一个简易共享内存池的实现

线程不安全

my_mem_pool.h

/*
  realize my own memory pool
*/
#include <iostream>
#include <list>
#include <cstdio>
#include <cstdlib>
#include <set>
class MemPool {
public:
    // every time we call get, we can get the BlockSize bytes of memory
    MemPool(int BlockSize, int PoolSize) : m_block_size(BlockSize), m_pool_size(PoolSize)
        ,m_free_num(0) {
        std::cout << __func__ << std::endl;
        m_free_list.clear();
        m_alloc_set.clear();
    }

    ~MemPool() {
        std::cout << __func__ << ",set_size = " << m_alloc_set.size() << std::endl;
        for (std::set<void*>::iterator it = m_alloc_set.begin(); it != m_alloc_set.end(); ++it) {
            free(*it);
        }
        for (std::list<void*>::iterator it = m_free_list.begin();
            it != m_free_list.end(); ++it) {
            free(*it);
        }
        m_free_num = 0;
    }

    inline void* get() __attribute__((always_inline)) {
        void* mem = NULL;
        if (m_free_num > 0) {
            --m_free_num;
            mem = m_free_list.front();
            m_free_list.pop_front();
        } else {
            mem = malloc(m_block_size);
        }
        m_alloc_set.insert(mem);
        return mem;
    }

    inline void release(void* p) __attribute__((always_inline)) {
        if (m_free_num < m_pool_size) {
            m_free_list.push_back(p);
            ++m_free_num;
        } else {
            // destroy
            free (p);
        }
        m_alloc_set.erase(p);
    }

    int get_free_num() {
        return m_free_num;
    }
private:
    int m_block_size;
    int m_pool_size;
    int m_free_num;  // the num of memory block in the pool which can be useed
    std::list<void*> m_free_list;
    std::set<void*>  m_alloc_set;
};

my_mem_pool.cpp

#include "my_mem_pool.h"
#include <iostream>
#include <boost/shared_ptr.hpp>
int main() {
    MemPool* pool = new MemPool(1024, 3);
    void* p1 = pool->get();
    void* p0 = pool->get();
    void* p2 = pool->get();
    std::cout << "p0 = " << p0 << std::endl;
    std::cout << "p1 = " << p1 << std::endl;
    std::cout << "p2 = " << p2 << std::endl;
    std::cout << "size = " << pool->get_free_num() << std::endl;
    pool->release(p0);
    pool->release(p1);
    pool->release(p2);
    std::cout << "size = " << pool->get_free_num() << std::endl;
    void* p3 = pool->get();
    std::cout << "size = " << pool->get_free_num() << std::endl;
    void* p4 = pool->get();
    void* p5 = pool->get();
    void* p6 = pool->get();
    std::cout << "size = " << pool->get_free_num() << std::endl;
    pool->release(p3);
    pool->release(p4);
    pool->release(p5);
    delete pool;
    std::cout << "size = " << pool->get_free_num() << std::endl;
}