--- /dev/null
+<?php
+
+namespace Drupal\Core\Queue;
+
+/**
+ * If the Drupal 'queue' service implements this interface, the
+ * garbageCollection() method will be called during cron.
+ *
+ * @see system_cron()
+ */
+interface QueueGarbageCollectionInterface {
+
+ /**
+ * Cleans queues of garbage.
+ */
+ public function garbageCollection();
+
+}