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// Copyright (C) Parity Technologies (UK) Ltd.
// This file is part of Polkadot.
// Polkadot is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Polkadot is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
use futures::prelude::*;
use futures_timer::Delay;
use std::{
pin::Pin,
task::{Context, Poll},
time::Duration,
};
#[derive(Copy, Clone)]
enum MetronomeState {
Snooze,
SetAlarm,
}
/// Create a stream of ticks with a defined cycle duration.
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
}
}