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50 lines
1.3 KiB
Rust
50 lines
1.3 KiB
Rust
// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
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//! This module helps deno implement timers.
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//!
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//! As an optimization, we want to avoid an expensive calls into rust for every
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//! setTimeout in JavaScript. Thus in //js/timers.ts a data structure is
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//! implemented that calls into Rust for only the smallest timeout. Thus we
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//! only need to be able to start and cancel a single timer (or Delay, as Tokio
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//! calls it) for an entire Isolate. This is what is implemented here.
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use crate::tokio_util::panic_on_error;
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use futures::Future;
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use std::time::Instant;
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use tokio::sync::oneshot;
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use tokio::timer::Delay;
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#[derive(Default)]
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pub struct GlobalTimer {
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tx: Option<oneshot::Sender<()>>,
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}
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impl GlobalTimer {
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pub fn new() -> Self {
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Self { tx: None }
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}
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pub fn cancel(&mut self) {
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if let Some(tx) = self.tx.take() {
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tx.send(()).ok();
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}
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}
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pub fn new_timeout(
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&mut self,
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deadline: Instant,
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) -> impl Future<Item = (), Error = ()> {
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if self.tx.is_some() {
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self.cancel();
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}
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assert!(self.tx.is_none());
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let (tx, rx) = oneshot::channel();
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self.tx = Some(tx);
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let delay = panic_on_error(Delay::new(deadline));
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let rx = panic_on_error(rx);
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delay.select(rx).then(|_| Ok(()))
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}
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}
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