Split DiscardHandler into DiscardClientHandler and DiscardServerHandler for easier understanding

src/main/java/org/jboss/netty/example/discard/DiscardClient.java

@@ -29,6 +29,14 @@ import org.jboss.netty.bootstrap.ClientBootstrap;
 import org.jboss.netty.channel.ChannelFactory;
 import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory;
 
+/**
+ * Keeps sending random data to the specified address.
+ *
+ * @author The Netty Project (netty-dev@lists.jboss.org)
+ * @author Trustin Lee (tlee@redhat.com)
+ *
+ * @version $Rev$, $Date$
+ */
 public class DiscardClient {
 
     public static void main(String[] args) throws Exception {
@@ -58,7 +66,7 @@ public class DiscardClient {
                     Executors.newCachedThreadPool());
 
         ClientBootstrap bootstrap = new ClientBootstrap(factory);
-        DiscardHandler handler = new DiscardHandler(firstMessageSize);
+        DiscardClientHandler handler = new DiscardClientHandler(firstMessageSize);
 
         bootstrap.getPipeline().addLast("handler", handler);
         bootstrap.setOption("tcpNoDelay", true);

src/main/java/org/jboss/netty/example/discard/DiscardClientHandler.java

@@ -38,22 +38,25 @@ import org.jboss.netty.channel.ExceptionEvent;
 import org.jboss.netty.channel.MessageEvent;
 import org.jboss.netty.channel.SimpleChannelHandler;
 
+/**
+ *
+ * @author The Netty Project (netty-dev@lists.jboss.org)
+ * @author Trustin Lee (tlee@redhat.com)
+ *
+ * @version $Rev$, $Date$
+ */
 @ChannelPipelineCoverage("all")
-public class DiscardHandler extends SimpleChannelHandler {
+public class DiscardClientHandler extends SimpleChannelHandler {
 
     private static final Logger logger = Logger.getLogger(
-            DiscardHandler.class.getName());
+            DiscardClientHandler.class.getName());
 
     private final Random random = new Random();
     private final int messageSize;
     private final AtomicLong transferredBytes = new AtomicLong();
 
-    public DiscardHandler() {
-        this(0);
-    }
-
-    public DiscardHandler(int messageSize) {
-        if (messageSize < 0) {
+    public DiscardClientHandler(int messageSize) {
+        if (messageSize <= 0) {
             throw new IllegalArgumentException(
                     "messageSize: " + messageSize);
         }
@@ -69,26 +72,32 @@ public class DiscardHandler extends SimpleChannelHandler {
         if (e instanceof ChannelStateEvent) {
             logger.info(e.toString());
         }
+
+        // Let SimpleChannelHandler call actual event handler methods below.
         super.handleUpstream(ctx, e);
     }
 
     @Override
     public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) {
+        // Send the initial messages.
         generateTraffic(e);
     }
 
     @Override
     public void channelInterestChanged(ChannelHandlerContext ctx, ChannelStateEvent e) {
+        // Keep sending messages whenever the current socket buffer has room.
         generateTraffic(e);
     }
 
     @Override
     public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
+        // Server is supposed to send nothing.  Therefore, do nothing.
         transferredBytes.addAndGet(((ChannelBuffer) e.getMessage()).readableBytes());
     }
 
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
+        // Close the connection when an exception is raised.
         logger.log(
                 Level.WARNING,
                 "Unexpected exception from downstream.",
@@ -108,10 +117,6 @@ public class DiscardHandler extends SimpleChannelHandler {
     }
 
     private ChannelBuffer nextMessage() {
-        if (messageSize == 0) {
-            return null;
-        }
-
         byte[] content = new byte[messageSize];
         random.nextBytes(content);
         return ChannelBuffers.wrappedBuffer(content);

src/main/java/org/jboss/netty/example/discard/DiscardServer.java

@@ -29,6 +29,14 @@ import org.jboss.netty.bootstrap.ServerBootstrap;
 import org.jboss.netty.channel.ChannelFactory;
 import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
 
