func main() {
snapshot, _ := zmq.NewSocket(zmq.DEALER)
snapshot.Connect("tcp://localhost:5556")
subscriber, _ := zmq.NewSocket(zmq.SUB)
subscriber.SetRcvhwm(100000) // or messages between snapshot and next are lost
subscriber.SetSubscribe("")
subscriber.Connect("tcp://localhost:5557")
time.Sleep(time.Second) // or messages between snapshot and next are lost
kvmap := make(map[string]*kvsimple.Kvmsg)
// Get state snapshot
sequence := int64(0)
snapshot.SendMessage("ICANHAZ?")
for {
kvmsg, err := kvsimple.RecvKvmsg(snapshot)
if err != nil {
fmt.Println(err)
break // Interrupted
}
if key, _ := kvmsg.GetKey(); key == "KTHXBAI" {
sequence, _ = kvmsg.GetSequence()
fmt.Printf("Received snapshot=%d\n", sequence)
break // Done
}
kvmsg.Store(kvmap)
}
snapshot.Close()
first := true
// Now apply pending updates, discard out-of-sequence messages
for {
kvmsg, err := kvsimple.RecvKvmsg(subscriber)
if err != nil {
fmt.Println(err)
break // Interrupted
}
if seq, _ := kvmsg.GetSequence(); seq > sequence {
sequence, _ = kvmsg.GetSequence()
kvmsg.Store(kvmap)
if first {
// Show what the first regular update is after the snapshot,
// to see if we missed updates.
first = false
fmt.Println("Next:", sequence)
}
}
}
}
func main() {
snapshot, _ := zmq.NewSocket(zmq.ROUTER)
snapshot.Bind("tcp://*:5556")
publisher, _ := zmq.NewSocket(zmq.PUB)
publisher.Bind("tcp://*:5557")
collector, _ := zmq.NewSocket(zmq.PULL)
collector.Bind("tcp://*:5558")
// The body of the main task collects updates from clients and
// publishes them back out to clients:
sequence := int64(0)
kvmap := make(map[string]*kvsimple.Kvmsg)
poller := zmq.NewPoller()
poller.Add(collector, zmq.POLLIN)
poller.Add(snapshot, zmq.POLLIN)
LOOP:
for {
polled, err := poller.Poll(1000 * time.Millisecond)
if err != nil {
break
}
for _, item := range polled {
switch socket := item.Socket; socket {
case collector:
// Apply state update sent from client
kvmsg, err := kvsimple.RecvKvmsg(collector)
if err != nil {
break LOOP // Interrupted
}
sequence++
kvmsg.SetSequence(sequence)
kvmsg.Send(publisher)
kvmsg.Store(kvmap)
fmt.Println("I: publishing update", sequence)
case snapshot:
// Execute state snapshot request
msg, err := snapshot.RecvMessage(0)
if err != nil {
break LOOP
}
identity := msg[0]
// Request is in second frame of message
request := msg[1]
if request != "ICANHAZ?" {
fmt.Println("E: bad request, aborting")
break LOOP
}
// Send state snapshot to client
// For each entry in kvmap, send kvmsg to client
for _, kvmsg := range kvmap {
snapshot.Send(identity, zmq.SNDMORE)
kvmsg.Send(snapshot)
}
// Now send END message with sequence number
fmt.Println("I: sending shapshot =", sequence)
snapshot.Send(identity, zmq.SNDMORE)
kvmsg := kvsimple.NewKvmsg(sequence)
kvmsg.SetKey("KTHXBAI")
kvmsg.SetBody("")
kvmsg.Send(snapshot)
}
}
}
fmt.Printf("Interrupted\n%d messages handled\n", sequence)
}
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]*kvsimple.Kvmsg)
rand.Seed(time.Now().UnixNano())
// We first request a state snapshot:
sequence := int64(0)
snapshot.SendMessage("ICANHAZ?", SUBTREE)
for {
kvmsg, err := kvsimple.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 := kvsimple.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 := kvsimple.NewKvmsg(0)
kvmsg.SetKey(fmt.Sprintf("%s%d", SUBTREE, rand.Intn(10000)))
kvmsg.SetBody(fmt.Sprint(rand.Intn(1000000)))
kvmsg.Send(publisher)
alarm = time.Now().Add(1000 * time.Millisecond)
}
}
fmt.Printf("Interrupted\n%d messages in\n", sequence)
}
func state_manager() {
kvmap := make(map[string]*kvsimple.Kvmsg)
pipe, _ := zmq.NewSocket(zmq.PAIR)
pipe.Connect("inproc://pipe")
pipe.SendMessage("READY")
snapshot, _ := zmq.NewSocket(zmq.ROUTER)
snapshot.Bind("tcp://*:5556")
poller := zmq.NewPoller()
poller.Add(pipe, zmq.POLLIN)
poller.Add(snapshot, zmq.POLLIN)
sequence := int64(0) // Current snapshot version number
LOOP:
for {
polled, err := poller.Poll(-1)
if err != nil {
break // Context has been shut down
}
for _, item := range polled {
switch socket := item.Socket; socket {
case pipe:
// Apply state update from main thread
kvmsg, err := kvsimple.RecvKvmsg(pipe)
if err != nil {
break LOOP // Interrupted
}
sequence, _ = kvmsg.GetSequence()
kvmsg.Store(kvmap)
case snapshot:
// Execute state snapshot request
msg, err := snapshot.RecvMessage(0)
if err != nil {
break LOOP // Interrupted
}
identity := msg[0]
// Request is in second frame of message
request := msg[1]
if request != "ICANHAZ?" {
fmt.Println("E: bad request, aborting")
break LOOP
}
// Send state snapshot to client
// For each entry in kvmap, send kvmsg to client
for _, kvmsg := range kvmap {
snapshot.Send(identity, zmq.SNDMORE)
kvmsg.Send(snapshot)
}
// Give client some time to deal with it.
// This reduces the risk that the client won't see
// the END message, but it doesn't eliminate the risk.
time.Sleep(100 * time.Millisecond)
// Now send END message with sequence number
fmt.Printf("Sending state shapshot=%d\n", sequence)
snapshot.Send(identity, zmq.SNDMORE)
kvmsg := kvsimple.NewKvmsg(sequence)
kvmsg.SetKey("KTHXBAI")
kvmsg.SetBody("")
kvmsg.Send(snapshot)
}
}
}
}