prefinalizer.h File Reference

#include "cppgc/internal/compiler-specific.h"
#include "cppgc/liveness-broker.h"

Include dependency graph for prefinalizer.h:

Go to the source code of this file.

Data Structures
class	PrefinalizerRegistration

Namespaces
	cppgc
	cppgc::internal

Macros
#define	CPPGC_USING_PRE_FINALIZER(Class, PreFinalizer)

Macro Definition Documentation

CPPGC_USING_PRE_FINALIZER

#define CPPGC_USING_PRE_FINALIZER	(		Class,
			PreFinalizer
	)

Value:

 public:                                                                     \
  static void InvokePreFinalizer(void* object) {                             \
    static_assert(cppgc::IsGarbageCollectedOrMixinTypeV<Class>,              \
                  "Only garbage collected objects can have prefinalizers");  \
    Class* self = static_cast<Class*>(object);                               \
    self->PreFinalizer();                                                    \
  }                                                                          \
                                                                             \
 private:                                                                    \
  CPPGC_NO_UNIQUE_ADDRESS cppgc::internal::PrefinalizerRegistration          \
      prefinalizer_dummy_{this,                                              \
                          cppgc::TraceTrait<Class>::GetTraceDescriptor(this) \
                              .base_object_payload,                          \
                          Class::InvokePreFinalizer};                        \
  static_assert(true, "Force semicolon.")

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:

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;
};

Definition at line 56 of file prefinalizer.h.