RefCnt.hpp

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/* This file is part of Berserk Engine project                                    */
/* https://github.com/EgorOrachyov/Berserk                                        */
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/* Copyright (c) 2018 - 2021 Egor Orachyov                                        */
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#ifndef BERSERK_REFCNT_HPP
#define BERSERK_REFCNT_HPP
 
#include <core/Config.hpp>
 
#include <atomic>
#include <cassert>
 
BRK_NS_BEGIN
 
class RefCnt {
public:
    virtual ~RefCnt() {
#ifdef BERSERK_DEBUG
        assert(mRefs.load() == 0);
        mRefs.store(0);
#endif
    }
 
    bool IsUnique() const {
        return GetRefs() <= 1;
    }
 
    std::int32_t GetRefs() const {
        return mRefs.load(std::memory_order_relaxed);
    }
 
    std::int32_t AddRef() const {
        assert(GetRefs() >= 0);
        return mRefs.fetch_add(1);
    }
 
    std::int32_t RelRef() const {
        assert(GetRefs() > 0);
        auto refs = mRefs.fetch_sub(1);
 
        if (refs == 1) {
            // Was last reference
            // Destroy object and release memory
            Destroy();
        }
 
        return refs;
    }
 
protected:
    virtual void Destroy() const {
        // Use default delete to destroy object
        // and free used memory
        delete this;
    }
 
private:
    // This type of object after creation always has no references
    mutable std::atomic_int32_t mRefs{0};
};
 
template<typename T>
static inline T *AddRef(T *object) {
    assert(object);
    object->AddRef();
    return object;
}
 
template<typename T>
static inline T *SafeAddRef(T *object) {
    if (object)
        object->AddRef();
    return object;
}
 
template<typename T>
static inline void Unref(T *object) {
    if (object)
        object->RelRef();
}
 
BRK_NS_END
 
#endif//BERSERK_REFCNT_HPP