Examples with Poller org.zeromq.ZMQ.Poller used on opensource projects

Example 21 with Poller

use of org.zeromq.ZMQ.Poller in project jeromq by zeromq.

the class lbbroker method main.

/**
     * This is the main task. It starts the clients and workers, and then
     * routes requests between the two layers. Workers signal READY when
     * they start; after that we treat them as ready when they reply with
     * a response back to a client. The load-balancing data structure is
     * just a queue of next available workers.
     */
public static void main(String[] args) {
    Context context = ZMQ.context(1);
    //  Prepare our context and sockets
    Socket frontend = context.socket(ZMQ.ROUTER);
    Socket backend = context.socket(ZMQ.ROUTER);
    frontend.bind("ipc://frontend.ipc");
    backend.bind("ipc://backend.ipc");
    int clientNbr;
    for (clientNbr = 0; clientNbr < NBR_CLIENTS; clientNbr++) new ClientTask().start();
    for (int workerNbr = 0; workerNbr < NBR_WORKERS; workerNbr++) new WorkerTask().start();
    //  Here is the main loop for the least-recently-used queue. It has two
    //  sockets; a frontend for clients and a backend for workers. It polls
    //  the backend in all cases, and polls the frontend only when there are
    //  one or more workers ready. This is a neat way to use 0MQ's own queues
    //  to hold messages we're not ready to process yet. When we get a client
    //  reply, we pop the next available worker, and send the request to it,
    //  including the originating client identity. When a worker replies, we
    //  re-queue that worker, and we forward the reply to the original client,
    //  using the reply envelope.
    //  Queue of available workers
    Queue<String> workerQueue = new LinkedList<String>();
    while (!Thread.currentThread().isInterrupted()) {
        //  Initialize poll set
        Poller items = context.poller(2);
        //  Always poll for worker activity on backend
        items.register(backend, Poller.POLLIN);
        //  Poll front-end only if we have available workers
        if (workerQueue.size() > 0)
            items.register(frontend, Poller.POLLIN);
        if (items.poll() < 0)
            //  Interrupted
            break;
        //  Handle worker activity on backend
        if (items.pollin(0)) {
            //  Queue worker address for LRU routing
            workerQueue.add(backend.recvStr());
            //  Second frame is empty
            String empty = backend.recvStr();
            assert (empty.length() == 0);
            //  Third frame is READY or else a client reply address
            String clientAddr = backend.recvStr();
            //  If client reply, send rest back to frontend
            if (!clientAddr.equals("READY")) {
                empty = backend.recvStr();
                assert (empty.length() == 0);
                String reply = backend.recvStr();
                frontend.sendMore(clientAddr);
                frontend.sendMore("");
                frontend.send(reply);
                if (--clientNbr == 0)
                    break;
            }
        }
        if (items.pollin(1)) {
            //  Now get next client request, route to LRU worker
            //  Client request is [address][empty][request]
            String clientAddr = frontend.recvStr();
            String empty = frontend.recvStr();
            assert (empty.length() == 0);
            String request = frontend.recvStr();
            String workerAddr = workerQueue.poll();
            backend.sendMore(workerAddr);
            backend.sendMore("");
            backend.sendMore(clientAddr);
            backend.sendMore("");
            backend.send(request);
        }
    }
    frontend.close();
    backend.close();
    context.term();
}

Example 22 with Poller

use of org.zeromq.ZMQ.Poller in project jeromq by zeromq.

the class flclient1 method tryRequest.

private static ZMsg tryRequest(ZContext ctx, String endpoint, ZMsg request) {
    System.out.printf("I: trying echo service at %s...\n", endpoint);
    Socket client = ctx.createSocket(ZMQ.REQ);
    client.connect(endpoint);
    //  Send request, wait safely for reply
    ZMsg msg = request.duplicate();
    msg.send(client);
    Poller poller = ctx.createPoller(1);
    poller.register(client, Poller.POLLIN);
    poller.poll(REQUEST_TIMEOUT);
    ZMsg reply = null;
    if (poller.pollin(0))
        reply = ZMsg.recvMsg(client);
    //  Close socket in any case, we're done with it now
    ctx.destroySocket(client);
    return reply;
}