chore(ext/web): refactor timer ops before landing op sanitizer (#22435)

Splitting the sleep and interval ops allows us to detect an interval
timer. We also remove the use of the `op_async_void_deferred` call.

A future PR will be able to split the op sanitizer messages for timers
and intervals.

3 files changed, 28 insertions, 13 deletions

diff --git a/ext/web/02_timers.js b/ext/web/02_timers.js
index 2241e9614..8096c2ab5 100644
--- a/ext/web/02_timers.js
+++ b/ext/web/02_timers.js
@@ -4,8 +4,8 @@ import { core, primordials } from "ext:core/mod.js";
 import {
   op_now,
   op_sleep,
+  op_sleep_interval,
   op_timer_handle,
-  op_void_async_deferred,
 } from "ext:core/ops";
 const {
   ArrayPrototypePush,
@@ -193,6 +193,7 @@ function initializeTimer(
     task,
     timeout,
     timerInfo,
+    repeat,
   );
 
   return id;
@@ -220,19 +221,13 @@ const scheduledTimers = { head: null, tail: null };
  * after the timeout, if it hasn't been cancelled.
  * @param {number} millis
  * @param {{ cancelRid: number, isRef: boolean, promise: Promise<void> }} timerInfo
+ * @param {boolean} repeat
  */
-function runAfterTimeout(task, millis, timerInfo) {
+function runAfterTimeout(task, millis, timerInfo, repeat) {
   const cancelRid = timerInfo.cancelRid;
-  let sleepPromise;
-  // If this timeout is scheduled for 0ms it means we want it to run at the
-  // end of the event loop turn. There's no point in setting up a Tokio timer,
-  // since its lowest resolution is 1ms. Firing of a "void async" op is better
-  // in this case, because the timer will take closer to 0ms instead of >1ms.
-  if (millis === 0) {
-    sleepPromise = op_void_async_deferred();
-  } else {
-    sleepPromise = op_sleep(millis, cancelRid);
-  }
+  const sleepPromise = repeat
+    ? op_sleep_interval(millis, cancelRid)
+    : op_sleep(millis, cancelRid);
   timerInfo.promise = sleepPromise;
   if (!timerInfo.isRef) {
     core.unrefOpPromise(timerInfo.promise);
@@ -395,7 +390,8 @@ function unrefTimer(id) {
 // for that reason: it lets promises make forward progress but can
 // still starve other parts of the event loop.
 function defer(go) {
-  PromisePrototypeThen(op_void_async_deferred(), () => go());
+  // If we pass a delay of zero to op_sleep, it returns at the next event spin
+  PromisePrototypeThen(op_sleep(0, 0), () => go());
 }
 
 export {
diff --git a/ext/web/lib.rs b/ext/web/lib.rs
index 3defbd74e..0601aff24 100644
--- a/ext/web/lib.rs
+++ b/ext/web/lib.rs
@@ -52,6 +52,7 @@ pub use crate::message_port::MessagePort;
 
 use crate::timers::op_now;
 use crate::timers::op_sleep;
+use crate::timers::op_sleep_interval;
 use crate::timers::op_timer_handle;
 use crate::timers::StartTime;
 pub use crate::timers::TimersPermission;
@@ -86,6 +87,7 @@ deno_core::extension!(deno_web,
     op_now<P>,
     op_timer_handle,
     op_sleep,
+    op_sleep_interval,
     op_transfer_arraybuffer,
     stream_resource::op_readable_stream_resource_allocate,
     stream_resource::op_readable_stream_resource_allocate_sized,
diff --git a/ext/web/timers.rs b/ext/web/timers.rs
index f7a0167df..f01dcb860 100644
--- a/ext/web/timers.rs
+++ b/ext/web/timers.rs
@@ -75,6 +75,16 @@ pub fn op_timer_handle(state: &mut OpState) -> ResourceId {
     .add(TimerHandle(CancelHandle::new_rc()))
 }
 
+/// Bifurcate the op_sleep op into an interval one we can use for sanitization purposes.
+#[op2(async(lazy), fast)]
+pub async fn op_sleep_interval(
+  state: Rc<RefCell<OpState>>,
+  #[smi] millis: u64,
+  #[smi] rid: ResourceId,
+) -> Result<bool, AnyError> {
+  op_sleep::call(state, millis, rid).await
+}
+
 /// Waits asynchronously until either `millis` milliseconds have passed or the
 /// [`TimerHandle`] resource given by `rid` has been canceled.
 ///
@@ -85,6 +95,13 @@ pub async fn op_sleep(
   #[smi] millis: u64,
   #[smi] rid: ResourceId,
 ) -> Result<bool, AnyError> {
+  // If this timeout is scheduled for 0ms it means we want it to run at the
+  // end of the event loop turn. Since this is a lazy op, we can just return
+  // having already spun the event loop.
+  if millis == 0 {
+    return Ok(true);
+  }
+
   // If the timer is not present in the resource table it was cancelled before
   // this op was polled.
   let Ok(handle) = state.borrow().resource_table.get::<TimerHandle>(rid) else {