mpsc channel. |
| /// |
| /// This value is created by the [`channel`](channel) function. |
| </span><span class="kw">pub struct </span>Receiver<T> { |
| inner: <span class="prelude-ty">Option</span><Arc<BoundedInner<T>>>, |
| } |
| |
| <span class="doccomment">/// The receiving end of an unbounded mpsc channel. |
| /// |
| /// This value is created by the [`unbounded`](unbounded) function. |
| </span><span class="kw">pub struct </span>UnboundedReceiver<T> { |
| inner: <span class="prelude-ty">Option</span><Arc<UnboundedInner<T>>>, |
| } |
| |
| <span class="comment">// `Pin<&mut UnboundedReceiver<T>>` is never projected to `Pin<&mut T>` |
| </span><span class="kw">impl</span><T> Unpin <span class="kw">for </span>UnboundedReceiver<T> {} |
| |
| <span class="doccomment">/// The error type for [`Sender`s](Sender) used as `Sink`s. |
| </span><span class="attribute">#[derive(Clone, Debug, PartialEq, Eq)] |
| </span><span class="kw">pub struct </span>SendError { |
| kind: SendErrorKind, |
| } |
| |
| <span class="doccomment">/// The error type returned from [`try_send`](Sender::try_send). |
| </span><span class="attribute">#[derive(Clone, PartialEq, Eq)] |
| </span><span class="kw">pub struct </span>TrySendError<T> { |
| err: SendError, |
| val: T, |
| } |
| |
| <span class="attribute">#[derive(Clone, Debug, PartialEq, Eq)] |
| </span><span class="kw">enum </span>SendErrorKind { |
| Full, |
| Disconnected, |
| } |
| |
| <span class="doccomment">/// The error type returned from [`try_next`](Receiver::try_next). |
| </span><span class="kw">pub struct </span>TryRecvError { |
| _priv: (), |
| } |
| |
| <span class="kw">impl </span>fmt::Display <span class="kw">for </span>SendError { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="kw">if </span><span class="self">self</span>.is_full() { |
| <span class="macro">write!</span>(f, <span class="string">"send failed because channel is full"</span>) |
| } <span class="kw">else </span>{ |
| <span class="macro">write!</span>(f, <span class="string">"send failed because receiver is gone"</span>) |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>std::error::Error <span class="kw">for </span>SendError {} |
| |
| <span class="kw">impl </span>SendError { |
| <span class="doccomment">/// Returns `true` if this error is a result of the channel being full. |
| </span><span class="kw">pub fn </span>is_full(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="kw">match </span><span class="self">self</span>.kind { |
| SendErrorKind::Full => <span class="bool-val">true</span>, |
| <span class="kw">_ </span>=> <span class="bool-val">false</span>, |
| } |
| } |
| |
| <span class="doccomment">/// Returns `true` if this error is a result of the receiver being dropped. |
| </span><span class="kw">pub fn </span>is_disconnected(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="kw">match </span><span class="self">self</span>.kind { |
| SendErrorKind::Disconnected => <span class="bool-val">true</span>, |
| <span class="kw">_ </span>=> <span class="bool-val">false</span>, |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> fmt::Debug <span class="kw">for </span>TrySendError<T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.debug_struct(<span class="string">"TrySendError"</span>).field(<span class="string">"kind"</span>, <span class="kw-2">&</span><span class="self">self</span>.err.kind).finish() |
| } |
| } |
| |
| <span class="kw">impl</span><T> fmt::Display <span class="kw">for </span>TrySendError<T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="kw">if </span><span class="self">self</span>.is_full() { |
| <span class="macro">write!</span>(f, <span class="string">"send failed because channel is full"</span>) |
| } <span class="kw">else </span>{ |
| <span class="macro">write!</span>(f, <span class="string">"send failed because receiver is gone"</span>) |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T: core::any::Any> std::error::Error <span class="kw">for </span>TrySendError<T> {} |
| |
| <span class="kw">impl</span><T> TrySendError<T> { |
| <span class="doccomment">/// Returns `true` if this error is a result of the channel being full. |
| </span><span class="kw">pub fn </span>is_full(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.err.is_full() |
| } |
| |
| <span class="doccomment">/// Returns `true` if this error is a result of the receiver being dropped. |
| </span><span class="kw">pub fn </span>is_disconnected(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.err.is_disconnected() |
| } |
| |
| <span class="doccomment">/// Returns the message that was attempted to be sent but failed. |
| </span><span class="kw">pub fn </span>into_inner(<span class="self">self</span>) -> T { |
| <span class="self">self</span>.val |
| } |
| |
| <span class="doccomment">/// Drops the message and converts into a `SendError`. |
| </span><span class="kw">pub fn </span>into_send_error(<span class="self">self</span>) -> SendError { |
| <span class="self">self</span>.err |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Debug <span class="kw">for </span>TryRecvError { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.debug_tuple(<span class="string">"TryRecvError"</span>).finish() |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Display <span class="kw">for </span>TryRecvError { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="macro">write!</span>(f, <span class="string">"receiver channel is empty"</span>) |
| } |
| } |
| |
| <span class="kw">impl </span>std::error::Error <span class="kw">for </span>TryRecvError {} |
| |
| <span class="kw">struct </span>UnboundedInner<T> { |
| <span class="comment">// Internal channel state. Consists of the number of messages stored in the |
| // channel as well as a flag signalling that the channel is closed. |
| </span>state: AtomicUsize, |
| |
| <span class="comment">// Atomic, FIFO queue used to send messages to the receiver |
| </span>message_queue: Queue<T>, |
| |
| <span class="comment">// Number of senders in existence |
| </span>num_senders: AtomicUsize, |
| |
| <span class="comment">// Handle to the receiver's task. |
| </span>recv_task: AtomicWaker, |
| } |
| |
| <span class="kw">struct </span>BoundedInner<T> { |
| <span class="comment">// Max buffer size of the channel. If `None` then the channel is unbounded. |
| </span>buffer: usize, |
| |
| <span class="comment">// Internal channel state. Consists of the number of messages stored in the |
| // channel as well as a flag signalling that the channel is closed. |
| </span>state: AtomicUsize, |
| |
| <span class="comment">// Atomic, FIFO queue used to send messages to the receiver |
| </span>message_queue: Queue<T>, |
| |
| <span class="comment">// Atomic, FIFO queue used to send parked task handles to the receiver. |
| </span>parked_queue: Queue<Arc<Mutex<SenderTask>>>, |
| |
| <span class="comment">// Number of senders in existence |
| </span>num_senders: AtomicUsize, |
| |
| <span class="comment">// Handle to the receiver's task. |
| </span>recv_task: AtomicWaker, |
| } |
| |
| <span class="comment">// Struct representation of `Inner::state`. |
| </span><span class="attribute">#[derive(Clone, Copy)] |
| </span><span class="kw">struct </span>State { |
| <span class="comment">// `true` when the channel is open |
| </span>is_open: bool, |
| |
| <span class="comment">// Number of messages in the channel |
| </span>num_messages: usize, |
| } |
| |
| <span class="comment">// The `is_open` flag is stored in the left-most bit of `Inner::state` |
| </span><span class="kw">const </span>OPEN_MASK: usize = usize::max_value() - (usize::max_value() >> <span class="number">1</span>); |
| |
| <span class="comment">// When a new channel is created, it is created in the open state with no |
| // pending messages. |
| </span><span class="kw">const </span>INIT_STATE: usize = OPEN_MASK; |
