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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="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/mio-0.8.8/src/poll.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>poll.rs - source</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="../../source-script.js"></script><script defer src="../../source-files.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 source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><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></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../mio/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><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="example-wrap"><pre class="src-line-numbers"><span id="1">1</span>
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</pre><pre class="rust"><code><span class="kw">use crate</span>::{event, sys, Events, Interest, Token};
<span class="attribute">#[cfg(unix)]
</span><span class="kw">use </span>std::os::unix::io::{AsRawFd, RawFd};
<span class="kw">use </span>std::time::Duration;
<span class="kw">use </span>std::{fmt, io};
<span class="doccomment">/// Polls for readiness events on all registered values.
///
/// `Poll` allows a program to monitor a large number of [`event::Source`]s,
/// waiting until one or more become &quot;ready&quot; 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. [`read`] or
/// [`write`].
///
/// To use `Poll`, an `event::Source` must first be registered with the `Poll`
/// instance using the [`register`] method on its associated `Register`,
/// supplying readiness interest. The readiness interest tells `Poll` which
/// specific operations on the handle to monitor for readiness. A `Token` is
/// also passed to the [`register`] function. When `Poll` returns a readiness
/// event, it will include this token. This associates the event with the
/// event source that generated the event.
///
/// [`event::Source`]: ./event/trait.Source.html
/// [`read`]: ./net/struct.TcpStream.html#method.read
/// [`write`]: ./net/struct.TcpStream.html#method.write
/// [`register`]: struct.Registry.html#method.register
///
/// # Examples
///
/// A basic example -- establishing a `TcpStream` connection.
///
</span><span class="attribute">#[cfg_attr(all(feature = <span class="string">&quot;os-poll&quot;</span>, feature = <span class="string">&quot;net&quot;</span>), doc = <span class="string">&quot;```&quot;</span>)]
#[cfg_attr(not(all(feature = <span class="string">&quot;os-poll&quot;</span>, feature = <span class="string">&quot;net&quot;</span>)), doc = <span class="string">&quot;```ignore&quot;</span>)]
</span><span class="doccomment">/// # use std::error::Error;
/// # fn main() -&gt; Result&lt;(), Box&lt;dyn Error&gt;&gt; {
/// use mio::{Events, Poll, Interest, Token};
/// use mio::net::TcpStream;
///
/// use std::net::{self, SocketAddr};
///
/// // Bind a server socket to connect to.
/// let addr: SocketAddr = &quot;127.0.0.1:0&quot;.parse()?;
/// let server = net::TcpListener::bind(addr)?;
///
/// // Construct a new `Poll` handle as well as the `Events` we&#39;ll store into
/// let mut poll = Poll::new()?;
/// let mut events = Events::with_capacity(1024);
///
/// // Connect the stream
/// let mut stream = TcpStream::connect(server.local_addr()?)?;
///
/// // Register the stream with `Poll`
/// poll.registry().register(&amp;mut stream, Token(0), Interest::READABLE | Interest::WRITABLE)?;
///
/// // Wait for the socket to become ready. This has to happens in a loop to
/// // handle spurious wakeups.
/// loop {
/// poll.poll(&amp;mut events, None)?;
///
/// for event in &amp;events {
/// if event.token() == Token(0) &amp;&amp; event.is_writable() {
/// // The socket connected (probably, it could still be a spurious
/// // wakeup)
/// return Ok(());
/// }
/// }
/// }
/// # }
/// ```
///
/// # Portability
///
/// Using `Poll` provides a portable interface across supported platforms as
/// long as the caller takes the following into consideration:
///
/// ### Spurious events
///
/// [`Poll::poll`] 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.
///
/// If operation fails with [`WouldBlock`], then the caller should not treat
/// this as an error, but instead should wait until another readiness event is
/// received.
///
/// ### Draining readiness
///
/// Once a readiness event is received, the corresponding operation must be
/// performed repeatedly until it returns [`WouldBlock`]. 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.
