GODT-1366: Simple lookup of index and select current user

pkg/listener/listener.go

@@ -35,6 +35,7 @@ type Listener interface {
 	Emit(eventName string, data string)
 	SetBuffer(eventName string)
 	RetryEmit(eventName string)
+	Book(eventName string)
 }
 
 type listener struct {
@@ -56,6 +57,19 @@ func New() Listener {
 	}
 }
 
+// Book wil create the list of channels for specific eventName. This should be
+// used when there is not always listening channel available and it should not
+// be logged when no channel is awaiting an emitted event.
+func (l *listener) Book(eventName string) {
+	if l.channels == nil {
+		l.channels = make(map[string][]chan<- string)
+	}
+	if _, ok := l.channels[eventName]; !ok {
+		l.channels[eventName] = []chan<- string{}
+	}
+	log.WithField("name", eventName).Debug("Channel booked")
+}
+
 // SetLimit sets the limit for the `eventName`. When the same event (name and data)
 // is emitted within last time duration (`limit`), event is dropped. Zero limit clears
 // the limit for the specific `eventName`.