| <!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>mio::unix::pipe::new - Rust</title><link rel="stylesheet" type="text/css" href="../../../normalize.css"><link rel="stylesheet" type="text/css" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../../light.css" id="themeStyle"><link rel="stylesheet" type="text/css" href="../../../dark.css" disabled ><link rel="stylesheet" type="text/css" href="../../../ayu.css" disabled ><script id="default-settings"></script><script src="../../../storage.js"></script><script src="../../../crates.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"> |
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| <a id="settings-menu" href="../../../settings.html"><img src="../../../wheel.svg" width="18" height="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class="fqn"><span class="in-band">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></span><span class="out-of-band"><span id="render-detail"><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span><a class="srclink" href="../../../src/mio/sys/unix/pipe.rs.html#147-204" title="goto source code">[src]</a></span></h1><pre class="rust fn">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="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a><a class="struct" href="../../../mio/unix/pipe/struct.Sender.html" title="struct mio::unix::pipe::Sender">Sender</a>, <a class="struct" href="../../../mio/unix/pipe/struct.Receiver.html" title="struct mio::unix::pipe::Receiver">Receiver</a><a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a>></pre><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> |
| <h1 id="events" class="section-header"><a href="#events">Events</a></h1> |
| <p>The <a href="../../../mio/unix/pipe/struct.Sender.html" title="Sender"><code>Sender</code></a> can be registered with <a href="../../../mio/struct.Interest.html#associatedconstant.WRITABLE"><code>WRITABLE</code></a> interest to receive |
| <a href="../../../mio/event/struct.Event.html#method.is_writable">writable events</a>, the <a href="../../../mio/unix/pipe/struct.Receiver.html" title="Receiver"><code>Receiver</code></a> with <a href="../../../mio/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="../../../mio/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="../../../mio/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="../../../mio/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> |
| <h1 id="deregistering" class="section-header"><a href="#deregistering">Deregistering</a></h1> |
| <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> |
| <h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1> |
| <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"> |
| <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>::{<span class="self">self</span>, <span class="ident">Read</span>, <span class="ident">Write</span>}; |
| |
| <span class="kw">use</span> <span class="ident">mio</span>::{<span class="ident">Poll</span>, <span class="ident">Events</span>, <span class="ident">Interest</span>, <span class="ident">Token</span>}; |
| <span class="kw">use</span> <span class="ident">mio</span>::<span class="ident">unix</span>::<span class="ident">pipe</span>; |
| |
| <span class="comment">// Unique tokens for the two ends of the channel.</span> |
| <span class="kw">const</span> <span class="ident">PIPE_RECV</span>: <span class="ident">Token</span> <span class="op">=</span> <span class="ident">Token</span>(<span class="number">0</span>); |
| <span class="kw">const</span> <span class="ident">PIPE_SEND</span>: <span class="ident">Token</span> <span class="op">=</span> <span class="ident">Token</span>(<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> <span class="ident">poll</span> <span class="op">=</span> <span class="ident">Poll</span>::<span class="ident">new</span>()<span class="question-mark">?</span>; |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">events</span> <span class="op">=</span> <span class="ident">Events</span>::<span class="ident">with_capacity</span>(<span class="number">8</span>); |
| |
| <span class="comment">// Create a new pipe.</span> |
| <span class="kw">let</span> (<span class="kw-2">mut</span> <span class="ident">sender</span>, <span class="kw-2">mut</span> <span class="ident">receiver</span>) <span class="op">=</span> <span class="ident">pipe</span>::<span class="ident">new</span>()<span class="question-mark">?</span>; |
| |
| <span class="comment">// Register both ends of the channel.</span> |
| <span class="ident">poll</span>.<span class="ident">registry</span>().<span class="ident">register</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">receiver</span>, <span class="ident">PIPE_RECV</span>, <span class="ident">Interest</span>::<span class="ident">READABLE</span>)<span class="question-mark">?</span>; |
| <span class="ident">poll</span>.<span class="ident">registry</span>().<span class="ident">register</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">sender</span>, <span class="ident">PIPE_SEND</span>, <span class="ident">Interest</span>::<span class="ident">WRITABLE</span>)<span class="question-mark">?</span>; |
| |
| <span class="kw">const</span> <span class="ident">MSG</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>; <span class="number">11</span>] <span class="op">=</span> <span class="string">b"Hello world"</span>; |
| |
| <span class="kw">loop</span> { |
