| <!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="Polls for readiness events on all registered values."><meta name="keywords" content="rust, rustlang, rust-lang, Poll"><title>mio::Poll - 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">Struct <a href="index.html">mio</a>::<wbr><a class="struct" href="">Poll</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/poll.rs.html#204-206" title="goto source code">[src]</a></span></h1><div class="docblock type-decl hidden-by-usual-hider"><pre class="rust struct">pub struct Poll { /* fields omitted */ }</pre></div><div class="docblock"><p>Polls for readiness events on all registered values.</p> |
| <p><code>Poll</code> allows a program to monitor a large number of <a href="./event/trait.Source.html"><code>event::Source</code></a>s, |
| waiting until one or more become “ready” for some class of operations; e.g. |
| reading and writing. An event source is considered ready if it is possible |
| to immediately perform a corresponding operation; e.g. <a href="./net/struct.TcpStream.html#method.read"><code>read</code></a> or |
| <a href="./net/struct.TcpStream.html#method.write"><code>write</code></a>.</p> |
| <p>To use <code>Poll</code>, an <code>event::Source</code> must first be registered with the <code>Poll</code> |
| instance using the <a href="struct.Registry.html#method.register"><code>register</code></a> method on its associated <code>Register</code>, |
| supplying readiness interest. The readiness interest tells <code>Poll</code> which |
| specific operations on the handle to monitor for readiness. A <code>Token</code> is |
| also passed to the <a href="struct.Registry.html#method.register"><code>register</code></a> function. When <code>Poll</code> returns a readiness |
| event, it will include this token. This associates the event with the |
| event source that generated the event.</p> |
| <h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1> |
| <p>A basic example – establishing a <code>TcpStream</code> connection.</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"> |
| <span class="kw">use</span> <span class="ident">mio</span>::{<span class="ident">Events</span>, <span class="ident">Poll</span>, <span class="ident">Interest</span>, <span class="ident">Token</span>}; |
| <span class="kw">use</span> <span class="ident">mio</span>::<span class="ident">net</span>::<span class="ident">TcpStream</span>; |
| |
| <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">net</span>::{<span class="self">self</span>, <span class="ident">SocketAddr</span>}; |
| |
| <span class="comment">// Bind a server socket to connect to.</span> |
| <span class="kw">let</span> <span class="ident">addr</span>: <span class="ident">SocketAddr</span> <span class="op">=</span> <span class="string">"127.0.0.1:0"</span>.<span class="ident">parse</span>()<span class="question-mark">?</span>; |
| <span class="kw">let</span> <span class="ident">server</span> <span class="op">=</span> <span class="ident">net</span>::<span class="ident">TcpListener</span>::<span class="ident">bind</span>(<span class="ident">addr</span>)<span class="question-mark">?</span>; |
| |
| <span class="comment">// Construct a new `Poll` handle as well as the `Events` we'll store into</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">1024</span>); |
| |
| <span class="comment">// Connect the stream</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">stream</span> <span class="op">=</span> <span class="ident">TcpStream</span>::<span class="ident">connect</span>(<span class="ident">server</span>.<span class="ident">local_addr</span>()<span class="question-mark">?</span>)<span class="question-mark">?</span>; |
| |
| <span class="comment">// Register the stream with `Poll`</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">stream</span>, <span class="ident">Token</span>(<span class="number">0</span>), <span class="ident">Interest</span>::<span class="ident">READABLE</span> <span class="op">|</span> <span class="ident">Interest</span>::<span class="ident">WRITABLE</span>)<span class="question-mark">?</span>; |
| |
| <span class="comment">// Wait for the socket to become ready. This has to happens in a loop to</span> |
| <span class="comment">// handle spurious wakeups.</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="kw-2">&</span><span class="ident">events</span> { |
