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///! Waking timers for Bluetooth. Implemented using timerfd, but supposed to feel similar to
///Tokio's time
use nix::sys::time::TimeSpec;
use nix::sys::timerfd::{ClockId, Expiration, TimerFd, TimerFlags, TimerSetTimeFlags};
use std::time::Duration;
use tokio::io::unix::AsyncFd;
/// A single shot Alarm
pub struct Alarm {
fd: AsyncFd<TimerFd>,
}
impl Alarm {
/// Construct a new alarm
pub fn new() -> Self {
let timer = TimerFd::new(get_clock(), TimerFlags::empty()).unwrap();
Self { fd: AsyncFd::new(timer).unwrap() }
}
/// Reset the alarm to duration, starting from now
pub fn reset(&self, duration: Duration) {
self.fd
.get_ref()
.set(Expiration::OneShot(TimeSpec::from(duration)), TimerSetTimeFlags::empty())
.unwrap();
}
/// Stop the alarm if it is currently started
pub fn cancel(&self) {
self.reset(Duration::from_millis(0));
}
/// Completes when the alarm has expired
pub async fn expired(&self) {
let mut read_ready = self.fd.readable().await.unwrap();
read_ready.clear_ready();
drop(read_ready);
// Will not block, since we have confirmed it is readable
if self.fd.get_ref().get().unwrap().is_some() {
self.fd.get_ref().wait().unwrap();
}
}
}
impl Default for Alarm {
fn default() -> Self {
Alarm::new()
}
}
/// Similar to tokio's interval, except the first tick does *not* complete immediately
pub fn interval(period: Duration) -> Interval {
let timer = TimerFd::new(get_clock(), TimerFlags::empty()).unwrap();
timer.set(Expiration::Interval(TimeSpec::from(period)), TimerSetTimeFlags::empty()).unwrap();
Interval { fd: AsyncFd::new(timer).unwrap() }
}
/// Future returned by interval()
pub struct Interval {
fd: AsyncFd<TimerFd>,
}
impl Interval {
/// Call this to get the future for the next tick of the interval
pub async fn tick(&mut self) {
let mut read_ready = self.fd.readable().await.unwrap();
read_ready.clear_ready();
drop(read_ready);
// Will not block, since we have confirmed it is readable
if self.fd.get_ref().get().unwrap().is_some() {
self.fd.get_ref().wait().unwrap();
}
}
}
fn get_clock() -> ClockId {
if cfg!(target_os = "android") {
ClockId::CLOCK_BOOTTIME_ALARM
} else {
ClockId::CLOCK_BOOTTIME
}
}
#[cfg(test)]
mod tests {
use super::interval;
use super::Alarm;
use crate::assert_near;
use std::time::{Duration, Instant};
#[test]
fn alarm_simple_case() {
let runtime = tokio::runtime::Runtime::new().unwrap();
runtime.block_on(async {
let timer = Instant::now();
let alarm = Alarm::new();
alarm.reset(Duration::from_millis(10));
alarm.expired().await;
assert_near!(timer.elapsed().as_millis(), 10, 3);
});
}
#[test]
fn alarm_cancel_after_expired() {
let runtime = tokio::runtime::Runtime::new().unwrap();
runtime.block_on(async {
let alarm = Alarm::new();
alarm.reset(Duration::from_millis(10));
tokio::time::sleep(Duration::from_millis(30)).await;
alarm.cancel();
for _ in 0..10 {
let ready_in_10_ms = async {
tokio::time::sleep(Duration::from_millis(10)).await;
};
tokio::select! {
_ = alarm.expired() => (),
_ = ready_in_10_ms => (),
}
}
});
}
#[test]
fn alarm_clear_ready_after_expired() {
// After an alarm expired, we need to make sure we clear ready from AsyncFdReadyGuard.
// Otherwise it's still ready and select! won't work.
let runtime = tokio::runtime::Runtime::new().unwrap();
runtime.block_on(async {
let timer = Instant::now();
let alarm = Alarm::new();
alarm.reset(Duration::from_millis(10));
alarm.expired().await;
let ready_in_10_ms = async {
tokio::time::sleep(Duration::from_millis(10)).await;
};
tokio::select! {
_ = alarm.expired() => (),
_ = ready_in_10_ms => (),
}
assert_near!(timer.elapsed().as_millis(), 20, 3);
});
}
#[test]
fn interval_schedule_and_then_drop() {
let runtime = tokio::runtime::Runtime::new().unwrap();
runtime.block_on(async {
interval(Duration::from_millis(10));
});
}
#[test]
fn interval_simple_case() {
let runtime = tokio::runtime::Runtime::new().unwrap();
runtime.block_on(async {
let timer = Instant::now();
let mut interval = interval(Duration::from_millis(10));
for n in 1..10 {
interval.tick().await;
println!("{}", n);
assert_near!(timer.elapsed().as_millis(), 10 * n, 3);
}
});
}
}
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