Make timers act like normal ops

This is in preperation for core integration.

8 files changed, 155 insertions, 105 deletions

diff --git a/js/dispatch.ts b/js/dispatch.ts
index 537291877..9dcd2f420 100644
--- a/js/dispatch.ts
+++ b/js/dispatch.ts
@@ -8,31 +8,20 @@ import * as util from "./util";
 let nextCmdId = 0;
 const promiseTable = new Map<number, util.Resolvable<msg.Base>>();
 
-let fireTimers: () => void;
-
-export function setFireTimersCallback(fn: () => void): void {
-  fireTimers = fn;
-}
-
 export function handleAsyncMsgFromRust(ui8: Uint8Array): void {
-  // If a the buffer is empty, recv() on the native side timed out and we
-  // did not receive a message.
-  if (ui8 && ui8.length) {
-    const bb = new flatbuffers.ByteBuffer(ui8);
-    const base = msg.Base.getRootAsBase(bb);
-    const cmdId = base.cmdId();
-    const promise = promiseTable.get(cmdId);
-    util.assert(promise != null, `Expecting promise in table. ${cmdId}`);
-    promiseTable.delete(cmdId);
-    const err = errors.maybeError(base);
-    if (err != null) {
-      promise!.reject(err);
-    } else {
-      promise!.resolve(base);
-    }
+  util.assert(ui8 != null && ui8.length > 0);
+  const bb = new flatbuffers.ByteBuffer(ui8);
+  const base = msg.Base.getRootAsBase(bb);
+  const cmdId = base.cmdId();
+  const promise = promiseTable.get(cmdId);
+  util.assert(promise != null, `Expecting promise in table. ${cmdId}`);
+  promiseTable.delete(cmdId);
+  const err = errors.maybeError(base);
+  if (err != null) {
+    promise!.reject(err);
+  } else {
+    promise!.resolve(base);
   }
-  // Fire timers that have become runnable.
-  fireTimers();
 }
 
 function sendInternal(
diff --git a/js/timers.ts b/js/timers.ts
index d06056cf2..4089d5f8b 100644
--- a/js/timers.ts
+++ b/js/timers.ts
@@ -2,7 +2,7 @@
 import { assert } from "./util";
 import * as msg from "gen/msg_generated";
 import * as flatbuffers from "./flatbuffers";
-import { sendSync, setFireTimersCallback } from "./dispatch";
+import { sendAsync, sendSync } from "./dispatch";
 
 interface Timer {
   id: number;
@@ -37,28 +37,39 @@ function getTime(): number {
   return now;
 }
 
-function setGlobalTimeout(due: number | null, now: number): void {
+function clearGlobalTimeout(): void {
+  const builder = flatbuffers.createBuilder();
+  msg.GlobalTimerStop.startGlobalTimerStop(builder);
+  const inner = msg.GlobalTimerStop.endGlobalTimerStop(builder);
+  globalTimeoutDue = null;
+  let res = sendSync(builder, msg.Any.GlobalTimerStop, inner);
+  assert(res == null);
+}
+
+async function setGlobalTimeout(due: number, now: number): Promise<void> {
   // Since JS and Rust don't use the same clock, pass the time to rust as a
   // relative time value. On the Rust side we'll turn that into an absolute
   // value again.
-  // Note that a negative time-out value stops the global timer.
-  let timeout;
-  if (due === null) {
-    timeout = -1;
-  } else {
-    timeout = due - now;
-    assert(timeout >= 0);
-  }
+  let timeout = due - now;
+  assert(timeout >= 0);
 
   // Send message to the backend.
   const builder = flatbuffers.createBuilder();
-  msg.SetTimeout.startSetTimeout(builder);
-  msg.SetTimeout.addTimeout(builder, timeout);
-  const inner = msg.SetTimeout.endSetTimeout(builder);
-  const res = sendSync(builder, msg.Any.SetTimeout, inner);
-  assert(res == null);
-  // Remember when when the global timer will fire.
+  msg.GlobalTimer.startGlobalTimer(builder);
+  msg.GlobalTimer.addTimeout(builder, timeout);
+  const inner = msg.GlobalTimer.endGlobalTimer(builder);
   globalTimeoutDue = due;
+  await sendAsync(builder, msg.Any.GlobalTimer, inner);
+  // eslint-disable-next-line @typescript-eslint/no-use-before-define
+  fireTimers();
+}
+
+function setOrClearGlobalTimeout(due: number | null, now: number): void {
+  if (due == null) {
+    clearGlobalTimeout();
+  } else {
+    setGlobalTimeout(due, now);
+  }
 }
 
