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

This example Akka source code file (NettyHelpers.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, channelhandlercontext, channelstateevent, closedchannelexception, exceptionevent, messageevent, netty, nettyclienthelpers, nettyhelpers, nettyserverhelpers, remote, simplechannelupstreamhandler, transport, unit, utilities

The NettyHelpers.scala Akka example source code

/**
 * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
 */
package akka.remote.transport.netty

import akka.AkkaException
import java.nio.channels.ClosedChannelException
import org.jboss.netty.channel._
import scala.util.control.NonFatal

/**
 * INTERNAL API
 */
private[netty] trait NettyHelpers {

  protected def onConnect(ctx: ChannelHandlerContext, e: ChannelStateEvent): Unit = ()

  protected def onDisconnect(ctx: ChannelHandlerContext, e: ChannelStateEvent): Unit = ()

  protected def onOpen(ctx: ChannelHandlerContext, e: ChannelStateEvent): Unit = ()

  protected def onMessage(ctx: ChannelHandlerContext, e: MessageEvent): Unit = ()

  protected def onException(ctx: ChannelHandlerContext, e: ExceptionEvent): Unit = ()

  final protected def transformException(ctx: ChannelHandlerContext, ev: ExceptionEvent): Unit = {
    val cause = if (ev.getCause ne null) ev.getCause else new AkkaException("Unknown cause")
    cause match {
      case _: ClosedChannelException ⇒ // Ignore
      case null | NonFatal(_)        ⇒ onException(ctx, ev)
      case e: Throwable              ⇒ throw e // Rethrow fatals
    }
  }
}

/**
 * INTERNAL API
 */
private[netty] trait NettyServerHelpers extends SimpleChannelUpstreamHandler with NettyHelpers {

  final override def messageReceived(ctx: ChannelHandlerContext, e: MessageEvent): Unit = {
    super.messageReceived(ctx, e)
    onMessage(ctx, e)
  }

  final override def exceptionCaught(ctx: ChannelHandlerContext, e: ExceptionEvent): Unit = transformException(ctx, e)

  final override def channelConnected(ctx: ChannelHandlerContext, e: ChannelStateEvent): Unit = {
    super.channelConnected(ctx, e)
    onConnect(ctx, e)
  }

  final override def channelOpen(ctx: ChannelHandlerContext, e: ChannelStateEvent): Unit = {
    super.channelOpen(ctx, e)
    onOpen(ctx, e)
  }

  final override def channelDisconnected(ctx: ChannelHandlerContext, e: ChannelStateEvent): Unit = {
    super.channelDisconnected(ctx, e)
    onDisconnect(ctx, e)
  }
}

/**
 * INTERNAL API
 */
private[netty] trait NettyClientHelpers extends SimpleChannelHandler with NettyHelpers {
  final override def messageReceived(ctx: ChannelHandlerContext, e: MessageEvent): Unit = {
    super.messageReceived(ctx, e)
    onMessage(ctx, e)
  }

  final override def exceptionCaught(ctx: ChannelHandlerContext, e: ExceptionEvent): Unit = transformException(ctx, e)

  final override def channelConnected(ctx: ChannelHandlerContext, e: ChannelStateEvent): Unit = {
    super.channelConnected(ctx, e)
    onConnect(ctx, e)
  }

  final override def channelOpen(ctx: ChannelHandlerContext, e: ChannelStateEvent): Unit = {
    super.channelOpen(ctx, e)
    onOpen(ctx, e)
  }

  final override def channelDisconnected(ctx: ChannelHandlerContext, e: ChannelStateEvent): Unit = {
    super.channelDisconnected(ctx, e)
    onDisconnect(ctx, e)
  }
}