| <!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-task-0.3.28/src/noop_waker.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>noop_waker.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_task/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_task/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">//! Utilities for creating zero-cost wakers that don't do anything. |
| |
| </span><span class="kw">use </span>core::ptr::null; |
| <span class="kw">use </span>core::task::{RawWaker, RawWakerVTable, Waker}; |
| |
| <span class="kw">unsafe fn </span>noop_clone(_data: <span class="kw-2">*const </span>()) -> RawWaker { |
| noop_raw_waker() |
| } |
| |
| <span class="kw">unsafe fn </span>noop(_data: <span class="kw-2">*const </span>()) {} |
| |
| <span class="kw">const </span>NOOP_WAKER_VTABLE: RawWakerVTable = RawWakerVTable::new(noop_clone, noop, noop, noop); |
| |
| <span class="kw">const fn </span>noop_raw_waker() -> RawWaker { |
| RawWaker::new(null(), <span class="kw-2">&</span>NOOP_WAKER_VTABLE) |
| } |
| |
| <span class="doccomment">/// Create a new [`Waker`] which does |
| /// nothing when `wake()` is called on it. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use futures::task::noop_waker; |
| /// let waker = noop_waker(); |
| /// waker.wake(); |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>noop_waker() -> Waker { |
| <span class="comment">// FIXME: Since 1.46.0 we can use transmute in consts, allowing this function to be const. |
| </span><span class="kw">unsafe </span>{ Waker::from_raw(noop_raw_waker()) } |
| } |
| |
| <span class="doccomment">/// Get a static reference to a [`Waker`] which |
| /// does nothing when `wake()` is called on it. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use futures::task::noop_waker_ref; |
| /// let waker = noop_waker_ref(); |
| /// waker.wake_by_ref(); |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>noop_waker_ref() -> <span class="kw-2">&</span><span class="lifetime">'static </span>Waker { |
| <span class="kw">struct </span>SyncRawWaker(RawWaker); |
| <span class="kw">unsafe impl </span>Sync <span class="kw">for </span>SyncRawWaker {} |
| |
| <span class="kw">static </span>NOOP_WAKER_INSTANCE: SyncRawWaker = SyncRawWaker(noop_raw_waker()); |
| |
| <span class="comment">// SAFETY: `Waker` is #[repr(transparent)] over its `RawWaker`. |
| </span><span class="kw">unsafe </span>{ <span class="kw-2">&*</span>(<span class="kw-2">&</span>NOOP_WAKER_INSTANCE.<span class="number">0 </span><span class="kw">as </span><span class="kw-2">*const </span>RawWaker <span class="kw">as </span><span class="kw-2">*const </span>Waker) } |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>tests { |
| <span class="attribute">#[test] |
| #[cfg(feature = <span class="string">"std"</span>)] |
| </span><span class="kw">fn </span>issue_2091_cross_thread_segfault() { |
| <span class="kw">let </span>waker = std::thread::spawn(<span class="kw">super</span>::noop_waker_ref).join().unwrap(); |
| waker.wake_by_ref(); |
| } |
| } |
| </code></pre></div> |
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