mir_server/sdk/srvlib/include/ObjectAllocator.hpp

#pragma once

/***********************************************************************
                               对象内存申请器

     仅适用于大量的小内存对象的申请优化，且对象是长时间使用而不需释放的场合★
                      ★！此内存管理器不是多线程安全的！★

   用于对连续的相同对象的小块内存申请进行优化。申请器只提供申请对象的功能并且能够将内存
 申请的效率进行最大化提升，不提供释放对象所占用内存的功能。所有对象所占用的内存将在申请
 器销毁时才被释放。

************************************************************************/
#include "ObjectAllocStat.hpp"
#include "Platform.h"

template <typename T>
class CObjectAllocator : public CObjectAllocatorStat
{
public:
//#ifdef _ENABLE_OBJ_COUNT_STATICS_
	typedef CObjectAllocatorStat Inherited;
//#endif

	//内存块描述结构，用于查询内存块信息
	struct DataBlockDesc
	{
		const char* lpBaseAddress;//内存块指针地址
		size_t dwBlockSize;		  //内存块大小
	};

private:
	//内存块链表节点
	struct DataBlock
	{
		T*			pFreePtr;	//指向空闲的对象
		T*			pEndPtr;	//指向对象内存块的结束
		DataBlock*	pPrev;
	}		*m_pDataBlock;

public:
	enum {
		AllocObjectCountOneTime = 1024
	};
	//申请属性指针
	T* allocObjects(const INT_PTR nCount = 1)
	{
		T* result;
		DataBlock *pBlock = m_pDataBlock;
		//尝试从当前内存块中申请nCount的对象，如果内存块中没有足够的对象，则向之前的内存块中查找是否具有足够的空闲对象
		if ( !pBlock || pBlock->pEndPtr - pBlock->pFreePtr < nCount )
		{
			//向之前的内存块中查找是否具有足够的空闲对象
			while (pBlock && (pBlock = pBlock->pPrev))
			{
				if ( pBlock->pEndPtr - pBlock->pFreePtr >= nCount )
					break;
			}
			//如果所有内存块中都没有足够的对象则申请新内存块
			if ( pBlock == NULL )
			{
				INT_PTR nAllocCount = __max(nCount, AllocObjectCountOneTime);
				pBlock = (DataBlock*)malloc(sizeof(DataBlock) + sizeof(T) * nAllocCount);
				memset(pBlock, 0, sizeof(DataBlock) + sizeof(T) * nAllocCount);
//#ifdef _ENABLE_OBJ_COUNT_STATICS_
				m_nAllocObjNum += nAllocCount;
//#endif
				pBlock->pFreePtr = (T*)(pBlock + 1);
				pBlock->pEndPtr = pBlock->pFreePtr + nAllocCount;
				pBlock->pPrev = m_pDataBlock;
				m_pDataBlock = pBlock;
			}
		}
		//返回对象指针
		result = pBlock->pFreePtr;
		pBlock->pFreePtr += nCount;
//#ifdef _ENABLE_OBJ_COUNT_STATICS_
		m_nUsedObjNum += nCount;
//#endif
		return result;
	}
	//获取内存块数量
	inline INT_PTR blockCount() const
	{
		INT_PTR result = 0;
		DataBlock *pBlock = m_pDataBlock;

		while (pBlock)
		{
			result++;
			pBlock = pBlock->pPrev;
		}
		return result;
	}
	/*
	* Comments: 枚举内存块描述信息
	* Param LPCVOID lpEnumKey: 上次枚举的返回值，作为枚举下一个的依据，第一次枚举此值必须为NULL。
	* Param DataBlockDesc & desc: 用于保存内存块描述的对象
	* @Return LPCVOID: 返回一个内存块枚举key指针，便于进行下次枚举。如果返回值为NULL则表示枚举结束
	*
	* ★★注意★★：枚举内存块描述的操作是倒叙进行的，第一个被枚举的内存块描述为左后一个内存块的描述！
	*
	* ★★示例代码★★：-------------------------------------------------
	*  LPCVOID lpEnumKey = NULL;
	*  CObjectAllocator<T>::DataBlockDesc desc;
	*  while (lpEnumKey = allocator.enumBlockDesc(lpEnumKey, desc))
	*  {
	*     printf("Memory Block Info { Address = %X, Size = %u }", 
	*	    desc.lpBaseAddress, desc.dwBlockSize);
	*  }
	* --------------------------------------------------------------
	*/
	inline LPCVOID enumBlockDesc(LPCVOID lpEnumKey, DataBlockDesc &desc) const 
	{
		DataBlock *pBlock = (DataBlock*)lpEnumKey;
		if (!pBlock) 
			pBlock = m_pDataBlock;
		else pBlock = pBlock->pPrev;

		if (pBlock)
		{
			desc.lpBaseAddress = ((const char*)pBlock) + sizeof(*pBlock);
			desc.dwBlockSize = pBlock->pEndPtr - desc.lpBaseAddress;
			return pBlock;
		}
		return NULL;
	}

//#ifdef _ENABLE_OBJ_COUNT_STATICS_
	CObjectAllocator(LPCTSTR lpszDesc = NULL) : Inherited(sizeof(T), CObjectAllocatorStat::enAT_ObjectAlloc, lpszDesc)
	{
		m_pDataBlock = NULL;
	}
/*
#else
	
	CObjectAllocator(LPCTSTR lpszDesc = NULL)
	{
		m_pDataBlock = NULL;
	}
#endif
*/

	~CObjectAllocator()
	{
		DataBlock *pBlock, *pPrev; 
		pBlock = m_pDataBlock;
		while (pBlock)
		{
			pPrev = pBlock->pPrev;
			free(pBlock);
			pBlock = pPrev;
		}
		m_pDataBlock = NULL;
	}

	inline CObjectAllocator& operator = (const CObjectAllocator &rhs)
	{

//#ifdef _ENABLE_OBJ_COUNT_STATICS_
		Inherited::operator=(rhs);
//#endif
		m_pDataBlock = rhs.m_pDataBlock;	
//#ifdef _ENABLE_OBJ_COUNT_STATICS_	
		
		((CObjectAllocatorStat*)(&rhs))->removeFromStat();
		Inherited::addToStat();
//#endif
		return *this;
	}

private:
	CObjectAllocator(const CObjectAllocator &rhs);
};