第36课：Kafka源码解读SocketServer下的Acceptor、Processor、Handler

第36课：Kafka源码解读SocketServer下的Acceptor、Processor、Handler
1 socketServer下的NIO
2 Acceptor、Processor、Handler

/**
 * An NIO socket server. The threading model is
 *   1 Acceptor thread that handles new connections
 *   Acceptor has N Processor threads that each have their own selector and read requests from sockets
 *   M Handler threads that handle requests and produce responses back to the processor threads for writing.
 */

class SocketServer(val config: KafkaConfig, val metrics: Metrics, val time: Time) extends Logging with KafkaMetricsGroup {

 

 

/** * Accept loop that checks for new connection attempts */def run() {  serverChannel.register(nioSelector, SelectionKey.OP_ACCEPT)  startupComplete()  try {    var currentProcessor = 0    while (isRunning) {      try {        val ready = nioSelector.select(500)        if (ready > 0) {          val keys = nioSelector.selectedKeys()          val iter = keys.iterator()          while (iter.hasNext && isRunning) {            try {              val key = iter.next              iter.remove()              if (key.isAcceptable)                accept(key, processors(currentProcessor))              else                throw new IllegalStateException("Unrecognized key state for acceptor thread.")              // round robin to the next processor thread              currentProcessor = (currentProcessor + 1) % processors.length            } catch {              case e: Throwable => error("Error while accepting connection", e)            }          }        }      }

 

 

 

 

 

/* * Create a server socket to listen for connections on. */private def openServerSocket(host: String, port: Int): ServerSocketChannel = {  val socketAddress =    if(host == null || host.trim.isEmpty)      new InetSocketAddress(port)    else      new InetSocketAddress(host, port)  val serverChannel = ServerSocketChannel.open()  serverChannel.configureBlocking(false)  serverChannel.socket().setReceiveBufferSize(recvBufferSize)  try {    serverChannel.socket.bind(socketAddress)    info("Awaiting socket connections on %s:%d.".format(socketAddress.getHostName, serverChannel.socket.getLocalPort))  } catch {    case e: SocketException =>      throw new KafkaException("Socket server failed to bind to %s:%d: %s.".format(socketAddress.getHostName, port, e.getMessage), e)  }  serverChannel}

 

 

 

 

/* * Accept a new connection */def accept(key: SelectionKey, processor: Processor) {  val serverSocketChannel = key.channel().asInstanceOf[ServerSocketChannel]  val socketChannel = serverSocketChannel.accept()  try {    connectionQuotas.inc(socketChannel.socket().getInetAddress)    socketChannel.configureBlocking(false)    socketChannel.socket().setTcpNoDelay(true)    socketChannel.socket().setKeepAlive(true)    socketChannel.socket().setSendBufferSize(sendBufferSize)    debug("Accepted connection from %s on %s. sendBufferSize [actual|requested]: [%d|%d] recvBufferSize [actual|requested]: [%d|%d]"          .format(socketChannel.socket.getInetAddress, socketChannel.socket.getLocalSocketAddress,                socketChannel.socket.getSendBufferSize, sendBufferSize,                socketChannel.socket.getReceiveBufferSize, recvBufferSize))    processor.accept(socketChannel)  } catch {    case e: TooManyConnectionsException =>      info("Rejected connection from %s, address already has the configured maximum of %d connections.".format(e.ip, e.count))      close(socketChannel)  }}

 

 

 

 

/** * Thread that processes all requests from a single connection. There are N of these running in parallel * each of which has its own selector */private[kafka] class Processor(val id: Int,                               time: Time,                               maxRequestSize: Int,                               requestChannel: RequestChannel,                               connectionQuotas: ConnectionQuotas,                               connectionsMaxIdleMs: Long,                               protocol: SecurityProtocol,                               channelConfigs: java.util.Map[String, _],                               metrics: Metrics) extends AbstractServerThread(connectionQuotas) with KafkaMetricsGroup {  private object ConnectionId {    def fromString(s: String): Option[ConnectionId] = s.split("-") match {      case Array(local, remote) => BrokerEndPoint.parseHostPort(local).flatMap { case (localHost, localPort) =>        BrokerEndPoint.parseHostPort(remote).map { case (remoteHost, remotePort) =>          ConnectionId(localHost, localPort, remoteHost, remotePort)        }      }      case _ => None    }  }