| <!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="Create a new non-blocking Unix pipe."><meta name="keywords" content="rust, rustlang, rust-lang, new"><title>new in mio::unix::pipe - 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="sidebar-items.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 fn"><!--[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><div class="sidebar-elems"><h2><a href="index.html">In mio::unix::pipe</a></h2></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">Function <a href="../../index.html">mio</a>::<wbr><a href="../index.html">unix</a>::<wbr><a href="index.html">pipe</a>::<wbr><a class="fn" href="#">new</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/sys/unix/pipe.rs.html#147-213">source</a> · <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><div class="item-decl"><pre class="rust fn"><code>pub fn new() -> <a class="type" href="https://doc.rust-lang.org/nightly/std/io/error/type.Result.html" title="type std::io::error::Result">Result</a><(<a class="struct" href="struct.Sender.html" title="struct mio::unix::pipe::Sender">Sender</a>, <a class="struct" href="struct.Receiver.html" title="struct mio::unix::pipe::Receiver">Receiver</a>)></code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Create a new non-blocking Unix pipe.</p> |
| <p>This is a wrapper around Unix’s <a href="https://pubs.opengroup.org/onlinepubs/9699919799/functions/pipe.html"><code>pipe(2)</code></a> system call and can be used as |
| inter-process or thread communication channel.</p> |
| <p>This channel may be created before forking the process and then one end used |
| in each process, e.g. the parent process has the sending end to send command |
| to the child process.</p> |
| <h2 id="events"><a href="#events">Events</a></h2> |
| <p>The <a href="struct.Sender.html" title="Sender"><code>Sender</code></a> can be registered with <a href="../../struct.Interest.html#associatedconstant.WRITABLE"><code>WRITABLE</code></a> interest to receive |
| <a href="../../event/struct.Event.html#method.is_writable">writable events</a>, the <a href="struct.Receiver.html" title="Receiver"><code>Receiver</code></a> with <a href="../../struct.Interest.html#associatedconstant.READABLE"><code>READABLE</code></a> interest. Once data is |
| written to the <code>Sender</code> the <code>Receiver</code> will receive an <a href="../../event/struct.Event.html#method.is_readable">readable event</a>.</p> |
| <p>In addition to those events, events will also be generated if the other side |
| is dropped. To check if the <code>Sender</code> is dropped you’ll need to check |
| <a href="../../event/struct.Event.html#method.is_read_closed"><code>is_read_closed</code></a> on events for the <code>Receiver</code>, if it returns true the |
| <code>Sender</code> is dropped. On the <code>Sender</code> end check <a href="../../event/struct.Event.html#method.is_write_closed"><code>is_write_closed</code></a>, if it |
| returns true the <code>Receiver</code> was dropped. Also see the second example below.</p> |
| <h2 id="deregistering"><a href="#deregistering">Deregistering</a></h2> |
| <p>Both <code>Sender</code> and <code>Receiver</code> will deregister themselves when dropped, |
| <strong>iff</strong> the file descriptors are not duplicated (via <a href="https://pubs.opengroup.org/onlinepubs/9699919799/functions/dup.html"><code>dup(2)</code></a>).</p> |
| <h2 id="examples"><a href="#examples">Examples</a></h2> |
| <p>Simple example that writes data into the sending end and read it from the |
| receiving end.</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::io::{<span class="self">self</span>, Read, Write}; |
| |
| <span class="kw">use </span>mio::{Poll, Events, Interest, Token}; |
| <span class="kw">use </span>mio::unix::pipe; |
| |
| <span class="comment">// Unique tokens for the two ends of the channel. |
| </span><span class="kw">const </span>PIPE_RECV: Token = Token(<span class="number">0</span>); |
| <span class="kw">const </span>PIPE_SEND: Token = Token(<span class="number">1</span>); |
| |
