UE4之智能指针：引用计数相关类_ue4 获取引用次数-优快云博客

本文链接：https://blog.youkuaiyun.com/JY_95/article/details/102057165

本文介绍了UE4中的智能指针实现，重点关注引用计数类，包括FSharedReferencer和FWeakReferencer。FSharedReferencer作为引用控制器的包装，用于跟踪对象的生存期，而FWeakReferencer则用于弱引用跟踪。内容涵盖了引用计数的构造、销毁以及FReferenceControllerOps的操作，阐述了如何通过增加和减少引用计数来管理对象生命周期。

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引用计数类

默认的Deleter:

template <typename Type>
struct DefaultDeleter
{
	FORCEINLINE void operator()(Type* Object) const
	{
		delete Object;
	}
};

引用计数的构造器, 分为带默认Deleter和自定义Deleter的版本 :

/** Creates a reference controller which just calls delete */
template <typename ObjectType>
inline FReferenceControllerBase* NewDefaultReferenceController(ObjectType* Object)
{
	return new TReferenceControllerWithDeleter<ObjectType, DefaultDeleter<ObjectType>>(Object, DefaultDeleter<ObjectType>());
}
/** Creates a custom reference controller with a specified deleter */
template <typename ObjectType, typename DeleterType>
inline FReferenceControllerBase* NewCustomReferenceController(ObjectType* Object, DeleterType&& Deleter)
{
	return new TReferenceControllerWithDeleter<ObjectType, typename TRemoveReference<DeleterType>::Type>(Object, Forward<DeleterType>(Deleter));
}

基类FReferenceControllerBase

class FReferenceControllerBase
{
public:
	// 这些引用计数器是32位值(而不是16位以节省内存)的主要原因是原子操作至少需要32位对象
	/* 对该对象的共享引用数. 当此计数达到零时,关联对象将被销毁(即使仍然存在弱引用)*/
	int32 SharedReferenceCount;

	/* 对该对象的弱引用数. 如果有任何共享引用, 那也算作一个弱引用 */
	int32 WeakReferenceCount;
private:
	FReferenceControllerBase( FReferenceControllerBase const& );
	FReferenceControllerBase& operator=( FReferenceControllerBase const& );
};

子类TReferenceControllerWithDeleter, 是实际上实例化的类, 继承自FReferenceControllerBase

template <typename ObjectType, typename DeleterType>
class TReferenceControllerWithDeleter : private DeleterType, public FReferenceControllerBase
{
public:
	virtual void DestroyObject() override
	{
		(*static_cast<DeleterType*>(this))(Object);
	}
private:
	/** The object associated with this reference counter.  */
	ObjectType* Object;
};

可以看到, 在DestroyObject里去释放引用的对象, 如果使用了默认的Deleter, 则直接delete Object.

操作类FReferen