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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/tokio-1.28.2/src/runtime/io/registration.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>registration.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="../../../../tokio/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="../../../../tokio/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="attribute">#![cfg_attr(not(feature = <span class="string">&quot;net&quot;</span>), allow(dead_code))]
</span><span class="kw">use </span><span class="kw">crate</span>::io::interest::Interest;
<span class="kw">use </span><span class="kw">crate</span>::runtime::io::{Direction, Handle, ReadyEvent, ScheduledIo};
<span class="kw">use </span><span class="kw">crate</span>::runtime::scheduler;
<span class="kw">use </span><span class="kw">crate</span>::util::slab;
<span class="kw">use </span>mio::event::Source;
<span class="kw">use </span>std::io;
<span class="kw">use </span>std::task::{Context, Poll};
<span class="macro">cfg_io_driver! </span>{
<span class="doccomment">/// Associates an I/O resource with the reactor instance that drives it.
///
/// A registration represents an I/O resource registered with a Reactor such
/// that it will receive task notifications on readiness. This is the lowest
/// level API for integrating with a reactor.
///
/// The association between an I/O resource is made by calling
/// [`new_with_interest_and_handle`].
/// Once the association is established, it remains established until the
/// registration instance is dropped.
///
/// A registration instance represents two separate readiness streams. One
/// for the read readiness and one for write readiness. These streams are
/// independent and can be consumed from separate tasks.
///
/// **Note**: while `Registration` is `Sync`, the caller must ensure that
/// there are at most two tasks that use a registration instance
/// concurrently. One task for [`poll_read_ready`] and one task for
/// [`poll_write_ready`]. While violating this requirement is &quot;safe&quot; from a
/// Rust memory safety point of view, it will result in unexpected behavior
/// in the form of lost notifications and tasks hanging.
///
/// ## Platform-specific events
///
/// `Registration` also allows receiving platform-specific `mio::Ready`
/// events. These events are included as part of the read readiness event
/// stream. The write readiness event stream is only for `Ready::writable()`
/// events.
///
/// [`new_with_interest_and_handle`]: method@Self::new_with_interest_and_handle
/// [`poll_read_ready`]: method@Self::poll_read_ready`
/// [`poll_write_ready`]: method@Self::poll_write_ready`
</span><span class="attribute">#[derive(Debug)]
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>Registration {
<span class="doccomment">/// Handle to the associated runtime.
</span>handle: scheduler::Handle,
<span class="doccomment">/// Reference to state stored by the driver.
</span>shared: slab::Ref&lt;ScheduledIo&gt;,
}
}
<span class="kw">unsafe impl </span>Send <span class="kw">for </span>Registration {}
<span class="kw">unsafe impl </span>Sync <span class="kw">for </span>Registration {}
<span class="comment">// ===== impl Registration =====
</span><span class="kw">impl </span>Registration {
<span class="doccomment">/// Registers the I/O resource with the reactor for the provided handle, for
/// a specific `Interest`. This does not add `hup` or `error` so if you are
/// interested in those states, you will need to add them to the readiness
/// state passed to this function.
///
/// # Return
///
/// - `Ok` if the registration happened successfully
/// - `Err` if an error was encountered during registration
</span><span class="attribute">#[track_caller]
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>new_with_interest_and_handle(
io: <span class="kw-2">&amp;mut </span><span class="kw">impl </span>Source,
interest: Interest,
handle: scheduler::Handle,
) -&gt; io::Result&lt;Registration&gt; {
<span class="kw">let </span>shared = handle.driver().io().add_source(io, interest)<span class="question-mark">?</span>;
<span class="prelude-val">Ok</span>(Registration { handle, shared })
}
<span class="doccomment">/// Deregisters the I/O resource from the reactor it is associated with.
///
/// This function must be called before the I/O resource associated with the
/// registration is dropped.
///
/// Note that deregistering does not guarantee that the I/O resource can be
/// registered with a different reactor. Some I/O resource types can only be
/// associated with a single reactor instance for their lifetime.
///
/// # Return
///
/// If the deregistration was successful, `Ok` is returned. Any calls to
/// `Reactor::turn` that happen after a successful call to `deregister` will
/// no longer result in notifications getting sent for this registration.
///
/// `Err` is returned if an error is encountered.
