/** Add $keepItems to the list of items which are protected from garbage collection. * @param $keepItems */ public static function addToGloballyProtectedItems($keepItems) { if (is_string($keepItems)) { $keepItems = array($keepItems); } if (!is_array(self::$globallyProtectedItems) && $keepItems) { self::$globallyProtectedItems = array(); } self::$globallyProtectedItems = array_merge(self::$globallyProtectedItems, $keepItems); }