| |
| <span class="comment">// The maximum number of messages that a channel can track is `usize::max_value() >> 1` |
| </span><span class="kw">const </span>MAX_CAPACITY: usize = !(OPEN_MASK); |
| |
| <span class="comment">// The maximum requested buffer size must be less than the maximum capacity of |
| // a channel. This is because each sender gets a guaranteed slot. |
| </span><span class="kw">const </span>MAX_BUFFER: usize = MAX_CAPACITY >> <span class="number">1</span>; |
| |
| <span class="comment">// Sent to the consumer to wake up blocked producers |
| </span><span class="kw">struct </span>SenderTask { |
| task: <span class="prelude-ty">Option</span><Waker>, |
| is_parked: bool, |
| } |
| |
| <span class="kw">impl </span>SenderTask { |
| <span class="kw">fn </span>new() -> <span class="self">Self </span>{ |
| <span class="self">Self </span>{ task: <span class="prelude-val">None</span>, is_parked: <span class="bool-val">false </span>} |
| } |
| |
| <span class="kw">fn </span>notify(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="self">self</span>.is_parked = <span class="bool-val">false</span>; |
| |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(task) = <span class="self">self</span>.task.take() { |
| task.wake(); |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Creates a bounded mpsc channel for communicating between asynchronous tasks. |
| /// |
| /// Being bounded, this channel provides backpressure to ensure that the sender |
| /// outpaces the receiver by only a limited amount. The channel's capacity is |
| /// equal to `buffer + num-senders`. In other words, each sender gets a |
| /// guaranteed slot in the channel capacity, and on top of that there are |
| /// `buffer` "first come, first serve" slots available to all senders. |
| /// |
| /// The [`Receiver`](Receiver) returned implements the |
| /// [`Stream`](futures_core::stream::Stream) trait, while [`Sender`](Sender) implements |
| /// `Sink`. |
| </span><span class="kw">pub fn </span>channel<T>(buffer: usize) -> (Sender<T>, Receiver<T>) { |
| <span class="comment">// Check that the requested buffer size does not exceed the maximum buffer |
| // size permitted by the system. |
| </span><span class="macro">assert!</span>(buffer < MAX_BUFFER, <span class="string">"requested buffer size too large"</span>); |
| |
| <span class="kw">let </span>inner = Arc::new(BoundedInner { |
| buffer, |
| state: AtomicUsize::new(INIT_STATE), |
| message_queue: Queue::new(), |
| parked_queue: Queue::new(), |
| num_senders: AtomicUsize::new(<span class="number">1</span>), |
| recv_task: AtomicWaker::new(), |
| }); |
| |
| <span class="kw">let </span>tx = BoundedSenderInner { |
| inner: inner.clone(), |
| sender_task: Arc::new(Mutex::new(SenderTask::new())), |
| maybe_parked: <span class="bool-val">false</span>, |
| }; |
| |
| <span class="kw">let </span>rx = Receiver { inner: <span class="prelude-val">Some</span>(inner) }; |
| |
| (Sender(<span class="prelude-val">Some</span>(tx)), rx) |
| } |
| |
| <span class="doccomment">/// Creates an unbounded mpsc channel for communicating between asynchronous |
| /// tasks. |
| /// |
| /// A `send` on this channel will always succeed as long as the receive half has |
| /// not been closed. If the receiver falls behind, messages will be arbitrarily |
| /// buffered. |
| /// |
| /// **Note** that the amount of available system memory is an implicit bound to |
| /// the channel. Using an `unbounded` channel has the ability of causing the |
| /// process to run out of memory. In this case, the process will be aborted. |
| </span><span class="kw">pub fn </span>unbounded<T>() -> (UnboundedSender<T>, UnboundedReceiver<T>) { |
| <span class="kw">let </span>inner = Arc::new(UnboundedInner { |
| state: AtomicUsize::new(INIT_STATE), |
| message_queue: Queue::new(), |
| num_senders: AtomicUsize::new(<span class="number">1</span>), |
| recv_task: AtomicWaker::new(), |
| }); |
| |
| <span class="kw">let </span>tx = UnboundedSenderInner { inner: inner.clone() }; |
| |
| <span class="kw">let </span>rx = UnboundedReceiver { inner: <span class="prelude-val">Some</span>(inner) }; |
| |
| (UnboundedSender(<span class="prelude-val">Some</span>(tx)), rx) |
| } |
| |
| <span class="comment">/* |
| * |
| * ===== impl Sender ===== |
| * |
| */ |
| |
| </span><span class="kw">impl</span><T> UnboundedSenderInner<T> { |
| <span class="kw">fn </span>poll_ready_nb(<span class="kw-2">&</span><span class="self">self</span>) -> Poll<<span class="prelude-ty">Result</span><(), SendError>> { |
| <span class="kw">let </span>state = decode_state(<span class="self">self</span>.inner.state.load(SeqCst)); |
| <span class="kw">if </span>state.is_open { |
| Poll::Ready(<span class="prelude-val">Ok</span>(())) |
| } <span class="kw">else </span>{ |
| Poll::Ready(<span class="prelude-val">Err</span>(SendError { kind: SendErrorKind::Disconnected })) |
| } |
| } |
| |
| <span class="comment">// Push message to the queue and signal to the receiver |
| </span><span class="kw">fn </span>queue_push_and_signal(<span class="kw-2">&</span><span class="self">self</span>, msg: T) { |
| <span class="comment">// Push the message onto the message queue |
| </span><span class="self">self</span>.inner.message_queue.push(msg); |
| |
| <span class="comment">// Signal to the receiver that a message has been enqueued. If the |
| // receiver is parked, this will unpark the task. |
| </span><span class="self">self</span>.inner.recv_task.wake(); |
| } |
| |
| <span class="comment">// Increment the number of queued messages. Returns the resulting number. |
| </span><span class="kw">fn </span>inc_num_messages(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="kw">let </span><span class="kw-2">mut </span>curr = <span class="self">self</span>.inner.state.load(SeqCst); |
| |
| <span class="kw">loop </span>{ |
| <span class="kw">let </span><span class="kw-2">mut </span>state = decode_state(curr); |
| |
| <span class="comment">// The receiver end closed the channel. |
| </span><span class="kw">if </span>!state.is_open { |
| <span class="kw">return </span><span class="prelude-val">None</span>; |
| } |
| |
| <span class="comment">// This probably is never hit? Odds are the process will run out of |
| // memory first. It may be worth to return something else in this |
| // case? |
| </span><span class="macro">assert!</span>( |
| state.num_messages < MAX_CAPACITY, |
| <span class="string">"buffer space \ |
| exhausted; sending this messages would overflow the state" |
| </span>); |
| |
| state.num_messages += <span class="number">1</span>; |
| |
| <span class="kw">let </span>next = encode_state(<span class="kw-2">&</span>state); |
| <span class="kw">match </span><span class="self">self</span>.inner.state.compare_exchange(curr, next, SeqCst, SeqCst) { |
| <span class="prelude-val">Ok</span>(<span class="kw">_</span>) => <span class="kw">return </span><span class="prelude-val">Some</span>(state.num_messages), |
| <span class="prelude-val">Err</span>(actual) => curr = actual, |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Returns whether the senders send to the same receiver. |
| </span><span class="kw">fn </span>same_receiver(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span><span class="self">Self</span>) -> bool { |
| Arc::ptr_eq(<span class="kw-2">&</span><span class="self">self</span>.inner, <span class="kw-2">&</span>other.inner) |
| } |
| |
| <span class="doccomment">/// Returns whether the sender send to this receiver. |
| </span><span class="kw">fn </span>is_connected_to(<span class="kw-2">&</span><span class="self">self</span>, inner: <span class="kw-2">&</span>Arc<UnboundedInner<T>>) -> bool { |
| Arc::ptr_eq(<span class="kw-2">&</span><span class="self">self</span>.inner, inner) |
| } |
| |
| <span class="doccomment">/// Returns pointer to the Arc containing sender |
