/**
* Constucts object.
*
* @param callable $callback Callable to call for each consumed event.
* @param AMQPStreamConnection $connection AMQP connection object.
* @param string $queue Queue to bind.
* @param string $exchange An events exchange.
* @param string $bindingKey A binding key.
*
* @throws ErrorException On network\transport errors.
*/
public function __construct(callable $callback, AMQPStreamConnection $connection, $queue, $exchange, $bindingKey)
{
// TODO: consumer shoud has own connection with heartbeat.
// The heartbeat is checked only during IO operations, so when AMQP connection
// not used for a long time, RabbitMQ terminates connection
$this->queue = $queue;
$this->bindingKey = $bindingKey;
$this->channel = $connection->channel();
Util::declareQueue($connection, $queue, ['durable' => true, 'exclusive' => false]);
Util::declareExchange($connection, $exchange, 'direct', ['auto_delete' => false]);
$ch->queue_bind($queue, $exchange, $bindingKey);
$wrapper = function ($msg) use($callback) {
$event = new Event($msg);
return $callback($event);
};
$ch->basic_consume($this->queue, '', false, false, false, false, $wrapper);
}
/**
* Initializes result objects: creates AMQP objects and binds result queue.
*
* @return void
*/
public function initialize()
{
$this->channel = $this->connection->channel();
// `auto-delete` argument makes sure that queue will be deleted after last queue
// consumer disconnected. (Won't be deleted if there weren't any consumers)
// `x-expires` queue option means that queue will be deleted if it's unused for the
// specified time in milliseconds. Unused means that queue has no consumers,
// the queue has not been redeclared, and basic.get has not been invoked.
Util::declareQueue($this->connection, $this->taskId, ['exclusive' => false, 'durable' => true, 'auto_delete' => true, 'arguments' => ['x-expires' => self::EXPIRE_TIME]]);
Util::declareExchange($this->connection, 'celeryresults', 'direct', ['exclusive' => false]);
$this->channel->queue_bind($this->taskId, 'celeryresults', $this->taskId);
}
/**
* Generic method to synchronously call Fatmouse Agent tasks.
*
* Create result queue for the task and bind it to results exchange.
* Scalr uses agent tasks directly in synchronous manner (mostly for
* retrieving server stats), and due to very high request rate we need
* to clean up per-task result queues ASAP.
*
* `auto-delete` argument makes sure that queue will be deleted after last queue
* consumer disconnected. (Won't be deleted if there weren't any consumers)
*
* `x-expires` queue option means that queue will be deleted if it's unused for the
* specified time in milliseconds. Unused means that queue has no consumers,
* the queue has not been redeclared, and basic.get has not been invoked.
*
* Example: Call Fatmouse Agent task
* <code>
* <?php
* $serverId = "cf3a320b-7ac6-4b88-810a-c760a94e1875";
* $taskName = "sys.set_hostname";
* $params = ["hostname" => "myexample.com"];
* $timeout = 5;
* $result = $fatmouse->callAgentSync($serverId, $taskName, $params, $timeout);
* ?>
* </code>
*
* @param string $serverId Scalr server-id to call task at
* @param string $taskName Agent task name
* @param array $kwargs optional Task parameters
* @param integer $timeout optional Result timeout in seconds
* @return \stdClass|mixed Task result
*/
public function callAgentSync($serverId, $taskName, $kwargs = null, $timeout = null)
{
list($taskId, $serializedTask) = $this->prepareCeleryTask($taskName, $kwargs);
$serverExchange = 'server.' . $serverId . '.celery';
$connection = $this->getConnection();
$channel = $connection->channel();
$timeout = $timeout === null ? $this->defaultCallAgentTimeout : $timeout;
try {
Util::declareQueue($connection, $taskId, ['durable' => false, 'auto_delete' => true, 'arguments' => $timeout ? ['x-expires' => $timeout * 1000] : null]);
Util::declareExchange($connection, 'celeryresults', 'direct');
$channel->queue_bind($taskId, 'celeryresults', $taskId);
// Sending task to server's queue
$msg = new AMQPMessage($serializedTask, $this->publishParams);
$channel->basic_publish($msg, $serverExchange);
$result = null;
$setResult = function ($msg) use(&$result) {
$result = Util::jsonDecode($msg->body);
};
// Setting callback for message
$channel->basic_consume($taskId, '', false, true, false, false, $setResult);
try {
$channel->wait(null, false, $timeout);
} catch (AMQPTimeoutException $e) {
throw new Errors\ClientException(sprintf("Timeout %d seconds exceeded while waiting for task '%s' to complete on server '%s'", $timeout, $taskName, $server_id));
}
return $result;
} finally {
$channel->close();
}
}
