api: introduce SealHandleScope

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 0d0bf3f75a6a8d2e01e1d57ac006ff2b7b5cb1c1..3d112e6b93ba4c7265c9646043bca66c263d7ada 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -686,6 +686,34 @@ i::Object** EscapableHandleScope::Escape(i::Object** escape_value) {
 }
 
 
+SealHandleScope::SealHandleScope(Isolate* isolate) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  // We do not want to check the correct usage of the Locker class all over the
+  // place, so we do it only here: Without a HandleScope, an embedder can do
+  // almost nothing, so it is enough to check in this central place.
+  // We make an exception if the serializer is enabled, which means that the
+  // Isolate is exclusively used to create a snapshot.
+  Utils::ApiCheck(
+      !v8::Locker::IsActive() ||
+          internal_isolate->thread_manager()->IsLockedByCurrentThread() ||
+          internal_isolate->serializer_enabled(),
+      "HandleScope::HandleScope",

[Yang, 2015/03/10 12:52:32]

Please update this line to SealHandleScope.

+      "Entering the V8 API without proper locking in place");
+
+  isolate_ = internal_isolate;
+  i::HandleScopeData* current = internal_isolate->handle_scope_data();
+  level_ = current->level;
+  current->level = 0;
+}
+
+
+SealHandleScope::~SealHandleScope() {
+  i::HandleScopeData* current = isolate_->handle_scope_data();
+  DCHECK_EQ(0, current->level);
+  current->level = level_;
+}
+
+
 void Context::Enter() {
   i::Handle<i::Context> env = Utils::OpenHandle(this);
   i::Isolate* isolate = env->GetIsolate();