[+] Safepoint parking apis

[+] Noted extension APIs
(private)
[+] IsolateSafepoint::NotifyParkEx
[+] IsolateSafepoint::NotifyUnpark
[*] Continued hacky bug fix as """described""" below

-------------------------------------------------------------------------------------------------
Last aurora commit: 7c599206 continued

"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
#	src/heap/safepoint.cc
-----------
[-] (USE AFTER FREE) quick hack: removing a mutex guard on shared RemoveClient to temporarily mitigate a crash on deinit
-----------
well, this is fucking dumb. i think someone at google also figured out this can lead to crashing. their solution: remove the mutex with a call to AssertActive.
considering my issue was related to a dead context with everything else alive, i dont want to find out what that AssertActive is doing. reverting v8 change.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""

3172b30fe4 - Dominik Inführ, and Michael Lippautz

Fuck safety for now. The entire file will be different in 3 months time, anyway. I just want my software to actually fucking work.

src/api/api.cc

@@ -1127,20 +1127,41 @@ bool Data::IsFunctionTemplate() const {
 
 bool Data::IsContext() const { return Utils::OpenHandle(this)->IsContext(); }
 
-size_t GetCPUFeatureMask() {
+// Reece:
+V8_EXPORT size_t GetCPUFeatureMask() {
   return internal::CpuFeatures::SupportedFeatures();
 }
 
-size_t GetCPUFeatureMaskRescan() {
+// Reece:
+V8_EXPORT size_t GetCPUFeatureMaskRescan() {
   internal::CpuFeatures::initialized_ = 0;
   internal::CpuFeatures::supported_ = 0;
   return internal::CpuFeatures::SupportedFeatures();
 }
 
-void SetCPUFeatureMask(size_t features) {
+// Reece:
+V8_EXPORT void SetCPUFeatureMask(size_t features) {
   internal::CpuFeatures::supported_ = features;
 }
 
+// Reece:
+V8_EXPORT void Safepoint(v8::Isolate* pIsolate) {
+  reinterpret_cast<i::Isolate*>(pIsolate)
+      ->heap()
+      ->main_thread_local_heap()
+      ->Safepoint();
+}
+
+// Reece:
+V8_EXPORT void SafepointParkIsolate(v8::Isolate* pIsolate) {
+  reinterpret_cast<i::Isolate*>(pIsolate)->heap()->safepoint()->NotifyParkEx();
+}
+
+// Reece:
+V8_EXPORT void SafepointUnparkIsolate(v8::Isolate* pIsolate) {
+  reinterpret_cast<i::Isolate*>(pIsolate)->heap()->safepoint()->NotifyUnpark();
+}
+
 void Context::Enter() {
   i::DisallowGarbageCollection no_gc;
   i::Context env = *Utils::OpenHandle(this);
@@ -2703,6 +2724,7 @@ MaybeLocal<UnboundScript> ScriptCompiler::CompileUnboundScript(
   return CompileUnboundInternal(v8_isolate, source, options, no_cache_reason);
 }
 
+// Reece:
 MaybeLocal<v8::Value> ScriptCompiler::EvaluateGlobal(
     v8::Isolate* isolate, v8::Local<v8::String> source,
     bool repl) {
@@ -5445,6 +5467,7 @@ MaybeLocal<Object> Function::NewInstanceWithSideEffectType(
   RETURN_ESCAPED(result);
 }
 
+// Reece:
 MaybeLocal<Function> Function::Bind(v8::Local<v8::Object> that,
                                     v8::Local<v8::Array> bound_args) {
   i::Handle<i::JSReceiver> self;
@@ -6053,6 +6076,7 @@ bool v8::String::IsExternalOneByte() const {
   return false;
 }
 
+// Reece:
 v8::Local<v8::String> v8::String::GloballyInternalize() {
   i::DisallowGarbageCollection no_gc;
   i::Handle<i::String> str = Utils::OpenHandle(this);

src/heap/safepoint.cc

@@ -206,6 +206,10 @@ void IsolateSafepoint::WaitInUnpark() { barrier_.WaitInUnpark(); }
 
 void IsolateSafepoint::NotifyPark() { barrier_.NotifyPark(); }
 
+void IsolateSafepoint::NotifyParkEx() { barrier_.NotifyParkEx(); }
+
+void IsolateSafepoint::NotifyUnpark() { barrier_.NotifyUnpark(); }
+
 void IsolateSafepoint::WaitUntilRunningThreadsInSafepoint(
     const PerClientSafepointData* client_data) {
   barrier_.WaitUntilRunningThreadsInSafepoint(client_data->running());
@@ -243,6 +247,19 @@ void IsolateSafepoint::Barrier::NotifyPark() {
   cv_stopped_.NotifyOne();
 }
 
+void IsolateSafepoint::Barrier::NotifyParkEx() {
+  base::MutexGuard guard(&mutex_);
+  armed_ = true;
+  stopped_++;
+  cv_stopped_.NotifyOne();
+}
+
+void IsolateSafepoint::Barrier::NotifyUnpark() {
+  base::MutexGuard guard(&mutex_);
+  stopped_--;
+  cv_stopped_.NotifyOne();
+}
+
 void IsolateSafepoint::Barrier::WaitInSafepoint() {
   base::MutexGuard guard(&mutex_);
   CHECK(IsArmed());

src/heap/safepoint.h

@@ -43,6 +43,18 @@ class IsolateSafepoint final {
 
   V8_EXPORT_PRIVATE void AssertMainThreadIsOnlyThread();
 
+  // Wait until unpark operation is safe again.
+  void WaitInUnpark();
+
+  // Enter the safepoint from a running thread.
+  void WaitInSafepoint();
+
+  // Running thread reached a safepoint by parking itself.
+  void NotifyPark();
+  void NotifyParkEx();
+  void NotifyUnpark();
+
+
  private:
   class Barrier {
     base::Mutex mutex_;
@@ -57,26 +69,20 @@ class IsolateSafepoint final {
    public:
     Barrier() : armed_(false), stopped_(0) {}
 
-    void Arm();
-    void Disarm();
     void WaitUntilRunningThreadsInSafepoint(size_t running);
 
+    void Arm();
+
+    void Disarm();
     void WaitInSafepoint();
     void WaitInUnpark();
+    void NotifyUnpark();
+    void NotifyParkEx();
     void NotifyPark();
   };
 
   enum class IncludeMainThread { kYes, kNo };
 
-  // Wait until unpark operation is safe again.
-  void WaitInUnpark();
-
-  // Enter the safepoint from a running thread.
-  void WaitInSafepoint();
-
-  // Running thread reached a safepoint by parking itself.
-  void NotifyPark();
-
   // Methods for entering/leaving local safepoint scopes.
   void EnterLocalSafepointScope();
   void LeaveLocalSafepointScope();