strip down mdns watcher

registry/mdns_registry.go

@@ -54,6 +54,17 @@ type mdnsRegistry struct {
 	listener chan *mdns.ServiceEntry
 }
 
+type mdnsWatcher struct {
+	id   string
+	wo   WatchOptions
+	ch   chan *mdns.ServiceEntry
+	exit chan struct{}
+	// the mdns domain
+	domain string
+	// the registry
+	registry *mdnsRegistry
+}
+
 func encode(txt *mdnsTxt) ([]string, error) {
 	b, err := json.Marshal(txt)
 	if err != nil {
@@ -534,6 +545,74 @@ func (m *mdnsRegistry) String() string {
 	return "mdns"
 }
 
+func (m *mdnsWatcher) Next() (*Result, error) {
+	for {
+		select {
+		case e := <-m.ch:
+			txt, err := decode(e.InfoFields)
+			if err != nil {
+				continue
+			}
+
+			if len(txt.Service) == 0 || len(txt.Version) == 0 {
+				continue
+			}
+
+			// Filter watch options
+			// wo.Service: Only keep services we care about
+			if len(m.wo.Service) > 0 && txt.Service != m.wo.Service {
+				continue
+			}
+
+			var action string
+
+			if e.TTL == 0 {
+				action = "delete"
+			} else {
+				action = "create"
+			}
+
+			service := &Service{
+				Name:      txt.Service,
+				Version:   txt.Version,
+				Endpoints: txt.Endpoints,
+			}
+
+			// skip anything without the domain we care about
+			suffix := fmt.Sprintf(".%s.%s.", service.Name, m.domain)
+			if !strings.HasSuffix(e.Name, suffix) {
+				continue
+			}
+
+			service.Nodes = append(service.Nodes, &Node{
+				Id:       strings.TrimSuffix(e.Name, suffix),
+				Address:  fmt.Sprintf("%s:%d", e.AddrV4.String(), e.Port),
+				Metadata: txt.Metadata,
+			})
+
+			return &Result{
+				Action:  action,
+				Service: service,
+			}, nil
+		case <-m.exit:
+			return nil, ErrWatcherStopped
+		}
+	}
+}
+
+func (m *mdnsWatcher) Stop() {
+	select {
+	case <-m.exit:
+		return
+	default:
+		close(m.exit)
+		// remove self from the registry
+		m.registry.mtx.Lock()
+		delete(m.registry.watchers, m.id)
+		m.registry.mtx.Unlock()
+	}
+}
+
 // NewRegistry returns a new default registry which is mdns
 func NewRegistry(opts ...Option) Registry {
 	return newRegistry(opts...)