+/**
+ * Discards any incoming data.
+ *
+ * @author The Netty Project (netty-dev@lists.jboss.org)
+ * @author Trustin Lee (tlee@redhat.com)
+ *
+ * @version $Rev$, $Date$
+ */
 public class DiscardServer {
 
     public static void main(String[] args) throws Exception {
@@ -39,7 +47,7 @@ public class DiscardServer {
                     Executors.newCachedThreadPool());
 
         ServerBootstrap bootstrap = new ServerBootstrap(factory);
-        DiscardHandler handler = new DiscardHandler();
+        DiscardServerHandler handler = new DiscardServerHandler();
 
         bootstrap.getPipeline().addLast("handler", handler);
         bootstrap.setOption("child.tcpNoDelay", true);

src/main/java/org/jboss/netty/example/discard/DiscardServerHandler.java

@@ -0,0 +1,82 @@
+/*
+ * JBoss, Home of Professional Open Source
+ *
+ * Copyright 2008, Red Hat Middleware LLC, and individual contributors
+ * by the @author tags. See the COPYRIGHT.txt in the distribution for a
+ * full listing of individual contributors.
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this software; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
+ */
+package org.jboss.netty.example.discard;
+
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import org.jboss.netty.buffer.ChannelBuffer;
+import org.jboss.netty.channel.ChannelEvent;
+import org.jboss.netty.channel.ChannelHandlerContext;
+import org.jboss.netty.channel.ChannelPipelineCoverage;
+import org.jboss.netty.channel.ChannelStateEvent;
+import org.jboss.netty.channel.ExceptionEvent;
+import org.jboss.netty.channel.MessageEvent;
+import org.jboss.netty.channel.SimpleChannelHandler;
+
+/**
+ *
+ * @author The Netty Project (netty-dev@lists.jboss.org)
+ * @author Trustin Lee (tlee@redhat.com)
+ *
+ * @version $Rev$, $Date$
+ */
+@ChannelPipelineCoverage("all")
+public class DiscardServerHandler extends SimpleChannelHandler {
+
+    private static final Logger logger = Logger.getLogger(
+            DiscardServerHandler.class.getName());
+
+    private final AtomicLong transferredBytes = new AtomicLong();
+
+    public long getTransferredBytes() {
+        return transferredBytes.get();
+    }
+
+    @Override
+    public void handleUpstream(ChannelHandlerContext ctx, ChannelEvent e) throws Exception {
+        if (e instanceof ChannelStateEvent) {
+            logger.info(e.toString());
+        }
+
+        // Let SimpleChannelHandler call actual event handler methods below.
+        super.handleUpstream(ctx, e);
+    }
+
+    @Override
+    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
+        // Discard received data silently by doing nothing.
+        transferredBytes.addAndGet(((ChannelBuffer) e.getMessage()).readableBytes());
+    }
+
+    @Override
+    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
+        // Close the connection when an exception is raised.
+        logger.log(
+                Level.WARNING,
+                "Unexpected exception from downstream.",
+                e.getCause());
+        e.getChannel().close();
+    }
+}

src/main/java/org/jboss/netty/example/discard/ThroughputMonitor.java

@@ -24,15 +24,15 @@ package org.jboss.netty.example.discard;
 
 public class ThroughputMonitor extends Thread {
 
-    private final DiscardHandler echoHandler;
+    private final DiscardServerHandler handler;
 
-    public ThroughputMonitor(DiscardHandler echoHandler) {
-        this.echoHandler = echoHandler;
+    public ThroughputMonitor(DiscardServerHandler echoHandler) {
+        this.handler = echoHandler;
     }
 
     @Override
     public void run() {
-        long oldCounter = echoHandler.getTransferredBytes();
+        long oldCounter = handler.getTransferredBytes();
         long startTime = System.currentTimeMillis();
         for (;;) {
             try {
@@ -42,7 +42,7 @@ public class ThroughputMonitor extends Thread {
             }
 
             long endTime = System.currentTimeMillis();
-            long newCounter = echoHandler.getTransferredBytes();
+            long newCounter = handler.getTransferredBytes();
             System.err.format(
                     "%4.3f MiB/s%n",
                     (newCounter - oldCounter) * 1000 / (endTime - startTime) /