src: exclude C++ SetImmediate() from count

There is no real reason to manage a count manually, given that
checking whether there are C++ callbacks is a single pointer
comparison.

This makes it easier to add other kinds of native C++ callbacks
that are managed in a similar way.

PR-URL: #31386
Refs: openjs-foundation/summit#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>

src/env-inl.h

@@ -242,14 +242,6 @@ inline bool ImmediateInfo::has_outstanding() const {
   return fields_[kHasOutstanding] == 1;
 }
 
-inline void ImmediateInfo::count_inc(uint32_t increment) {
-  fields_[kCount] += increment;
-}
-
-inline void ImmediateInfo::count_dec(uint32_t decrement) {
-  fields_[kCount] -= decrement;
-}
-
 inline void ImmediateInfo::ref_count_inc(uint32_t increment) {
   fields_[kRefCount] += increment;
 }
@@ -784,7 +776,6 @@ void Environment::CreateImmediate(Fn&& cb, bool ref) {
   auto callback = std::make_unique<NativeImmediateCallbackImpl<Fn>>(
       std::move(cb), ref);
   native_immediates_.Push(std::move(callback));
-  immediate_info()->count_inc(1);
 }
 
 template <typename Fn>

src/env.cc

@@ -665,7 +665,6 @@ void Environment::RunAndClearNativeImmediates(bool only_refed) {
   TraceEventScope trace_scope(TRACING_CATEGORY_NODE1(environment),
                               "RunAndClearNativeImmediates", this);
   size_t ref_count = 0;
-  size_t count = 0;
 
   NativeImmediateQueue queue;
   queue.ConcatMove(std::move(native_immediates_));
@@ -674,7 +673,6 @@ void Environment::RunAndClearNativeImmediates(bool only_refed) {
     TryCatchScope try_catch(this);
     DebugSealHandleScope seal_handle_scope(isolate());
     while (std::unique_ptr<NativeImmediateCallback> head = queue.Shift()) {
-      count++;
       if (head->is_refed())
         ref_count++;
 
@@ -692,9 +690,10 @@ void Environment::RunAndClearNativeImmediates(bool only_refed) {
   };
   while (queue.size() > 0 && drain_list()) {}
 
-  DCHECK_GE(immediate_info()->count(), count);
-  immediate_info()->count_dec(count);
   immediate_info()->ref_count_dec(ref_count);
+
+  if (immediate_info()->ref_count() == 0)
+    ToggleImmediateRef(false);
 }
 
 
@@ -780,15 +779,12 @@ void Environment::CheckImmediate(uv_check_t* handle) {
   TraceEventScope trace_scope(TRACING_CATEGORY_NODE1(environment),
                               "CheckImmediate", env);
 
-  if (env->immediate_info()->count() == 0)
-    return;
-
   HandleScope scope(env->isolate());
   Context::Scope context_scope(env->context());
 
   env->RunAndClearNativeImmediates();
 
-  if (!env->can_call_into_js())
+  if (env->immediate_info()->count() == 0 || !env->can_call_into_js())
     return;
 
   do {

src/env.h

@@ -736,8 +736,6 @@ class ImmediateInfo : public MemoryRetainer {
   inline uint32_t count() const;
   inline uint32_t ref_count() const;
   inline bool has_outstanding() const;
-  inline void count_inc(uint32_t increment);
-  inline void count_dec(uint32_t decrement);
   inline void ref_count_inc(uint32_t increment);
   inline void ref_count_dec(uint32_t decrement);