KafkaController分析3-ControllerChannelManager

controllerContext.liveBrokers.foreach(addNewBroker(_))

private def addNewBroker(broker: Broker) {
    ...
    val networkClient = {
      val selector = new Selector(
        ...
      )
      new NetworkClient(
        selector,
        new ManualMetadataUpdater(Seq(brokerNode).asJava),
        config.brokerId.toString,
        1,
        0,
        Selectable.USE_DEFAULT_BUFFER_SIZE,
        Selectable.USE_DEFAULT_BUFFER_SIZE,
        config.requestTimeoutMs,
        time
      )
    }
...
    val requestThread = new RequestSendThread(config.brokerId, controllerContext, messageQueue, networkClient,
      brokerNode, config, time, threadName)
    requestThread.setDaemon(false)
    brokerStateInfo.put(broker.id, new ControllerBrokerStateInfo(networkClient, brokerNode, messageQueue, requestThread))
  }

val response = ApiKeys.forId(clientResponse.request.request.header.apiKey) match {
            case ApiKeys.LEADER_AND_ISR => new LeaderAndIsrResponse(clientResponse.responseBody)
            case ApiKeys.STOP_REPLICA => new StopReplicaResponse(clientResponse.responseBody)
            case ApiKeys.UPDATE_METADATA_KEY => new UpdateMetadataResponse(clientResponse.responseBody)
            case apiKey => throw new KafkaException(s"Unexpected apiKey received: $apiKey")
          }

if (callback != null) {
            callback(response)
}

 val leaderAndIsrRequestMap = mutable.Map.empty[Int, mutable.Map[TopicPartition, PartitionStateInfo]]
  val stopReplicaRequestMap = mutable.Map.empty[Int, Seq[StopReplicaRequestInfo]]
  val updateMetadataRequestMap = mutable.Map.empty[Int, mutable.Map[TopicPartition, PartitionStateInfo]]