// SendResponse sends a message back to return identites of the received message.
func (receipt *MsgReceipt) SendResponse(socket *zmq.Socket, msg ComposedMsg) {
socket.SendMultipart(receipt.Identities, zmq.SNDMORE)
socket.Send([]byte("<IDS|MSG>"), zmq.SNDMORE)
socket.SendMultipart(msg.ToWireMsg(receipt.Sockets.Key), 0)
logger.Println("<--", msg.Header.Msg_type)
logger.Printf("%+v\n", msg.Content)
}
// Publishes stored events to event listeners.
//
// Pops previously stored messages off a channel and published them to a
// ZeroMQ socket.
func publishAllSavedEvents(toPublish chan eventstore.StoredEvent, evpub zmq.Socket) {
msg := make(zMsg, 3)
for stored := range toPublish {
msg[0] = stored.Event.Stream
msg[1] = stored.Id
msg[2] = stored.Event.Data
if err := evpub.SendMultipart(msg, 0); err != nil {
log.Println(err)
}
}
}
// SendResponse sends a message back to return identites of the received message.
func (receipt *MsgReceipt) SendResponse(socket *zmq.Socket, msg ComposedMsg) {
socket.SendMultipart(receipt.Identities, zmq.SNDMORE)
socket.Send([]byte("<IDS|MSG>"), zmq.SNDMORE)
msgParts, err := msg.ToWireMsg(receipt.Sockets.Key)
if err != nil {
log.Fatalln(err)
}
socket.SendMultipart(msgParts, 0)
logger.Println("<--", msg.Header.MsgType)
logger.Printf("%+v\n", msg.Content)
}
// A blocking function that will infinitely forward multi-part messages between two zmq.Sockets
func Forward(a, b zmq.Socket) {
for {
parts, err := a.RecvMultipart(0)
if err != nil {
log.Println("Error receiving message on frontend broker", err)
}
err = b.SendMultipart(parts, 0)
if err != nil {
log.Println("Error sending message on backend broker", err)
}
// log.Println("Brokered message:", Stringify(parts))
}
}
// The core ZeroMQ messaging loop. Handles requests and responses
// asynchronously using the router socket. Every request is delegated to
// a goroutine for maximum concurrency.
//
// `gozmq` does currently not support copy-free messages/frames. This
// means that every message passing through this function needs to be
// copied in-memory. If this becomes a bottleneck in the future,
// multiple router sockets can be hooked to this final router to scale
// message copying.
//
// TODO: Make this a type function of `Server` to remove a lot of
// parameters.
func loopServer(estore *eventstore.EventStore, evpubsock, frontend zmq.Socket,
stop chan bool) {
toPoll := zmq.PollItems{
zmq.PollItem{Socket: &frontend, zmq.Events: zmq.POLLIN},
}
pubchan := make(chan eventstore.StoredEvent)
estore.RegisterPublishedEventsChannel(pubchan)
go publishAllSavedEvents(pubchan, evpubsock)
defer close(pubchan)
pollchan := make(chan zmqPollResult)
respchan := make(chan zMsg)
pollCancel := make(chan bool)
defer stopPoller(pollCancel)
go asyncPoll(pollchan, toPoll, pollCancel)
for {
select {
case res := <-pollchan:
if res.err != nil {
log.Println("Could not poll:", res.err)
}
if res.err == nil && toPoll[0].REvents&zmq.POLLIN != 0 {
msg, _ := toPoll[0].Socket.RecvMultipart(0)
zmsg := zMsg(msg)
go handleRequest(respchan, estore, zmsg)
}
go asyncPoll(pollchan, toPoll, pollCancel)
case frames := <-respchan:
if err := frontend.SendMultipart(frames, 0); err != nil {
log.Println(err)
}
case <-stop:
log.Println("Server asked to stop. Stopping...")
return
}
}
}
