subprojects/s4-comm/src/main/java/org/apache/s4/comm/tcp/TCPListener.java

package org.apache.s4.comm.tcp;

import java.net.InetSocketAddress;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Executors;
import java.util.concurrent.SynchronousQueue;

import org.apache.s4.base.Listener;
import org.apache.s4.comm.topology.Assignment;
import org.apache.s4.comm.topology.ClusterNode;
import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelFactory;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
import org.jboss.netty.channel.group.ChannelGroup;
import org.jboss.netty.channel.group.DefaultChannelGroup;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
import org.jboss.netty.handler.codec.frame.LengthFieldBasedFrameDecoder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.inject.Inject;
import com.google.inject.name.Named;

public class TCPListener implements Listener {
    private static final Logger logger = LoggerFactory.getLogger(TCPListener.class);
    private BlockingQueue<byte[]> handoffQueue = new SynchronousQueue<byte[]>();
    private ClusterNode node;
    private ServerBootstrap bootstrap;
    private final ChannelGroup channels = new DefaultChannelGroup();
    private final int nettyTimeout;

    @Inject
    public TCPListener(Assignment assignment, @Named("comm.timeout") int timeout) {
        // wait for an assignment
        node = assignment.assignClusterNode();
        nettyTimeout = timeout;

        ChannelFactory factory = new NioServerSocketChannelFactory(Executors.newCachedThreadPool(),
                Executors.newCachedThreadPool());

        bootstrap = new ServerBootstrap(factory);

        bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
            public ChannelPipeline getPipeline() {
                ChannelPipeline p = Channels.pipeline();
                p.addLast("1", new LengthFieldBasedFrameDecoder(999999, 0, 4, 0, 4));
                p.addLast("2", new ChannelHandler(handoffQueue));

                return p;
            }
        });

        bootstrap.setOption("child.tcpNoDelay", true);
        bootstrap.setOption("child.keepAlive", true);
        bootstrap.setOption("child.reuseAddress", true);
        bootstrap.setOption("child.connectTimeoutMillis", nettyTimeout);
        bootstrap.setOption("readWriteFair", true);

        Channel c = bootstrap.bind(new InetSocketAddress(node.getPort()));
        channels.add(c);
    }

    public byte[] recv() {
        try {
            byte[] msg = handoffQueue.take();
            return msg;
        } catch (InterruptedException e) {
            return null;
        }
    }

    public int getPartitionId() {
        return node.getPartition();
    }

    public void close() {
        try {
            channels.close().await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        bootstrap.releaseExternalResources();
    }

    public class ChannelHandler extends SimpleChannelHandler {
        private BlockingQueue<byte[]> handoffQueue;

        public ChannelHandler(BlockingQueue<byte[]> handOffQueue) {
            this.handoffQueue = handOffQueue;
        }

        public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
            channels.add(e.getChannel());
            ChannelBuffer buffer = (ChannelBuffer) e.getMessage();
            try {
                handoffQueue.put(buffer.array()); // this holds up the Netty upstream I/O thread if
                                                  // there's no receiver at the other end of the handoff queue
            } catch (InterruptedException ie) {
                Thread.currentThread().interrupt();
            }
        }

        public void exceptionCaught(ChannelHandlerContext context, ExceptionEvent event) {
            logger.error("Error", event.getCause());
            Channel c = context.getChannel();
            if (c.isOpen()) {
                logger.error("Closing channel due to exception");
                try {
                    if (c.close().await().isSuccess())
                        channels.remove(c);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}