public function removeAll(): bool
    {
        if (!$this->adapter instanceof iAdapter) {
            return false;
        }

        // remove static-cache
        if (!empty(self::$STATIC_CACHE)) {
            self::$STATIC_CACHE = [];
            self::$STATIC_CACHE_COUNTER = [];
            self::$STATIC_CACHE_EXPIRE = [];
        }

        return $this->adapter->removeAll();
    }