}
self = argv[0];
System.out.printf("I: preparing broker at %s\n", self);
Random rand = new Random(System.nanoTime());
ZContext ctx = new ZContext();
// Bind cloud frontend to endpoint
Socket cloudfe = ctx.createSocket(ZMQ.ROUTER);
cloudfe.setIdentity(self.getBytes());
cloudfe.bind(String.format("ipc://%s-cloud.ipc", self));
// Connect cloud backend to all peers
Socket cloudbe = ctx.createSocket(ZMQ.ROUTER);
cloudbe.setIdentity(self.getBytes());
int argn;
for (argn = 1; argn < argv.length; argn++) {
String peer = argv[argn];
System.out.printf("I: connecting to cloud forintend at '%s'\n", peer);
cloudbe.connect(String.format("ipc://%s-cloud.ipc", peer));
}
// Prepare local frontend and backend
Socket localfe = ctx.createSocket(ZMQ.ROUTER);
localfe.bind(String.format("ipc://%s-localfe.ipc", self));
Socket localbe = ctx.createSocket(ZMQ.ROUTER);
localbe.bind(String.format("ipc://%s-localbe.ipc", self));
// Get user to tell us when we can start
System.out.println("Press Enter when all brokers are started: ");
try {
System.in.read();
} catch (IOException e) {
e.printStackTrace();
}
// Start local workers
int worker_nbr;
for (worker_nbr = 0; worker_nbr < NBR_WORKERS; worker_nbr++)
new worker_task().start();
// Start local clients
int client_nbr;
for (client_nbr = 0; client_nbr < NBR_CLIENTS; client_nbr++)
new client_task().start();
// Here we handle the request-reply flow. We're using the LRU approach
// to poll workers at all times, and clients only when there are one or
// more workers available.
// Least recently used queue of available workers
int capacity = 0;
ArrayList<ZFrame> workers = new ArrayList<ZFrame>();
while (true) {
// First, route any waiting replies from workers
PollItem backends[] = {
new PollItem(localbe, Poller.POLLIN),
new PollItem(cloudbe, Poller.POLLIN)
};
// If we have no workers anyhow, wait indefinitely
int rc = ZMQ.poll(backends,
capacity > 0 ? 1000 : -1);
if (rc == -1)
break; // Interrupted
// Handle reply from local worker
ZMsg msg = null;
if (backends[0].isReadable()) {
msg = ZMsg.recvMsg(localbe);
if (msg == null)
break; // Interrupted
ZFrame address = msg.unwrap();
workers.add(address);
capacity++;
// If it's READY, don't route the message any further
ZFrame frame = msg.getFirst();
if (new String(frame.getData()).equals(WORKER_READY)) {
msg.destroy();
msg = null;
}
}
// Or handle reply from peer broker
else if (backends[1].isReadable()) {
msg = ZMsg.recvMsg(cloudbe);
if (msg == null)
break; // Interrupted
// We don't use peer broker address for anything
ZFrame address = msg.unwrap();
address.destroy();
}
// Route reply to cloud if it's addressed to a broker
for (argn = 1; msg != null && argn < argv.length; argn++) {
byte[] data = msg.getFirst().getData();
if (argv[argn].equals(new String(data))) {
msg.send(cloudfe);
msg = null;
}
}
// Route reply to client if we still need to
if (msg != null)
msg.send(localfe);
// Now we route as many client requests as we have worker capacity
// for. We may reroute requests from our local frontend, but not from //
// the cloud frontend. We reroute randomly now, just to test things
// out. In the next version we'll do this properly by calculating
// cloud capacity://
while (capacity > 0) {
PollItem frontends[] = {
new PollItem(localfe, Poller.POLLIN),
new PollItem(cloudfe, Poller.POLLIN)
};
rc = ZMQ.poll(frontends, 0);
assert (rc >= 0);
int reroutable = 0;
// We'll do peer brokers first, to prevent starvation
if (frontends[1].isReadable()) {
msg = ZMsg.recvMsg(cloudfe);
reroutable = 0;
} else if (frontends[0].isReadable()) {
msg = ZMsg.recvMsg(localfe);
reroutable = 1;
} else
break; // No work, go back to backends
// If reroutable, send to cloud 20% of the time
// Here we'd normally use cloud status information
//
if (reroutable != 0 && argv.length > 1 && rand.nextInt(5) == 0) {
// Route to random broker peer
int random_peer = rand.nextInt(argv.length - 1) + 1;
msg.push(argv[random_peer]);
msg.send(cloudbe);
} else {
ZFrame frame = workers.remove(0);
msg.wrap(frame);
msg.send(localbe);
capacity--;
}
}
}
// When we're done, clean up properly
while (workers.size() > 0) {
ZFrame frame = workers.remove(0);
frame.destroy();
}
ctx.destroy();
}