| <span class="kw">if</span> <span class="ident">event</span>.<span class="ident">token</span>() <span class="op">=</span><span class="op">=</span> <span class="ident">Token</span>(<span class="number">0</span>) <span class="op">&&</span> <span class="ident">event</span>.<span class="ident">is_writable</span>() { |
| <span class="comment">// The socket connected (probably, it could still be a spurious</span> |
| <span class="comment">// wakeup)</span> |
| <span class="kw">return</span> <span class="prelude-val">Ok</span>(()); |
| } |
| } |
| }</pre></div> |
| <h1 id="portability" class="section-header"><a href="#portability">Portability</a></h1> |
| <p>Using <code>Poll</code> provides a portable interface across supported platforms as |
| long as the caller takes the following into consideration:</p> |
| <h3 id="spurious-events" class="section-header"><a href="#spurious-events">Spurious events</a></h3> |
| <p><a href="struct.Poll.html#method.poll"><code>Poll::poll</code></a> may return readiness events even if the associated |
| event source is not actually ready. Given the same code, this may |
| happen more on some platforms than others. It is important to never assume |
| that, just because a readiness event was received, that the associated |
| operation will succeed as well.</p> |
| <p>If operation fails with <a href="https://doc.rust-lang.org/nightly/std/io/error/enum.ErrorKind.html#variant.WouldBlock"><code>WouldBlock</code></a>, then the caller should not treat |
| this as an error, but instead should wait until another readiness event is |
| received.</p> |
| <h3 id="draining-readiness" class="section-header"><a href="#draining-readiness">Draining readiness</a></h3> |
| <p>Once a readiness event is received, the corresponding operation must be |
| performed repeatedly until it returns <a href="https://doc.rust-lang.org/nightly/std/io/error/enum.ErrorKind.html#variant.WouldBlock"><code>WouldBlock</code></a>. Unless this is done, |
| there is no guarantee that another readiness event will be delivered, even |
| if further data is received for the event source.</p> |
| <h3 id="readiness-operations" class="section-header"><a href="#readiness-operations">Readiness operations</a></h3> |
| <p>The only readiness operations that are guaranteed to be present on all |
| supported platforms are <a href="./event/struct.Event.html#method.is_readable"><code>readable</code></a> and <a href="./event/struct.Event.html#method.is_writable"><code>writable</code></a>. All other readiness |
| operations may have false negatives and as such should be considered |
| <strong>hints</strong>. This means that if a socket is registered with <a href="./event/struct.Event.html#method.is_readable"><code>readable</code></a> |
| interest and either an error or close is received, a readiness event will |
| be generated for the socket, but it <strong>may</strong> only include <code>readable</code> |
| readiness. Also note that, given the potential for spurious events, |
| receiving a readiness event with <code>read_closed</code>, <code>write_closed</code>, or <code>error</code> |
| doesn’t actually mean that a <code>read</code> on the socket will return a result |
| matching the readiness event.</p> |
| <p>In other words, portable programs that explicitly check for <a href="./event/struct.Event.html#method.is_read_closed"><code>read_closed</code></a>, |
| <a href="./event/struct.Event.html#method.is_write_closed"><code>write_closed</code></a>, or <a href="./event/struct.Event.html#method.is_error"><code>error</code></a> readiness should be doing so as an |
| <strong>optimization</strong> and always be able to handle an error or close situation |
| when performing the actual read operation.</p> |
| <h3 id="registering-handles" class="section-header"><a href="#registering-handles">Registering handles</a></h3> |
| <p>Unless otherwise noted, it should be assumed that types implementing |
| <a href="./event/trait.Source.html"><code>event::Source</code></a> will never become ready unless they are registered with |
| <code>Poll</code>.</p> |
| <p>For example:</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"> |
| <span class="kw">use</span> <span class="ident">mio</span>::{<span class="ident">Poll</span>, <span class="ident">Interest</span>, <span class="ident">Token</span>}; |
| <span class="kw">use</span> <span class="ident">mio</span>::<span class="ident">net</span>::<span class="ident">TcpStream</span>; |
| <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">net</span>::<span class="ident">SocketAddr</span>; |
| <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">time</span>::<span class="ident">Duration</span>; |
