| <!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/crossbeam-utils-0.8.15/src/sync/wait_group.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>wait_group.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="../../../crossbeam_utils/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="../../../crossbeam_utils/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="kw">use </span><span class="kw">crate</span>::primitive::sync::{Arc, Condvar, Mutex}; |
| <span class="kw">use </span>std::fmt; |
| |
| <span class="doccomment">/// Enables threads to synchronize the beginning or end of some computation. |
| /// |
| /// # Wait groups vs barriers |
| /// |
| /// `WaitGroup` is very similar to [`Barrier`], but there are a few differences: |
| /// |
| /// * [`Barrier`] needs to know the number of threads at construction, while `WaitGroup` is cloned to |
| /// register more threads. |
| /// |
| /// * A [`Barrier`] can be reused even after all threads have synchronized, while a `WaitGroup` |
| /// synchronizes threads only once. |
| /// |
| /// * All threads wait for others to reach the [`Barrier`]. With `WaitGroup`, each thread can choose |
| /// to either wait for other threads or to continue without blocking. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use crossbeam_utils::sync::WaitGroup; |
| /// use std::thread; |
| /// |
| /// // Create a new wait group. |
| /// let wg = WaitGroup::new(); |
| /// |
| /// for _ in 0..4 { |
| /// // Create another reference to the wait group. |
| /// let wg = wg.clone(); |
| /// |
| /// thread::spawn(move || { |
| /// // Do some work. |
| /// |
| /// // Drop the reference to the wait group. |
| /// drop(wg); |
| /// }); |
| /// } |
| /// |
| /// // Block until all threads have finished their work. |
| /// wg.wait(); |
| /// # std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371 |
| /// ``` |
| /// |
| /// [`Barrier`]: std::sync::Barrier |
| </span><span class="kw">pub struct </span>WaitGroup { |
| inner: Arc<Inner>, |
| } |
| |
| <span class="doccomment">/// Inner state of a `WaitGroup`. |
| </span><span class="kw">struct </span>Inner { |
| cvar: Condvar, |
| count: Mutex<usize>, |
| } |
| |
| <span class="kw">impl </span>Default <span class="kw">for </span>WaitGroup { |
| <span class="kw">fn </span>default() -> <span class="self">Self </span>{ |
| <span class="self">Self </span>{ |
| inner: Arc::new(Inner { |
| cvar: Condvar::new(), |
| count: Mutex::new(<span class="number">1</span>), |
| }), |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>WaitGroup { |
| <span class="doccomment">/// Creates a new wait group and returns the single reference to it. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use crossbeam_utils::sync::WaitGroup; |
| /// |
| /// let wg = WaitGroup::new(); |
| /// ``` |
| </span><span class="kw">pub fn </span>new() -> <span class="self">Self </span>{ |
| <span class="self">Self</span>::default() |
| } |
| |
| <span class="doccomment">/// Drops this reference and waits until all other references are dropped. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use crossbeam_utils::sync::WaitGroup; |
| /// use std::thread; |
| /// |
| /// let wg = WaitGroup::new(); |
| /// |
| /// thread::spawn({ |
| /// let wg = wg.clone(); |
| /// move || { |
| /// // Block until both threads have reached `wait()`. |
| /// wg.wait(); |
| /// } |
| /// }); |
| /// |
| /// // Block until both threads have reached `wait()`. |
| /// wg.wait(); |
| /// # std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371 |
| /// ``` |
| </span><span class="kw">pub fn </span>wait(<span class="self">self</span>) { |
| <span class="kw">if </span><span class="kw-2">*</span><span class="self">self</span>.inner.count.lock().unwrap() == <span class="number">1 </span>{ |
| <span class="kw">return</span>; |
| } |
| |
| <span class="kw">let </span>inner = <span class="self">self</span>.inner.clone(); |
| drop(<span class="self">self</span>); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>count = inner.count.lock().unwrap(); |
| <span class="kw">while </span><span class="kw-2">*</span>count > <span class="number">0 </span>{ |
| count = inner.cvar.wait(count).unwrap(); |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>Drop <span class="kw">for </span>WaitGroup { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="kw">let </span><span class="kw-2">mut </span>count = <span class="self">self</span>.inner.count.lock().unwrap(); |
| <span class="kw-2">*</span>count -= <span class="number">1</span>; |
| |
| <span class="kw">if </span><span class="kw-2">*</span>count == <span class="number">0 </span>{ |
| <span class="self">self</span>.inner.cvar.notify_all(); |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>Clone <span class="kw">for </span>WaitGroup { |
| <span class="kw">fn </span>clone(<span class="kw-2">&</span><span class="self">self</span>) -> WaitGroup { |
| <span class="kw">let </span><span class="kw-2">mut </span>count = <span class="self">self</span>.inner.count.lock().unwrap(); |
| <span class="kw-2">*</span>count += <span class="number">1</span>; |
| |
| WaitGroup { |
| inner: <span class="self">self</span>.inner.clone(), |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Debug <span class="kw">for </span>WaitGroup { |
| <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>count: <span class="kw-2">&</span>usize = <span class="kw-2">&*</span><span class="self">self</span>.inner.count.lock().unwrap(); |
| f.debug_struct(<span class="string">"WaitGroup"</span>).field(<span class="string">"count"</span>, count).finish() |
| } |
| } |
| </code></pre></div> |
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