///
/// [`WouldBlock`]: std::io::ErrorKind::WouldBlock
///
/// ### Readiness operations
///
/// The only readiness operations that are guaranteed to be present on all
/// supported platforms are [`readable`] and [`writable`]. All other readiness
/// operations may have false negatives and as such should be considered
/// **hints**. This means that if a socket is registered with [`readable`]
/// interest and either an error or close is received, a readiness event will
/// be generated for the socket, but it **may** only include `readable`
/// readiness. Also note that, given the potential for spurious events,
/// receiving a readiness event with `read_closed`, `write_closed`, or `error`
/// doesn&#39;t actually mean that a `read` on the socket will return a result
/// matching the readiness event.
///
/// In other words, portable programs that explicitly check for [`read_closed`],
/// [`write_closed`], or [`error`] readiness should be doing so as an
/// **optimization** and always be able to handle an error or close situation
/// when performing the actual read operation.
///
/// [`readable`]: ./event/struct.Event.html#method.is_readable
/// [`writable`]: ./event/struct.Event.html#method.is_writable
/// [`error`]: ./event/struct.Event.html#method.is_error
/// [`read_closed`]: ./event/struct.Event.html#method.is_read_closed
/// [`write_closed`]: ./event/struct.Event.html#method.is_write_closed
///
/// ### Registering handles
///
/// Unless otherwise noted, it should be assumed that types implementing
/// [`event::Source`] will never become ready unless they are registered with
/// `Poll`.
///
/// For example:
///
</span><span class="attribute">#[cfg_attr(all(feature = <span class="string">&quot;os-poll&quot;</span>, feature = <span class="string">&quot;net&quot;</span>), doc = <span class="string">&quot;```&quot;</span>)]
#[cfg_attr(not(all(feature = <span class="string">&quot;os-poll&quot;</span>, feature = <span class="string">&quot;net&quot;</span>)), doc = <span class="string">&quot;```ignore&quot;</span>)]
</span><span class="doccomment">/// # use std::error::Error;
/// # use std::net;
/// # fn main() -&gt; Result&lt;(), Box&lt;dyn Error&gt;&gt; {
/// use mio::{Poll, Interest, Token};
/// use mio::net::TcpStream;
/// use std::net::SocketAddr;
/// use std::time::Duration;
/// use std::thread;
///
/// let address: SocketAddr = &quot;127.0.0.1:0&quot;.parse()?;
/// let listener = net::TcpListener::bind(address)?;
/// let mut sock = TcpStream::connect(listener.local_addr()?)?;
///
/// thread::sleep(Duration::from_secs(1));
///
/// let poll = Poll::new()?;
///
/// // The connect is not guaranteed to have started until it is registered at
/// // this point
/// poll.registry().register(&amp;mut sock, Token(0), Interest::READABLE | Interest::WRITABLE)?;
/// # Ok(())
/// # }
/// ```
///
/// ### Dropping `Poll`
///
/// When the `Poll` instance is dropped it may cancel in-flight operations for
/// the registered [event sources], 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 `Poll` instance alive while
/// registered event sources are being used.
///
/// [event sources]: ./event/trait.Source.html
///
/// ### Accessing raw fd/socket/handle
///
/// Mio makes it possible for many types to be converted into a raw file
/// descriptor (fd, Unix), socket (Windows) or handle (Windows). This makes it
/// possible to support more operations on the type than Mio supports, for
/// example it makes [mio-aio] possible. However accessing the raw fd is not
/// without it&#39;s pitfalls.
///
/// Specifically performing I/O operations outside of Mio on these types (via
/// the raw fd) has unspecified behaviour. It could cause no more events to be
/// generated for the type even though it returned `WouldBlock` (in an operation
/// directly accessing the fd). The behaviour is OS specific and Mio can only
/// guarantee cross-platform behaviour if it can control the I/O.
