MySQL连接池的实现

class connect_pool
{
public:
    connect_pool();
    ~connect_pool();

public:
    MYSQL *get_connection();
    int free_connection(MYSQL *mysql);

private:
    int init(string db_server_ip, string user, string password, string db_name, unsigned int db_server_port, unsigned int pool_size);
    int connect();

private:
    unsigned int m_cur_connect;
    string m_db_server_ip;
    string m_user;
    string m_password;
    string m_db_name;
    unsigned int m_db_server_port;
    thread_lock m_thread_lock;
    deque<MYSQL*> m_deque_conn;
};

connect_pool::connect_pool()
{
    deque<MYSQL*>().swap(m_deque_conn);
    config_file_oper config_file("server_config.conf");
    string db_server_ip = config_file.get_config_value("db_server_ip");
    string user = config_file.get_config_value("user");
    string password = config_file.get_config_value("password");
    string db_name = config_file.get_config_value("db_name");
    unsigned int db_server_port = atoi(config_file.get_config_value("db_server_port"));
    unsigned int pool_size = atoi(config_file.get_config_value("connect_pool_size"));
    init(db_server_ip, user, password, db_name, db_server_port, pool_size);
}

connect_pool::~connect_pool()
{
    deque<MYSQL*>::iterator it = m_deque_conn.begin();
    for (; it != m_deque_conn.end(); it++)
    {
        if (NULL != *it)
        {
            mysql_close(*it);
            *it = NULL;
        }
    }
    deque<MYSQL*>().swap(m_deque_conn);
}

int connect_pool::init(string db_server_ip, string user, string password, string db_name, unsigned int db_server_port, unsigned int pool_size)
{
    int ret = 1;
    m_cur_connect = 0;
    m_db_server_ip = db_server_ip;
    m_db_server_port = db_server_port;
    m_user = user;
    m_password = password;
    m_db_name = db_name;
    for (unsigned int i = 0; i < pool_size; i++)
    {
        if (connect() == 0)
        {
            m_cur_connect++;
        }
    }
    if (m_cur_connect == pool_size)
    {
        ret = 0;
    }
    return ret;
}

int connect_pool::connect()
{
    int ret = 0;
    MYSQL *mysql = mysql_init(NULL);
    int value = true;
    mysql_options(mysql, MYSQL_OPT_RECONNECT, (char *)&value);//设置断线重连
    mysql_options(mysql, MYSQL_SET_CHARSET_NAME, "utf8");//设置字符集
    MYSQL *status = mysql_real_connect(mysql, m_db_server_ip.c_str(), m_user.c_str(), m_password.c_str(), m_db_name.c_str(), m_db_server_port, NULL, CLIENT_MULTI_STATEMENTS);
    if (NULL == status)
    {
        ret = 1;
    }
    else
    {
        m_deque_conn.push_back(mysql);
    }
    return ret;
}

MYSQL *connect_pool::get_connection()
{
    m_thread_lock.lock();
    while (m_deque_conn.empty())
    {
        m_thread_lock.wait();
    }
    MYSQL *mysql = m_deque_conn.front();
    m_deque_conn.pop_front();
    m_thread_lock.unlock();
    return mysql;
}

int connect_pool::free_connection(MYSQL *mysql)
{
    if(NULL == mysql)
    {
        return 0;
    }
    int ret = 0;
    m_thread_lock.lock();
    deque<MYSQL*>::iterator it = m_deque_conn.begin();
    //判断容器中是否已存在，避免重复归还
    for (; it != m_deque_conn.end(); it++)
    {
        if (mysql == *it)
        {
            break;
        }
    }
    if (it == m_deque_conn.end())
    {
        m_deque_conn.push_back(mysql);
        m_thread_lock.signal();
    }
    else
    {
        ret = 1;
    }
    m_thread_lock.unlock();
    return ret;
}