CmRefCountable.h

// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//  * Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//  * Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//  * Neither the name of NVIDIA CORPORATION nor the names of its
//    contributors may be used to endorse or promote products derived
//    from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Copyright (c) 2008-2022 NVIDIA Corporation. All rights reserved.
// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.  
 
#ifndef CM_REFCOUNTABLE_H
#define CM_REFCOUNTABLE_H
 
#include "foundation/PxAssert.h"
#include "foundation/PxAtomic.h"
#include "foundation/PxAllocator.h"
#include "common/PxBase.h"
 
namespace physx
{
namespace Cm
{
    // PT: this is used to re-implement RefCountable using the ref-counter in PxBase, i.e. to dissociate
    // the RefCountable data from the RefCountable code. The goal is to be able to store the ref counter
    // in the padding bytes of PxBase, and also to avoid two v-table pointers in the class.
    class RefCountableExt : public PxRefCounted
    {
        public:
 
        RefCountableExt() : PxRefCounted(0, PxBaseFlags(0)) {}
 
        void    preExportDataReset()
        {
            mBuiltInRefCount = 1;
        }
 
        void    incRefCount()
        {
            volatile PxI32* val = reinterpret_cast<volatile PxI32*>(&mBuiltInRefCount);
            PxAtomicIncrement(val);
            // value better be greater than 1, or we've created a ref to an undefined object
            PX_ASSERT(mBuiltInRefCount>1);
        }
 
        void    decRefCount()
        {
            PX_ASSERT(mBuiltInRefCount>0);
            volatile PxI32* val = reinterpret_cast<volatile PxI32*>(&mBuiltInRefCount);
            if(physx::PxAtomicDecrement(val) == 0)
                onRefCountZero();
        }
 
        PX_FORCE_INLINE PxU32 getRefCount() const
        {
            return mBuiltInRefCount;
        }
    };
 
    PX_FORCE_INLINE void RefCountable_preExportDataReset(PxRefCounted& base)    { static_cast<RefCountableExt&>(base).preExportDataReset();         }
    PX_FORCE_INLINE void RefCountable_incRefCount(PxRefCounted& base)           { static_cast<RefCountableExt&>(base).incRefCount();                }
    PX_FORCE_INLINE void RefCountable_decRefCount(PxRefCounted& base)           { static_cast<RefCountableExt&>(base).decRefCount();                }
    PX_FORCE_INLINE PxU32 RefCountable_getRefCount(const PxRefCounted& base)    { return static_cast<const RefCountableExt&>(base).getRefCount();   }
 
    // simple thread-safe reference count
    // when the ref count is zero, the object is in an undefined state (pending delete)
 
    class RefCountable
    {
    //= ATTENTION! =====================================================================================
    // Changing the data layout of this class breaks the binary serialization format.  See comments for 
    // PX_BINARY_SERIAL_VERSION.  If a modification is required, please adjust the getBinaryMetaData 
    // function.  If the modification is made on a custom branch, please change PX_BINARY_SERIAL_VERSION
    // accordingly.
    //==================================================================================================
    public:
// PX_SERIALIZATION
        RefCountable(const PxEMPTY) { PX_ASSERT(mRefCount == 1); }
                void    preExportDataReset() { mRefCount = 1; }
        static  void    getBinaryMetaData(PxOutputStream& stream);
//~PX_SERIALIZATION
        explicit RefCountable(PxU32 initialCount = 1)
            : mRefCount(PxI32(initialCount))
        {
            PX_ASSERT(mRefCount!=0);
        }
 
        virtual ~RefCountable() {}
 
        virtual void onRefCountZero()
        {
            PX_DELETE_THIS;
        }
 
        void incRefCount()
        {
            physx::PxAtomicIncrement(&mRefCount);
            // value better be greater than 1, or we've created a ref to an undefined object
            PX_ASSERT(mRefCount>1);
        }
 
        void decRefCount()
        {
            PX_ASSERT(mRefCount>0);
            if(physx::PxAtomicDecrement(&mRefCount) == 0)
                onRefCountZero();
        }
 
        PX_FORCE_INLINE PxU32 getRefCount() const
        {
            return PxU32(mRefCount);
        }
    private:
        volatile PxI32 mRefCount;
    };
 
 
} // namespace Cm
 
}
 
#endif