1use smol::prelude::*;
 2use std::{
 3    pin::Pin,
 4    task::Poll,
 5    time::{Duration, Instant},
 6};
 7
 8pub struct Repeat {
 9    timer: smol::Timer,
10    period: Duration,
11}
12
13impl Stream for Repeat {
14    type Item = Instant;
15
16    fn poll_next(
17        mut self: std::pin::Pin<&mut Self>,
18        cx: &mut std::task::Context<'_>,
19    ) -> Poll<Option<Self::Item>> {
20        match self.as_mut().timer().poll(cx) {
21            Poll::Ready(instant) => {
22                let period = self.as_ref().period;
23                self.as_mut().timer().set_after(period);
24                Poll::Ready(Some(instant))
25            }
26            Poll::Pending => Poll::Pending,
27        }
28    }
29}
30
31impl Repeat {
32    fn timer(self: std::pin::Pin<&mut Self>) -> Pin<&mut smol::Timer> {
33        unsafe { self.map_unchecked_mut(|s| &mut s.timer) }
34    }
35}
36
37pub fn repeat(period: Duration) -> Repeat {
38    Repeat {
39        timer: smol::Timer::after(period),
40        period,
41    }
42}