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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="Requires a `Future` to complete before the specified duration has elapsed."><title>timeout in tokio::time - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../static.files/rustdoc-ca0dd0c4.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="tokio" data-themes="" data-resource-suffix="" data-rustdoc-version="1.93.1 (01f6ddf75 2026-02-11) (Arch Linux rust 1:1.93.1-1)" data-channel="1.93.1" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-a3946164.js" data-settings-js="settings-c38705f0.js" ><script src="../../static.files/storage-e2aeef58.js"></script><script defer src="sidebar-items.js"></script><script defer src="../../static.files/main-a410ff4d.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-263c88ec.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-eab170b8.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-044be391.svg"></head><body class="rustdoc fn"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><rustdoc-topbar><h2><a href="#">timeout</a></h2></rustdoc-topbar><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../../tokio/index.html">tokio</a><span class="version">1.49.0</span></h2></div><div class="sidebar-elems"><section id="rustdoc-toc"><h2 class="location"><a href="#">timeout</a></h2><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#cancellation" title="Cancellation">Cancellation</a></li><li><a href="#examples" title="Examples">Examples</a></li><li><a href="#panics" title="Panics">Panics</a></li></ul></section><div id="rustdoc-modnav"><h2><a href="index.html">In tokio::<wbr>time</a></h2></div></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><div class="width-limiter"><section id="main-content" class="content"><div class="main-heading"><div class="rustdoc-breadcrumbs"><a href="../index.html">tokio</a>::<wbr><a href="index.html">time</a></div><h1>Function <span class="fn">timeout</span> <button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"><a class="src" href="../../src/tokio/time/timeout.rs.html#86-98">Source</a> </span></div><pre class="rust item-decl"><code>pub fn timeout<F>(duration: <a class="struct" href="https://doc.rust-lang.org/1.93.1/core/time/struct.Duration.html" title="struct core::time::Duration">Duration</a>, future: F) -> <a class="struct" href="struct.Timeout.html" title="struct tokio::time::Timeout">Timeout</a><F::<a class="associatedtype" href="https://doc.rust-lang.org/1.93.1/core/future/into_future/trait.IntoFuture.html#associatedtype.IntoFuture" title="type core::future::into_future::IntoFuture::IntoFuture">IntoFuture</a>> <a href="#" class="tooltip" data-notable-ty="Timeout<F::IntoFuture>">ⓘ</a><div class="where">where
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F: <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/future/into_future/trait.IntoFuture.html" title="trait core::future::into_future::IntoFuture">IntoFuture</a>,</div></code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Requires a <code>Future</code> to complete before the specified duration has elapsed.</p>
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<p>If the future completes before the duration has elapsed, then the completed
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value is returned. Otherwise, an error is returned and the future is
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canceled.</p>
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<p>Note that the timeout is checked before polling the future, so if the future
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does not yield during execution then it is possible for the future to complete
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and exceed the timeout <em>without</em> returning an error.</p>
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<p>This function returns a future whose return type is <a href="https://doc.rust-lang.org/1.93.1/core/result/enum.Result.html" title="enum core::result::Result"><code>Result</code></a><code><T,</code><a href="error/struct.Elapsed.html" title="struct tokio::time::error::Elapsed"><code>Elapsed</code></a><code>></code>, where <code>T</code> is the
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return type of the provided future.</p>
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<p>If the provided future completes immediately, then the future returned from
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this function is guaranteed to complete immediately with an <a href="https://doc.rust-lang.org/1.93.1/core/result/enum.Result.html#variant.Ok" title="variant core::result::Result::Ok"><code>Ok</code></a> variant
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no matter the provided duration.</p>
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<h2 id="cancellation"><a class="doc-anchor" href="#cancellation">§</a>Cancellation</h2>
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<p>Cancelling a timeout is done by dropping the future. No additional cleanup
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or other work is required.</p>
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<p>The original future may be obtained by calling <a href="struct.Timeout.html#method.into_inner" title="method tokio::time::Timeout::into_inner"><code>Timeout::into_inner</code></a>. This
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consumes the <code>Timeout</code>.</p>
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<h2 id="examples"><a class="doc-anchor" href="#examples">§</a>Examples</h2>
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<p>Create a new <code>Timeout</code> set to expire in 10 milliseconds.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::time::timeout;
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<span class="kw">use </span>tokio::sync::oneshot;
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<span class="kw">use </span>std::time::Duration;
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<span class="kw">let </span>(tx, rx) = oneshot::channel();
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<span class="comment">// Wrap the future with a `Timeout` set to expire in 10 milliseconds.
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</span><span class="kw">if let </span><span class="prelude-val">Err</span>(<span class="kw">_</span>) = timeout(Duration::from_millis(<span class="number">10</span>), rx).<span class="kw">await </span>{
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<span class="macro">println!</span>(<span class="string">"did not receive value within 10 ms"</span>);
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}</code></pre></div><h2 id="panics"><a class="doc-anchor" href="#panics">§</a>Panics</h2>
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<p>This function panics if there is no current timer set.</p>
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<p>It can be triggered when <a href="../runtime/struct.Builder.html#method.enable_time" title="method tokio::runtime::Builder::enable_time"><code>Builder::enable_time</code></a> or
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<a href="../runtime/struct.Builder.html#method.enable_all" title="method tokio::runtime::Builder::enable_all"><code>Builder::enable_all</code></a> are not included in the builder.</p>
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<p>It can also panic whenever a timer is created outside of a
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Tokio runtime. That is why <code>rt.block_on(sleep(...))</code> will panic,
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since the function is executed outside of the runtime.
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Whereas <code>rt.block_on(async {sleep(...).await})</code> doesn’t panic.
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And this is because wrapping the function on an async makes it lazy,
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and so gets executed inside the runtime successfully without
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panicking.</p>
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</div></details><script type="text/json" id="notable-traits-data">{"Timeout<F::IntoFuture>":"<h3>Notable traits for <code><a class=\"struct\" href=\"struct.Timeout.html\" title=\"struct tokio::time::Timeout\">Timeout</a><T></code></h3><pre><code><div class=\"where\">impl<T> <a class=\"trait\" href=\"https://doc.rust-lang.org/1.93.1/core/future/future/trait.Future.html\" title=\"trait core::future::future::Future\">Future</a> for <a class=\"struct\" href=\"struct.Timeout.html\" title=\"struct tokio::time::Timeout\">Timeout</a><T><div class=\"where\">where\n T: <a class=\"trait\" href=\"https://doc.rust-lang.org/1.93.1/core/future/future/trait.Future.html\" title=\"trait core::future::future::Future\">Future</a>,</div></div><div class=\"where\"> type <a href=\"https://doc.rust-lang.org/1.93.1/core/future/future/trait.Future.html#associatedtype.Output\" class=\"associatedtype\">Output</a> = <a class=\"enum\" href=\"https://doc.rust-lang.org/1.93.1/core/result/enum.Result.html\" title=\"enum core::result::Result\">Result</a><T::<a class=\"associatedtype\" href=\"https://doc.rust-lang.org/1.93.1/core/future/future/trait.Future.html#associatedtype.Output\" title=\"type core::future::future::Future::Output\">Output</a>, <a class=\"struct\" href=\"error/struct.Elapsed.html\" title=\"struct tokio::time::error::Elapsed\">Elapsed</a>>;</div>"}</script></section></div></main></body></html> |