| <span class="ident">poll</span>.<span class="ident">poll</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">events</span>, <span class="prelude-val">None</span>)<span class="question-mark">?</span>; |
| |
| <span class="kw">for</span> <span class="ident">event</span> <span class="kw">in</span> <span class="ident">events</span>.<span class="ident">iter</span>() { |
| <span class="kw">match</span> <span class="ident">event</span>.<span class="ident">token</span>() { |
| <span class="ident">PIPE_SEND</span> <span class="op">=</span><span class="op">></span> <span class="ident">sender</span>.<span class="ident">write</span>(<span class="ident">MSG</span>) |
| .<span class="ident">and_then</span>(<span class="op">|</span><span class="ident">n</span><span class="op">|</span> <span class="kw">if</span> <span class="ident">n</span> <span class="op">!</span><span class="op">=</span> <span class="ident">MSG</span>.<span class="ident">len</span>() { |
| <span class="comment">// We'll consider a short write an error in this</span> |
| <span class="comment">// example. NOTE: we can't use `write_all` with</span> |
| <span class="comment">// non-blocking I/O.</span> |
| <span class="prelude-val">Err</span>(<span class="ident">io</span>::<span class="ident">ErrorKind</span>::<span class="ident">WriteZero</span>.<span class="ident">into</span>()) |
| } <span class="kw">else</span> { |
| <span class="prelude-val">Ok</span>(()) |
| })<span class="question-mark">?</span>, |
| <span class="ident">PIPE_RECV</span> <span class="op">=</span><span class="op">></span> { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">buf</span> <span class="op">=</span> [<span class="number">0</span>; <span class="number">11</span>]; |
| <span class="kw">let</span> <span class="ident">n</span> <span class="op">=</span> <span class="ident">receiver</span>.<span class="ident">read</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">buf</span>)<span class="question-mark">?</span>; |
| <span class="macro">println</span><span class="macro">!</span>(<span class="string">"received: {:?}"</span>, <span class="kw-2">&</span><span class="ident">buf</span>[<span class="number">0</span>..<span class="ident">n</span>]); |
| <span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">n</span>, <span class="ident">MSG</span>.<span class="ident">len</span>()); |
| <span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">buf</span>, <span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">MSG</span>); |
| <span class="kw">return</span> <span class="prelude-val">Ok</span>(()); |
| }, |
| <span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="macro">unreachable</span><span class="macro">!</span>(), |
| } |
| } |
| }</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"> |
| <span class="comment">// Same setup as in the example above.</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">poll</span> <span class="op">=</span> <span class="ident">Poll</span>::<span class="ident">new</span>()<span class="question-mark">?</span>; |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">events</span> <span class="op">=</span> <span class="ident">Events</span>::<span class="ident">with_capacity</span>(<span class="number">8</span>); |
| |
| <span class="kw">let</span> (<span class="kw-2">mut</span> <span class="ident">sender</span>, <span class="kw-2">mut</span> <span class="ident">receiver</span>) <span class="op">=</span> <span class="ident">pipe</span>::<span class="ident">new</span>()<span class="question-mark">?</span>; |
| |
| <span class="ident">poll</span>.<span class="ident">registry</span>().<span class="ident">register</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">receiver</span>, <span class="ident">PIPE_RECV</span>, <span class="ident">Interest</span>::<span class="ident">READABLE</span>)<span class="question-mark">?</span>; |
| <span class="ident">poll</span>.<span class="ident">registry</span>().<span class="ident">register</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">sender</span>, <span class="ident">PIPE_SEND</span>, <span class="ident">Interest</span>::<span class="ident">WRITABLE</span>)<span class="question-mark">?</span>; |
| |
| <span class="comment">// Drop the sender.</span> |
| <span class="ident">drop</span>(<span class="ident">sender</span>); |
| |
| <span class="ident">poll</span>.<span class="ident">poll</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">events</span>, <span class="prelude-val">None</span>)<span class="question-mark">?</span>; |
| |
| <span class="kw">for</span> <span class="ident">event</span> <span class="kw">in</span> <span class="ident">events</span>.<span class="ident">iter</span>() { |
| <span class="kw">match</span> <span class="ident">event</span>.<span class="ident">token</span>() { |
| <span class="ident">PIPE_RECV</span> <span class="kw">if</span> <span class="ident">event</span>.<span class="ident">is_read_closed</span>() <span class="op">=</span><span class="op">></span> { |
| <span class="comment">// Detected that the sender was dropped.</span> |
| <span class="macro">println</span><span class="macro">!</span>(<span class="string">"Sender dropped!"</span>); |
| <span class="kw">return</span> <span class="prelude-val">Ok</span>(()); |
| }, |
| <span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="macro">unreachable</span><span class="macro">!</span>(), |
| } |
| }</pre></div> |
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