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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="Getting started guide."><title>mio::guide - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../static.files/rustdoc-ac92e1bbe349e143.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="mio" data-themes="" data-resource-suffix="" data-rustdoc-version="1.76.0 (07dca489a 2024-02-04)" data-channel="1.76.0" data-search-js="search-2b6ce74ff89ae146.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../../static.files/storage-f2adc0d6ca4d09fb.js"></script><script defer src="../sidebar-items.js"></script><script defer src="../../static.files/main-305769736d49e732.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-feafe1bb7466e4bd.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-2c020d218678b618.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></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../../mio/index.html">mio</a><span class="version">1.0.3</span></h2></div><h2 class="location"><a href="#">Module guide</a></h2><div class="sidebar-elems"><h2><a href="../index.html">In crate mio</a></h2></div></nav><div class="sidebar-resizer"></div>
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<main><div class="width-limiter"><nav class="sub"><form class="search-form"><span></span><div id="sidebar-button" tabindex="-1"><a href="../../mio/all.html" title="show sidebar"></a></div><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" tabindex="-1"><a href="../../help.html" title="help">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1>Module <a href="../index.html">mio</a>::<wbr><a class="mod" href="#">guide</a><button id="copy-path" title="Copy item path to clipboard"><img src="../../static.files/clipboard-7571035ce49a181d.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="src" href="../../src/mio/lib.rs.html#130">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>−</span>]</button></span></div><details class="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>
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<p>In this guide we’ll do the following:</p>
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<ol>
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<li>Create a <a href="../struct.Poll.html"><code>Poll</code></a> instance (and learn what it is).</li>
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<li>Register an <a href="../event/trait.Source.html">event source</a>.</li>
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<li>Create an event loop.</li>
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</ol>
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<p>At the end you’ll have a very small (but quick) TCP server that accepts
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connections and then drops (disconnects) them.</p>
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<h3 id="1-creating-a-poll-instance"><a href="#1-creating-a-poll-instance">1. Creating a <code>Poll</code> instance</a></h3>
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<p>Using Mio starts by creating a <a href="../struct.Poll.html"><code>Poll</code></a> instance, which monitors events
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from the OS and puts them into <a href="../event/struct.Events.html"><code>Events</code></a>. This allows us to execute I/O
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operations based on what operations are ready.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="comment">// `Poll` allows for polling of readiness events.
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</span><span class="kw">let </span>poll = Poll::new()<span class="question-mark">?</span>;
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<span class="comment">// `Events` is collection of readiness `Event`s and can be filled by
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// calling `Poll::poll`.
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</span><span class="kw">let </span>events = Events::with_capacity(<span class="number">128</span>);</code></pre></div>
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<p>For example if we’re using a <a href="../net/struct.TcpListener.html"><code>TcpListener</code></a>, we’ll only want to
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attempt to accept an incoming connection <em>iff</em> any connections are
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queued and ready to be accepted. We don’t want to waste our time if no
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connections are ready.</p>
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<h3 id="2-registering-event-source"><a href="#2-registering-event-source">2. Registering event source</a></h3>
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<p>After we’ve created a <a href="../struct.Poll.html"><code>Poll</code></a> instance that monitors events from the OS
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for us, we need to provide it with a source of events. This is done by
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registering an <a href="../event/trait.Source.html">event source</a>. As the name “event source” suggests it is
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a source of events which can be polled using a <code>Poll</code> instance. On Unix
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systems this is usually a file descriptor, or a socket/handle on
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Windows.</p>
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<p>In the example below we’ll use a <a href="../net/struct.TcpListener.html"><code>TcpListener</code></a> for which we’ll receive
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an event (from <a href="../struct.Poll.html"><code>Poll</code></a>) once a connection is ready to be accepted.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="comment">// Create a `TcpListener`, binding it to `address`.
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</span><span class="kw">let </span><span class="kw-2">mut </span>listener = TcpListener::bind(address)<span class="question-mark">?</span>;
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<span class="comment">// Next we register it with `Poll` to receive events for it. The `SERVER`
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// `Token` is used to determine that we received an event for the listener
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// later on.
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</span><span class="kw">const </span>SERVER: Token = Token(<span class="number">0</span>);
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poll.registry().register(<span class="kw-2">&mut </span>listener, SERVER, Interest::READABLE)<span class="question-mark">?</span>;</code></pre></div>
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<p>Multiple event sources can be <a href="../struct.Registry.html#method.register">registered</a> (concurrently), so we can
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monitor multiple sources at a time.</p>
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<h3 id="3-creating-the-event-loop"><a href="#3-creating-the-event-loop">3. Creating the event loop</a></h3>
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<p>After we’ve created a <a href="../struct.Poll.html"><code>Poll</code></a> instance and registered one or more
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<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
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is simple, we need a container to store the events: <a href="../event/struct.Events.html"><code>Events</code></a> and need
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to do something based on the polled events (this part is up to you, we
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can’t do it all!). If we do this in a loop we’ve got ourselves an event
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loop.</p>
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<p>The example below shows the event loop in action, completing our small
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TCP server.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="comment">// Start our event loop.
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</span><span class="kw">loop </span>{
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<span class="comment">// Poll the OS for events, waiting at most 100 milliseconds.
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</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>;
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<span class="comment">// Process each event.
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</span><span class="kw">for </span>event <span class="kw">in </span>events.iter() {
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<span class="comment">// We can use the token we previously provided to `register` to
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// determine for which type the event is.
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</span><span class="kw">match </span>event.token() {
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SERVER => <span class="kw">loop </span>{
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<span class="comment">// One or more connections are ready, so we'll attempt to
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// accept them (in a loop).
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</span><span class="kw">match </span>listener.accept() {
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<span class="prelude-val">Ok</span>((connection, address)) => {
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<span class="macro">println!</span>(<span class="string">"Got a connection from: {}"</span>, address);
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},
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<span class="comment">// A "would block error" is returned if the operation
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// is not ready, so we'll stop trying to accept
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// connections.
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</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>,
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<span class="prelude-val">Err</span>(err) => <span class="kw">return </span><span class="prelude-val">Err</span>(err),
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}
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}
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}
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}
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}
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<span class="kw">fn </span>would_block(err: <span class="kw-2">&</span>io::Error) -> bool {
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err.kind() == io::ErrorKind::WouldBlock
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}</code></pre></div>
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</div></details></section></div></main></body></html> |