| <!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/task/waker.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>waker.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="kw">use </span><span class="kw">crate</span>::future::Future; |
| <span class="kw">use </span><span class="kw">crate</span>::runtime::task::{Header, RawTask, Schedule}; |
| |
| <span class="kw">use </span>std::marker::PhantomData; |
| <span class="kw">use </span>std::mem::ManuallyDrop; |
| <span class="kw">use </span>std::ops; |
| <span class="kw">use </span>std::ptr::NonNull; |
| <span class="kw">use </span>std::task::{RawWaker, RawWakerVTable, Waker}; |
| |
| <span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">struct </span>WakerRef<<span class="lifetime">'a</span>, S: <span class="lifetime">'static</span>> { |
| waker: ManuallyDrop<Waker>, |
| _p: PhantomData<(<span class="kw-2">&</span><span class="lifetime">'a </span>Header, S)>, |
| } |
| |
| <span class="doccomment">/// Returns a `WakerRef` which avoids having to preemptively increase the |
| /// refcount if there is no need to do so. |
| </span><span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">fn </span>waker_ref<T, S>(header: <span class="kw-2">&</span>NonNull<Header>) -> WakerRef<<span class="lifetime">'_</span>, S> |
| <span class="kw">where |
| </span>T: Future, |
| S: Schedule, |
| { |
| <span class="comment">// `Waker::will_wake` uses the VTABLE pointer as part of the check. This |
| // means that `will_wake` will always return false when using the current |
| // task's waker. (discussion at rust-lang/rust#66281). |
| // |
| // To fix this, we use a single vtable. Since we pass in a reference at this |
| // point and not an *owned* waker, we must ensure that `drop` is never |
| // called on this waker instance. This is done by wrapping it with |
| // `ManuallyDrop` and then never calling drop. |
| </span><span class="kw">let </span>waker = <span class="kw">unsafe </span>{ ManuallyDrop::new(Waker::from_raw(raw_waker(<span class="kw-2">*</span>header))) }; |
| |
| WakerRef { |
| waker, |
| _p: PhantomData, |
| } |
| } |
| |
| <span class="kw">impl</span><S> ops::Deref <span class="kw">for </span>WakerRef<<span class="lifetime">'_</span>, S> { |
| <span class="kw">type </span>Target = Waker; |
| |
| <span class="kw">fn </span>deref(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>Waker { |
| <span class="kw-2">&</span><span class="self">self</span>.waker |
| } |
| } |
| |
| <span class="macro">cfg_trace! </span>{ |
| <span class="macro">macro_rules! </span>trace { |
| (<span class="macro-nonterminal">$header</span>:expr, <span class="macro-nonterminal">$op</span>:expr) => { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(id) = Header::get_tracing_id(<span class="kw-2">&</span><span class="macro-nonterminal">$header</span>) { |
| <span class="macro">tracing::trace!</span>( |
| target: <span class="string">"tokio::task::waker"</span>, |
| op = <span class="macro-nonterminal">$op</span>, |
| task.id = id.into_u64(), |
| ); |
| } |
| } |
| } |
| } |
| |
| <span class="macro">cfg_not_trace! </span>{ |
| <span class="macro">macro_rules! </span>trace { |
| (<span class="macro-nonterminal">$header</span>:expr, <span class="macro-nonterminal">$op</span>:expr) => { |
| <span class="comment">// noop |
| </span><span class="kw">let _ </span>= <span class="kw-2">&</span><span class="macro-nonterminal">$header</span>; |
| } |
| } |
| } |
| |
| <span class="kw">unsafe fn </span>clone_waker(ptr: <span class="kw-2">*const </span>()) -> RawWaker { |
| <span class="kw">let </span>header = NonNull::new_unchecked(ptr <span class="kw">as </span><span class="kw-2">*mut </span>Header); |
| <span class="macro">trace!</span>(header, <span class="string">"waker.clone"</span>); |
| header.as_ref().state.ref_inc(); |
| raw_waker(header) |
| } |
| |
| <span class="kw">unsafe fn </span>drop_waker(ptr: <span class="kw-2">*const </span>()) { |
| <span class="kw">let </span>ptr = NonNull::new_unchecked(ptr <span class="kw">as </span><span class="kw-2">*mut </span>Header); |
| <span class="macro">trace!</span>(ptr, <span class="string">"waker.drop"</span>); |
| <span class="kw">let </span>raw = RawTask::from_raw(ptr); |
| raw.drop_reference(); |
| } |
| |
| <span class="kw">unsafe fn </span>wake_by_val(ptr: <span class="kw-2">*const </span>()) { |
| <span class="kw">let </span>ptr = NonNull::new_unchecked(ptr <span class="kw">as </span><span class="kw-2">*mut </span>Header); |
| <span class="macro">trace!</span>(ptr, <span class="string">"waker.wake"</span>); |
| <span class="kw">let </span>raw = RawTask::from_raw(ptr); |
| raw.wake_by_val(); |
| } |
| |
| <span class="comment">// Wake without consuming the waker |
| </span><span class="kw">unsafe fn </span>wake_by_ref(ptr: <span class="kw-2">*const </span>()) { |
| <span class="kw">let </span>ptr = NonNull::new_unchecked(ptr <span class="kw">as </span><span class="kw-2">*mut </span>Header); |
| <span class="macro">trace!</span>(ptr, <span class="string">"waker.wake_by_ref"</span>); |
| <span class="kw">let </span>raw = RawTask::from_raw(ptr); |
| raw.wake_by_ref(); |
| } |
| |
| <span class="kw">static </span>WAKER_VTABLE: RawWakerVTable = |
| RawWakerVTable::new(clone_waker, wake_by_val, wake_by_ref, drop_waker); |
| |
| <span class="kw">fn </span>raw_waker(header: NonNull<Header>) -> RawWaker { |
| <span class="kw">let </span>ptr = header.as_ptr() <span class="kw">as </span><span class="kw-2">*const </span>(); |
| RawWaker::new(ptr, <span class="kw-2">&</span>WAKER_VTABLE) |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../../" data-current-crate="tokio" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
