use crate::futures::TryFutureExt;
use futures::channel::oneshot;
use futures::future::FutureExt;
use std::future::Future;
use std::time::Instant;
#[derive(Default)]
pub struct GlobalTimer {
tx: Option<oneshot::Sender<()>>,
}
impl GlobalTimer {
pub fn new() -> Self {
Self { tx: None }
}
pub fn cancel(&mut self) {
if let Some(tx) = self.tx.take() {
tx.send(()).ok();
}
}
pub fn new_timeout(
&mut self,
deadline: Instant,
) -> impl Future<Output = Result<(), ()>> {
if self.tx.is_some() {
self.cancel();
}
assert!(self.tx.is_none());
let (tx, rx) = oneshot::channel();
self.tx = Some(tx);
let delay = tokio::time::delay_until(deadline.into());
let rx = rx
.map_err(|err| panic!("Unexpected error in receiving channel {:?}", err));
futures::future::select(delay, rx).then(|_| futures::future::ok(()))
}
}