php - PDO:数据库离线时连接超时

Question

我有一个网站，它使用 PDO 连接到外部数据库。

好的，一切正常。

唯一的问题是数据库离线时。我刷新网站，浏览器加载找到的第一个查询，但需要 30+ 秒来加载它，完成后页面停止加载(因为连接时有一个 exit(); 函数失败)并出现以下错误:

SQLSTATE[HY000] [2002] Connection timed out

我希望网站在数据库离线时能够正常访问，因为离线是常态，但存在连接超时和页面加载时间超过 30 秒的问题.

如何解决这个问题？

这就是我进行连接和查询的方式:

class.db.php

<?php
class db
{
    private $db = NULL;
    private $host = NULL;
    private $user = NULL;
    private $password = NULL;
    private $port = NULL;

    public function __construct($host, $user, $password, $port) {
        $this->host = $host;
        $this->user = $user;
        $this->password = $password;
        $this->port = $port;
    }

    private function initDb() {
        if($this->db == NULL) {
            try {
                $this->db = new PDO('mysql:port='.$this->port.';host='.$this->host, $this->user, $this->password);
                $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
                $this->db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
            }
            catch (PDOException $error) {
                echo '<b>An error occured!</b><br />' . $error->getMessage();
                exit();
            }
        }
    }

    public function query($array) {
        $this->initDb();
        $sql = $array['sql'];
        $par = (isset($array['par'])) ? $array['par'] : array();
        $ret = (isset($array['ret'])) ? $array['ret'] : 'res';
        $obj = $this->db->prepare($sql);
        $result = $obj->execute($par);
        if (!$result) exit("Errore Query");
        switch ($ret) {
            case 'fetch-assoc':
                return $obj->fetch(PDO::FETCH_ASSOC);
            break;

            case 'fetch-all':
                return $obj->fetchAll(PDO::FETCH_ASSOC);
            break;

            case 'fetch-column':
                return $obj->fetchColumn();
            break;

            case 'result':
                return $result;
            break;

            default:
                return $result;
            break;
        }
    }

    public function __destruct() {
        $this->db = NULL;
    }
}

用法(我如何运行查询)

require_once ROOT . 'include/class.db.php';

$config['db']['servername'] = ""; // Database IP
$config['db']['username'] = ""; // Database Username
$config['db']['password'] = ""; // Database Password
$config['db']['port'] = 3306; // Database Port

$db = new db($config['db']['servername'], $config['db']['username'], $config['db']['password'], $config['db']['port']);

// Example of a query

$data = $db->query(array(  
    'sql' => "SELECT count(*) FROM player.player WHERE DATE_SUB(NOW(), INTERVAL 1 DAY) < player.last_play",
    'ret' => 'fetch-column'
));

echo $data;

感谢您的帮助。

Answer 1

您可以设置超时属性:

private function initDb() {
    if($this->db == NULL) {
        try {
            $this->db = new PDO('mysql:port='.$this->port.';host='.$this->host, $this->user, $this->password);
            $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
            $this->db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
            $this->db->setAttribute(PDO::ATTR_TIMEOUT, 5); //Add this.
        }
        catch (PDOException $error) {
            echo '<b>An error occured!</b><br />' . $error->getMessage();
            exit();
        }
    }
}

这将使查询在 5 秒后超时，而不是您在问题中描述的 30 秒。请注意，底层 mysql 引擎必须支持这一点，因为并非所有引擎都支持它。