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denoland-deno/cli/global_timer.rs
Bartek Iwańczuk c6bb3d5a10 remove tokio_util::block_on (#3388)
This PR removes tokio_util::block_on - refactored compiler and file 
fetcher slightly so that we can safely block there - that's because 
only blocking path consist of only synchronous operations.

Additionally I removed excessive use of tokio_util::panic_on_error 
and tokio_util::run_in_task and moved both functions to cli/worker.rs, 
to tests module.

Closes #2960
2019-11-22 12:46:57 -05:00

53 lines
1.5 KiB
Rust

// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
//! This module helps deno implement timers.
//!
//! As an optimization, we want to avoid an expensive calls into rust for every
//! setTimeout in JavaScript. Thus in //js/timers.ts a data structure is
//! implemented that calls into Rust for only the smallest timeout. Thus we
//! only need to be able to start and cancel a single timer (or Delay, as Tokio
//! calls it) for an entire Isolate. This is what is implemented here.
use crate::futures::TryFutureExt;
use futures::channel::oneshot;
use futures::future::FutureExt;
use std::future::Future;
use std::time::Instant;
use tokio::timer::Delay;
#[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 = futures::compat::Compat01As03::new(Delay::new(deadline))
.map_err(|err| panic!("Unexpected error in timeout {:?}", err));
let rx = rx
.map_err(|err| panic!("Unexpected error in receiving channel {:?}", err));
futures::future::select(delay, rx).then(|_| futures::future::ok(()))
}
}