CmFlushPool.h

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// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.  
 
#ifndef CM_FLUSH_POOL_H
#define CM_FLUSH_POOL_H
 
#include "foundation/Px.h"
#include "foundation/PxUserAllocated.h"
#include "foundation/PxBitUtils.h"
#include "foundation/PxMutex.h"
#include "foundation/PxArray.h"
 
/*
Pool used to allocate variable sized tasks. It's intended to be cleared after a short period (time step).
*/
 
namespace physx
{
namespace Cm
{
    static const PxU32 sSpareChunkCount = 2;
 
    class FlushPool
    {
        PX_NOCOPY(FlushPool)
    public:
        FlushPool(PxU32 chunkSize) : mChunks("FlushPoolChunk"), mChunkIndex(0), mOffset(0), mChunkSize(chunkSize)
        {
            mChunks.pushBack(static_cast<PxU8*>(PX_ALLOC(mChunkSize, "PxU8")));
        }
 
        ~FlushPool()
        {
            for (PxU32 i = 0; i < mChunks.size(); ++i)
                PX_FREE(mChunks[i]);
        }
 
        // alignment must be a power of two
        void* allocate(PxU32 size, PxU32 alignment=16)
        {
            PxMutex::ScopedLock lock(mMutex);
            return allocateNotThreadSafe(size, alignment);
        }
 
        // alignment must be a power of two
        void* allocateNotThreadSafe(PxU32 size, PxU32 alignment=16)
        {
            PX_ASSERT(PxIsPowerOfTwo(alignment));
            PX_ASSERT(size <= mChunkSize && !mChunks.empty());
            
            // padding for alignment
            size_t unalignedStart = size_t(mChunks[mChunkIndex]+mOffset);
            PxU32 pad = PxU32(((unalignedStart+alignment-1)&~(size_t(alignment)-1)) - unalignedStart);
 
            if (mOffset + size + pad > mChunkSize)
            {
                mChunkIndex++;
                mOffset = 0;
                if (mChunkIndex >= mChunks.size())
                    mChunks.pushBack(static_cast<PxU8*>(PX_ALLOC(mChunkSize, "PxU8")));
 
                // update padding to ensure new alloc is aligned
                unalignedStart = size_t(mChunks[mChunkIndex]);
                pad = PxU32(((unalignedStart+alignment-1)&~(size_t(alignment)-1)) - unalignedStart);
            }
 
            void* ptr = mChunks[mChunkIndex] + mOffset + pad;
            PX_ASSERT((size_t(ptr)&(size_t(alignment)-1)) == 0);
            mOffset += size + pad;
            return ptr;
        }
 
        void clear(PxU32 spareChunkCount = sSpareChunkCount)
        {
            PxMutex::ScopedLock lock(mMutex);
            
            clearNotThreadSafe(spareChunkCount);
        }
 
        void clearNotThreadSafe(PxU32 spareChunkCount = sSpareChunkCount)
        {
            PX_UNUSED(spareChunkCount);
 
            //release memory not used previously
            PxU32 targetSize = mChunkIndex+sSpareChunkCount;
            while (mChunks.size() > targetSize)
            {
                PxU8* ptr = mChunks.popBack();
                PX_FREE(ptr);
            }
 
            mChunkIndex = 0;
            mOffset = 0;
        }
 
        void resetNotThreadSafe()
        {
            PxU8* firstChunk = mChunks[0];
 
            for (PxU32 i = 1; i < mChunks.size(); ++i)
                PX_FREE(mChunks[i]);
 
            mChunks.clear();
            mChunks.pushBack(firstChunk);
            mChunkIndex = 0;
            mOffset = 0;
        }
 
        void lock()
        {
            mMutex.lock();
        }
 
        void unlock()
        {
            mMutex.unlock();    
        }
 
    private:
        PxMutex mMutex;
        PxArray<PxU8*> mChunks;
        PxU32 mChunkIndex;
        PxU32 mOffset;
        PxU32 mChunkSize;
    };
 
    
} // namespace Cm
 
}
 
#endif