Symfony\Component\HttpFoundation\Session::set PHP Method

    public function set($name, $value)
    {
        if (false === $this->started) {
            $this->start();
        }

        $this->attributes[$name] = $value;
    }

 /**
  * On kernel response event
  *
  * @param FilterResponseEvent $event
  */
 public function onKernelResponse(FilterResponseEvent $event)
 {
     // Only master request and 200 OK are processed
     if (HttpKernelInterface::MASTER_REQUEST === $event->getRequestType() && $event->getResponse()->isOk()) {
         $route = $this->router->match($this->request->getPathInfo());
         // Ignore internal route
         if (0 === stripos($route['_route'], '_')) {
             return;
         }
         $this->session->set('_unifik.last_master_request_uri', $this->request->getUri());
         $this->session->set('_unifik.last_master_request_route', $route);
     }
 }