Singleton between different controller actions in Symfony2 - symfony

Question

Assume we have singleton class
class Registry {
private static $_instance;
private function __construct() {}
private function __wakeup() {}
private function __clone() {}
private $_map = array();
public static function getInstance () {
if (self::$_instance === null)
self::$_instance = new self();
return self::$_instance;
}
public function set ($key, $val) {
self::getInstance()->_map[$key] = $val;
return self::getInstance();
}
public function get($key)
{
if (array_key_exists($key, self::getInstance()->_map))
return self::getInstance()->_map[$key];
return null;
}
}
And we have simple Symfony2 Controller with 2 actions
class IndexController {
public function indexAction () {
Registry::getInstance()->set('key',true);
return new Response(200);
}
public function secondAction () {
$val = Registry::getInstance()->get('key');
return new Response(200);
}
}
I call index action, then second action. But I can't find key, that was set in first action. I think, new instance of singleton creates in my second action. Why object is not saved in memory? What do I do wrong?

Answer 1

If you call indexAction and secondAction in different requests it won't work the way you want it because your Registry instance is not shared between requests.
Singleton itself does not store anything "in memory" (BTW Singleton is now considered as an anti-pattern).
What, I think, you want to achieve can be done by using session storage. Check doc for more info how to implement this.