c++ 内存池

初始申请内存，将内存分为内存区，各个内存区以链表相连，每个内存区中又有内存块链表

#ifndef UNTITLED5_MEMORY_POOL_H
#define UNTITLED5_MEMORY_POOL_H
#include<stdint.h>
#include <mutex>
template<size_t BlockSize,size_t BlockNum =10>
class MemoryPool
{
public:
    MemoryPool()
    {
        std::lock_guard<std::mutex>lock(mtx);
        free_block_head=NULL;
        mem_chunk_head=NULL;
    }
    ~MemoryPool()
    {
        std::lock_guard<std::mutex> lk(mtx);
        MemChunk *p;
        while(mem_chunk_head)//循环链表删除内存区
        {
            p=mem_chunk_head->next;
            delete mem_chunk_head;
            mem_chunk_head= NULL;
            mem_chunk_head=p;
        }
    }
    void *allocate()//分配空间
    {
        std::lock_guard<std::mutex>lk(mtx);
        if(!free_block_head) {//首内存块为空
            MemChunk *new_chunk = new MemChunk;//申请一个内存区
            std::cout<< sizeof(FreeBlock)<<" "<<sizeof(MemChunk)<<std::endl;
            new_chunk->next = NULL;

            free_block_head = &(new_chunk->blocks[0]);

            for (int i = 1; i < BlockNum; i++) {
                new_chunk->blocks[i - 1].next = &(new_chunk->blocks[i]);//构建内存区中的内存块链表
            }
            new_chunk->blocks[BlockNum - 1].next = NULL;

            if (!mem_chunk_head) {//首内存区为空
                mem_chunk_head = new_chunk;
            } else {//不为空直接插入到首部内存区链表
                mem_chunk_head->next = new_chunk;
                mem_chunk_head = new_chunk;
            }
        }
            void *object_block=free_block_head;//取出首内存块
            free_block_head=free_block_head->next;
            return object_block;
    }
    void *allocate(size_t size)//申请多少字节内存
    {
        std::lock_guard<std::mutex>lk(mtx);
        int n=size/BlockSize;

        void *p=allocate();//返回首内存块地址
        for(int i=1;i<n;i++)
        {
            allocate();
        }
        return p;
    }
    void deallocate(void *p)//回收内存
    {
        std::lock_guard<std::mutex>lk(mtx);

        FreeBlock *block= static_cast<FreeBlock*>(p);
        block->next=free_block_head;
        free_block_head=block;
    }
private:
    struct FreeBlock//内存块
    {
        unsigned char data[BlockSize];
        FreeBlock *next;
    };
    FreeBlock *free_block_head;

    struct MemChunk//内存区
    {
        FreeBlock blocks[BlockNum];
        MemChunk *next;
    };
    MemChunk *mem_chunk_head;
    //thread safe
    std::mutex mtx;
    std::mutex array_mtx;
};
#endif //UNTITLED5_MEMORY_POOL_H

#include <iostream>
#include "memory_pool.h"
class MyObject
{
public:
    MyObject(int x):data(x)
    {

    }
    ~MyObject()
    {

    }
    int data;
    void *operator new(size_t size);
    void operator delete(void *p);
    void *operator new[](size_t size);
    void operator delete[](void *p);
};
MemoryPool<sizeof(MyObject),3>gMemPook;
void * MyObject::operator new(size_t  size)
{
    return gMemPook.allocate();
}
void MyObject::operator delete(void *p)
{
    gMemPook.deallocate(p);
}

int main() {
    MyObject *p1=new MyObject(1);
    MyObject *p2=new MyObject(2);
    std::cout << "p1 " << p1<<" "<<p1->data<<std::endl;
    std::cout << "p2 " << p2<<" "<<p2->data<<std::endl;
    delete p1;
    delete p2;
    return 0;
}

 

来源：https://www.cnblogs.com/liweiggg/p/11644358.html