query( * new Query($name, Message::TYPE_AAAA, Message::CLASS_IN) * )->then(function (Message $message) { * foreach ($message->answers as $answer) { * echo 'IPv6: ' . $answer->data . PHP_EOL; * } * }, 'printf'); * ``` * * Note that this executor only implements the logic to select the correct * transport for the given DNS query. Implementing the correct transport logic, * implementing timeouts and any retry logic is left up to the given executors, * see also [`UdpTransportExecutor`](#udptransportexecutor) and * [`TcpTransportExecutor`](#tcptransportexecutor) for more details. * * Note that this executor is entirely async and as such allows you to execute * any number of queries concurrently. You should probably limit the number of * concurrent queries in your application or you're very likely going to face * rate limitations and bans on the resolver end. For many common applications, * you may want to avoid sending the same query multiple times when the first * one is still pending, so you will likely want to use this in combination with * a `CoopExecutor` like this: * * ```php * $executor = new CoopExecutor( * new SelectiveTransportExecutor( * $datagramExecutor, * $streamExecutor * ) * ); * ``` */ class SelectiveTransportExecutor implements ExecutorInterface { private $datagramExecutor; private $streamExecutor; public function __construct(ExecutorInterface $datagramExecutor, ExecutorInterface $streamExecutor) { $this->datagramExecutor = $datagramExecutor; $this->streamExecutor = $streamExecutor; } public function query(Query $query) { $stream = $this->streamExecutor; $pending = $this->datagramExecutor->query($query); return new Promise(function ($resolve, $reject) use(&$pending, $stream, $query) { $pending->then($resolve, function ($e) use(&$pending, $stream, $query, $resolve, $reject) { if ($e->getCode() === (\defined('SOCKET_EMSGSIZE') ? \SOCKET_EMSGSIZE : 90)) { $pending = $stream->query($query)->then($resolve, $reject); } else { $reject($e); } }); }, function () use(&$pending) { $pending->cancel(); $pending = null; }); } }