 function schedule(timer: Timer, now: number): void {
@@ -75,7 +86,7 @@ function schedule(timer: Timer, now: number): void {
   // If the new timer is scheduled to fire before any timer that existed before,
   // update the global timeout to reflect this.
   if (globalTimeoutDue === null || globalTimeoutDue > timer.due) {
-    setGlobalTimeout(timer.due, now);
+    setOrClearGlobalTimeout(timer.due, now);
   }
 }
 
@@ -97,7 +108,7 @@ function unschedule(timer: Timer): void {
         nextTimerDue = Number(key);
         break;
       }
-      setGlobalTimeout(nextTimerDue, getTime());
+      setOrClearGlobalTimeout(nextTimerDue, getTime());
     }
   } else {
     // Multiple timers that are due at the same point in time.
@@ -162,9 +173,10 @@ function fireTimers(): void {
       Promise.resolve(timer).then(fire);
     }
   }
+
   // Update the global alarm to go off when the first-up timer that hasn't fired
   // yet is due.
-  setGlobalTimeout(nextTimerDue, now);
+  setOrClearGlobalTimeout(nextTimerDue, now);
 }
 
 export type Args = unknown[];
@@ -226,7 +238,7 @@ export function setInterval(
   return setTimer(cb, delay, args, true);
 }
 
-/** Clears a previously set timer by id. */
+/** Clears a previously set timer by id. AKA clearTimeout and clearInterval. */
 export function clearTimer(id: number): void {
   const timer = idMap.get(id);
   if (timer === undefined) {
@@ -237,7 +249,3 @@ export function clearTimer(id: number): void {
   unschedule(timer);
   idMap.delete(timer.id);
 }
-
-// Tell the dispatcher which function it should call to fire timers that are
-// due. This is done using a callback because circular imports are disallowed.
-setFireTimersCallback(fireTimers);
diff --git a/src/global_timer.rs b/src/global_timer.rs
new file mode 100644
index 000000000..eef70ddc2
--- /dev/null
+++ b/src/global_timer.rs
@@ -0,0 +1,49 @@
+// 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::tokio_util::panic_on_error;
+use futures::Future;
+use std::time::Instant;
+use tokio::sync::oneshot;
+use tokio::timer::Delay;
+
+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<Item = (), Error = ()> {
+    if self.tx.is_some() {
+      self.cancel();
+    }
+    assert!(self.tx.is_none());
+
+    let (tx, rx) = oneshot::channel();
+    self.tx = Some(tx);
+
+    let delay = panic_on_error(Delay::new(deadline));
+    let rx = panic_on_error(rx);
+
+    delay.select(rx).then(|_| Ok(()))
+  }
+}
diff --git a/src/isolate.rs b/src/isolate.rs
index d4f0f2539..8a77777d2 100644
--- a/src/isolate.rs
+++ b/src/isolate.rs
@@ -12,6 +12,7 @@ use crate::errors::DenoError;
 use crate::errors::DenoResult;
 use crate::errors::RustOrJsError;
 use crate::flags;
+use crate::global_timer::GlobalTimer;
 use crate::isolate_init::IsolateInit;
 use crate::js_errors::apply_source_map;
 use crate::libdeno;
@@ -35,8 +36,6 @@ use std::sync::mpsc;
 use std::sync::Arc;
 use std::sync::Mutex;
 use std::sync::{Once, ONCE_INIT};
-use std::time::Duration;
-use std::time::Instant;
 use tokio;
 
