WordPress at a glance
function is not described

doing_action() WP 3.9.0

Retrieve the name of an action currently being processed.

No Hooks.

Return

true/false. Whether the action is currently in the stack.

Usage

doing_action( $action );
$action(string/null)
Action to check.
Default: null, which checks if any action is currently being run

Code of doing action: wp-includes/plugin.php VER 5.1.1

<?php
function doing_action( $action = null ) {
	return doing_filter( $action );
}