| <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">thread</span>; |
| |
| <span class="kw">let</span> <span class="ident">address</span>: <span class="ident">SocketAddr</span> <span class="op">=</span> <span class="string">"127.0.0.1:0"</span>.<span class="ident">parse</span>()<span class="question-mark">?</span>; |
| <span class="kw">let</span> <span class="ident">listener</span> <span class="op">=</span> <span class="ident">net</span>::<span class="ident">TcpListener</span>::<span class="ident">bind</span>(<span class="ident">address</span>)<span class="question-mark">?</span>; |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">sock</span> <span class="op">=</span> <span class="ident">TcpStream</span>::<span class="ident">connect</span>(<span class="ident">listener</span>.<span class="ident">local_addr</span>()<span class="question-mark">?</span>)<span class="question-mark">?</span>; |
| |
| <span class="ident">thread</span>::<span class="ident">sleep</span>(<span class="ident">Duration</span>::<span class="ident">from_secs</span>(<span class="number">1</span>)); |
| |
| <span class="kw">let</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="comment">// The connect is not guaranteed to have started until it is registered at</span> |
| <span class="comment">// this point</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">sock</span>, <span class="ident">Token</span>(<span class="number">0</span>), <span class="ident">Interest</span>::<span class="ident">READABLE</span> <span class="op">|</span> <span class="ident">Interest</span>::<span class="ident">WRITABLE</span>)<span class="question-mark">?</span>;</pre></div> |
| <h3 id="dropping-poll" class="section-header"><a href="#dropping-poll">Dropping <code>Poll</code></a></h3> |
| <p>When the <code>Poll</code> instance is dropped it may cancel in-flight operations for |
| the registered <a href="./event/trait.Source.html">event sources</a>, meaning that no further events for them may |
| be received. It also means operations on the registered event sources may no |
| longer work. It is up to the user to keep the <code>Poll</code> instance alive while |
| registered event sources are being used.</p> |
| <h1 id="implementation-notes" class="section-header"><a href="#implementation-notes">Implementation notes</a></h1> |
| <p><code>Poll</code> is backed by the selector provided by the operating system.</p> |
| <table><thead><tr><th>OS</th><th>Selector</th></tr></thead><tbody> |
| <tr><td>Android</td><td><a href="http://man7.org/linux/man-pages/man7/epoll.7.html">epoll</a></td></tr> |
| <tr><td>DragonFly BSD</td><td><a href="https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2">kqueue</a></td></tr> |
| <tr><td>FreeBSD</td><td><a href="https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2">kqueue</a></td></tr> |
| <tr><td>Linux</td><td><a href="http://man7.org/linux/man-pages/man7/epoll.7.html">epoll</a></td></tr> |
| <tr><td>NetBSD</td><td><a href="https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2">kqueue</a></td></tr> |
| <tr><td>OpenBSD</td><td><a href="https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2">kqueue</a></td></tr> |
| <tr><td>Solaris</td><td><a href="http://man7.org/linux/man-pages/man7/epoll.7.html">epoll</a></td></tr> |
| <tr><td>illumos</td><td><a href="http://man7.org/linux/man-pages/man7/epoll.7.html">epoll</a></td></tr> |
| <tr><td>Windows</td><td><a href="https://msdn.microsoft.com/en-us/library/windows/desktop/aa365198(v=vs.85).aspx">IOCP</a></td></tr> |
| <tr><td>iOS</td><td><a href="https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2">kqueue</a></td></tr> |
| <tr><td>macOS</td><td><a href="https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2">kqueue</a></td></tr> |
| </tbody></table> |
| <p>On all supported platforms, socket operations are handled by using the |
| system selector. Platform specific extensions (e.g. <a href="unix/struct.SourceFd.html"><code>SourceFd</code></a>) allow |
| accessing other features provided by individual system selectors. For |
| example, Linux’s <a href="http://man7.org/linux/man-pages/man2/signalfd.2.html"><code>signalfd</code></a> feature can be used by registering the FD with |
| <code>Poll</code> via <a href="unix/struct.SourceFd.html"><code>SourceFd</code></a>.</p> |
| <p>On all platforms except windows, a call to <a href="struct.Poll.html#method.poll"><code>Poll::poll</code></a> is mostly just a |
