| <!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="Getting started guide."><meta name="keywords" content="rust, rustlang, rust-lang, guide"><title>mio::guide - Rust</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="../../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 mod"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">☰</button><a class="sidebar-logo" href="../../mio/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../../mio/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2 class="location"><a href="#">Module guide</a></h2><div class="sidebar-elems"></div></nav><main><div class="width-limiter"><nav class="sub"><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="main-heading"><h1 class="fqn">Module <a href="../index.html">mio</a>::<wbr><a class="mod" href="#">guide</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../../clipboard.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../../src/mio/lib.rs.html#122">source</a> · <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><h2 id="getting-started-guide"><a href="#getting-started-guide">Getting started guide.</a></h2> |
| <p>In this guide we’ll do the following:</p> |
| <ol> |
| <li>Create a <a href="../struct.Poll.html"><code>Poll</code></a> instance (and learn what it is).</li> |
| <li>Register an <a href="../event/trait.Source.html">event source</a>.</li> |
| <li>Create an event loop.</li> |
| </ol> |
| <p>At the end you’ll have a very small (but quick) TCP server that accepts |
| connections and then drops (disconnects) them.</p> |
| <h3 id="1-creating-a-poll-instance"><a href="#1-creating-a-poll-instance">1. Creating a <code>Poll</code> instance</a></h3> |
| <p>Using Mio starts by creating a <a href="../struct.Poll.html"><code>Poll</code></a> instance, which monitors events |
| from the OS and puts them into <a href="../event/struct.Events.html"><code>Events</code></a>. This allows us to execute I/O |
| operations based on what operations are ready.</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="comment">// `Poll` allows for polling of readiness events. |
| </span><span class="kw">let </span>poll = Poll::new()<span class="question-mark">?</span>; |
| <span class="comment">// `Events` is collection of readiness `Event`s and can be filled by |
| // calling `Poll::poll`. |
| </span><span class="kw">let </span>events = Events::with_capacity(<span class="number">128</span>);</code></pre></div> |
| <p>For example if we’re using a <a href="../net/struct.TcpListener.html"><code>TcpListener</code></a>, we’ll only want to |
| attempt to accept an incoming connection <em>iff</em> any connections are |
| queued and ready to be accepted. We don’t want to waste our time if no |
| connections are ready.</p> |
| <h3 id="2-registering-event-source"><a href="#2-registering-event-source">2. Registering event source</a></h3> |
| <p>After we’ve created a <a href="../struct.Poll.html"><code>Poll</code></a> instance that monitors events from the OS |
| for us, we need to provide it with a source of events. This is done by |
| registering an <a href="../event/trait.Source.html">event source</a>. As the name “event source” suggests it is |
| a source of events which can be polled using a <code>Poll</code> instance. On Unix |
| systems this is usually a file descriptor, or a socket/handle on |
| Windows.</p> |
| <p>In the example below we’ll use a <a href="../net/struct.TcpListener.html"><code>TcpListener</code></a> for which we’ll receive |
| an event (from <a href="../struct.Poll.html"><code>Poll</code></a>) once a connection is ready to be accepted.</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="comment">// Create a `TcpListener`, binding it to `address`. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>listener = TcpListener::bind(address)<span class="question-mark">?</span>; |
| |
| <span class="comment">// Next we register it with `Poll` to receive events for it. The `SERVER` |
| // `Token` is used to determine that we received an event for the listener |
| // later on. |
| </span><span class="kw">const </span>SERVER: Token = Token(<span class="number">0</span>); |
| poll.registry().register(<span class="kw-2">&mut </span>listener, SERVER, Interest::READABLE)<span class="question-mark">?</span>;</code></pre></div> |
| <p>Multiple event sources can be <a href="../struct.Registry.html#method.register">registered</a> (concurrently), so we can |
| monitor multiple sources at a time.</p> |
| <h3 id="3-creating-the-event-loop"><a href="#3-creating-the-event-loop">3. Creating the event loop</a></h3> |
| <p>After we’ve created a <a href="../struct.Poll.html"><code>Poll</code></a> instance and registered one or more |
| <a href="../event/trait.Source.html">event sources</a> with it, we can <a href="../struct.Poll.html#method.poll">poll</a> it for events. Polling for events |
| is simple, we need a container to store the events: <a href="../event/struct.Events.html"><code>Events</code></a> and need |
| to do something based on the polled events (this part is up to you, we |
| can’t do it all!). If we do this in a loop we’ve got ourselves an event |
| loop.</p> |
| <p>The example below shows the event loop in action, completing our small |
| TCP server.</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="comment">// Start our event loop. |
| </span><span class="kw">loop </span>{ |
| <span class="comment">// Poll the OS for events, waiting at most 100 milliseconds. |
| </span>poll.poll(<span class="kw-2">&mut </span>events, <span class="prelude-val">Some</span>(Duration::from_millis(<span class="number">100</span>)))<span class="question-mark">?</span>; |
| |
| <span class="comment">// Process each event. |
| </span><span class="kw">for </span>event <span class="kw">in </span>events.iter() { |
| <span class="comment">// We can use the token we previously provided to `register` to |
| // determine for which type the event is. |
| </span><span class="kw">match </span>event.token() { |
| SERVER => <span class="kw">loop </span>{ |
| <span class="comment">// One or more connections are ready, so we'll attempt to |
| // accept them (in a loop). |
| </span><span class="kw">match </span>listener.accept() { |
| <span class="prelude-val">Ok</span>((connection, address)) => { |
| <span class="macro">println!</span>(<span class="string">"Got a connection from: {}"</span>, address); |
| }, |
| <span class="comment">// A "would block error" is returned if the operation |
| // is not ready, so we'll stop trying to accept |
| // connections. |
| </span><span class="prelude-val">Err</span>(<span class="kw-2">ref </span>err) <span class="kw">if </span>would_block(err) => <span class="kw">break</span>, |
| <span class="prelude-val">Err</span>(err) => <span class="kw">return </span><span class="prelude-val">Err</span>(err), |
| } |
| } |
| } |
| } |
| } |
| |
| <span class="kw">fn </span>would_block(err: <span class="kw-2">&</span>io::Error) -> bool { |
| err.kind() == io::ErrorKind::WouldBlock |
| }</code></pre></div> |
| </div></details></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="mio" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
