AtomicUniquePtr.h

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#pragma once
 
 
template <typename T>
class cAtomicUniquePtr
{
public:
    static_assert(!std::is_array<T>::value, "cAtomicUniquePtr does not support arrays");
    DISALLOW_COPY_AND_ASSIGN(cAtomicUniquePtr);
 
    cAtomicUniquePtr() noexcept:
        m_Ptr(nullptr)
    {
    }
 
 
    cAtomicUniquePtr(std::unique_ptr<T> a_Ptr) noexcept:
        m_Ptr(a_Ptr.release())
    {
    }
 
    cAtomicUniquePtr & operator = (std::unique_ptr<T> a_Ptr) noexcept
    {
        store(std::move(a_Ptr));
        return *this;
    }
 
    ~cAtomicUniquePtr() noexcept
    {
        delete load();
    }
 
    operator T * () const noexcept
    {
        return load();
    }
 
    bool compare_exchange_weak(T *& a_Expected, std::unique_ptr<T> && a_Desired, std::memory_order a_Order = std::memory_order_seq_cst) noexcept
    {
        bool DidExchange = m_Ptr.compare_exchange_weak(a_Expected, a_Desired.get(), a_Order);
        if (DidExchange)
        {
            // Only release ownership from the caller if the exchange occurred
            a_Desired.release();
        }
        return DidExchange;
    }
 
    bool compare_exchange_strong(T *& a_Expected, std::unique_ptr<T> && a_Desired, std::memory_order a_Order = std::memory_order_seq_cst) noexcept
    {
        bool DidExchange = m_Ptr.compare_exchange_strong(a_Expected, a_Desired.get(), a_Order);
        if (DidExchange)
        {
            // Only release ownership from the caller if the exchange occurred
            a_Desired.release();
        }
        return DidExchange;
    }
 
    std::unique_ptr<T> exchange(std::unique_ptr<T> a_Ptr, std::memory_order a_Order = std::memory_order_seq_cst) noexcept
    {
        return std::unique_ptr<T>{ m_Ptr.exchange(a_Ptr.release(), a_Order) };
    }
 
    T * load(std::memory_order a_Order = std::memory_order_seq_cst) const noexcept
    {
        return m_Ptr.load(a_Order);
    }
 
    void store(std::unique_ptr<T> a_Ptr, std::memory_order a_Order = std::memory_order_seq_cst) noexcept
    {
        // Store new value and delete old value
        delete m_Ptr.exchange(a_Ptr.release(), a_Order);
    }
 
private:
    std::atomic<T*> m_Ptr;
};