| direct call to the system selector. However, <a href="https://msdn.microsoft.com/en-us/library/windows/desktop/aa365198(v=vs.85).aspx">IOCP</a> uses a completion model |
| instead of a readiness model. In this case, <code>Poll</code> must adapt the completion |
| model Mio’s API. While non-trivial, the bridge layer is still quite |
| efficient. The most expensive part being calls to <code>read</code> and <code>write</code> require |
| data to be copied into an intermediate buffer before it is passed to the |
| kernel.</p> |
| </div><h2 id="implementations" class="small-section-header">Implementations<a href="#implementations" class="anchor"></a></h2><h3 id="impl" class="impl"><code class="in-band">impl <a class="struct" href="../mio/struct.Poll.html" title="struct mio::Poll">Poll</a></code><a href="#impl" class="anchor"></a><a class="srclink" href="../src/mio/poll.rs.html#213-316" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.registry" class="method"><code>pub fn <a href="#method.registry" class="fnname">registry</a>(&self) -> &<a class="struct" href="../mio/struct.Registry.html" title="struct mio::Registry">Registry</a></code><a class="srclink" href="../src/mio/poll.rs.html#216-218" title="goto source code">[src]</a></h4><div class="docblock"><p>Create a separate <code>Registry</code> which can be used to register |
| <code>event::Source</code>s.</p> |
| </div><h4 id="method.poll" class="method"><code>pub fn <a href="#method.poll" class="fnname">poll</a>(<br> &mut self, <br> events: &mut <a class="struct" href="../mio/event/struct.Events.html" title="struct mio::event::Events">Events</a>, <br> timeout: <a class="enum" href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a><<a class="struct" href="https://doc.rust-lang.org/nightly/core/time/struct.Duration.html" title="struct core::time::Duration">Duration</a>><br>) -> <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.unit.html">()</a>></code><a class="srclink" href="../src/mio/poll.rs.html#313-315" title="goto source code">[src]</a></h4><div class="docblock"><p>Wait for readiness events</p> |
| <p>Blocks the current thread and waits for readiness events for any of the |
| <a href="./event/trait.Source.html"><code>event::Source</code></a>s that have been registered with this <code>Poll</code> instance. |
| The function will block until either at least one readiness event has |
| been received or <code>timeout</code> has elapsed. A <code>timeout</code> of <code>None</code> means that |
| <code>poll</code> will block until a readiness event has been received.</p> |
| <p>The supplied <code>events</code> will be cleared and newly received readiness events |
| will be pushed onto the end. At most <code>events.capacity()</code> events will be |
| returned. If there are further pending readiness events, they will be |
| returned on the next call to <code>poll</code>.</p> |
| <p>A single call to <code>poll</code> may result in multiple readiness events being |
| returned for a single event source. For example, if a TCP socket becomes |
| both readable and writable, it may be possible for a single readiness |
| event to be returned with both <a href="struct.Interest.html#associatedconstant.READABLE"><code>readable</code></a> and <a href="struct.Interest.html#associatedconstant.WRITABLE"><code>writable</code></a> readiness |
| <strong>OR</strong> two separate events may be returned, one with <a href="struct.Interest.html#associatedconstant.READABLE"><code>readable</code></a> set |
| and one with <a href="struct.Interest.html#associatedconstant.WRITABLE"><code>writable</code></a> set.</p> |
| <p>Note that the <code>timeout</code> will be rounded up to the system clock |
| granularity (usually 1ms), and kernel scheduling delays mean that |
| the blocking interval may be overrun by a small amount.</p> |
| <p>See the <a href="struct.Poll.html">struct</a> level documentation for a higher level discussion of |
| polling.</p> |
| <h1 id="notes" class="section-header"><a href="#notes">Notes</a></h1> |
| <p>This returns any errors without attempting to retry, previous versions |
| of Mio would automatically retry the poll call if it was interrupted |
| (if <code>EINTR</code> was returned).</p> |
| <h1 id="examples-1" class="section-header"><a href="#examples-1">Examples</a></h1> |
| <p>A basic example – establishing a <code>TcpStream</code> connection.</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"> |
| <span class="kw">use</span> <span class="ident">mio</span>::{<span class="ident">Events</span>, <span class="ident">Poll</span>, <span class="ident">Interest</span>, <span class="ident">Token</span>}; |
