PDO: Connection timed out when database is offline - php

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.