Symfony session request timeout detect

symfony_session.md

config.yml :

services:
    mycompany.demobundle.listener.request:
        class: MyCompany\DemoBundle\RequestListener
        arguments: [@router, @security.context]
        tags:
             - { name: kernel.event_listener, event: kernel.request, method: onKernelRequest }

RequestListener

$inactive = 6000; 
$session_life = time() - $request->getSession()->('timeout');
if($session_life > $inactive && $request->isXmlHttpRequest() )
    {  
         $headers['Content-Type'] = 'application/json';
         return new Response(json_encode($data), $status, $headers);