| <span class="kw">use</span> <span class="ident">mio</span>::<span class="ident">net</span>::<span class="ident">TcpStream</span>; |
| |
| <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">net</span>::{<span class="ident">TcpListener</span>, <span class="ident">SocketAddr</span>}; |
| <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">thread</span>; |
| |
| <span class="comment">// Bind a server socket to connect to.</span> |
| <span class="kw">let</span> <span class="ident">addr</span>: <span class="ident">SocketAddr</span> <span class="op">=</span> <span class="string">"127.0.0.1:0"</span>.<span class="ident">parse</span>()<span class="question-mark">?</span>; |
| <span class="kw">let</span> <span class="ident">server</span> <span class="op">=</span> <span class="ident">TcpListener</span>::<span class="ident">bind</span>(<span class="ident">addr</span>)<span class="question-mark">?</span>; |
| <span class="kw">let</span> <span class="ident">addr</span> <span class="op">=</span> <span class="ident">server</span>.<span class="ident">local_addr</span>()<span class="question-mark">?</span>.<span class="ident">clone</span>(); |
| |
| <span class="comment">// Spawn a thread to accept the socket</span> |
| <span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span> <span class="op">|</span><span class="op">|</span> { |
| <span class="kw">let</span> <span class="kw">_</span> <span class="op">=</span> <span class="ident">server</span>.<span class="ident">accept</span>(); |
| }); |
| |
| <span class="comment">// Construct a new `Poll` handle as well as the `Events` we'll store into</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">1024</span>); |
| |
| <span class="comment">// Connect the stream</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">stream</span> <span class="op">=</span> <span class="ident">TcpStream</span>::<span class="ident">connect</span>(<span class="ident">addr</span>)<span class="question-mark">?</span>; |
| |
| <span class="comment">// Register the stream with `Poll`</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">stream</span>, |
| <span class="ident">Token</span>(<span class="number">0</span>), |
| <span class="ident">Interest</span>::<span class="ident">READABLE</span> <span class="op">|</span> <span class="ident">Interest</span>::<span class="ident">WRITABLE</span>)<span class="question-mark">?</span>; |
| |
| <span class="comment">// Wait for the socket to become ready. This has to happens in a loop to</span> |
| <span class="comment">// handle spurious wakeups.</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="kw-2">&</span><span class="ident">events</span> { |
| <span class="kw">if</span> <span class="ident">event</span>.<span class="ident">token</span>() <span class="op">=</span><span class="op">=</span> <span class="ident">Token</span>(<span class="number">0</span>) <span class="op">&&</span> <span class="ident">event</span>.<span class="ident">is_writable</span>() { |
| <span class="comment">// The socket connected (probably, it could still be a spurious</span> |
| <span class="comment">// wakeup)</span> |
| <span class="kw">return</span> <span class="prelude-val">Ok</span>(()); |
| } |
| } |
| }</pre></div> |
| </div></div><h3 id="impl-1" class="impl"><code class="in-band">impl <a class="struct" href="../mio/struct.Poll.html" title="struct mio::Poll">Poll</a></code><a href="#impl-1" class="anchor"></a><a class="srclink" href="../src/mio/poll.rs.html#319-358" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.new" class="method"><code>pub fn <a href="#method.new" class="fnname">new</a>() -> <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="../mio/struct.Poll.html" title="struct mio::Poll">Poll</a>></code><a class="srclink" href="../src/mio/poll.rs.html#353-357" title="goto source code">[src]</a></h4><div class="docblock"><p>Return a new <code>Poll</code> handle.</p> |
| <p>This function will make a syscall to the operating system to create |
| the system selector. If this syscall fails, <code>Poll::new</code> will return |
| with the error.</p> |
| <p>See <a href="struct.Poll.html">struct</a> level docs for more details.</p> |
| <h1 id="examples-2" class="section-header"><a href="#examples-2">Examples</a></h1> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"> |
| <span class="kw">use</span> <span class="ident">mio</span>::{<span class="ident">Poll</span>, <span class="ident">Events</span>}; |
