master/invalidate_8php_source.html

 <?php
 elgg_invalidate_caches();

 return elgg_ok_response('', elgg_echo('admin:cache:invalidated'));
elgg_ok_response
elgg_ok_response($content= '', string|array $message= '', string $forward_url=null, int $status_code=ELGG_HTTP_OK)
Prepares a successful response to be returned by a page or an action handler.
Definition: pagehandler.php:224

elgg_echo
elgg_echo(string $message_key, array $args=[], string $language= '')
Elgg language module Functions to manage language and translations.
Definition: languages.php:17

elgg_invalidate_caches
elgg_invalidate_caches()
Invalidate all the registered caches.
Definition: cache.php:88