src: remove AsyncRequest

Remove `AsyncRequest` from the source code, and replace its
usage with threadsafe `SetImmediate()` calls. This has the
advantage of being able to pass in any function, rather than
one that is defined when the `AsyncRequest` is “installed”.

This necessitates two changes:

- The stopping flag (which was only used in one case and ignored
  in the other) is now a direct member of the `Environment` class.
- Workers no longer have their own libuv handles, requiring
  manual management of their libuv ref count.

As a drive-by fix, the `can_call_into_js` variable was turned
into an atomic variable. While there have been no bug reports,
the flag is set from `Stop(env)` calls, which are supposed to
be possible from any thread.

PR-URL: https://github.com/nodejs/node/pull/31386
Refs: https://github.com/openjs-foundation/summit/pull/240
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

1 files changed, 2 insertions, 3 deletions

diff --git a/src/node_worker.h b/src/node_worker.h
index 7b1311734a2..632644202a5 100644
--- a/src/node_worker.h
+++ b/src/node_worker.h
@@ -41,7 +41,6 @@ class Worker : public AsyncWrap {
 
   void MemoryInfo(MemoryTracker* tracker) const override {
     tracker->TrackField("parent_port", parent_port_);
-    tracker->TrackInlineField(&on_thread_finished_, "on_thread_finished_");
   }
 
   SET_MEMORY_INFO_NAME(Worker)
@@ -107,14 +106,14 @@ class Worker : public AsyncWrap {
   // instance refers to it via its [kPort] property.
   MessagePort* parent_port_ = nullptr;
 
-  AsyncRequest on_thread_finished_;
-
   // A raw flag that is used by creator and worker threads to
   // sync up on pre-mature termination of worker  - while in the
   // warmup phase.  Once the worker is fully warmed up, use the
   // async handle of the worker's Environment for the same purpose.
   bool stopped_ = true;
 
+  bool has_ref_ = true;
+
   // The real Environment of the worker object. It has a lesser
   // lifespan than the worker object itself - comes to life
   // when the worker thread creates a new Environment, and gets