ref counting base class

class AIRefCount { private: mutable std::atomic<int> m_count; public: friend void intrusive_ptr_add_ref(AIRefCount const* ptr) { ptr->m_count.fetch_add(1, std::memory_order_relaxed); } friend void intrusive_ptr_release(AIRefCount const* ptr) { if (ptr->m_count.fetch_sub(1, std::memory_order_release) == 1) { std::atomic_thread_fence(std::memory_order_acquire); delete ptr; } } protected: AIRefCount() : m_count(0) { } AIRefCount(AIRefCount const&) : m_count(0) { } AIRefCount& operator=(AIRefCount const&) { return *this; } virtual ~AIRefCount() { } void swap(AIRefCount&) { } public: bool unique() const { return std::atomic_load_explicit(&m_count, std::memory_order_relaxed) == 1; } int count() const { return m_count; } };