| <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">time</span>::<span class="ident">Duration</span>; |
| |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">poll</span> <span class="op">=</span> <span class="kw">match</span> <span class="ident">Poll</span>::<span class="ident">new</span>() { |
| <span class="prelude-val">Ok</span>(<span class="ident">poll</span>) <span class="op">=</span><span class="op">></span> <span class="ident">poll</span>, |
| <span class="prelude-val">Err</span>(<span class="ident">e</span>) <span class="op">=</span><span class="op">></span> <span class="macro">panic</span><span class="macro">!</span>(<span class="string">"failed to create Poll instance; err={:?}"</span>, <span class="ident">e</span>), |
| }; |
| |
| <span class="comment">// Create a structure to receive polled events</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">1024</span>); |
| |
| <span class="comment">// Wait for events, but none will be received because no</span> |
| <span class="comment">// `event::Source`s have been registered with this `Poll` instance.</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">Some</span>(<span class="ident">Duration</span>::<span class="ident">from_millis</span>(<span class="number">500</span>)))<span class="question-mark">?</span>; |
| <span class="macro">assert</span><span class="macro">!</span>(<span class="ident">events</span>.<span class="ident">is_empty</span>());</pre></div> |
| </div></div><h2 id="trait-implementations" class="small-section-header">Trait Implementations<a href="#trait-implementations" class="anchor"></a></h2><div id="trait-implementations-list"><h3 id="impl-AsRawFd" class="impl"><code class="in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/std/sys/unix/ext/io/trait.AsRawFd.html" title="trait std::sys::unix::ext::io::AsRawFd">AsRawFd</a> for <a class="struct" href="../mio/struct.Poll.html" title="struct mio::Poll">Poll</a></code><a href="#impl-AsRawFd" class="anchor"></a><a class="srclink" href="../src/mio/poll.rs.html#362-366" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.as_raw_fd" class="method hidden"><code>fn <a href="https://doc.rust-lang.org/nightly/std/sys/unix/ext/io/trait.AsRawFd.html#tymethod.as_raw_fd" class="fnname">as_raw_fd</a>(&self) -> <a class="type" href="https://doc.rust-lang.org/nightly/std/sys/unix/ext/io/type.RawFd.html" title="type std::sys::unix::ext::io::RawFd">RawFd</a></code><a class="srclink" href="../src/mio/poll.rs.html#363-365" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Extracts the raw file descriptor. <a href="https://doc.rust-lang.org/nightly/std/sys/unix/ext/io/trait.AsRawFd.html#tymethod.as_raw_fd">Read more</a></p> |
| </div></div><h3 id="impl-Debug" class="impl"><code class="in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a> for <a class="struct" href="../mio/struct.Poll.html" title="struct mio::Poll">Poll</a></code><a href="#impl-Debug" class="anchor"></a><a class="srclink" href="../src/mio/poll.rs.html#368-372" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.fmt" class="method hidden"><code>fn <a href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt" class="fnname">fmt</a>(&self, fmt: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/fmt/struct.Formatter.html" title="struct core::fmt::Formatter">Formatter</a><'_>) -> <a class="type" href="https://doc.rust-lang.org/nightly/core/fmt/type.Result.html" title="type core::fmt::Result">Result</a></code><a class="srclink" href="../src/mio/poll.rs.html#369-371" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Formats the value using the given formatter. <a href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt">Read more</a></p> |
| </div></div></div><h2 id="synthetic-implementations" class="small-section-header">Auto Trait Implementations<a href="#synthetic-implementations" class="anchor"></a></h2><div id="synthetic-implementations-list"><h3 id="impl-RefUnwindSafe" class="impl"><code class="in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/std/panic/trait.RefUnwindSafe.html" title="trait std::panic::RefUnwindSafe">RefUnwindSafe</a> for <a class="struct" href="../mio/struct.Poll.html" title="struct mio::Poll">Poll</a></code><a href="#impl-RefUnwindSafe" class="anchor"></a></h3><div class="impl-items"></div><h3 id="impl-Send" class="impl"><code class="in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a> for <a class="struct" href="../mio/struct.Poll.html" title="struct mio::Poll">Poll</a></code><a href="#impl-Send" class="anchor"></a></h3><div