Can't use exit(0), how else can I terminate a response?

Question

Here's my code(using Drupal 8):

public function checkForRedirection(GetResponseEvent $event) {
    $is_authenticated = $this->currentUser->isAuthenticated();
    $route_name = $this->routeMatch->getRouteName();

    if (!$is_authenticated && $route_name !== "user.login") {
      header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
      header("Cache-Control: post-check=0, pre-check=0", FALSE);
      header("Pragma: no-cache");
      define("SITE", "www.google.com");
      $response = new RedirectResponse(SITE, $this->redirectCode);
      $response->send();
      $exit(0);
    }
  }

  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() {
    $events[KernelEvents::REQUEST][] = ["checkForRedirection", 30];
    return $events;
  }

So I'm redirecting an authenticated user away from my site. It works perfectly how I want it to, the only problem is PHP Mess Detector doesn't allow the exit(0) function, so wondering what are my alternatives to produce same functionality that exit(0) does here?

Answer 1

You need to terminate using the kernel. You'll have to generate $currentRequest and $response, which may already be available depending on where your code lies. After you have them, you can terminate the request using:

\Drupal::service('kernel')->terminate($currentRequest, $response);