o3de/Code/CryEngine/CryCommon/CryPool/Allocator.h

/*
* All or portions of this file Copyright (c) Amazon.com, Inc. or its affiliates or
* its licensors.
*
* For complete copyright and license terms please see the LICENSE at the root of this
* distribution (the "License"). All use of this software is governed by the License,
* or, if provided, by the license below or the license accompanying this file. Do not
* remove or modify any license notices. This file is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*
*/
// Original file Copyright Crytek GMBH or its affiliates, used under license.

#ifndef CRYINCLUDE_CRYPOOL_ALLOCATOR_H
#define CRYINCLUDE_CRYPOOL_ALLOCATOR_H
#pragma once


namespace NCryPoolAlloc
{
    template<class TPool, class TItem>
    class CFirstFit
        :   public TPool
    {
    public:
        ILINE                                           CFirstFit()
        {
        }

        template<class T>
        ILINE   T                                       Allocate(size_t Size, size_t Align = 1)
        {
            //fastpath?
            if (TPool::m_pEmpty &&   TPool::m_pEmpty->Available(Size, Align))
            {
                TItem* pItem    =   TPool::Split(TPool::m_pEmpty, Size, Align);
                if (!pItem)
                {
                    return 0;
                }
                pItem->InUse(Align);
                TPool::AllocatedMemory(pItem->MemSize());

                //not fully occupied empty space?
                TPool::m_pEmpty =   pItem != TPool::m_pEmpty ? TPool::m_pEmpty : 0;
                return TPool::Handle(pItem);
            }

            TItem* pBestItem;
            for (pBestItem = TPool::m_Items.First(); pBestItem; pBestItem = pBestItem->Next())
            {
                if (pBestItem->Available(Size, Align))                                              // && (!pBestItem || pItem->MemSize()<pBestItem->MemSize()))
                {
                    break;
                }
            }
            if (!pBestItem)
            {
                return 0;                                                   //out of mem
            }
            TItem* pItem    =   TPool::Split(pBestItem, Size, Align);
            if (!pItem)                                                 //no free node
            {
                return 0;
            }
            pItem->InUse(Align);
            TPool::AllocatedMemory(pItem->MemSize());

            //not fully occupied empty space?
            TPool::m_pEmpty =   pItem != pBestItem ? pBestItem : 0;
            return TPool::Handle(pItem);
        }
        template<class T>
        ILINE   bool                                Free(T Handle, bool ForceBoundsCheck = false)
        {
            return Handle ? TPool::Free(Handle, ForceBoundsCheck) : false;
        }
    };

    template<class TPool, class TItem>
    class CWorstFit
        :   public TPool
    {
    public:
        ILINE                                           CWorstFit()
        {
        }

        template<class T>
        ILINE   T                                       Allocate(size_t Size, size_t Align = 1)
        {
            TItem* pBestItem    =   0;
            for (TItem* pItem = TPool::m_Items.First(); pItem; pItem = pItem->Next())
            {
                if (pItem->IsFree() && (!pBestItem || pItem->MemSize() > pBestItem->MemSize()))
                {
                    pBestItem   =   pItem;
                }
            }
            if (!pBestItem || !pBestItem->Available(Size, Align))
            {
                return 0;                                                   //out of mem
            }
            TItem* pItem    =   Split(pBestItem, Size, Align);
            if (!pItem)                                                 //no free node
            {
                return 0;
            }
            pItem->InUse(Align);
            AllocatedMemory(pItem->MemSize());
            return Handle(pItem);
        }
    };

    template<class TPool, class TItem>
    class CBestFit
        :   public TPool
    {
    public:
        ILINE                                           CBestFit()
        {
        }

        template<class T>
        ILINE   T                                       Allocate(size_t Size, size_t Align = 1)
        {
            TItem* pBestItem    =   0;
            for (TItem* pItem = TPool::m_Items.First(); pItem; pItem = pItem->Next())
            {
                if ((!pBestItem || pItem->MemSize() < pBestItem->MemSize()) && pItem->Available(Size, Align))
                {
                    if (pItem->MemSize() == Size)
                    {
                        pItem->InUse(Align);
                        AllocatedMemory(pItem->MemSize());
                        return (T)Handle(pItem);
                    }
                    pBestItem   =   pItem;
                }
            }
            if (!pBestItem)
            {
                return 0;                                                   //out of mem
            }
            TItem* pItem    =   Split(pBestItem, Size, Align);
            if (!pItem)                                                 //no free node
            {
                return 0;
            }
            pItem->InUse(Align);
            AllocatedMemory(pItem->MemSize());
            return (T)Handle(pItem);
        }
    };


    template<class TAllocator>
    class CReallocator
        :   public TAllocator
    {
    public:

        template<class T>
        ILINE   bool                                Reallocate(T* pData, size_t Size, size_t Alignment)
        {
            //special cases
            if (!Size)                                                  //just free?
            {
                TAllocator::Free(*pData);
                *pData  =   0;
                return true;
            }

            if (!*pData)                                                //just alloc?
            {
                *pData  =   TAllocator::template Allocate<T>(Size, Alignment);
                return *pData != 0;
            }

            //same size, nothing to do at all?
            if (TAllocator::Item(*pData)->MemSize() == Size)
            {
                return true;
            }

            if (TAllocator::ReSize(pData, Size))
            {
                return true;
            }

            T pNewData  =   TAllocator::template Allocate<T>(Size, Alignment);
            if (!pNewData)
            {
                return false;
            }
            memcpy(TAllocator::template Resolve<uint8*>(pNewData),
                TAllocator::template Resolve<uint8*>(*pData), min(TAllocator::Item(*pData)->MemSize(), Size));
            TAllocator::template Free(*pData);
            *pData  =   pNewData;
            return true;
        }
    };
}


#endif // CRYINCLUDE_CRYPOOL_ALLOCATOR_H