///
/// [mio-aio]: https://github.com/asomers/mio-aio
///
/// *The following is **not** guaranteed, just a description of the current
/// situation!* Mio is allowed to change the following without it being considered
/// a breaking change, don&#39;t depend on this, it&#39;s just here to inform the user.
/// Currently the kqueue and epoll implementation support direct I/O operations
/// on the fd without Mio&#39;s knowledge. Windows however needs **all** I/O
/// operations to go through Mio otherwise it is not able to update it&#39;s
/// internal state properly and won&#39;t generate events.
///
/// ### Polling without registering event sources
///
///
/// *The following is **not** guaranteed, just a description of the current
/// situation!* Mio is allowed to change the following without it being
/// considered a breaking change, don&#39;t depend on this, it&#39;s just here to inform
/// the user. On platforms that use epoll, kqueue or IOCP (see implementation
/// notes below) polling without previously registering [event sources] will
/// result in sleeping forever, only a process signal will be able to wake up
/// the thread.
///
/// On WASM/WASI this is different as it doesn&#39;t support process signals,
/// furthermore the WASI specification doesn&#39;t specify a behaviour in this
/// situation, thus it&#39;s up to the implementation what to do here. As an
/// example, the wasmtime runtime will return `EINVAL` in this situation, but
/// different runtimes may return different results. If you have further
/// insights or thoughts about this situation (and/or how Mio should handle it)
/// please add you comment to [pull request#1580].
///
/// [event sources]: crate::event::Source
/// [pull request#1580]: https://github.com/tokio-rs/mio/pull/1580
///
/// # Implementation notes
///
/// `Poll` is backed by the selector provided by the operating system.
///
/// | OS | Selector |
/// |---------------|-----------|
/// | Android | [epoll] |
/// | DragonFly BSD | [kqueue] |
/// | FreeBSD | [kqueue] |
/// | iOS | [kqueue] |
/// | illumos | [epoll] |
/// | Linux | [epoll] |
/// | NetBSD | [kqueue] |
/// | OpenBSD | [kqueue] |
/// | Windows | [IOCP] |
/// | macOS | [kqueue] |
///
/// On all supported platforms, socket operations are handled by using the
/// system selector. Platform specific extensions (e.g. [`SourceFd`]) allow
/// accessing other features provided by individual system selectors. For
/// example, Linux&#39;s [`signalfd`] feature can be used by registering the FD with
/// `Poll` via [`SourceFd`].
///
/// On all platforms except windows, a call to [`Poll::poll`] is mostly just a
/// direct call to the system selector. However, [IOCP] uses a completion model
/// instead of a readiness model. In this case, `Poll` must adapt the completion
/// model Mio&#39;s API. While non-trivial, the bridge layer is still quite
/// efficient. The most expensive part being calls to `read` and `write` require
/// data to be copied into an intermediate buffer before it is passed to the
/// kernel.
///
/// [epoll]: https://man7.org/linux/man-pages/man7/epoll.7.html
/// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&amp;sektion=2
/// [IOCP]: https://docs.microsoft.com/en-us/windows/win32/fileio/i-o-completion-ports
/// [`signalfd`]: https://man7.org/linux/man-pages/man2/signalfd.2.html
/// [`SourceFd`]: unix/struct.SourceFd.html
/// [`Poll::poll`]: struct.Poll.html#method.poll
</span><span class="kw">pub struct </span>Poll {
registry: Registry,
}
<span class="doccomment">/// Registers I/O resources.
</span><span class="kw">pub struct </span>Registry {
selector: sys::Selector,
}
<span class="kw">impl </span>Poll {
<span class="macro">cfg_os_poll! </span>{
<span class="doccomment">/// Return a new `Poll` handle.
///
/// This function will make a syscall to the operating system to create
/// the system selector. If this syscall fails, `Poll::new` will return
/// with the error.