| /// |
| /// The returned pointer is not referenced and should be only used for hashing! |
| </span><span class="kw">fn </span>ptr(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">*const </span>UnboundedInner<T> { |
| <span class="kw-2">&*</span><span class="self">self</span>.inner |
| } |
| |
| <span class="doccomment">/// Returns whether this channel is closed without needing a context. |
| </span><span class="kw">fn </span>is_closed(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| !decode_state(<span class="self">self</span>.inner.state.load(SeqCst)).is_open |
| } |
| |
| <span class="doccomment">/// Closes this channel from the sender side, preventing any new messages. |
| </span><span class="kw">fn </span>close_channel(<span class="kw-2">&</span><span class="self">self</span>) { |
| <span class="comment">// There's no need to park this sender, its dropping, |
| // and we don't want to check for capacity, so skip |
| // that stuff from `do_send`. |
| |
| </span><span class="self">self</span>.inner.set_closed(); |
| <span class="self">self</span>.inner.recv_task.wake(); |
| } |
| } |
| |
| <span class="kw">impl</span><T> BoundedSenderInner<T> { |
| <span class="doccomment">/// Attempts to send a message on this `Sender`, returning the message |
| /// if there was an error. |
| </span><span class="kw">fn </span>try_send(<span class="kw-2">&mut </span><span class="self">self</span>, msg: T) -> <span class="prelude-ty">Result</span><(), TrySendError<T>> { |
| <span class="comment">// If the sender is currently blocked, reject the message |
| </span><span class="kw">if </span>!<span class="self">self</span>.poll_unparked(<span class="prelude-val">None</span>).is_ready() { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(TrySendError { err: SendError { kind: SendErrorKind::Full }, val: msg }); |
| } |
| |
| <span class="comment">// The channel has capacity to accept the message, so send it |
| </span><span class="self">self</span>.do_send_b(msg) |
| } |
| |
| <span class="comment">// Do the send without failing. |
| // Can be called only by bounded sender. |
| </span><span class="kw">fn </span>do_send_b(<span class="kw-2">&mut </span><span class="self">self</span>, msg: T) -> <span class="prelude-ty">Result</span><(), TrySendError<T>> { |
| <span class="comment">// Anyone calling do_send *should* make sure there is room first, |
| // but assert here for tests as a sanity check. |
| </span><span class="macro">debug_assert!</span>(<span class="self">self</span>.poll_unparked(<span class="prelude-val">None</span>).is_ready()); |
| |
| <span class="comment">// First, increment the number of messages contained by the channel. |
| // This operation will also atomically determine if the sender task |
| // should be parked. |
| // |
| // `None` is returned in the case that the channel has been closed by the |
| // receiver. This happens when `Receiver::close` is called or the |
| // receiver is dropped. |
| </span><span class="kw">let </span>park_self = <span class="kw">match </span><span class="self">self</span>.inc_num_messages() { |
| <span class="prelude-val">Some</span>(num_messages) => { |
| <span class="comment">// Block if the current number of pending messages has exceeded |
| // the configured buffer size |
| </span>num_messages > <span class="self">self</span>.inner.buffer |
| } |
| <span class="prelude-val">None </span>=> { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(TrySendError { |
| err: SendError { kind: SendErrorKind::Disconnected }, |
| val: msg, |
| }) |
| } |
| }; |
| |
| <span class="comment">// If the channel has reached capacity, then the sender task needs to |
| // be parked. This will send the task handle on the parked task queue. |
| // |
| // However, when `do_send` is called while dropping the `Sender`, |
| // `task::current()` can't be called safely. In this case, in order to |
| // maintain internal consistency, a blank message is pushed onto the |
| // parked task queue. |
| </span><span class="kw">if </span>park_self { |
| <span class="self">self</span>.park(); |
| } |
| |
| <span class="self">self</span>.queue_push_and_signal(msg); |
| |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="comment">// Push message to the queue and signal to the receiver |
| </span><span class="kw">fn </span>queue_push_and_signal(<span class="kw-2">&</span><span class="self">self</span>, msg: T) { |
| <span class="comment">// Push the message onto the message queue |
| </span><span class="self">self</span>.inner.message_queue.push(msg); |
| |
| <span class="comment">// Signal to the receiver that a message has been enqueued. If the |
| // receiver is parked, this will unpark the task. |
| </span><span class="self">self</span>.inner.recv_task.wake(); |
| } |
| |
| <span class="comment">// Increment the number of queued messages. Returns the resulting number. |
| </span><span class="kw">fn </span>inc_num_messages(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="kw">let </span><span class="kw-2">mut </span>curr = <span class="self">self</span>.inner.state.load(SeqCst); |
| |
| <span class="kw">loop </span>{ |
| <span class="kw">let </span><span class="kw-2">mut </span>state = decode_state(curr); |
| |
| <span class="comment">// The receiver end closed the channel. |
| </span><span class="kw">if </span>!state.is_open { |
| <span class="kw">return </span><span class="prelude-val">None</span>; |
| } |
| |
| <span class="comment">// This probably is never hit? Odds are the process will run out of |
| // memory first. It may be worth to return something else in this |
| // case? |
| </span><span class="macro">assert!</span>( |
| state.num_messages < MAX_CAPACITY, |
| <span class="string">"buffer space \ |
| exhausted; sending this messages would overflow the state" |
| </span>); |
| |
| state.num_messages += <span class="number">1</span>; |
| |
| <span class="kw">let </span>next = encode_state(<span class="kw-2">&</span>state); |
| <span class="kw">match </span><span class="self">self</span>.inner.state.compare_exchange(curr, next, SeqCst, SeqCst) { |
| <span class="prelude-val">Ok</span>(<span class="kw">_</span>) => <span class="kw">return </span><span class="prelude-val">Some</span>(state.num_messages), |
| <span class="prelude-val">Err</span>(actual) => curr = actual, |
| } |
| } |
| } |
| |
| <span class="kw">fn </span>park(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| { |
| <span class="kw">let </span><span class="kw-2">mut </span>sender = <span class="self">self</span>.sender_task.lock().unwrap(); |
| sender.task = <span class="prelude-val">None</span>; |
| sender.is_parked = <span class="bool-val">true</span>; |
| } |
| |
| <span class="comment">// Send handle over queue |
| </span><span class="kw">let </span>t = <span class="self">self</span>.sender_task.clone(); |
| <span class="self">self</span>.inner.parked_queue.push(t); |
| |
| <span class="comment">// Check to make sure we weren't closed after we sent our task on the |
| // queue |
| </span><span class="kw">let </span>state = decode_state(<span class="self">self</span>.inner.state.load(SeqCst)); |
| <span class="self">self</span>.maybe_parked = state.is_open; |
| } |
| |
| <span class="doccomment">/// Polls the channel to determine if there is guaranteed capacity to send |
| /// at least one item without waiting. |
| /// |
| /// # Return value |
| /// |
| /// This method returns: |
| /// |
| /// - `Poll::Ready(Ok(_))` if there is sufficient capacity; |
| /// - `Poll::Pending` if the channel may not have |
| /// capacity, in which case the current task is queued to be notified once |
| /// capacity is available; |
| /// - `Poll::Ready(Err(SendError))` if the receiver has been dropped. |
| </span><span class="kw">fn </span>poll_ready(<span class="kw-2">&mut </span><span class="self">self</span>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="prelude-ty">Result</span><(), SendError>> { |
