OmniPvdChunkAlloc.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 OMNI_PVD_CHUNK_ALLOC_H
#define OMNI_PVD_CHUNK_ALLOC_H
 
#include "foundation/PxUserAllocated.h"
 
// The usage reason for splitting the Chunk allocator into a ChunkPool and a
// ByteAllocator is so that similarly accessed objects get allocated next to each
// other within the same Chunk, which is managed by the ByteAllocator. The
// ChunkPool is basically just a resource pool. Not thread safe anything :-)
// Locking is bad mkkk...
 
// Usage example of setting up a ChunkPool, a ByteAllocator and allocating some
// bytes, for the lulz.
 
/*
    OmniPvdChunkPool pool;
    
    // set the individual Chunks to a size of 100k bytes
    pool.setChunkSize(100000);
    
    // all allocations must go through a ByteAllocator, so create one
    OmniPvdChunkByteAllocator allocator;
    
    // connect the ByteAllocator to the pool
    allocator.setPool(&pool); 
    
    // we allocate 100 bytes through the ByteAllocator
    unsigned char *someBytes=allocator.allocBytes(100);
*/
 
// Once we want to cleanup the allocations, return the Chunks to the ChunkPool,
// which is also done silently in the destructor of the ByteAllocator.
 
/*
    allocator.freeChunks();
*/
 
// Memory management warning! The ByteAllocator does not deallocate the Chunks,
// but must return the Chunks to the ChunkPool before going out of scope. The
// ChunkPool can only deallocate the Chunks that is has in its free Chunks list,
// so all ByteAllocators must either all go out of scope before the ChunkPool
// goes out of scope or the ByteAllocators must all call the function freeChunks
// before the ChunkPool goes out of scope.
 
class OmniPvdChunkElement
{
public:
    OmniPvdChunkElement();
    ~OmniPvdChunkElement();
    OmniPvdChunkElement*    mNextElement;
};
 
class OmniPvdChunk : public physx::PxUserAllocated
{
public:
    OmniPvdChunk();
    ~OmniPvdChunk();
 
    void            resetChunk(int nbrBytes);
    int             nbrBytesUSed();
 
    unsigned char*  mData;
    int             mNbrBytesAllocated;
    int             mNbrBytesFree;
    unsigned char*  mBytePtr;
    OmniPvdChunk*   mNextChunk;
};
 
class OmniPvdChunkList
{
public:
    OmniPvdChunkList();
    ~OmniPvdChunkList();
 
    void            resetList();
    void            appendList(OmniPvdChunkList* list);
    void            appendChunk(OmniPvdChunk* chunk);
    OmniPvdChunk*   removeFirst();
 
    OmniPvdChunk*   mFirstChunk;
    OmniPvdChunk*   mLastChunk;
    int             mNbrChunks;
};
 
class OmniPvdChunkPool
{
public:
    OmniPvdChunkPool();
    ~OmniPvdChunkPool();
 
    void                setChunkSize(int chunkSize);
    OmniPvdChunk*       getChunk();
 
    OmniPvdChunkList    mFreeChunks;
    int                 mChunkSize;
    int                 mNbrAllocatedChunks;
};
 
 
class OmniPvdChunkByteAllocator
{
public:
    OmniPvdChunkByteAllocator();
    ~OmniPvdChunkByteAllocator();
 
    OmniPvdChunkElement*    allocChunkElement(int totalStructSize);
    void                    setPool(OmniPvdChunkPool* pool);
    unsigned char*          allocBytes(int nbrBytes);
    void                    freeChunks();
 
    OmniPvdChunkList        mUsedChunks;
    OmniPvdChunkPool*       mPool;
};
 
#endif