///
/// close-on-exec flag is set on the file descriptors used by the selector to prevent
/// leaking it to executed processes. However, on some systems such as
/// old Linux systems that don&#39;t support `epoll_create1` syscall it is done
/// non-atomically, so a separate thread executing in parallel to this
/// function may accidentally leak the file descriptor if it executes a
/// new process before this function returns.
///
/// See [struct] level docs for more details.
///
/// [struct]: struct.Poll.html
///
/// # Examples
///
/// ```
/// # use std::error::Error;
/// # fn main() -&gt; Result&lt;(), Box&lt;dyn Error&gt;&gt; {
/// use mio::{Poll, Events};
/// use std::time::Duration;
///
/// let mut poll = match Poll::new() {
/// Ok(poll) =&gt; poll,
/// Err(e) =&gt; panic!(&quot;failed to create Poll instance; err={:?}&quot;, e),
/// };
///
/// // Create a structure to receive polled events
/// let mut events = Events::with_capacity(1024);
///
/// // Wait for events, but none will be received because no
/// // `event::Source`s have been registered with this `Poll` instance.
/// poll.poll(&amp;mut events, Some(Duration::from_millis(500)))?;
/// assert!(events.is_empty());
/// # Ok(())
/// # }
/// ```
</span><span class="kw">pub fn </span>new() -&gt; io::Result&lt;Poll&gt; {
sys::Selector::new().map(|selector| Poll {
registry: Registry { selector },
})
}
}
<span class="doccomment">/// Create a separate `Registry` which can be used to register
/// `event::Source`s.
</span><span class="kw">pub fn </span>registry(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>Registry {
<span class="kw-2">&amp;</span><span class="self">self</span>.registry
}
<span class="doccomment">/// Wait for readiness events
///
/// Blocks the current thread and waits for readiness events for any of the
/// [`event::Source`]s that have been registered with this `Poll` instance.
/// The function will block until either at least one readiness event has
/// been received or `timeout` has elapsed. A `timeout` of `None` means that
/// `poll` will block until a readiness event has been received.
///
/// The supplied `events` will be cleared and newly received readiness events
/// will be pushed onto the end. At most `events.capacity()` events will be
/// returned. If there are further pending readiness events, they will be
/// returned on the next call to `poll`.
///
/// A single call to `poll` 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 [`readable`] and [`writable`] readiness
/// **OR** two separate events may be returned, one with [`readable`] set
/// and one with [`writable`] set.
///
/// Note that the `timeout` 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.
///
/// See the [struct] level documentation for a higher level discussion of
/// polling.
///
/// [`event::Source`]: ./event/trait.Source.html
/// [`readable`]: struct.Interest.html#associatedconstant.READABLE
/// [`writable`]: struct.Interest.html#associatedconstant.WRITABLE
/// [struct]: struct.Poll.html
/// [`iter`]: ./event/struct.Events.html#method.iter
///
/// # Notes
///
/// This returns any errors without attempting to retry, previous versions
/// of Mio would automatically retry the poll call if it was interrupted
/// (if `EINTR` was returned).
///
/// Currently if the `timeout` elapses without any readiness events
/// triggering this will return `Ok(())`. However we&#39;re not guaranteeing
/// this behaviour as this depends on the OS.
///
/// # Examples
///
/// A basic example -- establishing a `TcpStream` connection.
///
</span><span class="attribute">#[cfg_attr(all(feature = <span class="string">&quot;os-poll&quot;</span>, feature = <span class="string">&quot;net&quot;</span>), doc = <span class="string">&quot;```&quot;</span>)]
#[cfg_attr(not(all(feature = <span class="string">&quot;os-poll&quot;</span>, feature = <span class="string">&quot;net&quot;</span>)), doc = <span class="string">&quot;```ignore&quot;</span>)]
</span><span class="doccomment">/// # use std::error::Error;
/// # fn main() -&gt; Result&lt;(), Box&lt;dyn Error&gt;&gt; {
/// use mio::{Events, Poll, Interest, Token};
/// use mio::net::TcpStream;
///
/// use std::net::{TcpListener, SocketAddr};
/// use std::thread;
///
/// // Bind a server socket to connect to.