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>deregister(<span class="kw-2">&amp;mut </span><span class="self">self</span>, io: <span class="kw-2">&amp;mut </span><span class="kw">impl </span>Source) -&gt; io::Result&lt;()&gt; {
<span class="self">self</span>.handle().deregister_source(io)
}
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>clear_readiness(<span class="kw-2">&amp;</span><span class="self">self</span>, event: ReadyEvent) {
<span class="self">self</span>.shared.clear_readiness(event);
}
<span class="comment">// Uses the poll path, requiring the caller to ensure mutual exclusion for
// correctness. Only the last task to call this function is notified.
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>poll_read_ready(<span class="kw-2">&amp;</span><span class="self">self</span>, cx: <span class="kw-2">&amp;mut </span>Context&lt;<span class="lifetime">&#39;_</span>&gt;) -&gt; Poll&lt;io::Result&lt;ReadyEvent&gt;&gt; {
<span class="self">self</span>.poll_ready(cx, Direction::Read)
}
<span class="comment">// Uses the poll path, requiring the caller to ensure mutual exclusion for
// correctness. Only the last task to call this function is notified.
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>poll_write_ready(<span class="kw-2">&amp;</span><span class="self">self</span>, cx: <span class="kw-2">&amp;mut </span>Context&lt;<span class="lifetime">&#39;_</span>&gt;) -&gt; Poll&lt;io::Result&lt;ReadyEvent&gt;&gt; {
<span class="self">self</span>.poll_ready(cx, Direction::Write)
}
<span class="comment">// Uses the poll path, requiring the caller to ensure mutual exclusion for
// correctness. Only the last task to call this function is notified.
</span><span class="attribute">#[cfg(not(tokio_wasi))]
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>poll_read_io&lt;R&gt;(
<span class="kw-2">&amp;</span><span class="self">self</span>,
cx: <span class="kw-2">&amp;mut </span>Context&lt;<span class="lifetime">&#39;_</span>&gt;,
f: <span class="kw">impl </span>FnMut() -&gt; io::Result&lt;R&gt;,
) -&gt; Poll&lt;io::Result&lt;R&gt;&gt; {
<span class="self">self</span>.poll_io(cx, Direction::Read, f)
}
<span class="comment">// Uses the poll path, requiring the caller to ensure mutual exclusion for
// correctness. Only the last task to call this function is notified.
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>poll_write_io&lt;R&gt;(
<span class="kw-2">&amp;</span><span class="self">self</span>,
cx: <span class="kw-2">&amp;mut </span>Context&lt;<span class="lifetime">&#39;_</span>&gt;,
f: <span class="kw">impl </span>FnMut() -&gt; io::Result&lt;R&gt;,
) -&gt; Poll&lt;io::Result&lt;R&gt;&gt; {
<span class="self">self</span>.poll_io(cx, Direction::Write, f)
}
<span class="doccomment">/// Polls for events on the I/O resource&#39;s `direction` readiness stream.
///
/// If called with a task context, notify the task when a new event is
/// received.
</span><span class="kw">fn </span>poll_ready(
<span class="kw-2">&amp;</span><span class="self">self</span>,
cx: <span class="kw-2">&amp;mut </span>Context&lt;<span class="lifetime">&#39;_</span>&gt;,
direction: Direction,
) -&gt; Poll&lt;io::Result&lt;ReadyEvent&gt;&gt; {
<span class="comment">// Keep track of task budget
</span><span class="kw">let </span>coop = <span class="macro">ready!</span>(<span class="kw">crate</span>::runtime::coop::poll_proceed(cx));
<span class="kw">let </span>ev = <span class="macro">ready!</span>(<span class="self">self</span>.shared.poll_readiness(cx, direction));
<span class="kw">if </span>ev.is_shutdown {
<span class="kw">return </span>Poll::Ready(<span class="prelude-val">Err</span>(gone()));
}
coop.made_progress();
Poll::Ready(<span class="prelude-val">Ok</span>(ev))
}
<span class="kw">fn </span>poll_io&lt;R&gt;(
<span class="kw-2">&amp;</span><span class="self">self</span>,
cx: <span class="kw-2">&amp;mut </span>Context&lt;<span class="lifetime">&#39;_</span>&gt;,
direction: Direction,
<span class="kw-2">mut </span>f: <span class="kw">impl </span>FnMut() -&gt; io::Result&lt;R&gt;,
