ghost-node/metrics/src/metronome.rs

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Rust
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use futures::prelude::*;
use futures_timer::Delay;
use std::{
pin::Pin,
task::{Context, Poll},
time::Duration,
};
#[derive(Copy, Clone)]
enum MetronomeState {
Snooze,
SetAlarm,
}
pub struct Metronome {
delay: Delay,
period: Duration,
state: MetronomeState,
}
impl Metronome {
/// Create a new metronome source with a defined cycle duration.
pub fn new(cycle: Duration) -> Self {
let period = cycle.into();
Self { period, delay: Delay::new(period), state: MetronomeState::Snooze }
}
}
impl futures::Stream for Metronome {
type Item = ();
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
loop {
match self.state {
MetronomeState::SetAlarm => {
let val = self.period;
self.delay.reset(val);
self.state = MetronomeState::Snooze;
},
MetronomeState::Snooze => {
if !Pin::new(&mut self.delay).poll(cx).is_ready() {
break
}
self.state = MetronomeState::SetAlarm;
return Poll::Ready(Some(()))
},
}
}
Poll::Pending
}
}