mysql连接池c++语言实现

完整源码下载地址：http://download.csdn.net/download/libaineu2004/10261201

里面使用的是c++版本mysql-connector-c++-1.1.8-linux-el7-x86-64bit.tar.gz，但是它依赖boost库，太啰嗦

https://downloads.mysql.com/archives/c-cpp/

dbpoll.h

#ifndef _DB_POOL_H_
#define _BD_POOL_H_

#include 
/*
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
*/
#include 
#include 
#include 

using namespace std;
using namespace sql;

class DBPool
{
public:
    // Singleton
    static DBPool& GetInstance();

    //init pool
    void initPool(std::string url_, std::string user_, std::string password_, int maxSize_);

    //get a conn from pool
    Connection* GetConnection();

    //put the conn back to pool
    void ReleaseConnection(Connection *conn);

    ~DBPool();

private:
    DBPool(){}

    //init DB pool
    void InitConnection(int initSize);

    // create a connection
    Connection* CreateConnection();

    //destory connection
    void DestoryConnection(Connection *conn);

    //destory db pool
    void DestoryConnPool();

private:
    string user;
    string password;
    string url;
    int maxSize;
    int curSize;

    Driver*             driver;     //sql driver (the sql will free it)
    list   connList;   //create conn list

    //thread lock mutex
    static pthread_mutex_t lock;
};

#endif

dbpool.cpp

#include 
#include 
#include 
#include 
#include "dbpool.h"

using namespace std;
using namespace sql;

pthread_mutex_t DBPool::lock = PTHREAD_MUTEX_INITIALIZER;

//Singleton: get the single object
DBPool& DBPool::GetInstance()
{
    static DBPool instance_;
    return instance_;
}

void DBPool::initPool(std::string url_, std::string user_, std::string password_, int maxSize_)
{
    this->user = user_;
    this->password = password_;
    this->url = url_;
    this->maxSize = maxSize_;
    this->curSize = 0;

    try{
        this->driver=sql::mysql::get_driver_instance();
    }
    catch(sql::SQLException& e)
    {
        perror("Get sql driver failed");
    }
    catch(std::runtime_error& e)
    {
        perror("Run error");
    }
    this->InitConnection(maxSize/2);
}

//init conn pool
void DBPool::InitConnection(int initSize)
{
    Connection* conn;
    pthread_mutex_lock(&lock);
    for(int i =0;i CreateConnection();

        if(conn)
        {
            connList.push_back(conn);
            ++(this->curSize);
        }
        else
        {
            perror("create conn error");
        }
    }
    pthread_mutex_unlock(&lock);

}

Connection* DBPool::CreateConnection()
{
    Connection* conn;
    try{
        conn = driver->connect(this->url,this->user,this->password);  //create a conn
        return conn;
    }
    catch(sql::SQLException& e)
    {
        perror("link error");
        return NULL;
    }
    catch(std::runtime_error& e)
    {
        perror("run error");
        return NULL;
    }
}

Connection* DBPool::GetConnection()
{
    Connection* conn;

    pthread_mutex_lock(&lock);

    if(connList.size()>0)//the pool have a conn
    {
        conn = connList.front();
        connList.pop_front();//move the first conn
        if(conn->isClosed())//if the conn is closed, delete it and recreate it
        {
            delete conn;
            conn = this->CreateConnection();
        }

        if(conn == NULL)
        {
            --curSize;
        }

        pthread_mutex_unlock(&lock);

        return conn;
    }
    else
    {
        if(curSize< maxSize)//the pool no conn
        {
            conn = this->CreateConnection();
            if(conn)
            {
                ++curSize;
                pthread_mutex_unlock(&lock);
                return conn;
            }
            else
            {
                pthread_mutex_unlock(&lock);
                return NULL;
            }
        }
        else //the conn count > maxSize
        {
            pthread_mutex_unlock(&lock);
            return NULL;
        }
    }
}

//put conn back to pool
void DBPool::ReleaseConnection(Connection *conn)
{
    if(conn)
    {
        pthread_mutex_lock(&lock);
        connList.push_back(conn);
        pthread_mutex_unlock(&lock);
    }
}

void DBPool::DestoryConnPool()
{
    list::iterator iter;
    pthread_mutex_lock(&lock);
    for(iter = connList.begin(); iter!=connList.end(); ++iter)
    {
        this->DestoryConnection(*iter);
    }
    curSize=0;
    connList.clear();
    pthread_mutex_unlock(&lock);
}


void DBPool::DestoryConnection(Connection* conn)
{
    if(conn)
    {
        try{
            conn->close();
        }
        catch(sql::SQLException&e)
        {
            perror(e.what());
        }
        catch(std::exception& e)
        {
            perror(e.what());
        }
        delete conn;
    }
}

DBPool::~DBPool()
{
    this->DestoryConnPool();
}

main.cpp

#include "dbpool.h"
#include 

/*--------------------------------------------------------------
    单例模式，全局唯一 db pool，程序中使用onnpool中获取一个
    db连接使用，使用完之后调用ReleaseConnection把conn放回pool中去.
----------------------------------------------------------------*/
DBPool  connpool = DBPool::GetInstance();

int main(int argc, char* argv[])
{
    //初始化连接，创建参数中maxSize一半的连接
    connpool.initPool("tcp://127.0.0.1:3306", "root", "123456", 100);

    Connection *con;
    Statement *state;
    ResultSet *result;
    con = connpool.GetConnection();//get a db conn
    for(int i = 0; i<1000; i++)
    {
        state = con->createStatement();
        state->execute("use mysql");

        // 查询
        result = state->executeQuery("select host,user from user");

        // 输出查询
        while (result->next())
        {
            try{
                string user = result->getString("user");
                string name = result->getString("host");
                cout << user << " : " << name << endl;
            }catch(sql::SQLException& e){
                std::cout << e.what() << std::endl;
            }
        }

        /*result = state->executeQuery("select cust_id,cust_name from customers");
        while (result->next())
        {
            try{
                string user = result->getString("cust_id");
                string name = result->getString("cust_name");
                cout << user << " : " << name << endl;
            }catch(sql::SQLException& e){
              std::cout << e.what() << std::endl;
            }
        }
    */
        std::cout << i << std::endl;

    }

    delete result;
    delete state;
    connpool.ReleaseConnection(con);//注意，con用完之后一定要记得归还

    return 0;
}