) -&gt; Poll&lt;io::Result&lt;R&gt;&gt; {
<span class="kw">loop </span>{
<span class="kw">let </span>ev = <span class="macro">ready!</span>(<span class="self">self</span>.poll_ready(cx, direction))<span class="question-mark">?</span>;
<span class="kw">match </span>f() {
<span class="prelude-val">Ok</span>(ret) =&gt; {
<span class="kw">return </span>Poll::Ready(<span class="prelude-val">Ok</span>(ret));
}
<span class="prelude-val">Err</span>(<span class="kw-2">ref </span>e) <span class="kw">if </span>e.kind() == io::ErrorKind::WouldBlock =&gt; {
<span class="self">self</span>.clear_readiness(ev);
}
<span class="prelude-val">Err</span>(e) =&gt; <span class="kw">return </span>Poll::Ready(<span class="prelude-val">Err</span>(e)),
}
}
}
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>try_io&lt;R&gt;(
<span class="kw-2">&amp;</span><span class="self">self</span>,
interest: Interest,
f: <span class="kw">impl </span>FnOnce() -&gt; io::Result&lt;R&gt;,
) -&gt; io::Result&lt;R&gt; {
<span class="kw">let </span>ev = <span class="self">self</span>.shared.ready_event(interest);
<span class="comment">// Don&#39;t attempt the operation if the resource is not ready.
</span><span class="kw">if </span>ev.ready.is_empty() {
<span class="kw">return </span><span class="prelude-val">Err</span>(io::ErrorKind::WouldBlock.into());
}
<span class="kw">match </span>f() {
<span class="prelude-val">Err</span>(<span class="kw-2">ref </span>e) <span class="kw">if </span>e.kind() == io::ErrorKind::WouldBlock =&gt; {
<span class="self">self</span>.clear_readiness(ev);
<span class="prelude-val">Err</span>(io::ErrorKind::WouldBlock.into())
}
res =&gt; res,
}
}
<span class="kw">fn </span>handle(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>Handle {
<span class="self">self</span>.handle.driver().io()
}
}
<span class="kw">impl </span>Drop <span class="kw">for </span>Registration {
<span class="kw">fn </span>drop(<span class="kw-2">&amp;mut </span><span class="self">self</span>) {
<span class="comment">// It is possible for a cycle to be created between wakers stored in
// `ScheduledIo` instances and `Arc&lt;driver::Inner&gt;`. To break this
// cycle, wakers are cleared. This is an imperfect solution as it is
// possible to store a `Registration` in a waker. In this case, the
// cycle would remain.
//
// See tokio-rs/tokio#3481 for more details.
</span><span class="self">self</span>.shared.clear_wakers();
}
}
<span class="kw">fn </span>gone() -&gt; io::Error {
io::Error::new(
io::ErrorKind::Other,
<span class="kw">crate</span>::util::error::RUNTIME_SHUTTING_DOWN_ERROR,
)
}
<span class="macro">cfg_io_readiness! </span>{
<span class="kw">impl </span>Registration {
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">async fn </span>readiness(<span class="kw-2">&amp;</span><span class="self">self</span>, interest: Interest) -&gt; io::Result&lt;ReadyEvent&gt; {
<span class="kw">let </span>ev = <span class="self">self</span>.shared.readiness(interest).<span class="kw">await</span>;
<span class="kw">if </span>ev.is_shutdown {
<span class="kw">return </span><span class="prelude-val">Err</span>(gone())
}
<span class="prelude-val">Ok</span>(ev)
}
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">async fn </span>async_io&lt;R&gt;(<span class="kw-2">&amp;</span><span class="self">self</span>, interest: Interest, <span class="kw-2">mut </span>f: <span class="kw">impl </span>FnMut() -&gt; io::Result&lt;R&gt;) -&gt; io::Result&lt;R&gt; {
<span class="kw">loop </span>{
<span class="kw">let </span>event = <span class="self">self</span>.readiness(interest).<span class="kw">await</span><span class="question-mark">?</span>;
<span class="kw">match </span>f() {
<span class="prelude-val">Err</span>(<span class="kw-2">ref </span>e) <span class="kw">if </span>e.kind() == io::ErrorKind::WouldBlock =&gt; {
<span class="self">self</span>.clear_readiness(event);
}
x =&gt; <span class="kw">return </span>x,
}
}
}
}
}
</code></pre></div>
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