ReferenceCountedImpl.h

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//==============================================================================================
//  FILENAME    :   ReferenceCountedImpl.h
//  AUTHOR      :   vovechkin
//  CREATION    :   Dec 13, 2001
//  Copyright (C) MicroStrategy Incorporated 2001
//==============================================================================================
#ifndef MSynch_ReferenceCountedImpl_h
#define MSynch_ReferenceCountedImpl_h

#include "Base/Defines/Asserte.h"
#include "Synch/Synch/AtomicLong.h"
#include "Base/Interfaces/ReferenceCounted.h"

#ifdef _MSC_VER
#pragma warning(disable:4250) // 'class1' : inherits 'class2::member' via dominance
#endif

namespace MSynch
{
    template< class T = AtomicLong >
    class ReferenceCountedImpl:
        virtual public MBase::ReferenceCounted
    {
    public:
        // we have to initialize to 0 because class T may be 
        // a built-in type, without a constructor
        ReferenceCountedImpl():
            mnReferenceCounter(0)
        {
        }

        virtual void AddRef() const throw()
        {
            ++mnReferenceCounter;

            _ASSERTE(mnReferenceCounter > 0 && mnReferenceCounter < 100000);
        }

        virtual void Release() const throw()
        {
            // reference counter is corrupted
            _ASSERTE(mnReferenceCounter > 0 && mnReferenceCounter < 100000);

            if (mnReferenceCounter == 1)
            {
                // At this time we know that we are about to release 
                // the last strong reference to this object.

                // But before we do, we notify the object via a virtual
                // method, so that the object has a chance to drop its 
                // weak references (if any).
                ReferenceCountIsAboutToReachZero();
            }

            if (--mnReferenceCounter == 0)
            {
                // that was the last reference
                delete this;
            }
        }

        virtual void ReferenceCountIsAboutToReachZero() const throw()
        {
        }

        inline const T& GetReferenceCount() const throw()
        {
            return mnReferenceCounter;
        }

    private:
        mutable T mnReferenceCounter;
    };
}

#endif // MSynch_ReferenceCountedImpl_h