Fix data races and leaks related to v8::Lockers

src/v8threads.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/api.h"
 #include "src/bootstrapper.h"
 #include "src/debug.h"
 #include "src/execution.h"
 #include "src/regexp-stack.h"
 #include "src/v8threads.h"
 
 namespace v8 {
 
 
+namespace {
+
 // Track whether this V8 instance has ever called v8::Locker. This allows the
 // API code to verify that the lock is always held when V8 is being entered.
-bool Locker::active_ = false;
+base::Atomic32 g_locker_was_ever_used_ = 0;
+
+}  // namespace
 
 
 // Once the Locker is initialized, the current thread will be guaranteed to have
 // the lock for a given isolate.
 void Locker::Initialize(v8::Isolate* isolate) {
   DCHECK(isolate != NULL);
   has_lock_= false;
   top_level_ = true;
   isolate_ = reinterpret_cast<i::Isolate*>(isolate);
   // Record that the Locker has been used at least once.
-  active_ = true;
+  base::NoBarrier_Store(&g_locker_was_ever_used_, 1);
   // Get the big lock if necessary.
   if (!isolate_->thread_manager()->IsLockedByCurrentThread()) {
     isolate_->thread_manager()->Lock();
     has_lock_ = true;
 
     // Make sure that V8 is initialized.  Archiving of threads interferes
     // with deserialization by adding additional root pointers, so we must
     // initialize here, before anyone can call ~Locker() or Unlocker().
     if (!isolate_->IsInitialized()) {
       isolate_->Enter();
@@ skipping 16 matching lines @@
 
 
 bool Locker::IsLocked(v8::Isolate* isolate) {
   DCHECK(isolate != NULL);
   i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
   return internal_isolate->thread_manager()->IsLockedByCurrentThread();
 }
 
 
 bool Locker::IsActive() {
-  return active_;
+  return !!base::NoBarrier_Load(&g_locker_was_ever_used_);
 }
 
 
 Locker::~Locker() {
   DCHECK(isolate_->thread_manager()->IsLockedByCurrentThread());
   if (has_lock_) {
     if (top_level_) {
       isolate_->thread_manager()->FreeThreadResources();
     } else {
       isolate_->thread_manager()->ArchiveThread();
@@ skipping 283 matching lines @@
        state = state->Next()) {
     if (thread_id.Equals(state->id())) {
       state->set_terminate_on_restore(true);
     }
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8