| <!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/git/checkouts/tokio-377c595163f99a10/dfe252d/tokio/src/time/timeout.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>timeout.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="doccomment">//! Allows a future to execute for a maximum amount of time. |
| //! |
| //! See [`Timeout`] documentation for more details. |
| //! |
| //! [`Timeout`]: struct@Timeout |
| |
| </span><span class="kw">use crate</span>::{ |
| runtime::coop, |
| time::{error::Elapsed, sleep_until, Duration, Instant, Sleep}, |
| util::trace, |
| }; |
| |
| <span class="kw">use </span>pin_project_lite::pin_project; |
| <span class="kw">use </span>std::future::Future; |
| <span class="kw">use </span>std::pin::Pin; |
| <span class="kw">use </span>std::task::{<span class="self">self</span>, Poll}; |
| |
| <span class="doccomment">/// Requires a `Future` to complete before the specified duration has elapsed. |
| /// |
| /// If the future completes before the duration has elapsed, then the completed |
| /// value is returned. Otherwise, an error is returned and the future is |
| /// canceled. |
| /// |
| /// Note that the timeout is checked before polling the future, so if the future |
| /// does not yield during execution then it is possible for the future to complete |
| /// and exceed the timeout _without_ returning an error. |
| /// |
| /// This function returns a future whose return type is [`Result`]`<T,`[`Elapsed`]`>`, where `T` is the |
| /// return type of the provided future. |
| /// |
| /// [`Result`]: std::result::Result |
| /// [`Elapsed`]: crate::time::error::Elapsed |
| /// |
| /// # Cancellation |
| /// |
| /// Cancelling a timeout is done by dropping the future. No additional cleanup |
| /// or other work is required. |
| /// |
| /// The original future may be obtained by calling [`Timeout::into_inner`]. This |
| /// consumes the `Timeout`. |
| /// |
| /// # Examples |
| /// |
| /// Create a new `Timeout` set to expire in 10 milliseconds. |
| /// |
| /// ```rust |
| /// use tokio::time::timeout; |
| /// use tokio::sync::oneshot; |
| /// |
| /// use std::time::Duration; |
| /// |
| /// # async fn dox() { |
| /// let (tx, rx) = oneshot::channel(); |
| /// # tx.send(()).unwrap(); |
| /// |
| /// // Wrap the future with a `Timeout` set to expire in 10 milliseconds. |
| /// if let Err(_) = timeout(Duration::from_millis(10), rx).await { |
| /// println!("did not receive value within 10 ms"); |
| /// } |
| /// # } |
| /// ``` |
| /// |
| /// # Panics |
| /// |
| /// This function panics if there is no current timer set. |
| /// |
| /// It can be triggered when [`Builder::enable_time`] or |
| /// [`Builder::enable_all`] are not included in the builder. |
| /// |
| /// It can also panic whenever a timer is created outside of a |
| /// Tokio runtime. That is why `rt.block_on(sleep(...))` will panic, |
| /// since the function is executed outside of the runtime. |
| /// Whereas `rt.block_on(async {sleep(...).await})` doesn't panic. |
| /// And this is because wrapping the function on an async makes it lazy, |
| /// and so gets executed inside the runtime successfully without |
| /// panicking. |
| /// |
| /// [`Builder::enable_time`]: crate::runtime::Builder::enable_time |
| /// [`Builder::enable_all`]: crate::runtime::Builder::enable_all |
| </span><span class="attribute">#[track_caller] |
| </span><span class="kw">pub fn </span>timeout<F>(duration: Duration, future: F) -> Timeout<F> |
| <span class="kw">where |
| </span>F: Future, |
| { |
| <span class="kw">let </span>location = trace::caller_location(); |
| |
| <span class="kw">let </span>deadline = Instant::now().checked_add(duration); |
| <span class="kw">let </span>delay = <span class="kw">match </span>deadline { |
| <span class="prelude-val">Some</span>(deadline) => Sleep::new_timeout(deadline, location), |
| <span class="prelude-val">None </span>=> Sleep::far_future(location), |
| }; |
| Timeout::new_with_delay(future, delay) |
| } |
| |
| <span class="doccomment">/// Requires a `Future` to complete before the specified instant in time. |
| /// |
| /// If the future completes before the instant is reached, then the completed |
| /// value is returned. Otherwise, an error is returned. |
| /// |
| /// This function returns a future whose return type is [`Result`]`<T,`[`Elapsed`]`>`, where `T` is the |
| /// return type of the provided future. |
| /// |
| /// [`Result`]: std::result::Result |
| /// [`Elapsed`]: crate::time::error::Elapsed |
| /// |
| /// # Cancellation |
| /// |
