// +optional
  optional string apiVersion = 3;
}

// ExternalMetricSource indicates how to scale on a metric not associated with
// any Kubernetes object (for example length of queue in cloud
// messaging service, or QPS from loadbalancer running outside of cluster).
message ExternalMetricSource {
  // metricName is the name of the metric in question.
  optional string metricName = 1;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.time.Duration;
import java.util.HashSet;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.ConcurrentLinkedQueue;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;

   * is used to calculate this value. It also doesn't include any bytes buffered by the operating
   * system or network intermediaries. This method returns 0 if no messages are waiting in the
   * queue. If may return a nonzero value after the web socket has been canceled; this indicates
   * that enqueued messages were not transmitted.
   */
  fun queueSize(): Long

  /**

Sie erfordern in der Regel komplexere Konfigurationen und einen Nachrichten-/Job-Queue-Manager wie RabbitMQ oder Redis, ermöglichen Ihnen jedoch die Ausführung von Hintergrundtasks in mehreren Prozessen und insbesondere auf mehreren Servern.

		queueStore = store.NewQueueStore[event.Event](queueDir, args.QueueLimit, event.StoreExtension)
		if err := queueStore.Open(); err != nil {
			cancel()
			return nil, fmt.Errorf("unable to initialize the queue store of Webhook `%s`: %w", id, err)
		}
	}

	target := &WebhookTarget{
		id:         event.TargetID{ID: id, Name: "webhook"},
		args:       args,
		loggerOnce: loggerOnce,
		transport:  transport,

 * concurrently.
 */
class Dispatcher() {
  internal val lock: ReentrantLock = ReentrantLock()

  /**
   * The maximum number of requests to execute concurrently. Above this requests queue in memory,
   * waiting for the running calls to complete.
   *
   * If more than [maxRequests] requests are in flight when this is invoked, those requests will
   * remain in flight.
   */
  var maxRequests = 64

    // contract.
    // This is somewhat annoying, but turns out to be very fast in practice. Alternatively, we could
    // drop the contract on the method that enforces this queue like behavior since depending on it
    // is likely to be a bug anyway.

    // N.B. All writes to the list and the next pointers must have happened before the above

		queueStore = store.NewQueueStore[event.Event](queueDir, args.QueueLimit, event.StoreExtension)
		if err := queueStore.Open(); err != nil {
			return nil, fmt.Errorf("unable to initialize the queue store of NSQ `%s`: %w", id, err)
		}
	}

	target := &NSQTarget{
		id:         event.TargetID{ID: id, Name: "nsq"},
		args:       args,
		loggerOnce: loggerOnce,
		store:      queueStore,

    this.assertThreadHoldsLock()

    val writerTask = writerTask
    if (writerTask != null) {
      taskQueue.schedule(writerTask)
    }
  }

  /**
   * Attempts to remove a single frame from a queue and send it. This prefers to write urgent pongs
   * before less urgent messages and close frames. For example it's possible that a caller will

		queueStore = store.NewQueueStore[event.Event](queueDir, args.QueueLimit, event.StoreExtension)
		if err := queueStore.Open(); err != nil {
			return nil, fmt.Errorf("unable to initialize the queue store of MQTT `%s`: %w", id, err)
		}
	}

	target := &MQTTTarget{
		id:         event.TargetID{ID: id, Name: "mqtt"},
		args:       args,
		store:      queueStore,
		quitCh:     make(chan struct{}),