fix(ext/http): Ensure Deno.serve works across --watch restarts (#18998)

Fixes #16699 and #18960 by ensuring that we release our HTTP
`spawn_local` tasks when the HTTP resource is dropped.

Because our cancel handle was being projected from the resource via
`RcMap`, the resource was never `Drop`ped. By splitting the handle out
into its own `Rc`, we can avoid keeping the resource alive and let it
drop to cancel everything.

1 files changed, 7 insertions, 0 deletions

diff --git a/cli/util/file_watcher.rs b/cli/util/file_watcher.rs
index 05415f2a6..1ad5e9ba0 100644
--- a/cli/util/file_watcher.rs
+++ b/cli/util/file_watcher.rs
@@ -304,6 +304,13 @@ where
   }
 
   loop {
+    // We may need to give the runtime a tick to settle, as cancellations may need to propagate
+    // to tasks. We choose yielding 10 times to the runtime as a decent heuristic. If watch tests
+    // start to fail, this may need to be increased.
+    for _ in 0..10 {
+      tokio::task::yield_now().await;
+    }
+
     let mut watcher = new_watcher(watcher_sender.clone())?;
     consume_paths_to_watch(&mut watcher, &mut paths_to_watch_receiver);