| <span class="kw">let </span>state = decode_state(<span class="self">self</span>.inner.state.load(SeqCst)); |
| <span class="kw">if </span>!state.is_open { |
| <span class="kw">return </span>Poll::Ready(<span class="prelude-val">Err</span>(SendError { kind: SendErrorKind::Disconnected })); |
| } |
| |
| <span class="self">self</span>.poll_unparked(<span class="prelude-val">Some</span>(cx)).map(<span class="prelude-val">Ok</span>) |
| } |
| |
| <span class="doccomment">/// Returns whether the senders send to the same receiver. |
| </span><span class="kw">fn </span>same_receiver(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span><span class="self">Self</span>) -> bool { |
| Arc::ptr_eq(<span class="kw-2">&</span><span class="self">self</span>.inner, <span class="kw-2">&</span>other.inner) |
| } |
| |
| <span class="doccomment">/// Returns whether the sender send to this receiver. |
| </span><span class="kw">fn </span>is_connected_to(<span class="kw-2">&</span><span class="self">self</span>, receiver: <span class="kw-2">&</span>Arc<BoundedInner<T>>) -> bool { |
| Arc::ptr_eq(<span class="kw-2">&</span><span class="self">self</span>.inner, receiver) |
| } |
| |
| <span class="doccomment">/// Returns pointer to the Arc containing sender |
| /// |
| /// The returned pointer is not referenced and should be only used for hashing! |
| </span><span class="kw">fn </span>ptr(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">*const </span>BoundedInner<T> { |
| <span class="kw-2">&*</span><span class="self">self</span>.inner |
| } |
| |
| <span class="doccomment">/// Returns whether this channel is closed without needing a context. |
| </span><span class="kw">fn </span>is_closed(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| !decode_state(<span class="self">self</span>.inner.state.load(SeqCst)).is_open |
| } |
| |
| <span class="doccomment">/// Closes this channel from the sender side, preventing any new messages. |
| </span><span class="kw">fn </span>close_channel(<span class="kw-2">&</span><span class="self">self</span>) { |
| <span class="comment">// There's no need to park this sender, its dropping, |
| // and we don't want to check for capacity, so skip |
| // that stuff from `do_send`. |
| |
| </span><span class="self">self</span>.inner.set_closed(); |
| <span class="self">self</span>.inner.recv_task.wake(); |
| } |
| |
| <span class="kw">fn </span>poll_unparked(<span class="kw-2">&mut </span><span class="self">self</span>, cx: <span class="prelude-ty">Option</span><<span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>>) -> Poll<()> { |
| <span class="comment">// First check the `maybe_parked` variable. This avoids acquiring the |
| // lock in most cases |
| </span><span class="kw">if </span><span class="self">self</span>.maybe_parked { |
| <span class="comment">// Get a lock on the task handle |
| </span><span class="kw">let </span><span class="kw-2">mut </span>task = <span class="self">self</span>.sender_task.lock().unwrap(); |
| |
| <span class="kw">if </span>!task.is_parked { |
| <span class="self">self</span>.maybe_parked = <span class="bool-val">false</span>; |
| <span class="kw">return </span>Poll::Ready(()); |
| } |
| |
| <span class="comment">// At this point, an unpark request is pending, so there will be an |
| // unpark sometime in the future. We just need to make sure that |
| // the correct task will be notified. |
| // |
| // Update the task in case the `Sender` has been moved to another |
| // task |
| </span>task.task = cx.map(|cx| cx.waker().clone()); |
| |
| Poll::Pending |
| } <span class="kw">else </span>{ |
| Poll::Ready(()) |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> Sender<T> { |
| <span class="doccomment">/// Attempts to send a message on this `Sender`, returning the message |
| /// if there was an error. |
| </span><span class="kw">pub fn </span>try_send(<span class="kw-2">&mut </span><span class="self">self</span>, msg: T) -> <span class="prelude-ty">Result</span><(), TrySendError<T>> { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner) = <span class="kw-2">&mut </span><span class="self">self</span>.<span class="number">0 </span>{ |
| inner.try_send(msg) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Err</span>(TrySendError { err: SendError { kind: SendErrorKind::Disconnected }, val: msg }) |
| } |
| } |
| |
| <span class="doccomment">/// Send a message on the channel. |
| /// |
| /// This function should only be called after |
| /// [`poll_ready`](Sender::poll_ready) has reported that the channel is |
| /// ready to receive a message. |
| </span><span class="kw">pub fn </span>start_send(<span class="kw-2">&mut </span><span class="self">self</span>, msg: T) -> <span class="prelude-ty">Result</span><(), SendError> { |
| <span class="self">self</span>.try_send(msg).map_err(|e| e.err) |
| } |
| |
| <span class="doccomment">/// Polls the channel to determine if there is guaranteed capacity to send |
| /// at least one item without waiting. |
| /// |
| /// # Return value |
| /// |
| /// This method returns: |
| /// |
| /// - `Poll::Ready(Ok(_))` if there is sufficient capacity; |
| /// - `Poll::Pending` if the channel may not have |
| /// capacity, in which case the current task is queued to be notified once |
| /// capacity is available; |
| /// - `Poll::Ready(Err(SendError))` if the receiver has been dropped. |
| </span><span class="kw">pub fn </span>poll_ready(<span class="kw-2">&mut </span><span class="self">self</span>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="prelude-ty">Result</span><(), SendError>> { |
| <span class="kw">let </span>inner = <span class="self">self</span>.<span class="number">0</span>.as_mut().ok_or(SendError { kind: SendErrorKind::Disconnected })<span class="question-mark">?</span>; |
| inner.poll_ready(cx) |
| } |
| |
| <span class="doccomment">/// Returns whether this channel is closed without needing a context. |
| </span><span class="kw">pub fn </span>is_closed(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.<span class="number">0</span>.as_ref().map(BoundedSenderInner::is_closed).unwrap_or(<span class="bool-val">true</span>) |
| } |
| |
| <span class="doccomment">/// Closes this channel from the sender side, preventing any new messages. |
| </span><span class="kw">pub fn </span>close_channel(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner) = <span class="kw-2">&mut </span><span class="self">self</span>.<span class="number">0 </span>{ |
| inner.close_channel(); |
| } |
| } |
| |
| <span class="doccomment">/// Disconnects this sender from the channel, closing it if there are no more senders left. |
| </span><span class="kw">pub fn </span>disconnect(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="self">self</span>.<span class="number">0 </span>= <span class="prelude-val">None</span>; |
| } |
| |
| <span class="doccomment">/// Returns whether the senders send to the same receiver. |
| </span><span class="kw">pub fn </span>same_receiver(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span><span class="self">Self</span>) -> bool { |
| <span class="kw">match </span>(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>, <span class="kw-2">&</span>other.<span class="number">0</span>) { |
| (<span class="prelude-val">Some</span>(inner), <span class="prelude-val">Some</span>(other)) => inner.same_receiver(other), |
| <span class="kw">_ </span>=> <span class="bool-val">false</span>, |
| } |
| } |
| |
| <span class="doccomment">/// Returns whether the sender send to this receiver. |
| </span><span class="kw">pub fn </span>is_connected_to(<span class="kw-2">&</span><span class="self">self</span>, receiver: <span class="kw-2">&</span>Receiver<T>) -> bool { |
| <span class="kw">match </span>(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>, <span class="kw-2">&</span>receiver.inner) { |
