src: unify the top level resource in JS and C++

Use a shared object as the top level async resource in JS and C++ so
that when there is no active async resource, the same top level async
resource object is returned from
`async_hooks.executionAsyncResource()`.

Author: legendecas

lib/internal/async_hooks.js

@@ -79,7 +79,10 @@ const active_hooks = {
   tmp_fields: null,
 };
 
-const { registerDestroyHook } = async_wrap;
+const {
+  registerDestroyHook,
+  topLevelResource,
+} = async_wrap;
 const { enqueueMicrotask } = internalBinding('task_queue');
 const { resource_symbol, owner_symbol } = internalBinding('symbols');
 
@@ -137,8 +140,6 @@ function callbackTrampoline(asyncId, resource, cb, ...args) {
   return result;
 }
 
-const topLevelResource = {};
-
 function executionAsyncResource() {
   // Indicate to the native layer that this function is likely to be used,
   // in which case it will inform JS about the current async resource via
@@ -597,6 +598,7 @@ module.exports = {
   clearAsyncIdStack,
   hasAsyncIdStack,
   executionAsyncResource,
+  topLevelResource,
   // Internal Embedder API
   newAsyncId,
   getOrSetAsyncId,

src/async_wrap.cc

@@ -412,6 +412,9 @@ void AsyncWrap::CreatePerContextProperties(Local<Object> target,
                          "execution_async_resources",
                          env->async_hooks()->js_execution_async_resources());
 
+  FORCE_SET_TARGET_FIELD(
+      target, "topLevelResource", realm->async_hooks_top_level_resource());
+
   target->Set(context,
               env->async_ids_stack_string(),
               env->async_hooks()->async_ids_stack().GetJSArray()).Check();

src/env_properties.h

@@ -404,6 +404,7 @@
   V(async_hooks_destroy_function, v8::Function)                                \
   V(async_hooks_init_function, v8::Function)                                   \
   V(async_hooks_promise_resolve_function, v8::Function)                        \
+  V(async_hooks_top_level_resource, v8::Object)                                \
   V(buffer_prototype_object, v8::Object)                                       \
   V(crypto_key_object_constructor, v8::Function)                               \
   V(crypto_key_object_private_constructor, v8::Function)                       \

src/node.cc

@@ -311,8 +311,8 @@ std::optional<StartExecutionCallbackInfo> CallbackInfoFromArray(
 MaybeLocal<Value> StartExecution(Environment* env, StartExecutionCallback cb) {
   InternalCallbackScope callback_scope(
       env,
-      Object::New(env->isolate()),
-      { 1, 0 },
+      env->principal_realm()->async_hooks_top_level_resource(),
+      {1, 0},
       InternalCallbackScope::kSkipAsyncHooks);
 
   // Only snapshot builder or embedder applications set the

src/node_realm.cc

@@ -81,6 +81,9 @@ void Realm::CreateProperties() {
   Local<Object> process_object =
       node::CreateProcessObject(this).FromMaybe(Local<Object>());
   set_process_object(process_object);
+
+  set_async_hooks_top_level_resource(
+      Object::New(isolate_, v8::Null(isolate_), nullptr, nullptr, 0));
 }
 
 RealmSerializeInfo Realm::Serialize(SnapshotCreator* creator) {