Akka/Scala example source code file (TcpOutgoingConnection.scala)

This example Akka source code file (TcpOutgoingConnection.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Akka and Scala source code examples by using tags.

All credit for the original source code belongs to akka.io; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Akka tags/keywords

akka, attempting, channelregistration, channelregistry, clear, collection, concurrent, connect, could, io, nonfatal, receive, tcpoutgoingconnection, time, unit, utilities

The TcpOutgoingConnection.scala Akka example source code

/**
 * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
 */

package akka.io

import java.nio.channels.{ SelectionKey, SocketChannel }
import scala.util.control.NonFatal
import scala.collection.immutable
import scala.concurrent.duration._
import akka.actor.{ ReceiveTimeout, ActorRef }
import akka.io.Inet.SocketOption
import akka.io.TcpConnection.CloseInformation
import akka.io.SelectionHandler._
import akka.io.Tcp._

/**
 * An actor handling the connection state machine for an outgoing connection
 * to be established.
 *
 * INTERNAL API
 */
private[io] class TcpOutgoingConnection(_tcp: TcpExt,
                                        channelRegistry: ChannelRegistry,
                                        commander: ActorRef,
                                        connect: Connect)
  extends TcpConnection(_tcp, SocketChannel.open().configureBlocking(false).asInstanceOf[SocketChannel], connect.pullMode) {

  import connect._

  context.watch(commander) // sign death pact

  options.foreach(_.beforeConnect(channel.socket))
  localAddress.foreach(channel.socket.bind)
  channelRegistry.register(channel, 0)
  timeout foreach context.setReceiveTimeout //Initiate connection timeout if supplied

  private def stop(): Unit = stopWith(CloseInformation(Set(commander), connect.failureMessage))

  private def reportConnectFailure(thunk: ⇒ Unit): Unit = {
    try {
      thunk
    } catch {
      case NonFatal(e) ⇒
        log.debug("Could not establish connection to [{}] due to {}", remoteAddress, e)
        stop()
    }
  }

  def receive: Receive = {
    case registration: ChannelRegistration ⇒
      log.debug("Attempting connection to [{}]", remoteAddress)
      reportConnectFailure {
        if (channel.connect(remoteAddress))
          completeConnect(registration, commander, options)
        else {
          registration.enableInterest(SelectionKey.OP_CONNECT)
          context.become(connecting(registration, tcp.Settings.FinishConnectRetries))
        }
      }
  }

  def connecting(registration: ChannelRegistration, remainingFinishConnectRetries: Int): Receive = {
    {
      case ChannelConnectable ⇒
        reportConnectFailure {
          if (channel.finishConnect()) {
            if (timeout.isDefined) context.setReceiveTimeout(Duration.Undefined) // Clear the timeout
            log.debug("Connection established to [{}]", remoteAddress)
            completeConnect(registration, commander, options)
          } else {
            if (remainingFinishConnectRetries > 0) {
              context.system.scheduler.scheduleOnce(1.millisecond) {
                channelRegistry.register(channel, SelectionKey.OP_CONNECT)
              }(context.dispatcher)
              context.become(connecting(registration, remainingFinishConnectRetries - 1))
            } else {
              log.debug("Could not establish connection because finishConnect " +
                "never returned true (consider increasing akka.io.tcp.finish-connect-retries)")
              stop()
            }
          }
        }

      case ReceiveTimeout ⇒
        if (timeout.isDefined) context.setReceiveTimeout(Duration.Undefined) // Clear the timeout
        log.debug("Connect timeout expired, could not establish connection to [{}]", remoteAddress)
        stop()
    }
  }
}