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https://github.com/async-rs/async-std.git
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commit
206bedfd12
2 changed files with 73 additions and 0 deletions
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@ -1,3 +1,11 @@
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cfg_unstable! {
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mod delay;
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use std::time::Duration;
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use delay::DelayFuture;
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}
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extension_trait! {
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use std::pin::Pin;
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use std::ops::{Deref, DerefMut};
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@ -99,6 +107,28 @@ extension_trait! {
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}
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pub trait FutureExt: std::future::Future {
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/// Returns a Future that delays execution for a specified time.
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///
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/// # Examples
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///
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/// ```
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/// # async_std::task::block_on(async {
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/// use async_std::prelude::*;
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/// use async_std::future;
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/// use std::time::Duration;
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///
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/// let a = future::ready(1).delay(Duration::from_millis(2000));
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/// dbg!(a.await);
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/// # })
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/// ```
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#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
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#[cfg(any(feature = "unstable", feature = "docs"))]
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fn delay(self, dur: Duration) -> impl Future<Output = Self::Output> [DelayFuture<Self>]
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where
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Self: Future + Sized
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{
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DelayFuture::new(self, dur)
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}
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}
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impl<F: Future + Unpin + ?Sized> Future for Box<F> {
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43
src/future/future/delay.rs
Normal file
43
src/future/future/delay.rs
Normal file
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@ -0,0 +1,43 @@
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use std::pin::Pin;
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use std::time::Duration;
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use futures_timer::Delay;
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use pin_project_lite::pin_project;
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use crate::future::Future;
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use crate::task::{Context, Poll};
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pin_project! {
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#[doc(hidden)]
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#[derive(Debug)]
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pub struct DelayFuture<F> {
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#[pin]
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future: F,
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#[pin]
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delay: Delay,
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}
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}
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impl<F> DelayFuture<F> {
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pub fn new(future: F, dur: Duration) -> DelayFuture<F> {
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let delay = Delay::new(dur);
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DelayFuture { future, delay }
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}
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}
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impl<F: Future> Future for DelayFuture<F> {
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type Output = F::Output;
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fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
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let this = self.project();
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match this.delay.poll(cx) {
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Poll::Pending => Poll::Pending,
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Poll::Ready(_) => match this.future.poll(cx) {
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Poll::Ready(v) => Poll::Ready(v),
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Poll::Pending => Poll::Pending,
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},
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}
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}
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}
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