update_menu_item_cache

update_menu_item_cache: 这个函数更新当前站点的菜单项数据的缓存。每当一个菜单项被创建、更新或删除时，它就被调用。

更新一个菜单项列表的所有链接对象的后缓存和术语缓存。

function update_menu_item_cache( $menu_items ) {
	$post_ids = array();
	$term_ids = array();

	foreach ( $menu_items as $menu_item ) {
		if ( 'nav_menu_item' !== $menu_item->post_type ) {
			continue;
		}

		$object_id = get_post_meta( $menu_item->ID, '_menu_item_object_id', true );
		$type      = get_post_meta( $menu_item->ID, '_menu_item_type', true );

		if ( 'post_type' === $type ) {
			$post_ids[] = (int) $object_id;
		} elseif ( 'taxonomy' === $type ) {
			$term_ids[] = (int) $object_id;
		}
	}

	if ( ! empty( $post_ids ) ) {
		_prime_post_caches( $post_ids, false );
	}

	if ( ! empty( $term_ids ) ) {
		_prime_term_caches( $term_ids );
	}
}