/// let addr: SocketAddr = &quot;127.0.0.1:0&quot;.parse()?;
/// let server = TcpListener::bind(addr)?;
/// let addr = server.local_addr()?.clone();
///
/// // Spawn a thread to accept the socket
/// thread::spawn(move || {
/// let _ = server.accept();
/// });
///
/// // Construct a new `Poll` handle as well as the `Events` we&#39;ll store into
/// let mut poll = Poll::new()?;
/// let mut events = Events::with_capacity(1024);
///
/// // Connect the stream
/// let mut stream = TcpStream::connect(addr)?;
///
/// // Register the stream with `Poll`
/// poll.registry().register(
/// &amp;mut stream,
/// Token(0),
/// Interest::READABLE | Interest::WRITABLE)?;
///
/// // Wait for the socket to become ready. This has to happens in a loop to
/// // handle spurious wakeups.
/// loop {
/// poll.poll(&amp;mut events, None)?;
///
/// for event in &amp;events {
/// if event.token() == Token(0) &amp;&amp; event.is_writable() {
/// // The socket connected (probably, it could still be a spurious
/// // wakeup)
/// return Ok(());
/// }
/// }
/// }
/// # }
/// ```
///
/// [struct]: #
</span><span class="kw">pub fn </span>poll(<span class="kw-2">&amp;mut </span><span class="self">self</span>, events: <span class="kw-2">&amp;mut </span>Events, timeout: <span class="prelude-ty">Option</span>&lt;Duration&gt;) -&gt; io::Result&lt;()&gt; {
<span class="self">self</span>.registry.selector.select(events.sys(), timeout)
}
}
<span class="attribute">#[cfg(unix)]
</span><span class="kw">impl </span>AsRawFd <span class="kw">for </span>Poll {
<span class="kw">fn </span>as_raw_fd(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; RawFd {
<span class="self">self</span>.registry.as_raw_fd()
}
}
<span class="kw">impl </span>fmt::Debug <span class="kw">for </span>Poll {
<span class="kw">fn </span>fmt(<span class="kw-2">&amp;</span><span class="self">self</span>, fmt: <span class="kw-2">&amp;mut </span>fmt::Formatter&lt;<span class="lifetime">&#39;_</span>&gt;) -&gt; fmt::Result {
fmt.debug_struct(<span class="string">&quot;Poll&quot;</span>).finish()
}
}
<span class="kw">impl </span>Registry {
<span class="doccomment">/// Register an [`event::Source`] with the `Poll` instance.
///
/// Once registered, the `Poll` instance will monitor the event source for
/// readiness state changes. When it notices a state change, it will return
/// a readiness event for the handle the next time [`poll`] is called.
///
/// See [`Poll`] docs for a high level overview.
///
/// # Arguments
///
/// `source: &amp;mut S: event::Source`: This is the source of events that the
/// `Poll` instance should monitor for readiness state changes.
///
/// `token: Token`: The caller picks a token to associate with the socket.
/// When [`poll`] returns an event for the handle, this token is included.
/// This allows the caller to map the event to its source. The token
/// associated with the `event::Source` can be changed at any time by
/// calling [`reregister`].
///
/// See documentation on [`Token`] for an example showing how to pick
/// [`Token`] values.
///
/// `interest: Interest`: Specifies which operations `Poll` should monitor
/// for readiness. `Poll` will only return readiness events for operations
/// specified by this argument.
///
/// If a socket is registered with readable interest and the socket becomes
/// writable, no event will be returned from [`poll`].
///
/// The readiness interest for an `event::Source` can be changed at any time
/// by calling [`reregister`].
