4

1、Introduction

之前写过2篇文章,分别是:

Mysql主从同步的原理
Myql主从同步实战

基于此,我们再实现简单的PHP+Mysql读写分离,从而提高数据库的负载能力。

2、代码实战

<?php
class Db
{
    private $res;
    function __construct($sql)
    {
        $querystr = strtolower(trim(substr($sql,0,6)));
        //如果是select,就连接slave服务器
        if($querystr == 'select')
        {
            $res=$this->slave_select($sql);
            $this->res=$res;
        }
        //如果不是select,就连接master服务器
        else
        {
            $res=$this->master_change($sql);
            $this->res=$res;
        }
    }

    /**
     * slave从库返回sql查询结果
     * @param $sql
     * @return array
     */
    private function slave_select($sql){
        //该处只是随机获取slave节点的ip,当然,还可以采用其他算法获取slave_ip
        $slave_server=$this->get_slave_ip();
        $dsn="mysql:host=$slave_server;dbname=test";
        $user='root';
        $pass='123456';
        $dbh=new PDO($dsn, $user, $pass);
        return $dbh->query($sql)->fetchAll(PDO::FETCH_ASSOC);
    }

    /**master主库返回sql执行结果
     * @param $sql
     * @return int
     */
    private function master_change($sql){
        $master_server='192.168.33.22';
        $dsn="mysql:host=$master_server;dbname=test";
        $user='root';
        $pass='123456';
        $dbh=new PDO($dsn, $user, $pass);
        return $dbh->exec($sql);
    }

    /**
     * 随机获取slave-ip
     * @return mixed
     */
    private function get_slave_ip(){
        $slave_ips=['192.168.33.33','192.168.33.44'];
        $count=count($slave_ips)-1;
        $random_key=mt_rand(0,$count);
        return $slave_ips[$random_key];
    }

    /**
     * 获取结果
     * @return int
     */
    public function get_res(){
        return $this->res;
    }
}

$sql1 = "select * from t1";
$sql2 = "insert into t1 (name) values ('haha')";
$sql3 = "delete from t1 where id=1";
$sql4 = "update t1 set name='Jerry' where id=2";

$db = new Db($sql1);
//$db = new Db($sql2);
//$db = new Db($sql3);
//$db = new Db($sql4);

var_dump($db->get_res());

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zilu
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