_update_blog_date_on_post_publish() WordPress Function

function _update_blog_date_on_post_publish( $new_status, $old_status, $post ) {
	$post_type_obj = get_post_type_object( $post->post_type );
	if ( ! $post_type_obj || ! $post_type_obj->public ) {
		return;
	}

	if ( 'publish' !== $new_status && 'publish' !== $old_status ) {
		return;
	}

	// Post was freshly published, published post was saved, or published post was unpublished.

	wpmu_update_blogs_date();
}