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Edit File: prefinalizer.h
// Copyright 2020 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. #ifndef INCLUDE_CPPGC_PREFINALIZER_H_ #define INCLUDE_CPPGC_PREFINALIZER_H_ #include "cppgc/internal/compiler-specific.h" #include "cppgc/liveness-broker.h" namespace cppgc { namespace internal { class V8_EXPORT PrefinalizerRegistration final { public: using Callback = bool (*)(const cppgc::LivenessBroker&, void*); PrefinalizerRegistration(void*, Callback); void* operator new(size_t, void* location) = delete; void* operator new(size_t) = delete; }; } // namespace internal /** * Macro must be used in the private section of `Class` and registers a * prefinalization callback `void Class::PreFinalizer()`. The callback is * invoked on garbage collection after the collector has found an object to be * dead. * * Callback properties: * - The callback is invoked before a possible destructor for the corresponding * object. * - The callback may access the whole object graph, irrespective of whether * objects are considered dead or alive. * - The callback is invoked on the same thread as the object was created on. * * Example: * \code * class WithPrefinalizer : public GarbageCollected<WithPrefinalizer> { * CPPGC_USING_PRE_FINALIZER(WithPrefinalizer, Dispose); * * public: * void Trace(Visitor*) const {} * void Dispose() { prefinalizer_called = true; } * ~WithPrefinalizer() { * // prefinalizer_called == true * } * private: * bool prefinalizer_called = false; * }; * \endcode */ #define CPPGC_USING_PRE_FINALIZER(Class, PreFinalizer) \ public: \ static bool InvokePreFinalizer(const cppgc::LivenessBroker& liveness_broker, \ void* object) { \ static_assert(cppgc::IsGarbageCollectedOrMixinTypeV<Class>, \ "Only garbage collected objects can have prefinalizers"); \ Class* self = static_cast<Class*>(object); \ if (liveness_broker.IsHeapObjectAlive(self)) return false; \ self->PreFinalizer(); \ return true; \ } \ \ private: \ CPPGC_NO_UNIQUE_ADDRESS cppgc::internal::PrefinalizerRegistration \ prefinalizer_dummy_{this, Class::InvokePreFinalizer}; \ static_assert(true, "Force semicolon.") } // namespace cppgc #endif // INCLUDE_CPPGC_PREFINALIZER_H_