clonesrv3.java

package guide;

import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;

import org.zeromq.SocketType;
import org.zeromq.ZContext;
import org.zeromq.ZMQ;
import org.zeromq.ZMQ.Poller;
import org.zeromq.ZMQ.Socket;

/**
 * Clone server Model Three
 * @author Danish Shrestha <dshrestha06@gmail.com>
 *
 */
public class clonesrv3
{
    private static Map<String, kvsimple> kvMap = new LinkedHashMap<String, kvsimple>();

    public void run()
    {
        try (ZContext ctx = new ZContext()) {
            Socket snapshot = ctx.createSocket(SocketType.ROUTER);
            snapshot.bind("tcp://*:5556");

            Socket publisher = ctx.createSocket(SocketType.PUB);
            publisher.bind("tcp://*:5557");

            Socket collector = ctx.createSocket(SocketType.PULL);
            collector.bind("tcp://*:5558");

            Poller poller = ctx.createPoller(2);
            poller.register(collector, Poller.POLLIN);
            poller.register(snapshot, Poller.POLLIN);

            long sequence = 0;
            while (!Thread.currentThread().isInterrupted()) {
                if (poller.poll(1000) < 0)
                    break; //  Context has been shut down

                // apply state updates from main thread
                if (poller.pollin(0)) {
                    kvsimple kvMsg = kvsimple.recv(collector);
                    if (kvMsg == null) //  Interrupted
                        break;
                    kvMsg.setSequence(++sequence);
                    kvMsg.send(publisher);
                    clonesrv3.kvMap.put(kvMsg.getKey(), kvMsg);
                    System.out.printf("I: publishing update %5d\n", sequence);
                }

                // execute state snapshot request
                if (poller.pollin(1)) {
                    byte[] identity = snapshot.recv(0);
                    if (identity == null)
                        break; //  Interrupted
                    String request = snapshot.recvStr();

                    if (!request.equals("ICANHAZ?")) {
                        System.out.println("E: bad request, aborting");
                        break;
                    }

                    Iterator<Entry<String, kvsimple>> iter = kvMap.entrySet()
                                                                  .iterator();
                    while (iter.hasNext()) {
                        Entry<String, kvsimple> entry = iter.next();
                        kvsimple msg = entry.getValue();
                        System.out.println(
                            "Sending message " + entry.getValue().getSequence()
                        );
                        this.sendMessage(msg, identity, snapshot);
                    }

                    // now send end message with getSequence number
                    System.out.println("Sending state snapshot = " + sequence);
                    snapshot.send(identity, ZMQ.SNDMORE);
                    kvsimple message = new kvsimple(
                        "KTHXBAI", sequence, ZMQ.SUBSCRIPTION_ALL
                    );
                    message.send(snapshot);
                }
            }

            System.out.printf(" Interrupted\n%d messages handled\n", sequence);
        }
    }

    private void sendMessage(kvsimple msg, byte[] identity, Socket snapshot)
    {
        snapshot.send(identity, ZMQ.SNDMORE);
        msg.send(snapshot);
    }

    public static void main(String[] args)
    {
        new clonesrv3().run();
    }
}