vexide_async/
time.rs

1//! Utilities for tracking time.
2//!
3//! This module provides a types for executing code after a set period of time.
4//!
5//! - [`Sleep`] is a future that does no work and completes at a specific [`Instant`]
6//!   in time.
7//! - [`sleep`] and [`sleep_until`] provide ways to yield control away from a future
8//!   for or until a specific instant in time.
9
10use core::{
11    future::Future,
12    pin::Pin,
13    task::{Context, Poll},
14    time::Duration,
15};
16use std::time::Instant;
17
18use crate::{executor::EXECUTOR, reactor::Sleeper};
19
20/// A future that will complete after a certain instant is reached in time.
21///
22/// This type is returned by the [`sleep`] and [`sleep_until`] functions.
23#[derive(Debug)]
24#[must_use = "futures do nothing unless you `.await` or poll them"]
25pub struct Sleep(Instant);
26
27impl Future for Sleep {
28    type Output = ();
29
30    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> core::task::Poll<Self::Output> {
31        if Instant::now() > self.0 {
32            Poll::Ready(())
33        } else {
34            EXECUTOR.with(|ex| {
35                ex.with_reactor(|reactor| {
36                    reactor.sleepers.push(Sleeper {
37                        deadline: self.0,
38                        waker: cx.waker().clone(),
39                    });
40                });
41            });
42
43            Poll::Pending
44        }
45    }
46}
47
48/// Waits until `duration` has elapsed.
49///
50/// This function returns a future that will complete after the given
51/// duration, effectively yielding the current task for a period of time.
52///
53/// Equivalent to `sleep_until(Instant::now() + duration)`.
54///
55/// # Examples
56///
57/// ```
58/// println!("See you in 5 minutes.");
59/// sleep(Duration::from_secs(300)).await;
60/// println!("Hello again!");
61/// ```
62pub fn sleep(duration: Duration) -> Sleep {
63    Sleep(Instant::now() + duration)
64}
65
66/// Waits until `deadline` is reached.
67///
68/// This function returns a future that will complete once a given
69/// `Instant` in time has been reached.
70///
71/// # Examples
72///
73/// ```
74/// let now = Instant::now();
75/// let deadline = now + Duration::from_secs(2); // 5 minutes in the future
76///
77/// println!("See you in 5 minutes.");
78/// sleep_until(deadline).await;
79/// println!("Hello again!");
80/// ```
81pub const fn sleep_until(deadline: Instant) -> Sleep {
82    Sleep(deadline)
83}
vexide_async/time.rs

vexide_async/
time.rs
