Documentation

It returns a Promise which either fulfills with a response React\Dns\Model\Message on success or rejects with an Exception if the query is not successful. A response message may indicate an error condition in its rcode, but this is considered a valid response message.

$executor->query($query)->then(
    function (React\Dns\Model\Message $response) {
        // response message successfully received
        var_dump($response->rcode, $response->answers);
    },
    function (Exception $error) {
        // failed to query due to $error
    }
);

The returned Promise MUST be implemented in such a way that it can be cancelled when it is still pending. Cancelling a pending promise MUST reject its value with an Exception. It SHOULD clean up any underlying resources and references as applicable.

$promise = $executor->query($query);

$promise->cancel();