 // Buf represents a byte array returned from a "Op".
@@ -62,7 +61,6 @@ pub struct Isolate {
   rx: mpsc::Receiver<(usize, Buf)>,
   tx: mpsc::Sender<(usize, Buf)>,
   ntasks: Cell<i32>,
-  timeout_due: Cell<Option<Instant>>,
   pub modules: RefCell<Modules>,
   pub state: Arc<IsolateState>,
   pub permissions: Arc<DenoPermissions>,
@@ -83,6 +81,7 @@ pub struct IsolateState {
   pub flags: flags::DenoFlags,
   pub metrics: Metrics,
   pub worker_channels: Option<Mutex<WorkerChannels>>,
+  pub global_timer: Mutex<GlobalTimer>,
 }
 
 impl IsolateState {
@@ -100,6 +99,7 @@ impl IsolateState {
       flags,
       metrics: Metrics::default(),
       worker_channels: worker_channels.map(Mutex::new),
+      global_timer: Mutex::new(GlobalTimer::new()),
     }
   }
 
@@ -194,7 +194,6 @@ impl Isolate {
       rx,
       tx,
       ntasks: Cell::new(0),
-      timeout_due: Cell::new(None),
       modules: RefCell::new(Modules::new()),
       state,
       permissions: Arc::new(permissions),
@@ -223,16 +222,6 @@ impl Isolate {
   }
 
   #[inline]
-  pub fn get_timeout_due(&self) -> Option<Instant> {
-    self.timeout_due.clone().into_inner()
-  }
-
-  #[inline]
-  pub fn set_timeout_due(&self, inst: Option<Instant>) {
-    self.timeout_due.set(inst);
-  }
-
-  #[inline]
   pub fn check_read(&self, filename: &str) -> DenoResult<()> {
     self.permissions.check_read(filename)
   }
@@ -463,10 +452,9 @@ impl Isolate {
   pub fn event_loop(&self) -> Result<(), JSError> {
     // Main thread event loop.
     while !self.is_idle() {
-      match recv_deadline(&self.rx, self.get_timeout_due()) {
+      match self.rx.recv() {
         Ok((zero_copy_id, buf)) => self.complete_op(zero_copy_id, buf),
-        Err(mpsc::RecvTimeoutError::Timeout) => self.timeout(),
-        Err(e) => panic!("recv_deadline() failed: {:?}", e),
+        Err(e) => panic!("Isolate.rx.recv() failed: {:?}", e),
       }
       self.check_promise_errors();
       if let Some(err) = self.last_exception() {
@@ -495,7 +483,7 @@ impl Isolate {
 
   #[inline]
   fn is_idle(&self) -> bool {
-    self.ntasks.get() == 0 && self.get_timeout_due().is_none()
+    self.ntasks.get() == 0
   }
 }
 
@@ -596,28 +584,6 @@ extern "C" fn pre_dispatch(
   }
 }
 
-fn recv_deadline<T>(
-  rx: &mpsc::Receiver<T>,
-  maybe_due: Option<Instant>,
-) -> Result<T, mpsc::RecvTimeoutError> {
-  match maybe_due {
-    None => rx.recv().map_err(|e| e.into()),
-    Some(due) => {
-      // Subtracting two Instants causes a panic if the resulting duration
-      // would become negative. Avoid this.
-      let now = Instant::now();
-      let timeout = if due > now {
-        due - now
-      } else {
-        Duration::new(0, 0)
-      };
-      // TODO: use recv_deadline() instead of recv_timeout() when this
-      // feature becomes stable/available.
-      rx.recv_timeout(timeout)
-    }
-  }
-}
-
 #[cfg(test)]
 mod tests {
   use super::*;
diff --git a/src/main.rs b/src/main.rs
index 48d96b04a..7bafe5c3c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -14,6 +14,7 @@ pub mod deno_dir;
 pub mod errors;
 pub mod flags;
 mod fs;
+mod global_timer;
 mod http_body;
 mod http_util;
 pub mod isolate;
diff --git a/src/msg.fbs b/src/msg.fbs
index 4d54b185e..279264a45 100644
--- a/src/msg.fbs
+++ b/src/msg.fbs
@@ -16,6 +16,9 @@ union Any {
   FetchRes,
   FormatError,
   FormatErrorRes,
+  GlobalTimer,
+  GlobalTimerRes,
+  GlobalTimerStop,
   IsTTY,
   IsTTYRes,
   Listen,
@@ -55,7 +58,6 @@ union Any {
   RunStatusRes,
   Seek,
   SetEnv,
-  SetTimeout,
   Shutdown,
   Start,
   StartRes,
@@ -210,10 +212,14 @@ table Chdir {
   directory: string;
 }
 
