SimpleBuffer.h

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//==============================================================================================
//  FILENAME    :   SimpleBuffer.h
//  AUTHOR      :   ydong
//  CREATION    :   1/28/2013
//  Copyright (C) MicroStrategy Incorporated 2001
//  All Rights Reserved
//==============================================================================================
#ifndef MBase_SimpleBuffer_h
#define MBase_SimpleBuffer_h

#include <vector>

#include "Base/Base/Buffer.h"


namespace MBase 
{
    //No Lock, auto release memory when destructure.
    class SimpleBuffer : public Buffer
    {
    public:
        SimpleBuffer() :
        mBuffer(){}
        virtual void Delete() throw() {
            for(size_t i=0; i<mBuffer.size(); ++i)
                delete [] mBuffer[i].first;
            mBuffer.clear();
        }
        
        // Allocates a chunk of memory according to the size.
        // Any further memory request will be allocated from this chunk until the chunk is used up.
        // return true if success
        virtual bool Reserve(size_t iSize) { return false; }
        
        // Returns a pointer to the memory (equivalent of doing a new)
        // throws BufferException if buffer was previously locked
        // throws ContractManagerException (defined in BaseMemoryContract.h)
        virtual void* GetMem(size_t iSize) {
            unsigned char* lBuffer = new unsigned char[iSize];
            mBuffer.push_back(MemBlock(lBuffer, iSize));
            return lBuffer;
        }
        
        // returns the total memory reserved by the buffer, in KB
        virtual unsigned Int32 GetTotalMemSize() const { return -1; }
        
        // returns the total memory reserved AND used by the buffer, in KB
        virtual unsigned Int32 GetAllocMemSize() const { return -1; }
        
        //xfan. 4/13/09, TQMS 354241. Add new interface
        virtual unsigned Int64 GetTotalMemSizeInBytes() const { return -1; }
        virtual unsigned Int64 GetAllocMemSizeInBytes() const { return -1; }
        
        // Use this function to make the buffer "read-only"
        // when this function is called the memory contained by the
        // the buffer gets locked from writes
        // throws BufferException if unable to lock
        virtual void WriteLock() {}
        
        // set the maxium limit for the total allocated space size, if the size is over the limit,
        // the buffer.GetMem operation will throw an BufferException
        // it is currently to be used by SQL Engine only
        virtual void SetTotalAllocatedSpaceLimit(Int64 iLimit) {}
        
        typedef std::pair<unsigned char*, int> MemBlock;
        typedef std::vector<MemBlock> MemVec;
        ~SimpleBuffer() throw() {
            for(size_t i=0; i<mBuffer.size(); ++i)
                delete [] mBuffer[i].first;
            mBuffer.clear();
        }
    private:
        MemVec mBuffer;
    };
}

#endif // MBase_BufferImplementation_h