C++简单实现一个内存池的分配

#include<iostream>#include<malloc.h>using namespace std;//C++实现一个简单的内存池class CMemPool{private://链表节点typedef struct _Node{struct _Node* prev;struct _Node* next;}Node;//内存池的首地址void* m_pMemBlockAdd;//已分配出去的内存节点Node* m_pAllocatedMemBlock;//未分配出去的内存节点Node* m_pFreeMemBlock;//内存单元个数int m_count;//内存单元大小（这里指总大小）int m_BlockSize;public:CMemPool(int count = 50, int size = 1024);~CMemPool();//分配内存void* Alloc(int size, bool useMemPool = true);//释放内存void Free(void* p);};CMemPool::CMemPool(int count, int size):m_pMemBlockAdd(NULL), m_pAllocatedMemBlock(NULL), m_pFreeMemBlock(NULL)   //除了内存空间大小，还有加上每个节点的两个指针,m_count(count), m_BlockSize(count*(size+sizeof(Node))){m_pMemBlockAdd = ::malloc(m_BlockSize);if (m_pMemBlockAdd != NULL){//将所有节点连接起来,刚开始的时候都是空闲的for (int i = 0; i<count; i++)    //将所有内存结点链接起来{//每个节点的起始位置Node *pCurUnit = (Node *)((char *)m_pMemBlockAdd + i*(size + sizeof(Node)));//这里采用的是头插法，双向单链表，不带头结点pCurUnit->prev = NULL;pCurUnit->next = m_pFreeMemBlock;if (NULL != m_pFreeMemBlock){m_pFreeMemBlock->prev = pCurUnit;}m_pFreeMemBlock = pCurUnit;}}}CMemPool::~CMemPool(){::free(m_pMemBlockAdd);}//分配内存void* CMemPool::Alloc(int size, bool useMemPool){if (size > m_BlockSize || useMemPool == false || m_pMemBlockAdd == NULL || m_pFreeMemBlock == NULL){//内存池中没有空闲的内存了，那么重新给分配内存，就不是从内存池中分配内存了return ::malloc(size);}//内存池中有空闲内存Node* r = m_pFreeMemBlock;//先从表中取出一个内存单元，放入已分配的内存链表中，并且返回该单元的内存地址m_pFreeMemBlock = r->next;if (m_pFreeMemBlock == NULL){m_pFreeMemBlock->prev = NULL;}r->next = m_pFreeMemBlock;if (m_pAllocatedMemBlock != NULL){m_pAllocatedMemBlock->prev = r;}m_pAllocatedMemBlock = r;return (void *)((char *)r + sizeof(Node));}//释放内存void CMemPool::Free(void* p){//p在内存池分配的内存中间if (m_pMemBlockAdd<p && p<(void *)((char *)m_pMemBlockAdd + m_BlockSize)){Node *pCurUnit = (Node *)((char *)p - sizeof(Node));m_pAllocatedMemBlock = pCurUnit->next;  //从已分配链表取出回收的内存单元，放入空闲链表中if (NULL != m_pAllocatedMemBlock){m_pAllocatedMemBlock->prev = NULL;}pCurUnit->next = m_pFreeMemBlock;if (NULL != m_pFreeMemBlock){m_pFreeMemBlock->prev = pCurUnit;}m_pFreeMemBlock = pCurUnit;}//如果不是在内存池中分配的直接销毁它else{free(p);}}