Add watcher.... OH YEAAA

registry/mdns/mdns.go

@@ -19,6 +19,7 @@ import (
 )
 
 type mdnsTxt struct {
+	Service   string
 	Version   string
 	Endpoints []*registry.Endpoint
 	Metadata  map[string]string
@@ -110,6 +111,7 @@ func (m *mdnsRegistry) Register(service *registry.Service, opts ...registry.Regi
 		}
 
 		txt, err := encode(&mdnsTxt{
+			Service:   service.Name,
 			Version:   service.Version,
 			Endpoints: service.Endpoints,
 			Metadata:  node.Metadata,
@@ -207,6 +209,10 @@ func (m *mdnsRegistry) GetService(service string) ([]*registry.Service, error) {
 					continue
 				}
 
+				if e.TTL == 0 {
+					continue
+				}
+
 				txt, err := decode(e.InfoFields)
 				if err != nil {
 					continue
@@ -265,6 +271,10 @@ func (m *mdnsRegistry) ListServices() ([]*registry.Service, error) {
 		for {
 			select {
 			case e := <-entryCh:
+				if e.TTL == 0 {
+					continue
+				}
+
 				name := strings.TrimSuffix(e.Name, "."+p.Service+"."+p.Domain+".")
 				if !serviceMap[name] {
 					serviceMap[name] = true
@@ -284,7 +294,18 @@ func (m *mdnsRegistry) ListServices() ([]*registry.Service, error) {
 }
 
 func (m *mdnsRegistry) Watch() (registry.Watcher, error) {
-	return nil, nil
+	md := &mdnsWatcher{
+		ch:   make(chan *mdns.ServiceEntry, 32),
+		exit: make(chan struct{}),
+	}
+
+	go func() {
+		if err := mdns.Listen(md.ch, md.exit); err != nil {
+			md.Stop()
+		}
+	}()
+
+	return md, nil
 }
 
 func (m *mdnsRegistry) String() string {

registry/mdns/watcher.go

@@ -0,0 +1,72 @@
+package mdns
+
+import (
+	"errors"
+	"strings"
+
+	"github.com/micro/go-micro/registry"
+	"github.com/micro/mdns"
+)
+
+type mdnsWatcher struct {
+	ch   chan *mdns.ServiceEntry
+	exit chan struct{}
+}
+
+func (m *mdnsWatcher) Next() (*registry.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
+			}
+
+			var action string
+
+			if e.TTL == 0 {
+				action = "delete"
+			} else {
+				action = "create"
+			}
+
+			service := &registry.Service{
+				Name:      txt.Service,
+				Version:   txt.Version,
+				Endpoints: txt.Endpoints,
+			}
+
+			// TODO: don't hardcode .local.
+			if !strings.HasSuffix(e.Name, "."+service.Name+".local.") {
+				continue
+			}
+
+			service.Nodes = append(service.Nodes, &registry.Node{
+				Id:       strings.TrimSuffix(e.Name, "."+service.Name+".local."),
+				Address:  e.AddrV4.String(),
+				Port:     e.Port,
+				Metadata: txt.Metadata,
+			})
+
+			return &registry.Result{
+				Action:  action,
+				Service: service,
+			}, nil
+		case <-m.exit:
+			return nil, errors.New("watcher stopped")
+		}
+	}
+}
+
+func (m *mdnsWatcher) Stop() {
+	select {
+	case <-m.exit:
+		return
+	default:
+		close(m.exit)
+	}
+}