<?php
/**
 * Created by PhpStorm.
 * User: Luke
 * Date: 2019/10/30
 * Time: 14:12
 */
//编写mysql连接池，这个类只能被实例化一次（单例）
class MysqlConnectionPool
{
    private static $instance;//单例对象
    private $connection_num = 10;//连接数量
    private $connection_obj = [];
 
    //构造方法连接mysql，创建20mysql连接
    private function __construct()
    {
        for($i=0;$i<$this->connection_num;$i++){
            $dsn = "mysql:host=127.0.0.1;dbnane=swoole";
            $this->connection_obj[] =  new Pdo($dsn,'root','rootmysql123');
        }
    }
    private function __clone()
    {
        // TODO: Implement __clone() method.
    }
    public static function getInstance()
    {
        if(is_null(self::$instance)){
            self::$instance = new self();
        }
    }
}
MysqlConnectionPool::getInstance();
//创建swool的http服务器对象
$serv = new swoole_http_server('0.0.0.0',8000);
//当浏览器链接点这个http服务器的时候,向浏览器发送helloworld
$serv->on('request', function($request,$response){
    //$request包含这个请求的所有信息，比如参数
    //$response包含返回给浏览器的所有信息，比如helloworld
 
    //(2.3)向浏览器发送helloworld
    $response->end("hello world");
});
//启动http服务器
$serv->start();

<?php
/**
 * Created by PhpStorm.
 * User: Luke
 * Date: 2019/10/30
 * Time: 14:12
 */
//编写mysql连接池，这个类只能被实例化一次（单例）
class MysqlConnectionPool
{
    private static $instance;//单例对象
    private $connection_num = 20;//连接数量
    private $connection_obj = [];
    private $avil_connection_num = 20;//可用连接
 
    //构造方法连接mysql，创建20mysql连接
    private function __construct()
    {
        for($i=0;$i<$this->connection_num;$i++){
            $dsn = "mysql:host=127.0.0.1;dbname=swoole";
            $this->connection_obj[] =  new Pdo($dsn,'root','rootmysql123');
        }
    }
    private function __clone()
    {
        // TODO: Implement __clone() method.
    }
    public static function getInstance()
    {
        if(is_null(self::$instance)){
            self::$instance = new self();
        }
        return self::$instance;
    }
 
    //执行sql操作
    public function query($sql)
    {
        if($this->avil_connection_num==0){
            throw new Exception("暂时没有可用的连接诶，请稍后");
        }
        //执行sql语句
        $pdo = array_pop($this->connection_obj);
        //可用连接数减1
        $this->avil_connection_num --;
        //使用从连接池中取出的mysql连接执行查询，并且把数据取成关联数组
        $rows = $pdo->query($sql)->fetchAll(PDO::FETCH_ASSOC);
        //把mysql连接放回连接池，可用连接数+1
        array_push($this->connection_obj,$pdo);
        $this->avil_connection_num ++;
        return $rows;
    }
}
//创建swool的http服务器对象
$serv = new swoole_http_server('0.0.0.0',8000);
//当浏览器链接点这个http服务器的时候,向浏览器发送helloworld
$serv->on('request', function($request,$response){
    //$request包含这个请求的所有信息，比如参数
    //$response包含返回给浏览器的所有信息，比如helloworld
    //向浏览器发送helloworld
    $stop = false;
    while (!$stop){
        try{
            $sql = "SELECT * FROM user ORDER BY id  DESC LIMIT 5";
            $rows = MysqlConnectionPool::getInstance()->query($sql);
            $response->end(json_encode($rows));
            $stop = true;
        }catch (Exception $e){
            usleep(100000);
        }
    }
 
});
//启动http服务器
$serv->start();