Trigger NATS events non blocking through buffered channel.

src/app/spreed-webrtc-server/bus_manager.go

@@ -22,6 +22,7 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"log"
 
@@ -95,9 +96,10 @@ func (bus *noopBus) Trigger(name, from, payload string, data interface{}) error
 }
 
 type natsBus struct {
-	id     string
-	prefix string
-	ec     *nats.EncodedConn
+	id           string
+	prefix       string
+	ec           *nats.EncodedConn
+	triggerQueue chan *busQueueEntry
 }
 
 func newNatsBus(id, prefix string) (*natsBus, error) {
@@ -108,7 +110,11 @@ func newNatsBus(id, prefix string) (*natsBus, error) {
 	if prefix == "" {
 		prefix = "channelling.trigger"
 	}
-	return &natsBus{id, prefix, ec}, nil
+	// Create buffered channel for outbound NATS data.
+	triggerQueue := make(chan *busQueueEntry, 50)
+	// Start go routine to process outbount NATS publishing.
+	go chPublish(ec, triggerQueue)
+	return &natsBus{id, prefix, ec, triggerQueue}, nil
 }
 
 func (bus *natsBus) Trigger(name, from, payload string, data interface{}) (err error) {
@@ -120,10 +126,29 @@ func (bus *natsBus) Trigger(name, from, payload string, data interface{}) (err e
 			Payload: payload,
 			Data:    data,
 		}
-		err = bus.ec.Publish(BusSubjectTrigger(bus.prefix, name), trigger)
-		if err != nil {
-			log.Println("Failed to trigger NATS event", err)
+		entry := &busQueueEntry{BusSubjectTrigger(bus.prefix, name), trigger}
+		select {
+		case bus.triggerQueue <- entry:
+			// sent ok
+		default:
+			log.Println("Failed to queue NATS event - queue full?")
+			err = errors.New("NATS trigger queue full")
 		}
 	}
 	return err
 }
+
+type busQueueEntry struct {
+	subject string
+	data    interface{}
+}
+
+func chPublish(ec *nats.EncodedConn, channel chan (*busQueueEntry)) {
+	for {
+		entry := <-channel
+		err := ec.Publish(entry.subject, entry.data)
+		if err != nil {
+			log.Println("Failed to publish to NATS", entry.subject, err)
+		}
+	}
+}