fbxcontainerallocators.h

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/****************************************************************************************
 
   Copyright (C) 2015 Autodesk, Inc.
   All rights reserved.
 
   Use of this software is subject to the terms of the Autodesk license agreement
   provided at the time of installation or download, or which otherwise accompanies
   this software in either electronic or hard copy form.
 
****************************************************************************************/

#ifndef _FBXSDK_CORE_BASE_CONTAINER_ALLOCATORS_H_
#define _FBXSDK_CORE_BASE_CONTAINER_ALLOCATORS_H_

#include <fbxsdk/fbxsdk_def.h>

#include <fbxsdk/fbxsdk_nsbegin.h>

class FBXSDK_DLL FbxBaseAllocator
{
public:
    FbxBaseAllocator(const size_t pRecordSize) :
        mRecordSize(pRecordSize)
    {
    }

    void Reserve(const size_t /*pRecordCount*/)
    {
        // By default, ignore all preallocating requests.
    }

    void* AllocateRecords(const size_t pRecordCount=1)
    {
        return FbxMalloc(pRecordCount * mRecordSize);
    }

    void FreeMemory(void* pRecord)
    {
        FbxFree(pRecord);
    }

    size_t GetRecordSize() const
    {
        return mRecordSize;
    }

private:
    size_t mRecordSize;
};

class FbxHungryAllocator
{
public:
    FbxHungryAllocator(size_t pRecordSize) :
        mRecordSize(pRecordSize),
        mRecordPoolSize(0),
        mData(NULL)
    {
    }

    FbxHungryAllocator(const FbxHungryAllocator& pOther) :
        mRecordSize(pOther.mRecordSize),
        mRecordPoolSize(pOther.mRecordPoolSize),
        mData(NULL)
    {
    }

    ~FbxHungryAllocator()
    {
        MemoryBlock* lCurrent = mData;
        MemoryBlock* lNext = lCurrent ? lCurrent->mNextBlock : 0;
        while (lCurrent)
        {
            FbxDelete(lCurrent);
            lCurrent = lNext;
            lNext = lCurrent ? lCurrent->mNextBlock : 0;
        }
    }

    void Reserve(const size_t pRecordCount)
    {
        MemoryBlock* lMem = FbxNew< MemoryBlock >(pRecordCount* mRecordSize);
        lMem->mNextBlock = mData;
        mData = lMem;
        mRecordPoolSize += pRecordCount;
    }

    void* AllocateRecords(const size_t pRecordCount = 1)
    {
        MemoryBlock* lBlock = mData;
        void* lRecord = NULL;

        while( (lBlock != NULL) && ((lRecord = lBlock->GetChunk(pRecordCount * mRecordSize)) == NULL) )
        {
            lBlock = lBlock->mNextBlock;
        }

        if( lRecord == NULL )
        {
            size_t lNumRecordToAllocate = mRecordPoolSize / 8 == 0 ? 2 : mRecordPoolSize / 8;
            if( lNumRecordToAllocate < pRecordCount )
            {
                lNumRecordToAllocate = pRecordCount;
            }
            Reserve(lNumRecordToAllocate);
            lRecord = AllocateRecords(pRecordCount);
        }
        return lRecord;
    }

    void FreeMemory(void* /*pRecord*/)
    {
        // "Hungry": release memory only when the allocator is destroyed.
    }

    size_t GetRecordSize() const
    {
        return mRecordSize;
    }

    FbxHungryAllocator& operator=(const FbxHungryAllocator& pOther)
    {
        if( this != &pOther )
        {
            // The next call to AllocateRecords() may skip over currently reserved
            // records if the size changes drastically, but otherwise GetChunk()
            // is size-oblivious.
            if( mRecordSize < pOther.mRecordSize )
            {
                mRecordPoolSize = 0;
            }

            mRecordSize = pOther.mRecordSize;
        }
        return(*this);
    }

private:
    class MemoryBlock
    {
    public:
        MemoryBlock(size_t pSize) :
            mNextBlock(NULL),
            mData(NULL),
            mFreeData(NULL),
            mEnd(NULL)
        {
            mData = FbxMalloc(pSize);
            mFreeData = mData;
            mEnd = reinterpret_cast<char*>(mData) + pSize;
        }

        ~MemoryBlock()
        {
            FbxFree(mData);
        }

        void* GetChunk(const size_t pSize)
        {
            if( reinterpret_cast<char*>(mFreeData) + pSize < mEnd )
            {
                void* lChunk = mFreeData;
                mFreeData = reinterpret_cast<char*>(mFreeData) + pSize;
                return lChunk;
            }
            return NULL;
        }

        MemoryBlock*    mNextBlock;
        void*           mData;
        void*           mFreeData;
        void*           mEnd;
    };

    size_t          mRecordSize;
    size_t          mRecordPoolSize;
    MemoryBlock*    mData;
};

#include <fbxsdk/fbxsdk_nsend.h>

#endif /* _FBXSDK_CORE_BASE_CONTAINER_ALLOCATORS_H_ */