| <span class="comment">// Create our `Poll` instance and the `Events` container. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>poll = Poll::new()<span class="question-mark">?</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>events = Events::with_capacity(<span class="number">8</span>); |
| |
| <span class="comment">// Create a new pipe. |
| </span><span class="kw">let </span>(<span class="kw-2">mut </span>sender, <span class="kw-2">mut </span>receiver) = pipe::new()<span class="question-mark">?</span>; |
| |
| <span class="comment">// Register both ends of the channel. |
| </span>poll.registry().register(<span class="kw-2">&mut </span>receiver, PIPE_RECV, Interest::READABLE)<span class="question-mark">?</span>; |
| poll.registry().register(<span class="kw-2">&mut </span>sender, PIPE_SEND, Interest::WRITABLE)<span class="question-mark">?</span>; |
| |
| <span class="kw">const </span>MSG: <span class="kw-2">&</span>[u8; <span class="number">11</span>] = <span class="string">b"Hello world"</span>; |
| |
| <span class="kw">loop </span>{ |
| poll.poll(<span class="kw-2">&mut </span>events, <span class="prelude-val">None</span>)<span class="question-mark">?</span>; |
| |
| <span class="kw">for </span>event <span class="kw">in </span>events.iter() { |
| <span class="kw">match </span>event.token() { |
| PIPE_SEND => sender.write(MSG) |
| .and_then(|n| <span class="kw">if </span>n != MSG.len() { |
| <span class="comment">// We'll consider a short write an error in this |
| // example. NOTE: we can't use `write_all` with |
| // non-blocking I/O. |
| </span><span class="prelude-val">Err</span>(io::ErrorKind::WriteZero.into()) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Ok</span>(()) |
| })<span class="question-mark">?</span>, |
| PIPE_RECV => { |
| <span class="kw">let </span><span class="kw-2">mut </span>buf = [<span class="number">0</span>; <span class="number">11</span>]; |
| <span class="kw">let </span>n = receiver.read(<span class="kw-2">&mut </span>buf)<span class="question-mark">?</span>; |
| <span class="macro">println!</span>(<span class="string">"received: {:?}"</span>, <span class="kw-2">&</span>buf[<span class="number">0</span>..n]); |
| <span class="macro">assert_eq!</span>(n, MSG.len()); |
| <span class="macro">assert_eq!</span>(<span class="kw-2">&</span>buf, <span class="kw-2">&*</span>MSG); |
| <span class="kw">return </span><span class="prelude-val">Ok</span>(()); |
| }, |
| <span class="kw">_ </span>=> <span class="macro">unreachable!</span>(), |
| } |
| } |
| }</code></pre></div> |
| <p>Example that receives an event once the <code>Sender</code> is dropped.</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="comment">// Same setup as in the example above. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>poll = Poll::new()<span class="question-mark">?</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>events = Events::with_capacity(<span class="number">8</span>); |
| |
| <span class="kw">let </span>(<span class="kw-2">mut </span>sender, <span class="kw-2">mut </span>receiver) = pipe::new()<span class="question-mark">?</span>; |
| |
| poll.registry().register(<span class="kw-2">&mut </span>receiver, PIPE_RECV, Interest::READABLE)<span class="question-mark">?</span>; |
| poll.registry().register(<span class="kw-2">&mut </span>sender, PIPE_SEND, Interest::WRITABLE)<span class="question-mark">?</span>; |
| |
| <span class="comment">// Drop the sender. |
| </span>drop(sender); |
| |
| poll.poll(<span class="kw-2">&mut </span>events, <span class="prelude-val">None</span>)<span class="question-mark">?</span>; |
| |
| <span class="kw">for </span>event <span class="kw">in </span>events.iter() { |
| <span class="kw">match </span>event.token() { |
| PIPE_RECV <span class="kw">if </span>event.is_read_closed() => { |
| <span class="comment">// Detected that the sender was dropped. |
| </span><span class="macro">println!</span>(<span class="string">"Sender dropped!"</span>); |
| <span class="kw">return </span><span class="prelude-val">Ok</span>(()); |
| }, |
| <span class="kw">_ </span>=> <span class="macro">unreachable!</span>(), |
| } |
| }</code></pre></div> |
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