///
/// # Notes
///
/// Callers must ensure that if a source being registered with a `Poll`
/// instance was previously registered with that `Poll` instance, then a
/// call to [`deregister`] has already occurred. Consecutive calls to
/// `register` is unspecified behavior.
///
/// Unless otherwise specified, the caller should assume that once an event
/// source is registered with a `Poll` instance, it is bound to that `Poll`
/// instance for the lifetime of the event source. This remains true even
/// if the event source is deregistered from the poll instance using
/// [`deregister`].
///
/// [`event::Source`]: ./event/trait.Source.html
/// [`poll`]: struct.Poll.html#method.poll
/// [`reregister`]: struct.Registry.html#method.reregister
/// [`deregister`]: struct.Registry.html#method.deregister
/// [`Token`]: struct.Token.html
///
/// # Examples
///
</span><span class="attribute">#[cfg_attr(all(feature = <span class="string">&quot;os-poll&quot;</span>, feature = <span class="string">&quot;net&quot;</span>), doc = <span class="string">&quot;```&quot;</span>)]
#[cfg_attr(not(all(feature = <span class="string">&quot;os-poll&quot;</span>, feature = <span class="string">&quot;net&quot;</span>)), doc = <span class="string">&quot;```ignore&quot;</span>)]
</span><span class="doccomment">/// # use std::error::Error;
/// # use std::net;
/// # fn main() -&gt; Result&lt;(), Box&lt;dyn Error&gt;&gt; {
/// use mio::{Events, Poll, Interest, Token};
/// use mio::net::TcpStream;
/// use std::net::SocketAddr;
/// use std::time::{Duration, Instant};
///
/// let mut poll = Poll::new()?;
///
/// let address: SocketAddr = &quot;127.0.0.1:0&quot;.parse()?;
/// let listener = net::TcpListener::bind(address)?;
/// let mut socket = TcpStream::connect(listener.local_addr()?)?;
///
/// // Register the socket with `poll`
/// poll.registry().register(
/// &amp;mut socket,
/// Token(0),
/// Interest::READABLE | Interest::WRITABLE)?;
///
/// let mut events = Events::with_capacity(1024);
/// let start = Instant::now();
/// let timeout = Duration::from_millis(500);
///
/// loop {
/// let elapsed = start.elapsed();
///
/// if elapsed &gt;= timeout {
/// // Connection timed out
/// return Ok(());
/// }
///
/// let remaining = timeout - elapsed;
/// poll.poll(&amp;mut events, Some(remaining))?;
///
/// for event in &amp;events {
/// if event.token() == Token(0) {
/// // Something (probably) happened on the socket.
/// return Ok(());
/// }
/// }
/// }
/// # }
/// ```
</span><span class="kw">pub fn </span>register&lt;S&gt;(<span class="kw-2">&amp;</span><span class="self">self</span>, source: <span class="kw-2">&amp;mut </span>S, token: Token, interests: Interest) -&gt; io::Result&lt;()&gt;
<span class="kw">where
</span>S: event::Source + <span class="question-mark">?</span>Sized,
{
<span class="macro">trace!</span>(
<span class="string">&quot;registering event source with poller: token={:?}, interests={:?}&quot;</span>,
token,
interests
);
source.register(<span class="self">self</span>, token, interests)
}
<span class="doccomment">/// Re-register an [`event::Source`] with the `Poll` instance.
///
/// Re-registering an event source allows changing the details of the
/// registration. Specifically, it allows updating the associated `token`
/// and `interests` specified in previous `register` and `reregister` calls.
///
/// The `reregister` arguments fully override the previous values. In other
/// words, if a socket is registered with [`readable`] interest and the call
/// to `reregister` specifies [`writable`], then read interest is no longer
/// requested for the handle.
///
/// The event source must have previously been registered with this instance
/// of `Poll`, otherwise the behavior is unspecified.