class="impl-items"></div><h3 id="impl-Sync" class="impl"><code class="in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sync.html" title="trait core::marker::Sync">Sync</a> for <a class="struct" href="../mio/struct.Poll.html" title="struct mio::Poll">Poll</a></code><a href="#impl-Sync" class="anchor"></a></h3><div class="impl-items"></div><h3 id="impl-Unpin" class="impl"><code class="in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> for <a class="struct" href="../mio/struct.Poll.html" title="struct mio::Poll">Poll</a></code><a href="#impl-Unpin" class="anchor"></a></h3><div class="impl-items"></div><h3 id="impl-UnwindSafe" class="impl"><code class="in-band">impl <a class="trait" href="https://doc.rust-lang.org/nightly/std/panic/trait.UnwindSafe.html" title="trait std::panic::UnwindSafe">UnwindSafe</a> for <a class="struct" href="../mio/struct.Poll.html" title="struct mio::Poll">Poll</a></code><a href="#impl-UnwindSafe" class="anchor"></a></h3><div class="impl-items"></div></div><h2 id="blanket-implementations" class="small-section-header">Blanket Implementations<a href="#blanket-implementations" class="anchor"></a></h2><div id="blanket-implementations-list"><h3 id="impl-Any" class="impl"><code class="in-band">impl<T> <a class="trait" href="https://doc.rust-lang.org/nightly/core/any/trait.Any.html" title="trait core::any::Any">Any</a> for T <span class="where fmt-newline">where<br> T: 'static + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, </span></code><a href="#impl-Any" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/any.rs.html#131-135" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.type_id" class="method hidden"><code>pub fn <a href="https://doc.rust-lang.org/nightly/core/any/trait.Any.html#tymethod.type_id" class="fnname">type_id</a>(&self) -> <a class="struct" href="https://doc.rust-lang.org/nightly/core/any/struct.TypeId.html" title="struct core::any::TypeId">TypeId</a></code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/any.rs.html#132" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Gets the <code>TypeId</code> of <code>self</code>. <a href="https://doc.rust-lang.org/nightly/core/any/trait.Any.html#tymethod.type_id">Read more</a></p> |
| </div></div><h3 id="impl-Borrow%3CT%3E" class="impl"><code class="in-band">impl<T> <a class="trait" href="https://doc.rust-lang.org/nightly/core/borrow/trait.Borrow.html" title="trait core::borrow::Borrow">Borrow</a><T> for T <span class="where fmt-newline">where<br> T: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, </span></code><a href="#impl-Borrow%3CT%3E" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#208-213" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.borrow" class="method hidden"><code>pub fn <a href="https://doc.rust-lang.org/nightly/core/borrow/trait.Borrow.html#tymethod.borrow" class="fnname">borrow</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&</a>T</code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#210" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Immutably borrows from an owned value. <a href="https://doc.rust-lang.org/nightly/core/borrow/trait.Borrow.html#tymethod.borrow">Read more</a></p> |
| </div></div><h3 id="impl-BorrowMut%3CT%3E" class="impl"><code class="in-band">impl<T> <a class="trait" href="https://doc.rust-lang.org/nightly/core/borrow/trait.BorrowMut.html" title="trait core::borrow::BorrowMut">BorrowMut</a><T> for T <span class="where fmt-newline">where<br> T: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, </span></code><a href="#impl-BorrowMut%3CT%3E" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#216-220" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.borrow_mut" class="method hidden"><code>pub fn <a href="https://doc.rust-lang.org/nightly/core/borrow/trait.BorrowMut.html#tymethod.borrow_mut" class="fnname">borrow_mut</a>(&mut self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>T</code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#217" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Mutably borrows from an owned value. <a href="https://doc.rust-lang.org/nightly/core/borrow/trait.BorrowMut.html#tymethod.borrow_mut">Read more</a></p> |
