44143cfd14
Add docs for: - cppgc namespace (to have doxygen generate the namespace doc) - Heap - LivenessBroker Bug: chromium:1056170 Change-Id: I5e4664458b7209f4adebb4d5e7b5119c341f59a9 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2214834 Commit-Queue: Michael Lippautz <mlippautz@chromium.org> Reviewed-by: Omer Katz <omerkatz@chromium.org> Cr-Commit-Position: refs/heads/master@{#68015}
75 lines
2.1 KiB
C++
75 lines
2.1 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_CPPGC_LIVENESS_BROKER_H_
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#define INCLUDE_CPPGC_LIVENESS_BROKER_H_
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#include "cppgc/heap.h"
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#include "cppgc/member.h"
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#include "cppgc/trace-trait.h"
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#include "v8config.h" // NOLINT(build/include_directory)
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namespace cppgc {
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namespace internal {
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class LivenessBrokerFactory;
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} // namespace internal
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/**
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* The broker is passed to weak callbacks to allow (temporarily) querying
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* the liveness state of an object. References to non-live objects must be
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* cleared when IsHeapObjectAlive() returns false.
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*
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* \code
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* class GCedWithCustomWeakCallback final
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* : public GarbageCollected<GCedWithCustomWeakCallback> {
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* public:
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* UntracedMember<Bar> bar;
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*
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* void CustomWeakCallbackMethod(const LivenessBroker& broker) {
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* if (!broker.IsHeapObjectAlive(bar))
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* bar = nullptr;
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* }
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*
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* void Trace(cppgc::Visitor* visitor) const {
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* visitor->RegisterWeakCallbackMethod<
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* GCedWithCustomWeakCallback,
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* &GCedWithCustomWeakCallback::CustomWeakCallbackMethod>(this);
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* }
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* };
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* \endcode
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*/
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class V8_EXPORT LivenessBroker final {
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public:
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template <typename T>
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bool IsHeapObjectAlive(const T* object) const {
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return object &&
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IsHeapObjectAliveImpl(
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TraceTrait<T>::GetTraceDescriptor(object).base_object_payload);
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}
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template <typename T>
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bool IsHeapObjectAlive(const WeakMember<T>& weak_member) const {
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return (weak_member != kSentinelPointer) &&
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IsHeapObjectAlive<T>(weak_member.Get());
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}
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template <typename T>
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bool IsHeapObjectAlive(const UntracedMember<T>& untraced_member) const {
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return (untraced_member != kSentinelPointer) &&
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IsHeapObjectAlive<T>(untraced_member.Get());
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}
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private:
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LivenessBroker() = default;
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bool IsHeapObjectAliveImpl(const void*) const;
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friend class internal::LivenessBrokerFactory;
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};
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} // namespace cppgc
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#endif // INCLUDE_CPPGC_LIVENESS_BROKER_H_
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