AuroraMiddleware/v8
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heap: Use atomic writes in TracedReference.

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Bug: chromium:1108537
Change-Id: I82a64d57432b7e0854a3787f309c85477d37f701
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2327910
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69142}
This commit is contained in:
Omer Katz 2020-07-30 11:29:05 +02:00 committed by Commit Bot
parent e8c8ba9a13
commit af92046ad3
1 changed files with 28 additions and 4 deletions
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32
include/v8.h
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@ -904,6 +904,23 @@ class TracedReferenceBase {
const_cast<TracedReferenceBase<T>&>(*this));
}
protected:
/**
* Update this reference in a thread-safe way
*/
void SetSlotThreadSafe(T* new_val) {
reinterpret_cast<std::atomic<T*>*>(&val_)->store(new_val,
std::memory_order_relaxed);
}
/**
* Get this reference in a thread-safe way
*/
T* GetSlotThreadSafe() {
return reinterpret_cast<std::atomic<T*>*>(&val_)->load(
std::memory_order_relaxed);
}
private:
enum DestructionMode { kWithDestructor, kWithoutDestructor };
@ -1156,6 +1173,12 @@ class TracedReference : public TracedReferenceBase<T> {
return reinterpret_cast<TracedReference<S>&>(
const_cast<TracedReference<T>&>(*this));
}
/**
* Returns true if this TracedReference is empty, i.e., has not been
* assigned an object. This version of IsEmpty is thread-safe.
*/
bool IsEmptyThreadSafe() const { return this->GetSlotThreadSafe(); }
};
/**
@ -10957,7 +10980,7 @@ template <class T>
void TracedReferenceBase<T>::Reset() {
if (IsEmpty()) return;
V8::DisposeTracedGlobal(reinterpret_cast<internal::Address*>(val_));
val_ = nullptr;
SetSlotThreadSafe(nullptr);
}
template <class T>
@ -11013,10 +11036,11 @@ template <class T>
template <class S>
void TracedReference<T>::Reset(Isolate* isolate, const Local<S>& other) {
static_assert(std::is_base_of<T, S>::value, "type check");
Reset();
this->Reset();
if (other.IsEmpty()) return;
this->val_ = this->New(isolate, other.val_, &this->val_,
TracedReferenceBase<T>::kWithoutDestructor);
this->SetSlotThreadSafe(
this->New(isolate, other.val_, &this->val_,
TracedReferenceBase<T>::kWithoutDestructor));
}
template <class T>