///
/// See the [`register`] documentation for details about the function
/// arguments and see the [`struct`] docs for a high level overview of
/// polling.
///
/// # Examples
///
</span><span class="attribute">#[cfg_attr(all(feature = <span class="string">&quot;os-poll&quot;</span>, feature = <span class="string">&quot;net&quot;</span>), doc = <span class="string">&quot;```&quot;</span>)]
#[cfg_attr(not(all(feature = <span class="string">&quot;os-poll&quot;</span>, feature = <span class="string">&quot;net&quot;</span>)), doc = <span class="string">&quot;```ignore&quot;</span>)]
</span><span class="doccomment">/// # use std::error::Error;
/// # use std::net;
/// # fn main() -&gt; Result&lt;(), Box&lt;dyn Error&gt;&gt; {
/// use mio::{Poll, Interest, Token};
/// use mio::net::TcpStream;
/// use std::net::SocketAddr;
///
/// let poll = Poll::new()?;
///
/// let address: SocketAddr = &quot;127.0.0.1:0&quot;.parse()?;
/// let listener = net::TcpListener::bind(address)?;
/// let mut socket = TcpStream::connect(listener.local_addr()?)?;
///
/// // Register the socket with `poll`, requesting readable
/// poll.registry().register(
/// &amp;mut socket,
/// Token(0),
/// Interest::READABLE)?;
///
/// // Reregister the socket specifying write interest instead. Even though
/// // the token is the same it must be specified.
/// poll.registry().reregister(
/// &amp;mut socket,
/// Token(0),
/// Interest::WRITABLE)?;
/// # Ok(())
/// # }
/// ```
///
/// [`event::Source`]: ./event/trait.Source.html
/// [`struct`]: struct.Poll.html
/// [`register`]: struct.Registry.html#method.register
/// [`readable`]: ./event/struct.Event.html#is_readable
/// [`writable`]: ./event/struct.Event.html#is_writable
</span><span class="kw">pub fn </span>reregister&lt;S&gt;(<span class="kw-2">&amp;</span><span class="self">self</span>, source: <span class="kw-2">&amp;mut </span>S, token: Token, interests: Interest) -&gt; io::Result&lt;()&gt;
<span class="kw">where
</span>S: event::Source + <span class="question-mark">?</span>Sized,
{
<span class="macro">trace!</span>(
<span class="string">&quot;reregistering event source with poller: token={:?}, interests={:?}&quot;</span>,
token,
interests
);
source.reregister(<span class="self">self</span>, token, interests)
}
<span class="doccomment">/// Deregister an [`event::Source`] with the `Poll` instance.
///
/// When an event source is deregistered, the `Poll` instance will no longer
/// monitor it for readiness state changes. Deregistering clears up any
/// internal resources needed to track the handle. After an explicit call
/// to this method completes, it is guaranteed that the token previously
/// registered to this handle will not be returned by a future poll, so long
/// as a happens-before relationship is established between this call and
/// the poll.
///
/// The event source must have previously been registered with this instance
/// of `Poll`, otherwise the behavior is unspecified.
///
/// A handle can be passed back to `register` after it has been
/// deregistered; however, it must be passed back to the **same** `Poll`
/// instance, otherwise the behavior is unspecified.