| (<span class="prelude-val">Some</span>(inner), <span class="prelude-val">Some</span>(receiver)) => inner.is_connected_to(receiver), |
| <span class="kw">_ </span>=> <span class="bool-val">false</span>, |
| } |
| } |
| |
| <span class="doccomment">/// Hashes the receiver into the provided hasher |
| </span><span class="kw">pub fn </span>hash_receiver<H>(<span class="kw-2">&</span><span class="self">self</span>, hasher: <span class="kw-2">&mut </span>H) |
| <span class="kw">where |
| </span>H: std::hash::Hasher, |
| { |
| <span class="kw">use </span>std::hash::Hash; |
| |
| <span class="kw">let </span>ptr = <span class="self">self</span>.<span class="number">0</span>.as_ref().map(|inner| inner.ptr()); |
| ptr.hash(hasher); |
| } |
| } |
| |
| <span class="kw">impl</span><T> UnboundedSender<T> { |
| <span class="doccomment">/// Check if the channel is ready to receive a message. |
| </span><span class="kw">pub fn </span>poll_ready(<span class="kw-2">&</span><span class="self">self</span>, <span class="kw">_</span>: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="prelude-ty">Result</span><(), SendError>> { |
| <span class="kw">let </span>inner = <span class="self">self</span>.<span class="number">0</span>.as_ref().ok_or(SendError { kind: SendErrorKind::Disconnected })<span class="question-mark">?</span>; |
| inner.poll_ready_nb() |
| } |
| |
| <span class="doccomment">/// Returns whether this channel is closed without needing a context. |
| </span><span class="kw">pub fn </span>is_closed(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.<span class="number">0</span>.as_ref().map(UnboundedSenderInner::is_closed).unwrap_or(<span class="bool-val">true</span>) |
| } |
| |
| <span class="doccomment">/// Closes this channel from the sender side, preventing any new messages. |
| </span><span class="kw">pub fn </span>close_channel(<span class="kw-2">&</span><span class="self">self</span>) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner) = <span class="kw-2">&</span><span class="self">self</span>.<span class="number">0 </span>{ |
| inner.close_channel(); |
| } |
| } |
| |
| <span class="doccomment">/// Disconnects this sender from the channel, closing it if there are no more senders left. |
| </span><span class="kw">pub fn </span>disconnect(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="self">self</span>.<span class="number">0 </span>= <span class="prelude-val">None</span>; |
| } |
| |
| <span class="comment">// Do the send without parking current task. |
| </span><span class="kw">fn </span>do_send_nb(<span class="kw-2">&</span><span class="self">self</span>, msg: T) -> <span class="prelude-ty">Result</span><(), TrySendError<T>> { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner) = <span class="kw-2">&</span><span class="self">self</span>.<span class="number">0 </span>{ |
| <span class="kw">if </span>inner.inc_num_messages().is_some() { |
| inner.queue_push_and_signal(msg); |
| <span class="kw">return </span><span class="prelude-val">Ok</span>(()); |
| } |
| } |
| |
| <span class="prelude-val">Err</span>(TrySendError { err: SendError { kind: SendErrorKind::Disconnected }, val: msg }) |
| } |
| |
| <span class="doccomment">/// Send a message on the channel. |
| /// |
| /// This method should only be called after `poll_ready` has been used to |
| /// verify that the channel is ready to receive a message. |
| </span><span class="kw">pub fn </span>start_send(<span class="kw-2">&mut </span><span class="self">self</span>, msg: T) -> <span class="prelude-ty">Result</span><(), SendError> { |
| <span class="self">self</span>.do_send_nb(msg).map_err(|e| e.err) |
| } |
| |
| <span class="doccomment">/// Sends a message along this channel. |
| /// |
| /// This is an unbounded sender, so this function differs from `Sink::send` |
| /// by ensuring the return type reflects that the channel is always ready to |
| /// receive messages. |
| </span><span class="kw">pub fn </span>unbounded_send(<span class="kw-2">&</span><span class="self">self</span>, msg: T) -> <span class="prelude-ty">Result</span><(), TrySendError<T>> { |
| <span class="self">self</span>.do_send_nb(msg) |
| } |
| |
| <span class="doccomment">/// Returns whether the senders send to the same receiver. |
| </span><span class="kw">pub fn </span>same_receiver(<span class="kw-2">&</span><span class="self">self</span>, other: <span class="kw-2">&</span><span class="self">Self</span>) -> bool { |
| <span class="kw">match </span>(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>, <span class="kw-2">&</span>other.<span class="number">0</span>) { |
| (<span class="prelude-val">Some</span>(inner), <span class="prelude-val">Some</span>(other)) => inner.same_receiver(other), |
| <span class="kw">_ </span>=> <span class="bool-val">false</span>, |
| } |
| } |
| |
| <span class="doccomment">/// Returns whether the sender send to this receiver. |
| </span><span class="kw">pub fn </span>is_connected_to(<span class="kw-2">&</span><span class="self">self</span>, receiver: <span class="kw-2">&</span>UnboundedReceiver<T>) -> bool { |
| <span class="kw">match </span>(<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>, <span class="kw-2">&</span>receiver.inner) { |
| (<span class="prelude-val">Some</span>(inner), <span class="prelude-val">Some</span>(receiver)) => inner.is_connected_to(receiver), |
| <span class="kw">_ </span>=> <span class="bool-val">false</span>, |
| } |
| } |
| |
| <span class="doccomment">/// Hashes the receiver into the provided hasher |
| </span><span class="kw">pub fn </span>hash_receiver<H>(<span class="kw-2">&</span><span class="self">self</span>, hasher: <span class="kw-2">&mut </span>H) |
| <span class="kw">where |
| </span>H: std::hash::Hasher, |
| { |
| <span class="kw">use </span>std::hash::Hash; |
| |
| <span class="kw">let </span>ptr = <span class="self">self</span>.<span class="number">0</span>.as_ref().map(|inner| inner.ptr()); |
| ptr.hash(hasher); |
| } |
| } |
| |
| <span class="kw">impl</span><T> Clone <span class="kw">for </span>Sender<T> { |
| <span class="kw">fn </span>clone(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self </span>{ |
| <span class="self">Self</span>(<span class="self">self</span>.<span class="number">0</span>.clone()) |
| } |
| } |
| |
| <span class="kw">impl</span><T> Clone <span class="kw">for </span>UnboundedSender<T> { |
| <span class="kw">fn </span>clone(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self </span>{ |
| <span class="self">Self</span>(<span class="self">self</span>.<span class="number">0</span>.clone()) |
| } |
| } |
| |
| <span class="kw">impl</span><T> Clone <span class="kw">for </span>UnboundedSenderInner<T> { |
| <span class="kw">fn </span>clone(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self </span>{ |
| <span class="comment">// Since this atomic op isn't actually guarding any memory and we don't |
| // care about any orderings besides the ordering on the single atomic |
| // variable, a relaxed ordering is acceptable. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>curr = <span class="self">self</span>.inner.num_senders.load(SeqCst); |
| |
| <span class="kw">loop </span>{ |
| <span class="comment">// If the maximum number of senders has been reached, then fail |
| </span><span class="kw">if </span>curr == MAX_BUFFER { |
| <span class="macro">panic!</span>(<span class="string">"cannot clone `Sender` -- too many outstanding senders"</span>); |
| } |
| |
| <span class="macro">debug_assert!</span>(curr < MAX_BUFFER); |
| |
| <span class="kw">let </span>next = curr + <span class="number">1</span>; |
| <span class="kw">match </span><span class="self">self</span>.inner.num_senders.compare_exchange(curr, next, SeqCst, SeqCst) { |
| <span class="prelude-val">Ok</span>(<span class="kw">_</span>) => { |
