mysql c api简单连接池

来源：互联网发布：sql优化书籍推荐知乎编辑：程序博客网时间：2024/05/22 01:44

连接池为了解决频繁的创建、销毁所带来的系统开销。

简而言之，就是自己先创建一定量的连接，然后在需要的时候取出一条连接使用。

当然如果你只有一个线程连接数据库，而且不是实时返回结果，那么你完全不必用连接池。

想一下网络大型游戏服务器，你就明白为什么需要连接池了。

自己敲代码写了一个简单的类，实现连接池，虽然没有mysql++那么强大，但是还是自己有收获。

Csqlpool.h 头文件实现如下：

#pragma once#include <WinSock2.h>#include <mysql.h>#include <list>#pragma comment( lib , "libmysql.lib" )using namespace std;class Csqlpool{public:~Csqlpool(void);static Csqlpool *GetSqlPool();bool IniSqlPool( const char *host , const char *name , const char *pwd , unsigned int port , unsigned int conMax );  //初始化连接池bool SelectDB( MYSQL *sql, const char *DB);//选择数据库MYSQL *GetConnect();          // 获取连接void RelConnect(MYSQL *sql) ;  // 释放连接MYSQL_RES* GetQuery( MYSQL *sql , const char *query);      //mysql操作  增删查改void RelQuery(MYSQL_RES *res);   //释放MYSQL_RES资源bool Query(MYSQL *sql , const char *query);  //增、删、改操作protected:Csqlpool(void);private:list<MYSQL *> m_sql_free;   //空闲连接     static Csqlpool *pSqlPool;      CRITICAL_SECTION m_session;    //获取空闲线程};

Csqlpool.cpp 实现如下：

#include "StdAfx.h"#include "Csqlpool.h"Csqlpool *Csqlpool::pSqlPool = NULL;Csqlpool::Csqlpool(void){InitializeCriticalSection( &m_session );}Csqlpool::~Csqlpool(void){while ( m_sql_free.size() ){mysql_close( m_sql_free.front() );m_sql_free.pop_front();}DeleteCriticalSection(&m_session);}Csqlpool* Csqlpool::GetSqlPool(){if (  pSqlPool == NULL ){return new Csqlpool;}return pSqlPool;}bool Csqlpool::IniSqlPool( const char *host ,const char *name , const char *pwd , unsigned int port , unsigned int conMax )  //初始化连接池{int nsum = 0 ;for (unsigned int i = 0 ; i < conMax ;++i  ){MYSQL *pmysql;pmysql = mysql_init( (MYSQL*)NULL );if ( pmysql != NULL ){if ( mysql_real_connect( pmysql , host , name , pwd , NULL , 3306 , NULL , 0 ) ){m_sql_free.push_back(pmysql);}else{if ( nsum++ == 100 ){return false;}continue;}}continue;}return true;}bool Csqlpool::SelectDB( MYSQL *sql, const char *DB)//选择数据库{if(mysql_select_db(sql , DB)){return false;}return true;}MYSQL* Csqlpool::GetConnect()          // 获取连接{if ( m_sql_free.size()  ){EnterCriticalSection(&m_session);MYSQL *mysql = m_sql_free.front();m_sql_free.pop_front();LeaveCriticalSection(&m_session);return mysql;}elsereturn NULL;}void Csqlpool::RelConnect(MYSQL *sql)  // 释放连接{EnterCriticalSection(&m_session);m_sql_free.push_back(sql);LeaveCriticalSection(&m_session);}MYSQL_RES* Csqlpool::GetQuery( MYSQL *sql , const char *query)         //查询操作{if ( mysql_query( sql , query ) == 0 ){return mysql_store_result( sql );}elsereturn NULL;}void Csqlpool::RelQuery(MYSQL_RES *res)   //mysql_res release{mysql_free_result(res);}bool Csqlpool::Query(MYSQL *sql , const char *query)  //增、删、改操作{if ( mysql_query( sql , query ) ){return false;}return true;}

testsqlpool.cpp 测试文件实现如下：

// testsqlpool.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include "Csqlpool.h"#include <iostream>using namespace std;Csqlpool *psql = Csqlpool::GetSqlPool();DWORD WINAPI ThreadProc( LPVOID lpParameter);int _tmain(int argc, _TCHAR* argv[]){if(!psql->IniSqlPool("127.0.0.1" , "root" ,"123",3306,10)){cout<<"连接错误"<<endl;}HANDLE phan[2] ;DWORD threadid[2];int n1 = 0, n2 = 100;;phan[0]  = CreateThread( NULL , 0 ,  ThreadProc , &n1 ,  0 , &threadid[0] );phan[1]  = CreateThread( NULL , 0 , ThreadProc , &n2 ,   0 , &threadid[1] );WaitForMultipleObjects( 2 , phan , true ,  INFINITE );CloseHandle(phan[0]);CloseHandle(phan[1]);return 0;}DWORD WINAPI ThreadProc( LPVOID lpParameter){int index = *(int *)lpParameter ;int i = 1; MYSQL *sql = psql->GetConnect();string stemp = "insert into actor( actor_id , first_name , last_name,last_update )values(\"";string strsql;char str[10];if ( psql->SelectDB(sql , "sakila") ){while ( i != 100 ){sprintf( str , "%d" , i+index );strsql = stemp ;strsql +=  str;strsql += "\",\"0\",\"0\",\"0\")";if(!sql)return 0;if(!psql->Query(  sql ,strsql.c_str()  )){cout<<"add false"<<endl;}++i;}psql->RelConnect(sql);}return 0;}

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