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20 lines
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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="Creates a value that is always at EOF for reads, and ignores all data written."><title>empty in tokio::io - 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="#">empty</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="#">empty</a></h2><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#examples" title="Examples">Examples</a></li></ul></section><div id="rustdoc-modnav"><h2><a href="index.html">In tokio::<wbr>io</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">io</a></div><h1>Function <span class="fn">empty</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/io/util/empty.rs.html#62-64">Source</a> </span></div><pre class="rust item-decl"><code>pub fn empty() -> <a class="struct" href="struct.Empty.html" title="struct tokio::io::Empty">Empty</a></code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Creates a value that is always at EOF for reads, and ignores all data written.</p>
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<p>All writes on the returned instance will return <code>Poll::Ready(Ok(buf.len()))</code>
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and the contents of the buffer will not be inspected.</p>
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<p>All reads from the returned instance will return <code>Poll::Ready(Ok(0))</code>.</p>
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<p>This is an asynchronous version of <a href="https://doc.rust-lang.org/1.93.1/std/io/util/fn.empty.html" title="fn std::io::util::empty"><code>std::io::empty</code></a>.</p>
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<h2 id="examples"><a class="doc-anchor" href="#examples">§</a>Examples</h2>
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<p>A slightly sad example of not reading anything into a buffer:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::io::{<span class="self">self</span>, AsyncReadExt};
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<span class="kw">let </span><span class="kw-2">mut </span>buffer = String::new();
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io::empty().read_to_string(<span class="kw-2">&mut </span>buffer).<span class="kw">await</span>.unwrap();
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<span class="macro">assert!</span>(buffer.is_empty());</code></pre></div>
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<p>A convoluted way of getting the length of a buffer:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::io::{<span class="self">self</span>, AsyncWriteExt};
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<span class="kw">let </span>buffer = <span class="macro">vec!</span>[<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">5</span>, <span class="number">8</span>];
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<span class="kw">let </span>num_bytes = io::empty().write(<span class="kw-2">&</span>buffer).<span class="kw">await</span>.unwrap();
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<span class="macro">assert_eq!</span>(num_bytes, <span class="number">5</span>);</code></pre></div></div></details></section></div></main></body></html> |