feat(ext/web): Request higher-resolution timer on Windows if user requests setTimeout w/short delay (#19149)

If a timer is requested with <=100ms resolution, request the high-res
timer. Since the default Windows timer period is 15ms, this means a
100ms timer could fire at 115ms (15% late). We assume that timers longer
than 100ms are a reasonable cutoff here.

The high-res timers on Windows are still limited. Unfortuntely this
means that our shortest duration 4ms timers can still be 25% late, but
without a more complex timer system or spinning on the clock itself,
we're somewhat bounded by the OS' scheduler itself.

1 files changed, 17 insertions, 1 deletions

diff --git a/ext/web/timers.rs b/ext/web/timers.rs
index 252cd4ad4..54e185abd 100644
--- a/ext/web/timers.rs
+++ b/ext/web/timers.rs
@@ -2,9 +2,9 @@
 
 //! This module helps deno implement timers and performance APIs.
 
+use crate::hr_timer_lock::hr_timer_lock;
 use deno_core::error::AnyError;
 use deno_core::op;
-
 use deno_core::CancelFuture;
 use deno_core::CancelHandle;
 use deno_core::OpState;
@@ -86,8 +86,24 @@ pub async fn op_sleep(
   rid: ResourceId,
 ) -> Result<bool, AnyError> {
   let handle = state.borrow().resource_table.get::<TimerHandle>(rid)?;
+
+  // If a timer is requested with <=100ms resolution, request the high-res timer. Since the default
+  // Windows timer period is 15ms, this means a 100ms timer could fire at 115ms (15% late). We assume that
+  // timers longer than 100ms are a reasonable cutoff here.
+
+  // The high-res timers on Windows are still limited. Unfortuntely this means that our shortest duration 4ms timers
+  // can still be 25% late, but without a more complex timer system or spinning on the clock itself, we're somewhat
+  // bounded by the OS' scheduler itself.
+  let _hr_timer_lock = if millis <= 100 {
+    Some(hr_timer_lock())
+  } else {
+    None
+  };
+
   let res = tokio::time::sleep(Duration::from_millis(millis))
     .or_cancel(handle.0.clone())
     .await;
+
+  // We release the high-res timer lock here, either by being cancelled or resolving.
   Ok(res.is_ok())
 }