Amp\Mysql\ResultSet::getFields PHP Method

    public function getFields()
    {
        if ($this->result->state >= ResultProxy::COLUMNS_FETCHED) {
            return new Success($this->result->columns);
        } else {
            $deferred = new Deferred();
            $this->result->deferreds[ResultProxy::COLUMNS_FETCHED][] = [$deferred, &$this->result->columns, null];
            return $deferred->promise();
        }
    }