| <span class="comment">// The ABA problem doesn't matter here. We only care that the |
| // number of senders never exceeds the maximum. |
| </span><span class="kw">return </span><span class="self">Self </span>{ inner: <span class="self">self</span>.inner.clone() }; |
| } |
| <span class="prelude-val">Err</span>(actual) => curr = actual, |
| } |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> Clone <span class="kw">for </span>BoundedSenderInner<T> { |
| <span class="kw">fn </span>clone(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self </span>{ |
| <span class="comment">// Since this atomic op isn't actually guarding any memory and we don't |
| // care about any orderings besides the ordering on the single atomic |
| // variable, a relaxed ordering is acceptable. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>curr = <span class="self">self</span>.inner.num_senders.load(SeqCst); |
| |
| <span class="kw">loop </span>{ |
| <span class="comment">// If the maximum number of senders has been reached, then fail |
| </span><span class="kw">if </span>curr == <span class="self">self</span>.inner.max_senders() { |
| <span class="macro">panic!</span>(<span class="string">"cannot clone `Sender` -- too many outstanding senders"</span>); |
| } |
| |
| <span class="macro">debug_assert!</span>(curr < <span class="self">self</span>.inner.max_senders()); |
| |
| <span class="kw">let </span>next = curr + <span class="number">1</span>; |
| <span class="kw">match </span><span class="self">self</span>.inner.num_senders.compare_exchange(curr, next, SeqCst, SeqCst) { |
| <span class="prelude-val">Ok</span>(<span class="kw">_</span>) => { |
| <span class="comment">// The ABA problem doesn't matter here. We only care that the |
| // number of senders never exceeds the maximum. |
| </span><span class="kw">return </span><span class="self">Self </span>{ |
| inner: <span class="self">self</span>.inner.clone(), |
| sender_task: Arc::new(Mutex::new(SenderTask::new())), |
| maybe_parked: <span class="bool-val">false</span>, |
| }; |
| } |
| <span class="prelude-val">Err</span>(actual) => curr = actual, |
| } |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> Drop <span class="kw">for </span>UnboundedSenderInner<T> { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="comment">// Ordering between variables don't matter here |
| </span><span class="kw">let </span>prev = <span class="self">self</span>.inner.num_senders.fetch_sub(<span class="number">1</span>, SeqCst); |
| |
| <span class="kw">if </span>prev == <span class="number">1 </span>{ |
| <span class="self">self</span>.close_channel(); |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> Drop <span class="kw">for </span>BoundedSenderInner<T> { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="comment">// Ordering between variables don't matter here |
| </span><span class="kw">let </span>prev = <span class="self">self</span>.inner.num_senders.fetch_sub(<span class="number">1</span>, SeqCst); |
| |
| <span class="kw">if </span>prev == <span class="number">1 </span>{ |
| <span class="self">self</span>.close_channel(); |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> fmt::Debug <span class="kw">for </span>Sender<T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.debug_struct(<span class="string">"Sender"</span>).field(<span class="string">"closed"</span>, <span class="kw-2">&</span><span class="self">self</span>.is_closed()).finish() |
| } |
| } |
| |
| <span class="kw">impl</span><T> fmt::Debug <span class="kw">for </span>UnboundedSender<T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.debug_struct(<span class="string">"UnboundedSender"</span>).field(<span class="string">"closed"</span>, <span class="kw-2">&</span><span class="self">self</span>.is_closed()).finish() |
| } |
| } |
| |
| <span class="comment">/* |
| * |
| * ===== impl Receiver ===== |
| * |
| */ |
| |
| </span><span class="kw">impl</span><T> Receiver<T> { |
| <span class="doccomment">/// Closes the receiving half of a channel, without dropping it. |
| /// |
| /// This prevents any further messages from being sent on the channel while |
| /// still enabling the receiver to drain messages that are buffered. |
| </span><span class="kw">pub fn </span>close(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner) = <span class="kw-2">&mut </span><span class="self">self</span>.inner { |
| inner.set_closed(); |
| |
| <span class="comment">// Wake up any threads waiting as they'll see that we've closed the |
| // channel and will continue on their merry way. |
| </span><span class="kw">while let </span><span class="prelude-val">Some</span>(task) = <span class="kw">unsafe </span>{ inner.parked_queue.pop_spin() } { |
| task.lock().unwrap().notify(); |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Tries to receive the next message without notifying a context if empty. |
| /// |
| /// It is not recommended to call this function from inside of a future, |
| /// only when you've otherwise arranged to be notified when the channel is |
| /// no longer empty. |
| /// |
| /// This function returns: |
| /// * `Ok(Some(t))` when message is fetched |
| /// * `Ok(None)` when channel is closed and no messages left in the queue |
| /// * `Err(e)` when there are no messages available, but channel is not yet closed |
| </span><span class="kw">pub fn </span>try_next(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="prelude-ty">Result</span><<span class="prelude-ty">Option</span><T>, TryRecvError> { |
| <span class="kw">match </span><span class="self">self</span>.next_message() { |
| Poll::Ready(msg) => <span class="prelude-val">Ok</span>(msg), |
| Poll::Pending => <span class="prelude-val">Err</span>(TryRecvError { _priv: () }), |
| } |
| } |
| |
| <span class="kw">fn </span>next_message(<span class="kw-2">&mut </span><span class="self">self</span>) -> Poll<<span class="prelude-ty">Option</span><T>> { |
| <span class="kw">let </span>inner = <span class="kw">match </span><span class="self">self</span>.inner.as_mut() { |
| <span class="prelude-val">None </span>=> <span class="kw">return </span>Poll::Ready(<span class="prelude-val">None</span>), |
| <span class="prelude-val">Some</span>(inner) => inner, |
| }; |
| <span class="comment">// Pop off a message |
| </span><span class="kw">match unsafe </span>{ inner.message_queue.pop_spin() } { |
| <span class="prelude-val">Some</span>(msg) => { |
| <span class="comment">// If there are any parked task handles in the parked queue, |
| // pop one and unpark it. |
| </span><span class="self">self</span>.unpark_one(); |
| |
| <span class="comment">// Decrement number of messages |
| </span><span class="self">self</span>.dec_num_messages(); |
| |
| Poll::Ready(<span class="prelude-val">Some</span>(msg)) |
| } |
| <span class="prelude-val">None </span>=> { |
| <span class="kw">let </span>state = decode_state(inner.state.load(SeqCst)); |
| <span class="kw">if </span>state.is_closed() { |
| <span class="comment">// If closed flag is set AND there are no pending messages |
| // it means end of stream |
| </span><span class="self">self</span>.inner = <span class="prelude-val">None</span>; |
| Poll::Ready(<span class="prelude-val">None</span>) |
| } <span class="kw">else </span>{ |
| <span class="comment">// If queue is open, we need to return Pending |
| // to be woken up when new messages arrive. |
| // If queue is closed but num_messages is non-zero, |
| // it means that senders updated the state, |
| // but didn't put message to queue yet, |
| // so we need to park until sender unparks the task |
| // after queueing the message. |
| </span>Poll::Pending |
| } |
| } |
| } |
| } |
| |
| <span class="comment">// Unpark a single task handle if there is one pending in the parked queue |
