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// 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_