<?php
//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();