| </span><span class="kw">fn </span>unpark_one(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner) = <span class="kw-2">&mut </span><span class="self">self</span>.inner { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(task) = <span class="kw">unsafe </span>{ inner.parked_queue.pop_spin() } { |
| task.lock().unwrap().notify(); |
| } |
| } |
| } |
| |
| <span class="kw">fn </span>dec_num_messages(<span class="kw-2">&</span><span class="self">self</span>) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner) = <span class="kw-2">&</span><span class="self">self</span>.inner { |
| <span class="comment">// OPEN_MASK is highest bit, so it's unaffected by subtraction |
| // unless there's underflow, and we know there's no underflow |
| // because number of messages at this point is always > 0. |
| </span>inner.state.fetch_sub(<span class="number">1</span>, SeqCst); |
| } |
| } |
| } |
| |
| <span class="comment">// The receiver does not ever take a Pin to the inner T |
| </span><span class="kw">impl</span><T> Unpin <span class="kw">for </span>Receiver<T> {} |
| |
| <span class="kw">impl</span><T> FusedStream <span class="kw">for </span>Receiver<T> { |
| <span class="kw">fn </span>is_terminated(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.inner.is_none() |
| } |
| } |
| |
| <span class="kw">impl</span><T> Stream <span class="kw">for </span>Receiver<T> { |
| <span class="kw">type </span>Item = T; |
| |
| <span class="kw">fn </span>poll_next(<span class="kw-2">mut </span><span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="prelude-ty">Option</span><T>> { |
| <span class="comment">// Try to read a message off of the message queue. |
| </span><span class="kw">match </span><span class="self">self</span>.next_message() { |
| Poll::Ready(msg) => { |
| <span class="kw">if </span>msg.is_none() { |
| <span class="self">self</span>.inner = <span class="prelude-val">None</span>; |
| } |
| Poll::Ready(msg) |
| } |
| Poll::Pending => { |
| <span class="comment">// There are no messages to read, in this case, park. |
| </span><span class="self">self</span>.inner.as_ref().unwrap().recv_task.register(cx.waker()); |
| <span class="comment">// Check queue again after parking to prevent race condition: |
| // a message could be added to the queue after previous `next_message` |
| // before `register` call. |
| </span><span class="self">self</span>.next_message() |
| } |
| } |
| } |
| |
| <span class="kw">fn </span>size_hint(<span class="kw-2">&</span><span class="self">self</span>) -> (usize, <span class="prelude-ty">Option</span><usize>) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner) = <span class="kw-2">&</span><span class="self">self</span>.inner { |
| decode_state(inner.state.load(SeqCst)).size_hint() |
| } <span class="kw">else </span>{ |
| (<span class="number">0</span>, <span class="prelude-val">Some</span>(<span class="number">0</span>)) |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> Drop <span class="kw">for </span>Receiver<T> { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="comment">// Drain the channel of all pending messages |
| </span><span class="self">self</span>.close(); |
| <span class="kw">if </span><span class="self">self</span>.inner.is_some() { |
| <span class="kw">loop </span>{ |
| <span class="kw">match </span><span class="self">self</span>.next_message() { |
| Poll::Ready(<span class="prelude-val">Some</span>(<span class="kw">_</span>)) => {} |
| Poll::Ready(<span class="prelude-val">None</span>) => <span class="kw">break</span>, |
| Poll::Pending => { |
| <span class="kw">let </span>state = decode_state(<span class="self">self</span>.inner.as_ref().unwrap().state.load(SeqCst)); |
| |
| <span class="comment">// If the channel is closed, then there is no need to park. |
| </span><span class="kw">if </span>state.is_closed() { |
| <span class="kw">break</span>; |
| } |
| |
| <span class="comment">// TODO: Spinning isn't ideal, it might be worth |
| // investigating using a condvar or some other strategy |
| // here. That said, if this case is hit, then another thread |
| // is about to push the value into the queue and this isn't |
| // the only spinlock in the impl right now. |
| </span>thread::yield_now(); |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> fmt::Debug <span class="kw">for </span>Receiver<T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="kw">let </span>closed = <span class="kw">if let </span><span class="prelude-val">Some</span>(<span class="kw-2">ref </span>inner) = <span class="self">self</span>.inner { |
| decode_state(inner.state.load(SeqCst)).is_closed() |
| } <span class="kw">else </span>{ |
| <span class="bool-val">false |
| </span>}; |
| |
| f.debug_struct(<span class="string">"Receiver"</span>).field(<span class="string">"closed"</span>, <span class="kw-2">&</span>closed).finish() |
| } |
| } |
| |
| <span class="kw">impl</span><T> UnboundedReceiver<T> { |
| <span class="doccomment">/// Closes the receiving half of a channel, without dropping it. |
| /// |
| /// This prevents any further messages from being sent on the channel while |
| /// still enabling the receiver to drain messages that are buffered. |
| </span><span class="kw">pub fn </span>close(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner) = <span class="kw-2">&mut </span><span class="self">self</span>.inner { |
| inner.set_closed(); |
| } |
| } |
| |
| <span class="doccomment">/// Tries to receive the next message without notifying a context if empty. |
| /// |
| /// It is not recommended to call this function from inside of a future, |
| /// only when you've otherwise arranged to be notified when the channel is |
| /// no longer empty. |
| /// |
| /// This function returns: |
| /// * `Ok(Some(t))` when message is fetched |
| /// * `Ok(None)` when channel is closed and no messages left in the queue |
| /// * `Err(e)` when there are no messages available, but channel is not yet closed |
| </span><span class="kw">pub fn </span>try_next(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="prelude-ty">Result</span><<span class="prelude-ty">Option</span><T>, TryRecvError> { |
| <span class="kw">match </span><span class="self">self</span>.next_message() { |
| Poll::Ready(msg) => <span class="prelude-val">Ok</span>(msg), |
| Poll::Pending => <span class="prelude-val">Err</span>(TryRecvError { _priv: () }), |
| } |
| } |
| |
| <span class="kw">fn </span>next_message(<span class="kw-2">&mut </span><span class="self">self</span>) -> Poll<<span class="prelude-ty">Option</span><T>> { |
| <span class="kw">let </span>inner = <span class="kw">match </span><span class="self">self</span>.inner.as_mut() { |
| <span class="prelude-val">None </span>=> <span class="kw">return </span>Poll::Ready(<span class="prelude-val">None</span>), |
| <span class="prelude-val">Some</span>(inner) => inner, |
| }; |
| <span class="comment">// Pop off a message |
| </span><span class="kw">match unsafe </span>{ inner.message_queue.pop_spin() } { |
| <span class="prelude-val">Some</span>(msg) => { |
| <span class="comment">// Decrement number of messages |
| </span><span class="self">self</span>.dec_num_messages(); |
| |
| Poll::Ready(<span class="prelude-val">Some</span>(msg)) |
| } |
| <span class="prelude-val">None </span>=> { |
| <span class="kw">let </span>state = decode_state(inner.state.load(SeqCst)); |
| <span class="kw">if </span>state.is_closed() { |
| <span class="comment">// If closed flag is set AND there are no pending messages |
| // it means end of stream |
| </span><span class="self">self</span>.inner = <span class="prelude-val">None</span>; |
| Poll::Ready(<span class="prelude-val">None</span>) |
| } <span class="kw">else </span>{ |
| <span class="comment">// If queue is open, we need to return Pending |
| // to be woken up when new messages arrive. |
| // If queue is closed but num_messages is non-zero, |
| // it means that senders updated the state, |
| // but didn't put message to queue yet, |
