class RoutePreloader in Drupal 8

Defines a class which preloads non-admin routes.

On an actual site we want to avoid too many database queries so we build a list of all routes which most likely appear on the actual site, which are all HTML routes not starting with "/admin".

Hierarchy

• class \Drupal\Core\Routing\RoutePreloader implements \Symfony\Component\EventDispatcher\EventSubscriberInterface

1 file declares its use of RoutePreloader

RoutePreloaderTest.php in core/tests/Drupal/Tests/Core/Routing/RoutePreloaderTest.php

1 string reference to 'RoutePreloader'

core.services.yml in core/core.services.yml

core/core.services.yml

1 service uses RoutePreloader

router.route_preloader in core/core.services.yml

Drupal\Core\Routing\RoutePreloader

File

core/lib/Drupal/Core/Routing/RoutePreloader.php, line 21

Namespace

Drupal\Core\Routing

class RoutePreloader implements EventSubscriberInterface {

  /**
   * The route provider.
   *
   * @var \Drupal\Core\Routing\RouteProviderInterface|\Drupal\Core\Routing\PreloadableRouteProviderInterface
   */
  protected $routeProvider;

  /**
   * The state key value store.
   *
   * @var \Drupal\Core\State\StateInterface
   */
  protected $state;

  /**
   * Contains the non-admin routes while rebuilding the routes.
   *
   * @var array
   */
  protected $nonAdminRoutesOnRebuild = [];

  /**
   * The cache backend used to skip the state loading.
   *
   * @var \Drupal\Core\Cache\CacheBackendInterface
   */
  protected $cache;

  /**
   * Constructs a new RoutePreloader.
   *
   * @param \Drupal\Core\Routing\RouteProviderInterface $route_provider
   *   The route provider.
   * @param \Drupal\Core\State\StateInterface $state
   *   The state key value store.
   * @param \Drupal\Core\Cache\CacheBackendInterface $cache
   */
  public function __construct(RouteProviderInterface $route_provider, StateInterface $state, CacheBackendInterface $cache) {
    $this->routeProvider = $route_provider;
    $this->state = $state;
    $this->cache = $cache;
  }

  /**
   * Loads all non-admin routes right before the actual page is rendered.
   *
   * @param \Symfony\Component\HttpKernel\Event\KernelEvent $event
   *   The event to process.
   */
  public function onRequest(KernelEvent $event) {

    // Only preload on normal HTML pages, as they will display menu links.
    if ($this->routeProvider instanceof PreloadableRouteProviderInterface && $event
      ->getRequest()
      ->getRequestFormat() == 'html') {

      // Ensure that the state query is cached to skip the database query, if
      // possible.
      $key = 'routing.non_admin_routes';
      if ($cache = $this->cache
        ->get($key)) {
        $routes = $cache->data;
      }
      else {
        $routes = $this->state
          ->get($key, []);
        $this->cache
          ->set($key, $routes, Cache::PERMANENT, [
          'routes',
        ]);
      }
      if ($routes) {

        // Preload all the non-admin routes at once.
        $this->routeProvider
          ->preLoadRoutes($routes);
      }
    }
  }

  /**
   * Alters existing routes for a specific collection.
   *
   * @param \Drupal\Core\Routing\RouteBuildEvent $event
   *   The route build event.
   */
  public function onAlterRoutes(RouteBuildEvent $event) {
    $collection = $event
      ->getRouteCollection();
    foreach ($collection
      ->all() as $name => $route) {
      if (strpos($route
        ->getPath(), '/admin/') !== 0 && $route
        ->getPath() != '/admin' && static::isGetAndHtmlRoute($route)) {
        $this->nonAdminRoutesOnRebuild[] = $name;
      }
    }
    $this->nonAdminRoutesOnRebuild = array_unique($this->nonAdminRoutesOnRebuild);
  }

  /**
   * Store the non admin routes in state when the route building is finished.
   *
   * @param \Symfony\Component\EventDispatcher\Event $event
   *   The route finish event.
   */
  public function onFinishedRoutes(Event $event) {
    $this->state
      ->set('routing.non_admin_routes', $this->nonAdminRoutesOnRebuild);
    $this->nonAdminRoutesOnRebuild = [];
  }

  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() {

    // Set a really low priority to catch as many as possible routes.
    $events[RoutingEvents::ALTER] = [
      'onAlterRoutes',
      -1024,
    ];
    $events[RoutingEvents::FINISHED] = [
      'onFinishedRoutes',
    ];

    // Load the routes before the controller is executed (which happens after
    // the kernel request event).
    $events[KernelEvents::REQUEST][] = [
      'onRequest',
    ];
    return $events;
  }

  /**
   * Determines whether the given route is a GET and HTML route.
   *
   * @param \Symfony\Component\Routing\Route $route
   *   The route to analyze.
   *
   * @return bool
   *   TRUE if GET is a valid method and HTML is a valid format for this route.
   */
  protected static function isGetAndHtmlRoute(Route $route) {
    $methods = $route
      ->getMethods() ?: [
      'GET',
    ];

    // If a route has no explicit format, then HTML is valid.
    // @see \Drupal\Core\Routing\RequestFormatRouteFilter::getAvailableFormats()
    $format = $route
      ->hasRequirement('_format') ? explode('|', $route
      ->getRequirement('_format')) : [
      'html',
    ];
    return in_array('GET', $methods, TRUE) && in_array('html', $format, TRUE);
  }

}

Members

Name	Modifiers	Type	Description	Overrides
RoutePreloader::$cache	protected	property	The cache backend used to skip the state loading.
RoutePreloader::$nonAdminRoutesOnRebuild	protected	property	Contains the non-admin routes while rebuilding the routes.
RoutePreloader::$routeProvider	protected	property	The route provider.
RoutePreloader::$state	protected	property	The state key value store.
RoutePreloader::getSubscribedEvents	public static	function	Returns an array of event names this subscriber wants to listen to.
RoutePreloader::isGetAndHtmlRoute	protected static	function	Determines whether the given route is a GET and HTML route.
RoutePreloader::onAlterRoutes	public	function	Alters existing routes for a specific collection.
RoutePreloader::onFinishedRoutes	public	function	Store the non admin routes in state when the route building is finished.
RoutePreloader::onRequest	public	function	Loads all non-admin routes right before the actual page is rendered.
RoutePreloader::__construct	public	function	Constructs a new RoutePreloader.