9a11ada5fc
Adds support for main-thread handling of JSMember during the atomic pause. Follow-ups for later: - Copy/Move/Heterogenous assignment - Write barrier - Atomic handling for concurrent processing. Bug: chromium:1056170 Change-Id: Ia9ac4599ca85cf7cc2d67066e89485744d7d56b6 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2289781 Commit-Queue: Michael Lippautz <mlippautz@chromium.org> Reviewed-by: Omer Katz <omerkatz@chromium.org> Reviewed-by: Anton Bikineev <bikineev@chromium.org> Reviewed-by: Ulan Degenbaev <ulan@chromium.org> Cr-Commit-Position: refs/heads/master@{#68813}
118 lines
2.9 KiB
C++
118 lines
2.9 KiB
C++
// Copyright 2020 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef INCLUDE_V8_CPPGC_H_
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#define INCLUDE_V8_CPPGC_H_
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#include "cppgc/visitor.h"
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#include "v8-internal.h" // NOLINT(build/include_directory)
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#include "v8.h" // NOLINT(build/include_directory)
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namespace v8 {
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class Isolate;
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template <typename T>
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class JSMember;
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namespace internal {
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class JSMemberBaseExtractor;
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// TODO(chromium:1056170): Provide implementation based on global handles.
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class JSMemberBase {
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public:
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/**
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* Returns true if the reference is empty, i.e., has not been assigned
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* object.
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*/
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bool IsEmpty() const { return val_ == kNullAddress; }
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/**
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* Clears the reference. IsEmpty() will return true after this call.
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*/
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V8_INLINE void Reset();
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private:
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static internal::Address New(v8::Isolate* isolate, internal::Address* object,
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internal::Address* slot);
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static void Delete(internal::Address* slot);
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JSMemberBase() = default;
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JSMemberBase(v8::Isolate* isolate, internal::Address* object)
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: val_(New(isolate, object, &this->val_)) {}
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internal::Address val_ = kNullAddress;
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template <typename T>
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friend class v8::JSMember;
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friend class v8::internal::JSMemberBaseExtractor;
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};
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void JSMemberBase::Reset() {
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if (IsEmpty()) return;
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Delete(reinterpret_cast<internal::Address*>(val_));
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val_ = kNullAddress;
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}
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} // namespace internal
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/**
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* A traced handle without destructor that clears the handle. The handle may
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* only be used in GarbageCollected objects and must be processed in a Trace()
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* method.
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*
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* TODO(chromium:1056170): Implementation.
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*/
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template <typename T>
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class JSMember : public internal::JSMemberBase {
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static_assert(std::is_base_of<v8::Value, T>::value,
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"JSMember only supports references to v8::Value");
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public:
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JSMember() = default;
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template <typename U,
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typename = std::enable_if_t<std::is_base_of<T, U>::value>>
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JSMember(Isolate* isolate, Local<U> that)
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: internal::JSMemberBase(isolate, that.val_) {}
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// Heterogeneous construction.
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// TODO(chromium:1056170): Implementation.
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template <typename U,
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typename = std::enable_if_t<std::is_base_of<T, U>::value>>
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JSMember(const JSMember<U>& other) {} // NOLINT
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};
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class JSVisitor : public cppgc::Visitor {
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public:
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explicit JSVisitor(cppgc::Visitor::Key key) : cppgc::Visitor(key) {}
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template <typename T>
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void Trace(const JSMember<T>& ref) {
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if (ref.IsEmpty()) return;
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Visit(ref);
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}
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protected:
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using cppgc::Visitor::Visit;
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virtual void Visit(const internal::JSMemberBase& ref) {}
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};
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} // namespace v8
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namespace cppgc {
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template <typename T>
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struct TraceTrait<v8::JSMember<T>> {
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static void Trace(Visitor* visitor, const v8::JSMember<T>* self) {
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static_cast<v8::JSVisitor*>(visitor)->Trace(*self);
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}
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};
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} // namespace cppgc
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#endif // INCLUDE_V8_CPPGC_H_
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