| </div></div><h3 id="impl-From%3CT%3E" class="impl"><code class="in-band">impl<T> <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.From.html" title="trait core::convert::From">From</a><T> for T</code><a href="#impl-From%3CT%3E" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#544-548" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.from" class="method hidden"><code>pub fn <a href="https://doc.rust-lang.org/nightly/core/convert/trait.From.html#tymethod.from" class="fnname">from</a>(t: T) -> T</code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#545" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Performs the conversion.</p> |
| </div></div><h3 id="impl-Into%3CU%3E" class="impl"><code class="in-band">impl<T, U> <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.Into.html" title="trait core::convert::Into">Into</a><U> for T <span class="where fmt-newline">where<br> U: <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.From.html" title="trait core::convert::From">From</a><T>, </span></code><a href="#impl-Into%3CU%3E" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#533-540" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="method.into" class="method hidden"><code>pub fn <a href="https://doc.rust-lang.org/nightly/core/convert/trait.Into.html#tymethod.into" class="fnname">into</a>(self) -> U</code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#537" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Performs the conversion.</p> |
| </div></div><h3 id="impl-TryFrom%3CU%3E" class="impl"><code class="in-band">impl<T, U> <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><U> for T <span class="where fmt-newline">where<br> U: <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.Into.html" title="trait core::convert::Into">Into</a><T>, </span></code><a href="#impl-TryFrom%3CU%3E" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#581-590" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="associatedtype.Error" class="type"><code>type <a href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error" class="type">Error</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/convert/enum.Infallible.html" title="enum core::convert::Infallible">Infallible</a></code></h4><div class='docblock'><p>The type returned in the event of a conversion error.</p> |
| </div><h4 id="method.try_from" class="method hidden"><code>pub fn <a href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#tymethod.try_from" class="fnname">try_from</a>(value: U) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, <T as <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><U>>::<a class="type" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error" title="type core::convert::TryFrom::Error">Error</a>></code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#587" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Performs the conversion.</p> |
| </div></div><h3 id="impl-TryInto%3CU%3E" class="impl"><code class="in-band">impl<T, U> <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryInto.html" title="trait core::convert::TryInto">TryInto</a><U> for T <span class="where fmt-newline">where<br> U: <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><T>, </span></code><a href="#impl-TryInto%3CU%3E" class="anchor"></a><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#567-576" title="goto source code">[src]</a></h3><div class="impl-items"><h4 id="associatedtype.Error-1" class="type"><code>type <a href="https://doc.rust-lang.org/nightly/core/convert/trait.TryInto.html#associatedtype.Error" class="type">Error</a> = <U as <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><T>>::<a class="type" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error" title="type core::convert::TryFrom::Error">Error</a></code></h4><div class='docblock'><p>The type returned in the event of a conversion error.</p> |
| </div><h4 id="method.try_into" class="method hidden"><code>pub fn <a href="https://doc.rust-lang.org/nightly/core/convert/trait.TryInto.html#tymethod.try_into" class="fnname">try_into</a>(self) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><U, <U as <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><T>>::<a class="type" href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error" title="type core::convert::TryFrom::Error">Error</a>></code><a class="srclink" href="https://doc.rust-lang.org/nightly/src/core/convert/mod.rs.html#573" title="goto source code">[src]</a></h4><div class='docblock hidden'><p>Performs the conversion.</p> |
| </div></div></div></section><section id="search" class="content hidden"></section><section class="footer"></section><div id="rustdoc-vars" data-root-path="../" data-current-crate="mio" data-search-js="../search-index.js"></div> |
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