PDO: Connection timed out when database is offline

Question

I have a website that makes a connection to an external database with PDO.

All right, all works.

The only problem is when the database goes offline. I refresh the website, the browser load the first query that finds but it takes 30+ seconds to load it and when finish the page stop to load (because there is an exit(); function when the connection fails) with this error:

SQLSTATE[HY000] [2002] Connection timed out

I want the website accessible normally when the database goes offline, because is a routine that it goes offline but there's this problem of the Connection timed out and of the page that takes 30+ seconds to load.

How can I resolve this problem?

This is how I do a connection and a query:

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;
    }
}

Usage (how I run a query)

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;

Thanks for the help.

Answer 1

You could set the timeout attribute:

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();
        }
    }
}

This would make the query time out after 5 seconds instead of the 30 seconds you describe in your question. Please note that the underlying mysql engine has to support this as not all support it.

Answer 2

If you want your website to be accessible, even when you can't access the database, I see two solutions : caching the results of the query ; or caching the entire page.