Ping Pong in Netty 4.0.

PingPongChannelInitializer.java

package example;

import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

class PingPongChannelInitializer extends ChannelInitializer<SocketChannel> {

  private ChannelHandler handler;

  public PingPongChannelInitializer (ChannelHandler handler) {
    this.handler = handler;
  }

  @Override
  public void initChannel (SocketChannel ch) throws Exception {
    ch.pipeline().addLast (
        new LengthFieldBasedFrameDecoder (Integer.MAX_VALUE, 0, 2),
        new LengthFieldPrepender (2),
        new StringDecoder (CharsetUtil.UTF_8),
        new StringEncoder (CharsetUtil.UTF_8),
        handler);
  }
}

PingPongClient.java

package example;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;

public class PingPongClient {

  public static void main(String[] args) throws Exception {

    String host;
    if (args.length > 0) {
      host = args[0];
    } else {
      host = "localhost";
    }

    int port;
    if (args.length > 1) {
      port = Integer.parseInt(args[1]);
    } else {
      port = 8080;
    }

    EventLoopGroup workerGroup = new NioEventLoopGroup ();

    try {
      Bootstrap b = new Bootstrap();
      ChannelFuture f = b.group (workerGroup)
          .channel (NioSocketChannel.class)
          .option (ChannelOption.SO_KEEPALIVE, true)
          .handler (new PingPongChannelInitializer (new PingPongClientHandler ()))
          .connect (host, port).sync ();
      f.channel().closeFuture().sync ();
    } finally {
      workerGroup.shutdownGracefully();
    }
  }
}

PingPongClientHandler.java

package example;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

class PingPongClientHandler extends ChannelInboundHandlerAdapter {

  final int M = 1000, N = 10000;

  long start = System.currentTimeMillis();
  int i = M, j = N;

  @Override
  public void channelActive (ChannelHandlerContext ctx) {
    ctx.writeAndFlush ("Hello World.\n");
    j--;
  }

  @Override
  public void channelRead (ChannelHandlerContext ctx, Object msg) {
    ctx.write ("Hello World.\n");
    j--;
    if (j == 0) {
      long end = System.currentTimeMillis();
      double ms = (double)(end - start) / (double)(N);
      double qps = 1.0 / ms * 1000.0;
      System.out.println (String.format ("%d trials: %10.3f ms, %10.0f rps", N, ms, qps));
      j = N;
      i--;
      if (i == 0)
        ctx.close();
    }
  }

  @Override
  public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
    ctx.flush();
  }

  @Override
  public void exceptionCaught (ChannelHandlerContext ctx, Throwable cause) {
    cause.printStackTrace();
    ctx.close();
  }
}

PingPongServer.java

package example;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;

public class PingPongServer {

  private int port;

  public PingPongServer (int port) {
    this.port = port;
  }

  public void run() throws Exception {
    EventLoopGroup bossGroup = new NioEventLoopGroup();
    EventLoopGroup workerGroup = new NioEventLoopGroup();
    try {
      ServerBootstrap b = new ServerBootstrap();
      ChannelFuture f = b.group (bossGroup, workerGroup)
          .channel (NioServerSocketChannel.class)
          .childHandler (new PingPongChannelInitializer (new PingPongServerHandler ()))
          .option (ChannelOption.SO_BACKLOG, 128)
          .childOption (ChannelOption.SO_KEEPALIVE, true)
          .bind (port) .sync ();
      f.channel().closeFuture().sync();
    } finally {
      workerGroup.shutdownGracefully();
      bossGroup.shutdownGracefully();
    }
  }

  public static void main(String[] args) throws Exception {
    int port;
    if (args.length > 0) {
      port = Integer.parseInt(args[0]);
    } else {
      port = 8080;
    }
    new PingPongServer (port).run();
  }
}

PingPongServerHandler.java

package example;

import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

@ChannelHandler.Sharable
class PingPongServerHandler extends ChannelInboundHandlerAdapter {

  @Override
  public void channelRead (ChannelHandlerContext ctx, Object msg) {
    ctx.write (msg);
  }

  @Override
  public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
    ctx.flush();
  }

  @Override
  public void exceptionCaught (ChannelHandlerContext ctx, Throwable cause) {
    cause.printStackTrace();
    ctx.close();
  }
}