Example #1
0
func subscriber(srv *clonesrv_t) (err error) {
	//  Get state snapshot if necessary
	if !srv.kvmap_init {
		srv.kvmap_init = true
		snapshot, _ := zmq.NewSocket(zmq.DEALER)
		snapshot.Connect(fmt.Sprint("tcp://localhost:", srv.peer))
		fmt.Printf("I: asking for snapshot from: tcp://localhost:%v\n", srv.peer)
		snapshot.SendMessage("ICANHAZ?", "") // blank subtree to get all
		for {
			kvmsg, e := kvmsg.RecvKvmsg(snapshot)
			if e != nil {
				err = e
				break
			}
			if key, _ := kvmsg.GetKey(); key == "KTHXBAI" {
				srv.sequence, _ = kvmsg.GetSequence()
				break //  Done
			}
			kvmsg.Store(srv.kvmap)
		}
		fmt.Println("I: received snapshot =", srv.sequence)
	}
	//  Find and remove update off pending list
	kvmsg, e := kvmsg.RecvKvmsg(srv.subscriber)
	if e != nil {
		err = e
		return
	}

	if key, _ := kvmsg.GetKey(); key != "HUGZ" {
		if !srv.was_pending(kvmsg) {
			//  If active update came before client update, flip it
			//  around, store active update (with sequence) on pending
			//  list and use to clear client update when it comes later
			srv.pending = append(srv.pending, kvmsg)
		}
		//  If update is more recent than our kvmap, apply it
		if seq, _ := kvmsg.GetSequence(); seq > srv.sequence {
			srv.sequence = seq
			kvmsg.Store(srv.kvmap)
			fmt.Println("I: received update =", srv.sequence)
		}
	}
	return
}
Example #2
0
func clone_agent(pipename string) {

	pipe, _ := zmq.NewSocket(zmq.PAIR)
	pipe.Connect(pipename)

	agent := agent_new(pipe)

LOOP:
	for {
		poller := zmq.NewPoller()
		poller.Add(pipe, zmq.POLLIN)
		server := agent.server[agent.cur_server]
		switch agent.state {
		case state_INITIAL:
			//  In this state we ask the server for a snapshot,
			//  if we have a server to talk to...
			if agent.nbr_servers > 0 {
				fmt.Printf("I: waiting for server at %s:%d...\n", server.address, server.port)
				if server.requests < 2 {
					server.snapshot.SendMessage("ICANHAZ?", agent.subtree)
					server.requests++
				}
				server.expiry = time.Now().Add(server_TTL)
				agent.state = state_SYNCING
				poller.Add(server.snapshot, zmq.POLLIN)
			}

		case state_SYNCING:
			//  In this state we read from snapshot and we expect
			//  the server to respond, else we fail over.
			poller.Add(server.snapshot, zmq.POLLIN)

		case state_ACTIVE:
			//  In this state we read from subscriber and we expect
			//  the server to give hugz, else we fail over.
			poller.Add(server.subscriber, zmq.POLLIN)
			break
		}
		poll_timer := time.Duration(-1)
		if server != nil {
			poll_timer = server.expiry.Sub(time.Now())
			if poll_timer < 0 {
				poll_timer = 0
			}
		}
		//  We're ready to process incoming messages; if nothing at all
		//  comes from our server within the timeout, that means the
		//  server is dead:

		polled, err := poller.Poll(poll_timer)
		if err != nil {
			break
		}

		if len(polled) > 0 {
			for _, item := range polled {
				switch socket := item.Socket; socket {
				case pipe:

					err = agent.control_message()
					if err != nil {
						break LOOP
					}

				default:
					kvmsg, e := kvmsg.RecvKvmsg(socket)
					if e != nil {
						err = e
						break LOOP
					}

					//  Anything from server resets its expiry time
					server.expiry = time.Now().Add(server_TTL)
					if agent.state == state_SYNCING {
						//  Store in snapshot until we're finished
						server.requests = 0
						if key, _ := kvmsg.GetKey(); key == "KTHXBAI" {
							agent.sequence, _ = kvmsg.GetSequence()
							agent.state = state_ACTIVE
							fmt.Printf("I: received from %s:%d snapshot=%d\n", server.address, server.port, agent.sequence)
						} else {
							kvmsg.Store(agent.kvmap)
						}
					} else if agent.state == state_ACTIVE {
						//  Discard out-of-sequence updates, incl. hugz
						if seq, _ := kvmsg.GetSequence(); seq > agent.sequence {
							agent.sequence = seq
							kvmsg.Store(agent.kvmap)
							fmt.Printf("I: received from %s:%d update=%d\n", server.address, server.port, agent.sequence)
						}
					}
				}
			}
		} else {
			//  Server has died, failover to next
			fmt.Printf("I: server at %s:%d didn't give hugz\n", server.address, server.port)
			agent.cur_server = (agent.cur_server + 1) % agent.nbr_servers
			agent.state = state_INITIAL
		}
	}
}
Example #3
0
func main() {
	snapshot, _ := zmq.NewSocket(zmq.DEALER)
	snapshot.Connect("tcp://localhost:5556")
	subscriber, _ := zmq.NewSocket(zmq.SUB)
	subscriber.SetSubscribe(SUBTREE)
	subscriber.Connect("tcp://localhost:5557")
	publisher, _ := zmq.NewSocket(zmq.PUSH)
	publisher.Connect("tcp://localhost:5558")

	kvmap := make(map[string]*kvmsg.Kvmsg)
	rand.Seed(time.Now().UnixNano())

	//  We first request a state snapshot:
	sequence := int64(0)
	snapshot.SendMessage("ICANHAZ?", SUBTREE)
	for {
		kvmsg, err := kvmsg.RecvKvmsg(snapshot)
		if err != nil {
			break //  Interrupted
		}
		if key, _ := kvmsg.GetKey(); key == "KTHXBAI" {
			sequence, _ := kvmsg.GetSequence()
			fmt.Println("I: received snapshot =", sequence)
			break //  Done
		}
		kvmsg.Store(kvmap)
	}
	snapshot.Close()

	poller := zmq.NewPoller()
	poller.Add(subscriber, zmq.POLLIN)
	alarm := time.Now().Add(1000 * time.Millisecond)
	for {
		tickless := alarm.Sub(time.Now())
		if tickless < 0 {
			tickless = 0
		}
		polled, err := poller.Poll(tickless)
		if err != nil {
			break //  Context has been shut down
		}
		if len(polled) == 1 {
			kvmsg, err := kvmsg.RecvKvmsg(subscriber)
			if err != nil {
				break //  Interrupted
			}

			//  Discard out-of-sequence kvmsgs, incl. heartbeats
			if seq, _ := kvmsg.GetSequence(); seq > sequence {
				sequence = seq
				kvmsg.Store(kvmap)
				fmt.Println("I: received update =", sequence)
			}
		}
		//  If we timed-out, generate a random kvmsg
		if time.Now().After(alarm) {
			kvmsg := kvmsg.NewKvmsg(0)
			kvmsg.SetKey(fmt.Sprintf("%s%d", SUBTREE, rand.Intn(10000)))
			kvmsg.SetBody(fmt.Sprint(rand.Intn(1000000)))
			kvmsg.SetProp("ttl", fmt.Sprintf("%d", rand.Intn((30)))) // seconds
			kvmsg.Send(publisher)
			alarm = time.Now().Add(1000 * time.Millisecond)
		}
	}
	fmt.Printf("Interrupted\n%d messages in\n", sequence)
}