Added warning if queue factory is not set.

quant.module

@@ -6,15 +6,28 @@
  */
 
 use Drupal\Core\Access\AccessResult;
-use Drupal\Core\Session\AccountInterface;
-use Drupal\node\NodeInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Core\Site\Settings;
 use Drupal\Core\Url;
+use Drupal\node\NodeInterface;
 use Drupal\quant\Exception\TokenValidationDisabledException;
 use Drupal\quant\Plugin\QueueItem\RouteItem;
-use Drupal\quant\Seed;
 use Drupal\quant\QuantQueueFactory;
+use Drupal\quant\Seed;
+
+/**
+ * Implements hook_preprocess_page().
+ */
+function quant_preprocess_page(&$variables) {
+
+  // Add warning on Quant admin pages if queue factory is not set.
+  $current_path = \Drupal::requestStack()->getCurrentRequest()->getPathInfo();
+  if ((strpos($current_path, '/admin/config/quant') === 0) && Settings::get('queue_service_quant_seed_worker') != "quant.queue_factory") {
+    \Drupal::messenger()->addWarning(t("For the best performance, it is highly recommended you update <em>queue_service_quant_seed_worker</em> in your settings. See the <a href=\"https://docs.quantcdn.io/docs/integrations/drupal">Drupal docs</a> for setup information."));
+  }
+}
 
 /**
  * Implements hook_menu_local_tasks_alter().