private function initialize()
    {
        if ($this->callable !== null) {
            // $func will be $adapter->fetchObjectFromCache();
            $func                      = $this->callable;
            $result                    = $func();
            $this->hasValue            = $result[0];
            $this->value               = $result[1];
            $this->prevTags            = isset($result[2]) ? $result[2] : [];
            $this->expirationTimestamp = null;

            if (isset($result[3]) && is_int($result[3])) {
                $this->expirationTimestamp = $result[3];
            }

            $this->callable = null;
        }
    }