///
/// # Examples
///
</span><span class="attribute">#[cfg_attr(all(feature = <span class="string">&quot;os-poll&quot;</span>, feature = <span class="string">&quot;net&quot;</span>), doc = <span class="string">&quot;```&quot;</span>)]
#[cfg_attr(not(all(feature = <span class="string">&quot;os-poll&quot;</span>, feature = <span class="string">&quot;net&quot;</span>)), doc = <span class="string">&quot;```ignore&quot;</span>)]
</span><span class="doccomment">/// # use std::error::Error;
/// # use std::net;
/// # fn main() -&gt; Result&lt;(), Box&lt;dyn Error&gt;&gt; {
/// use mio::{Events, Poll, Interest, Token};
/// use mio::net::TcpStream;
/// use std::net::SocketAddr;
/// use std::time::Duration;
///
/// let mut poll = Poll::new()?;
///
/// let address: SocketAddr = &quot;127.0.0.1:0&quot;.parse()?;
/// let listener = net::TcpListener::bind(address)?;
/// let mut socket = TcpStream::connect(listener.local_addr()?)?;
///
/// // Register the socket with `poll`
/// poll.registry().register(
/// &amp;mut socket,
/// Token(0),
/// Interest::READABLE)?;
///
/// poll.registry().deregister(&amp;mut socket)?;
///
/// let mut events = Events::with_capacity(1024);
///
/// // Set a timeout because this poll should never receive any events.
/// poll.poll(&amp;mut events, Some(Duration::from_secs(1)))?;
/// assert!(events.is_empty());
/// # Ok(())
/// # }
/// ```
</span><span class="kw">pub fn </span>deregister&lt;S&gt;(<span class="kw-2">&amp;</span><span class="self">self</span>, source: <span class="kw-2">&amp;mut </span>S) -&gt; io::Result&lt;()&gt;
<span class="kw">where
</span>S: event::Source + <span class="question-mark">?</span>Sized,
{
<span class="macro">trace!</span>(<span class="string">&quot;deregistering event source from poller&quot;</span>);
source.deregister(<span class="self">self</span>)
}
<span class="doccomment">/// Creates a new independently owned `Registry`.
///
/// Event sources registered with this `Registry` will be registered with
/// the original `Registry` and `Poll` instance.
</span><span class="kw">pub fn </span>try_clone(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; io::Result&lt;Registry&gt; {
<span class="self">self</span>.selector
.try_clone()
.map(|selector| Registry { selector })
}
<span class="doccomment">/// Internal check to ensure only a single `Waker` is active per [`Poll`]
/// instance.
</span><span class="attribute">#[cfg(all(debug_assertions, not(target_os = <span class="string">&quot;wasi&quot;</span>)))]
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>register_waker(<span class="kw-2">&amp;</span><span class="self">self</span>) {
<span class="macro">assert!</span>(
!<span class="self">self</span>.selector.register_waker(),
<span class="string">&quot;Only a single `Waker` can be active per `Poll` instance&quot;
</span>);
}
<span class="doccomment">/// Get access to the `sys::Selector`.
</span><span class="attribute">#[cfg(any(not(target_os = <span class="string">&quot;wasi&quot;</span>), feature = <span class="string">&quot;net&quot;</span>))]
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>selector(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>sys::Selector {
<span class="kw-2">&amp;</span><span class="self">self</span>.selector
}
}
<span class="kw">impl </span>fmt::Debug <span class="kw">for </span>Registry {
<span class="kw">fn </span>fmt(<span class="kw-2">&amp;</span><span class="self">self</span>, fmt: <span class="kw-2">&amp;mut </span>fmt::Formatter&lt;<span class="lifetime">&#39;_</span>&gt;) -&gt; fmt::Result {
fmt.debug_struct(<span class="string">&quot;Registry&quot;</span>).finish()
}
}
<span class="attribute">#[cfg(unix)]
</span><span class="kw">impl </span>AsRawFd <span class="kw">for </span>Registry {
<span class="kw">fn </span>as_raw_fd(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; RawFd {
<span class="self">self</span>.selector.as_raw_fd()
}
}
<span class="macro">cfg_os_poll! </span>{
<span class="attribute">#[cfg(unix)]
#[test]
</span><span class="kw">pub fn </span>as_raw_fd() {
<span class="kw">let </span>poll = Poll::new().unwrap();
<span class="macro">assert!</span>(poll.as_raw_fd() &gt; <span class="number">0</span>);
}
}
</code></pre></div>
</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>