31 lines
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31 lines
5.7 KiB
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<!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="API documentation for the Rust `block_in_place` fn in crate `tokio`."><meta name="keywords" content="rust, rustlang, rust-lang, block_in_place"><title>tokio::task::block_in_place - Rust</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css" disabled ><link rel="stylesheet" type="text/css" href="../../ayu.css" disabled ><script id="default-settings"></script><script src="../../storage.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="icon" type="image/svg+xml" href="../../favicon.svg">
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<link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><style type="text/css">#crate-search{background-image:url("../../down-arrow.svg");}</style></head><body class="rustdoc fn"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../../tokio/index.html'><div class='logo-container rust-logo'><img src='../../rust-logo.png' alt='logo'></div></a><div class="sidebar-elems"><p class="location"><a href="../index.html">tokio</a>::<wbr><a href="index.html">task</a></p><script>window.sidebarCurrent = {name: "block_in_place", ty: "fn", relpath: ""};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!" aria-haspopup="menu"><img src="../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices" role="menu"></div></div><script src="../../theme.js"></script><nav class="sub"><form class="search-form"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" disabled autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><span class="help-button">?</span>
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<a id="settings-menu" href="../../settings.html"><img src="../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class="fqn"><span class="out-of-band"><span id="render-detail"><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span><a class="srclink" href="../../src/tokio/task/blocking.rs.html#46-51" title="goto source code">[src]</a></span><span class="in-band">Function <a href="../index.html">tokio</a>::<wbr><a href="index.html">task</a>::<wbr><a class="fn" href="">block_in_place</a></span></h1><pre class="rust fn">pub fn block_in_place<F, R>(f: F) -> R <span class="where fmt-newline">where<br> F: <a class="trait" href="https://doc.rust-lang.org/nightly/core/ops/function/trait.FnOnce.html" title="trait core::ops::function::FnOnce">FnOnce</a>() -> R, </span></pre><div class="docblock"><p>Runs the provided blocking function on the current thread without
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blocking the executor.</p>
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<p>In general, issuing a blocking call or performing a lot of compute in a
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future without yielding is not okay, as it may prevent the executor from
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driving other futures forward. This function runs the closure on the
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current thread by having the thread temporarily cease from being a core
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thread, and turns it into a blocking thread. See the <a href="../index.html#cpu-bound-tasks-and-blocking-code">CPU-bound tasks
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and blocking code</a> section for more information.</p>
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<p>Although this function avoids starving other independently spawned
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tasks, any other code running concurrently in the same task will be
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suspended during the call to <code>block_in_place</code>. This can happen e.g. when
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using the <a href="../../tokio/macro.join.html"><code>join!</code></a> macro. To avoid this issue, use <a href="../../tokio/task/fn.spawn_blocking.html"><code>spawn_blocking</code></a>
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instead.</p>
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<p>Note that this function can only be used when using the <code>multi_thread</code> runtime.</p>
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<p>Code running behind <code>block_in_place</code> cannot be cancelled. When you shut
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down the executor, it will wait indefinitely for all blocking operations
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to finish. You can use <a href="../../tokio/runtime/struct.Runtime.html#method.shutdown_timeout"><code>shutdown_timeout</code></a> to stop waiting for them
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after a certain timeout. Be aware that this will still not cancel the
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tasks — they are simply allowed to keep running after the method
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returns.</p>
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<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="kw">use</span> <span class="ident">tokio</span>::<span class="ident">task</span>;
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<span class="ident">task</span>::<span class="ident">block_in_place</span>(<span class="kw">move</span> <span class="op">|</span><span class="op">|</span> {
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<span class="comment">// do some compute-heavy work or call synchronous code</span>
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});</pre></div>
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</div></section><section id="search" class="content hidden"></section><section class="footer"></section><script>window.rootPath = "../../";window.currentCrate = "tokio";</script><script src="../../main.js"></script><script defer src="../../search-index.js"></script></body></html>
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