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