-table SetTimeout {
+table GlobalTimer {
   timeout: int;
 }
 
+table GlobalTimerRes { }
+
+table GlobalTimerStop { }
+
 table Exit {
   code: int;
 }
diff --git a/src/ops.rs b/src/ops.rs
index f4ee2434e..17cb008db 100644
--- a/src/ops.rs
+++ b/src/ops.rs
@@ -80,13 +80,7 @@ pub fn dispatch(
   let inner_type = base.inner_type();
   let cmd_id = base.cmd_id();
 
-  let op: Box<Op> = if inner_type == msg::Any::SetTimeout {
-    // SetTimeout is an exceptional op: the global timeout field is part of the
-    // Isolate state (not the IsolateState state) and it must be updated on the
-    // main thread.
-    assert_eq!(is_sync, true);
-    op_set_timeout(isolate, &base, data)
-  } else {
+  let op: Box<Op> = {
     // Handle regular ops.
     let op_creator: OpCreator = match inner_type {
       msg::Any::Accept => op_accept,
@@ -101,6 +95,8 @@ pub fn dispatch(
       msg::Any::Fetch => op_fetch,
       msg::Any::FetchModuleMetaData => op_fetch_module_meta_data,
       msg::Any::FormatError => op_format_error,
+      msg::Any::GlobalTimer => op_global_timer,
+      msg::Any::GlobalTimerStop => op_global_timer_stop,
       msg::Any::IsTTY => op_is_tty,
       msg::Any::Listen => op_listen,
       msg::Any::MakeTempDir => op_make_temp_dir,
@@ -440,23 +436,50 @@ fn op_chdir(
   }()))
 }
 
-fn op_set_timeout(
+fn op_global_timer_stop(
   isolate: &Isolate,
   base: &msg::Base<'_>,
   data: libdeno::deno_buf,
 ) -> Box<Op> {
+  assert!(base.sync());
   assert_eq!(data.len(), 0);
-  let inner = base.inner_as_set_timeout().unwrap();
-  let val = inner.timeout();
-  let timeout_due = if val >= 0 {
-    Some(Instant::now() + Duration::from_millis(val as u64))
-  } else {
-    None
-  };
-  isolate.set_timeout_due(timeout_due);
+  let mut t = isolate.state.global_timer.lock().unwrap();
+  t.cancel();
   ok_future(empty_buf())
 }
 
+fn op_global_timer(
+  isolate: &Isolate,
+  base: &msg::Base<'_>,
+  data: libdeno::deno_buf,
+) -> Box<Op> {
+  assert!(!base.sync());
+  assert_eq!(data.len(), 0);
+  let cmd_id = base.cmd_id();
+  let inner = base.inner_as_global_timer().unwrap();
+  let val = inner.timeout();
+  assert!(val >= 0);
+
+  let mut t = isolate.state.global_timer.lock().unwrap();
+  let deadline = Instant::now() + Duration::from_millis(val as u64);
+  let f = t.new_timeout(deadline);
+
+  Box::new(f.then(move |_| {
+    let builder = &mut FlatBufferBuilder::new();
+    let inner =
+      msg::GlobalTimerRes::create(builder, &msg::GlobalTimerResArgs {});
+    Ok(serialize_response(
+      cmd_id,
+      builder,
+      msg::BaseArgs {
+        inner: Some(inner.as_union_value()),
+        inner_type: msg::Any::GlobalTimerRes,
+        ..Default::default()
+      },
+    ))
+  }))
+}
+
 fn op_set_env(
   isolate: &Isolate,
   base: &msg::Base<'_>,
diff --git a/src/tokio_util.rs b/src/tokio_util.rs
index 3dddff9c2..ef66f4610 100644
--- a/src/tokio_util.rs
+++ b/src/tokio_util.rs
@@ -122,3 +122,11 @@ where
     f()
   }
 }
+
+pub fn panic_on_error<I, E, F>(f: F) -> impl Future<Item = I, Error = ()>
+where
+  F: Future<Item = I, Error = E>,
+  E: std::fmt::Debug,
+{
+  f.map_err(|err| panic!("Future got unexpected error: {:?}", err))
+}