/** * Returns an AJAX response to render the toolbar subtrees. * * @return \Drupal\Core\Ajax\AjaxResponse */ public function subtreesAjax() { list($subtrees, $cacheability) = toolbar_get_rendered_subtrees(); $response = new AjaxResponse(); $response->addCommand(new SetSubtreesCommand($subtrees)); // The Expires HTTP header is the heart of the client-side HTTP caching. The // additional server-side page cache only takes effect when the client // accesses the callback URL again (e.g., after clearing the browser cache // or when force-reloading a Drupal page). $max_age = 365 * 24 * 60 * 60; $response->setPrivate(); $response->setMaxAge($max_age); $expires = new \DateTime(); $expires->setTimestamp(REQUEST_TIME + $max_age); $response->setExpires($expires); return $response; }