| // so we need to park until sender unparks the task |
| // after queueing the message. |
| </span>Poll::Pending |
| } |
| } |
| } |
| } |
| |
| <span class="kw">fn </span>dec_num_messages(<span class="kw-2">&</span><span class="self">self</span>) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner) = <span class="kw-2">&</span><span class="self">self</span>.inner { |
| <span class="comment">// OPEN_MASK is highest bit, so it's unaffected by subtraction |
| // unless there's underflow, and we know there's no underflow |
| // because number of messages at this point is always > 0. |
| </span>inner.state.fetch_sub(<span class="number">1</span>, SeqCst); |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> FusedStream <span class="kw">for </span>UnboundedReceiver<T> { |
| <span class="kw">fn </span>is_terminated(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.inner.is_none() |
| } |
| } |
| |
| <span class="kw">impl</span><T> Stream <span class="kw">for </span>UnboundedReceiver<T> { |
| <span class="kw">type </span>Item = T; |
| |
| <span class="kw">fn </span>poll_next(<span class="kw-2">mut </span><span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="prelude-ty">Option</span><T>> { |
| <span class="comment">// Try to read a message off of the message queue. |
| </span><span class="kw">match </span><span class="self">self</span>.next_message() { |
| Poll::Ready(msg) => { |
| <span class="kw">if </span>msg.is_none() { |
| <span class="self">self</span>.inner = <span class="prelude-val">None</span>; |
| } |
| Poll::Ready(msg) |
| } |
| Poll::Pending => { |
| <span class="comment">// There are no messages to read, in this case, park. |
| </span><span class="self">self</span>.inner.as_ref().unwrap().recv_task.register(cx.waker()); |
| <span class="comment">// Check queue again after parking to prevent race condition: |
| // a message could be added to the queue after previous `next_message` |
| // before `register` call. |
| </span><span class="self">self</span>.next_message() |
| } |
| } |
| } |
| |
| <span class="kw">fn </span>size_hint(<span class="kw-2">&</span><span class="self">self</span>) -> (usize, <span class="prelude-ty">Option</span><usize>) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner) = <span class="kw-2">&</span><span class="self">self</span>.inner { |
| decode_state(inner.state.load(SeqCst)).size_hint() |
| } <span class="kw">else </span>{ |
| (<span class="number">0</span>, <span class="prelude-val">Some</span>(<span class="number">0</span>)) |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> Drop <span class="kw">for </span>UnboundedReceiver<T> { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="comment">// Drain the channel of all pending messages |
| </span><span class="self">self</span>.close(); |
| <span class="kw">if </span><span class="self">self</span>.inner.is_some() { |
| <span class="kw">loop </span>{ |
| <span class="kw">match </span><span class="self">self</span>.next_message() { |
| Poll::Ready(<span class="prelude-val">Some</span>(<span class="kw">_</span>)) => {} |
| Poll::Ready(<span class="prelude-val">None</span>) => <span class="kw">break</span>, |
| Poll::Pending => { |
| <span class="kw">let </span>state = decode_state(<span class="self">self</span>.inner.as_ref().unwrap().state.load(SeqCst)); |
| |
| <span class="comment">// If the channel is closed, then there is no need to park. |
| </span><span class="kw">if </span>state.is_closed() { |
| <span class="kw">break</span>; |
| } |
| |
| <span class="comment">// TODO: Spinning isn't ideal, it might be worth |
| // investigating using a condvar or some other strategy |
| // here. That said, if this case is hit, then another thread |
| // is about to push the value into the queue and this isn't |
| // the only spinlock in the impl right now. |
| </span>thread::yield_now(); |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> fmt::Debug <span class="kw">for </span>UnboundedReceiver<T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="kw">let </span>closed = <span class="kw">if let </span><span class="prelude-val">Some</span>(<span class="kw-2">ref </span>inner) = <span class="self">self</span>.inner { |
| decode_state(inner.state.load(SeqCst)).is_closed() |
| } <span class="kw">else </span>{ |
| <span class="bool-val">false |
| </span>}; |
| |
| f.debug_struct(<span class="string">"Receiver"</span>).field(<span class="string">"closed"</span>, <span class="kw-2">&</span>closed).finish() |
| } |
| } |
| |
| <span class="comment">/* |
| * |
| * ===== impl Inner ===== |
| * |
| */ |
| |
| </span><span class="kw">impl</span><T> UnboundedInner<T> { |
| <span class="comment">// Clear `open` flag in the state, keep `num_messages` intact. |
| </span><span class="kw">fn </span>set_closed(<span class="kw-2">&</span><span class="self">self</span>) { |
| <span class="kw">let </span>curr = <span class="self">self</span>.state.load(SeqCst); |
| <span class="kw">if </span>!decode_state(curr).is_open { |
| <span class="kw">return</span>; |
| } |
| |
| <span class="self">self</span>.state.fetch_and(!OPEN_MASK, SeqCst); |
| } |
| } |
| |
| <span class="kw">impl</span><T> BoundedInner<T> { |
| <span class="comment">// The return value is such that the total number of messages that can be |
| // enqueued into the channel will never exceed MAX_CAPACITY |
| </span><span class="kw">fn </span>max_senders(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| MAX_CAPACITY - <span class="self">self</span>.buffer |
| } |
| |
| <span class="comment">// Clear `open` flag in the state, keep `num_messages` intact. |
| </span><span class="kw">fn </span>set_closed(<span class="kw-2">&</span><span class="self">self</span>) { |
| <span class="kw">let </span>curr = <span class="self">self</span>.state.load(SeqCst); |
| <span class="kw">if </span>!decode_state(curr).is_open { |
| <span class="kw">return</span>; |
| } |
| |
| <span class="self">self</span>.state.fetch_and(!OPEN_MASK, SeqCst); |
| } |
| } |
| |
| <span class="kw">unsafe impl</span><T: Send> Send <span class="kw">for </span>UnboundedInner<T> {} |
| <span class="kw">unsafe impl</span><T: Send> Sync <span class="kw">for </span>UnboundedInner<T> {} |
| |
| <span class="kw">unsafe impl</span><T: Send> Send <span class="kw">for </span>BoundedInner<T> {} |
| <span class="kw">unsafe impl</span><T: Send> Sync <span class="kw">for </span>BoundedInner<T> {} |
| |
| <span class="kw">impl </span>State { |
| <span class="kw">fn </span>is_closed(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| !<span class="self">self</span>.is_open && <span class="self">self</span>.num_messages == <span class="number">0 |
| </span>} |
| |
| <span class="kw">fn </span>size_hint(<span class="kw-2">&</span><span class="self">self</span>) -> (usize, <span class="prelude-ty">Option</span><usize>) { |
| <span class="kw">if </span><span class="self">self</span>.is_open { |
| (<span class="self">self</span>.num_messages, <span class="prelude-val">None</span>) |
| } <span class="kw">else </span>{ |
| (<span class="self">self</span>.num_messages, <span class="prelude-val">Some</span>(<span class="self">self</span>.num_messages)) |
| } |
| } |
| } |
| |
| <span class="comment">/* |
| * |
| * ===== Helpers ===== |
| * |
| */ |
| |
| </span><span class="kw">fn </span>decode_state(num: usize) -> State { |
| State { is_open: num & OPEN_MASK == OPEN_MASK, num_messages: num & MAX_CAPACITY } |
| } |
| |
| <span class="kw">fn </span>encode_state(state: <span class="kw-2">&</span>State) -> usize { |
| <span class="kw">let </span><span class="kw-2">mut </span>num = state.num_messages; |
| |
| <span class="kw">if </span>state.is_open { |
| num |= OPEN_MASK; |
| } |
| |
| num |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="futures_channel" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |