1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156
/************************************************************************************************** * * * This Source Code Form is subject to the terms of the Mozilla Public * * License, v. 2.0. If a copy of the MPL was not distributed with this * * file, You can obtain one at http://mozilla.org/MPL/2.0/. * * * **************************************************************************************************/ // ======================================== Configuration ======================================= \\ #![no_std] // ======================================== Documentation ======================================= \\ //! A way to poll a future until it or a `smol::Timer` completes. //! //! ## Example //! //! ```rust //! use smol::Timer; //! use smol_timeout::TimeoutExt; //! use std::time::Duration; //! //! smol::block_on(async { //! let foo = async { //! Timer::after(Duration::from_millis(250)).await; //! 24 //! }; //! //! let foo = foo.timeout(Duration::from_millis(100)); //! assert_eq!(foo.await, None); //! //! let bar = async { //! Timer::after(Duration::from_millis(100)).await; //! 42 //! }; //! //! let bar = bar.timeout(Duration::from_millis(250)); //! assert_eq!(bar.await, Some(42)); //! }); //! ``` // =========================================== Imports ========================================== \\ use core::future::Future; use core::pin::Pin; use core::task::{Context, Poll}; use core::time::Duration; use pin_project_lite::pin_project; use smol::Timer; // ============================================ Types =========================================== \\ pin_project! { #[derive(Debug)] /// A future polling both another future and a [`Timer`] that will complete after a specified /// timeout, and returning the future's output or [`None`] if the timer completes first. /// /// ## Example /// /// ```rust /// # use smol::Timer; /// use smol_timeout::TimeoutExt; /// use std::time::Duration; /// /// # smol::block_on(async { /// let foo = async { /// Timer::after(Duration::from_millis(250)).await; /// 24 /// }; /// /// let foo = foo.timeout(Duration::from_millis(100)); /// assert_eq!(foo.await, None); /// /// let bar = async { /// Timer::after(Duration::from_millis(100)).await; /// 42 /// }; /// /// let bar = bar.timeout(Duration::from_millis(250)); /// assert_eq!(bar.await, Some(42)); /// # }) /// ``` pub struct Timeout<Fut: Future> { #[pin] future: Fut, #[pin] timer: Timer, } } // ========================================= Interfaces ========================================= \\ /// An extension trait for [`Future`]s that provides a way to create [`Timeout`]s. pub trait TimeoutExt: Future { /// Given a [`Duration`], creates and returns a new [`Timeout`] that will poll both the future /// and a [`Timer`] that will complete after the provided duration, and return the future's /// output or [`None`] if the timer completes first. /// /// ## Example /// /// ```rust /// # use smol::Timer; /// use smol_timeout::TimeoutExt; /// use std::time::Duration; /// /// # smol::block_on(async { /// let foo = async { /// Timer::after(Duration::from_millis(250)).await; /// 24 /// }; /// /// let foo = foo.timeout(Duration::from_millis(100)); /// assert_eq!(foo.await, None); /// /// let bar = async { /// Timer::after(Duration::from_millis(100)).await; /// 42 /// }; /// /// let bar = bar.timeout(Duration::from_millis(250)); /// assert_eq!(bar.await, Some(42)); /// # }) /// ``` fn timeout(self, after: Duration) -> Timeout<Self> where Self: Sized, { Timeout { future: self, timer: Timer::after(after), } } } impl<Fut: Future> TimeoutExt for Fut {} // ========================================= impl Future ======================================== \\ impl<Fut: Future> Future for Timeout<Fut> { type Output = Option<Fut::Output>; fn poll(self: Pin<&mut Self>, ctx: &mut Context) -> Poll<Self::Output> { let this = self.project(); if this.timer.poll(ctx).is_ready() { return Poll::Ready(None); } if let Poll::Ready(output) = this.future.poll(ctx) { return Poll::Ready(Some(output)); } Poll::Pending } }