refactor: move timers to deno_timers op crate (#10179)

Move timers out of runtime/ and into a standalone op crate.

1 files changed, 165 insertions, 0 deletions

diff --git a/op_crates/timers/lib.rs b/op_crates/timers/lib.rs
new file mode 100644
index 000000000..047b6923c
--- /dev/null
+++ b/op_crates/timers/lib.rs
@@ -0,0 +1,165 @@
+// Copyright 2018-2021 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, cancel and await a single timer (or Delay, as Tokio
+//! calls it) for an entire Isolate. This is what is implemented here.
+
+use deno_core::error::AnyError;
+use deno_core::futures;
+use deno_core::futures::channel::oneshot;
+use deno_core::futures::FutureExt;
+use deno_core::futures::TryFutureExt;
+use deno_core::OpState;
+use deno_core::ZeroCopyBuf;
+use std::cell::RefCell;
+use std::future::Future;
+use std::pin::Pin;
+use std::rc::Rc;
+use std::thread::sleep;
+use std::time::Duration;
+use std::time::Instant;
+
+pub trait TimersPermission {
+  fn allow_hrtime(&mut self) -> bool;
+  fn check_unstable(&self, state: &OpState, api_name: &'static str);
+}
+
+pub fn init(rt: &mut deno_core::JsRuntime) {
+  rt.execute(
+    "deno:op_crates/timers/01_timers.js",
+    include_str!("01_timers.js"),
+  )
+  .unwrap();
+}
+
+pub type StartTime = Instant;
+
+type TimerFuture = Pin<Box<dyn Future<Output = Result<(), ()>>>>;
+
+#[derive(Default)]
+pub struct GlobalTimer {
+  tx: Option<oneshot::Sender<()>>,
+  pub future: Option<TimerFuture>,
+}
+
+impl GlobalTimer {
+  pub fn cancel(&mut self) {
+    if let Some(tx) = self.tx.take() {
+      tx.send(()).ok();
+    }
+  }
+
+  pub fn new_timeout(&mut self, deadline: Instant) {
+    if self.tx.is_some() {
+      self.cancel();
+    }
+    assert!(self.tx.is_none());
+    self.future.take();
+
+    let (tx, rx) = oneshot::channel();
+    self.tx = Some(tx);
+
+    let delay = tokio::time::sleep_until(deadline.into()).boxed_local();
+    let rx = rx
+      .map_err(|err| panic!("Unexpected error in receiving channel {:?}", err));
+
+    let fut = futures::future::select(delay, rx)
+      .then(|_| futures::future::ok(()))
+      .boxed_local();
+    self.future = Some(fut);
+  }
+}
+
+#[allow(clippy::unnecessary_wraps)]
+pub fn op_global_timer_stop(
+  state: &mut OpState,
+  _args: (),
+  _zero_copy: Option<ZeroCopyBuf>,
+) -> Result<(), AnyError> {
+  let global_timer = state.borrow_mut::<GlobalTimer>();
+  global_timer.cancel();
+  Ok(())
+}
+
+// Set up a timer that will be later awaited by JS promise.
+// It's a separate op, because canceling a timeout immediately
+// after setting it caused a race condition (because Tokio timeout)
+// might have been registered after next event loop tick.
+//
+// See https://github.com/denoland/deno/issues/7599 for more
+// details.
+#[allow(clippy::unnecessary_wraps)]
+pub fn op_global_timer_start(
+  state: &mut OpState,
+  timeout: u64,
+  _zero_copy: Option<ZeroCopyBuf>,
+) -> Result<(), AnyError> {
+  let deadline = Instant::now() + Duration::from_millis(timeout);
+  let global_timer = state.borrow_mut::<GlobalTimer>();
+  global_timer.new_timeout(deadline);
+  Ok(())
+}
+
+pub async fn op_global_timer(
+  state: Rc<RefCell<OpState>>,
+  _args: (),
+  _zero_copy: Option<ZeroCopyBuf>,
+) -> Result<(), AnyError> {
+  let maybe_timer_fut = {
+    let mut s = state.borrow_mut();
+    let global_timer = s.borrow_mut::<GlobalTimer>();
+    global_timer.future.take()
+  };
+  if let Some(timer_fut) = maybe_timer_fut {
+    let _ = timer_fut.await;
+  }
+  Ok(())
+}
+
+// Returns a milliseconds and nanoseconds subsec
+// since the start time of the deno runtime.
+// If the High precision flag is not set, the
+// nanoseconds are rounded on 2ms.
+#[allow(clippy::unnecessary_wraps)]
+pub fn op_now<TP>(
+  state: &mut OpState,
+  _argument: (),
+  _zero_copy: Option<ZeroCopyBuf>,
+) -> Result<f64, AnyError>
+where
+  TP: TimersPermission + 'static,
+{
+  let start_time = state.borrow::<StartTime>();
+  let seconds = start_time.elapsed().as_secs();
+  let mut subsec_nanos = start_time.elapsed().subsec_nanos() as f64;
+  let reduced_time_precision = 2_000_000.0; // 2ms in nanoseconds
+
+  // If the permission is not enabled
+  // Round the nano result on 2 milliseconds
+  // see: https://developer.mozilla.org/en-US/docs/Web/API/DOMHighResTimeStamp#Reduced_time_precision
+  if !state.borrow_mut::<TP>().allow_hrtime() {
+    subsec_nanos -= subsec_nanos % reduced_time_precision;
+  }
+
+  let result = (seconds * 1_000) as f64 + (subsec_nanos / 1_000_000.0);
+
+  Ok(result)
+}
+
+#[allow(clippy::unnecessary_wraps)]
+pub fn op_sleep_sync<TP>(
+  state: &mut OpState,
+  millis: u64,
+  _zero_copy: Option<ZeroCopyBuf>,
+) -> Result<(), AnyError>
+where
+  TP: TimersPermission + 'static,
+{
+  state.borrow::<TP>().check_unstable(state, "Deno.sleepSync");
+  sleep(Duration::from_millis(millis));
+  Ok(())
+}