swoole框架栏目介绍swoole实现mysql连接池的方法

前言

传统的nginx+FPM模式的PHP程序而言，每次请求FPM的worker都会连接一次mysql，然后请求结束便会断开连接。对于并发小的应用来说这不会有什么问题，但是对于高并发的应用来说，频繁建立连接Connect和销毁连接Close，数据库便会成为瓶颈，相信不少人也遇到过to many connection的mysql报错吧。

连接池的优势

连接池采用的是长连接模式，会一直保持与MySQL的连接，用完后会重新放回连接池，从而节省了建立连接和断开连接的消耗，大大降低了系统IO的消耗，一定程度上提高了程序的并发性能。如果连接池空闲，就从连接池分配一个连接，否则，请求将被加入到等待队列中。

实现

我们采用swoole实现mysql连接池

连接池类

<?php

require_once "MysqlDB.php";class MysqlPool{
    private static $instance;
    private $pool;
    private $config;
    private $pool_get_timeout;

    /**
     * 获取mysql进程池单例
     * @param null $config
     * @return MysqlPool
     */
    public static function getInstance($config = null)
    {
        if (empty(self::$instance)) {
            if (empty($config)) {
                throw new RuntimeException("mysql config is empty");
            }
            self::$instance = new static($config);
        }
        return self::$instance;
    }

    public function __construct($config)
    {
        if (empty($this->pool)) {
            $this->config = $config;
            $this->pool = new \Swoole\Coroutine\Channel($config['pool_size']);
            for ($i = 0; $i < $config['pool_size']; $i++) {
                \go(function() use ($config) {
                    $mysql = new MysqlDB();
                    $res = $mysql->connect($config['mysql']);
                    if ($res === false) {
                        throw new RuntimeException("Failed to connect mysql server");
                    } else {
                        $this->pool->push($mysql);
                    }
                });
            }
        }
    }

    public function get()
    {
        if ($this->pool->length() > 0) {
            $mysql = $this->pool->pop($this->config['pool_get_timeout']);
            if (false === $mysql) {
                throw new RuntimeException("Pop mysql timeout");
            }
            return $mysql;
        } else {
            throw new RuntimeException("Pool length <= 0");
        }
    }

    public function recycle(MysqlDB $mysql){
        $this->pool->push($mysql);
    }

    /**
     * 获取连接池长度
     * @return mixed
     */
    public function getPoolSize(){
        return $this->pool->length();
    }}

数据库DB类

<?phpclass MysqlDB{
    private $connection;

    public function connect($config)
    {
        $connection = new \Swoole\Coroutine\MySQL();
        $res = $connection->connect($config);
        if ($res === false) {
            throw new RuntimeException($connection->connect_error, $connection->errno);
        } else {
            $this->connection = $connection;
        }
        return $res;
    }


    public function query($sql){
        $result = $this->connection->query($sql);
        return $result;
    }}

在HTTP协程服务器中创建连接池

<?php
require_once "MysqlPool.php";\Co\run(function () {
    $server = new \Co\Http\Server("0.0.0.0", 9501, false);
    $pool = MysqlPool::getInstance([
        'pool_size'=>5,
        'pool_get_timeout'=>1,
        'timeout'=>1,
        'charset'=>'utf8',
        'strict_type'=>false,
        'fetch_mode'=>true,
        'mysql'=>[
            'host'=>'127.0.0.1',
            'port'=>'3306',
            'user'=>'homestead',
            'password'=>'secret',
            'database'=>'blog',
        ]
    ]);
    $server->handle('/', function ($request, $response) use ($pool){
        $mysql = $pool->get();
        $res = $mysql->query("select id,phone,username from user limit 1");
        var_dump($res);
        $pool->recycle($mysql);
        $response->end("<h1>Test</h1>");
    });
    $server->handle('/test', function ($request, $response) {
        $response->end("<h1>Test</h1>");
    });
    $server->handle('/stop', function ($request, $response) use ($server) {
        $response->end("<h1>Stop</h1>");
        $server->shutdown();
    });
    $server->start();});