Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/lib/Drupal/Core/DestructableInterface.php

@@ -0,0 +1,26 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\DestructableInterface.
+ */
+
+namespace Drupal\Core;
+
+/**
+ * The interface for services that need explicit destruction.
+ *
+ * This is useful for services that need to perform additional tasks to
+ * finalize operations or clean up after the response is sent and before the
+ * service is terminated.
+ *
+ * Services using this interface need to be registered with the
+ * "needs_destruction" tag.
+ */
+interface DestructableInterface {
+
+  /**
+   * Performs destruct operations.
+   */
+  public function destruct();
+}