| /// Cancelling a timeout is done by dropping the future. No additional cleanup |
| /// or other work is required. |
| /// |
| /// The original future may be obtained by calling [`Timeout::into_inner`]. This |
| /// consumes the `Timeout`. |
| /// |
| /// # Examples |
| /// |
| /// Create a new `Timeout` set to expire in 10 milliseconds. |
| /// |
| /// ```rust |
| /// use tokio::time::{Instant, timeout_at}; |
| /// use tokio::sync::oneshot; |
| /// |
| /// use std::time::Duration; |
| /// |
| /// # async fn dox() { |
| /// let (tx, rx) = oneshot::channel(); |
| /// # tx.send(()).unwrap(); |
| /// |
| /// // Wrap the future with a `Timeout` set to expire 10 milliseconds into the |
| /// // future. |
| /// if let Err(_) = timeout_at(Instant::now() + Duration::from_millis(10), rx).await { |
| /// println!("did not receive value within 10 ms"); |
| /// } |
| /// # } |
| /// ``` |
| </span><span class="kw">pub fn </span>timeout_at<F>(deadline: Instant, future: F) -> Timeout<F> |
| <span class="kw">where |
| </span>F: Future, |
| { |
| <span class="kw">let </span>delay = sleep_until(deadline); |
| |
| Timeout { |
| value: future, |
| delay, |
| } |
| } |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="doccomment">/// Future returned by [`timeout`](timeout) and [`timeout_at`](timeout_at). |
| </span><span class="attribute">#[must_use = <span class="string">"futures do nothing unless you `.await` or poll them"</span>] |
| #[derive(Debug)] |
| </span><span class="kw">pub struct </span>Timeout<T> { |
| <span class="attribute">#[pin] |
| </span>value: T, |
| <span class="attribute">#[pin] |
| </span>delay: Sleep, |
| } |
| } |
| |
| <span class="kw">impl</span><T> Timeout<T> { |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>new_with_delay(value: T, delay: Sleep) -> Timeout<T> { |
| Timeout { value, delay } |
| } |
| |
| <span class="doccomment">/// Gets a reference to the underlying value in this timeout. |
| </span><span class="kw">pub fn </span>get_ref(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>T { |
| <span class="kw-2">&</span><span class="self">self</span>.value |
| } |
| |
| <span class="doccomment">/// Gets a mutable reference to the underlying value in this timeout. |
| </span><span class="kw">pub fn </span>get_mut(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span>T { |
| <span class="kw-2">&mut </span><span class="self">self</span>.value |
| } |
| |
| <span class="doccomment">/// Consumes this timeout, returning the underlying value. |
| </span><span class="kw">pub fn </span>into_inner(<span class="self">self</span>) -> T { |
| <span class="self">self</span>.value |
| } |
| } |
| |
| <span class="kw">impl</span><T> Future <span class="kw">for </span>Timeout<T> |
| <span class="kw">where |
| </span>T: Future, |
| { |
| <span class="kw">type </span>Output = <span class="prelude-ty">Result</span><T::Output, Elapsed>; |
| |
| <span class="kw">fn </span>poll(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>task::Context<<span class="lifetime">'_</span>>) -> Poll<<span class="self">Self</span>::Output> { |
| <span class="kw">let </span>me = <span class="self">self</span>.project(); |
| |
| <span class="kw">let </span>had_budget_before = coop::has_budget_remaining(); |
| |
| <span class="comment">// First, try polling the future |
| </span><span class="kw">if let </span>Poll::Ready(v) = me.value.poll(cx) { |
| <span class="kw">return </span>Poll::Ready(<span class="prelude-val">Ok</span>(v)); |
| } |
| |
| <span class="kw">let </span>has_budget_now = coop::has_budget_remaining(); |
| |
| <span class="kw">let </span>delay = me.delay; |
| |
| <span class="kw">let </span>poll_delay = || -> Poll<<span class="self">Self</span>::Output> { |
| <span class="kw">match </span>delay.poll(cx) { |
| Poll::Ready(()) => Poll::Ready(<span class="prelude-val">Err</span>(Elapsed::new())), |
| Poll::Pending => Poll::Pending, |
| } |
| }; |
| |
| <span class="kw">if let </span>(<span class="bool-val">true</span>, <span class="bool-val">false</span>) = (had_budget_before, has_budget_now) { |
| <span class="comment">// if it is the underlying future that exhausted the budget, we poll |
| // the `delay` with an unconstrained one. This prevents pathological |
| // cases where the underlying future always exhausts the budget and |
| // we never get a chance to evaluate whether the timeout was hit or |
| // not. |
| </span>coop::with_unconstrained(poll_delay) |
| } <span class="kw">else </span>{ |
| poll_delay() |
| } |
| } |
| } |
| </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> |
