| <!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-channel-0.5.8/src/utils.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>utils.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_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="../../crossbeam_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">//! Miscellaneous utilities. |
| |
| </span><span class="kw">use </span>std::cell::Cell; |
| <span class="kw">use </span>std::num::Wrapping; |
| <span class="kw">use </span>std::thread; |
| <span class="kw">use </span>std::time::{Duration, Instant}; |
| |
| <span class="doccomment">/// Randomly shuffles a slice. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>shuffle<T>(v: <span class="kw-2">&mut </span>[T]) { |
| <span class="kw">let </span>len = v.len(); |
| <span class="kw">if </span>len <= <span class="number">1 </span>{ |
| <span class="kw">return</span>; |
| } |
| |
| <span class="macro">thread_local! </span>{ |
| <span class="kw">static </span>RNG: Cell<Wrapping<u32>> = Cell::new(Wrapping(<span class="number">1_406_868_647</span>)); |
| } |
| |
| <span class="kw">let _ </span>= RNG.try_with(|rng| { |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">1</span>..len { |
| <span class="comment">// This is the 32-bit variant of Xorshift. |
| // |
| // Source: https://en.wikipedia.org/wiki/Xorshift |
| </span><span class="kw">let </span><span class="kw-2">mut </span>x = rng.get(); |
| x ^= x << <span class="number">13</span>; |
| x ^= x >> <span class="number">17</span>; |
| x ^= x << <span class="number">5</span>; |
| rng.set(x); |
| |
| <span class="kw">let </span>x = x.<span class="number">0</span>; |
| <span class="kw">let </span>n = i + <span class="number">1</span>; |
| |
| <span class="comment">// This is a fast alternative to `let j = x % n`. |
| // |
| // Author: Daniel Lemire |
| // Source: https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/ |
| </span><span class="kw">let </span>j = ((x <span class="kw">as </span>u64).wrapping_mul(n <span class="kw">as </span>u64) >> <span class="number">32</span>) <span class="kw">as </span>u32 <span class="kw">as </span>usize; |
| |
| v.swap(i, j); |
| } |
| }); |
| } |
| |
| <span class="doccomment">/// Sleeps until the deadline, or forever if the deadline isn't specified. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>sleep_until(deadline: <span class="prelude-ty">Option</span><Instant>) { |
| <span class="kw">loop </span>{ |
| <span class="kw">match </span>deadline { |
| <span class="prelude-val">None </span>=> thread::sleep(Duration::from_secs(<span class="number">1000</span>)), |
| <span class="prelude-val">Some</span>(d) => { |
| <span class="kw">let </span>now = Instant::now(); |
| <span class="kw">if </span>now >= d { |
| <span class="kw">break</span>; |
| } |
| thread::sleep(d - now); |
| } |
| } |
| } |
| } |
| </code></pre></div> |
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