From 1d69bd4a1673a9fbb5a74d537656e56b6cf93386 Mon Sep 17 00:00:00 2001
From: Asim Aslam <asim@chuhnk.me>
Date: Mon, 19 Feb 2018 20:27:36 +0000
Subject: [PATCH] watch branch

---
 gossip.go |  4 ++--
 watch.go  | 29 +++++++++++++++++++++--------
 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/gossip.go b/gossip.go
index 3c95bd0..2350f37 100644
--- a/gossip.go
+++ b/gossip.go
@@ -418,9 +418,9 @@ func (m *gossipRegistry) ListServices() ([]*registry.Service, error) {
 	return services, nil
 }
 
-func (m *gossipRegistry) Watch() (registry.Watcher, error) {
+func (m *gossipRegistry) Watch(opts ...registry.WatchOption) (registry.Watcher, error) {
 	n, e := m.subscribe()
-	return newGossipWatcher(n, e)
+	return newGossipWatcher(n, e, opts...)
 }
 
 func (m *gossipRegistry) String() string {
diff --git a/watch.go b/watch.go
index bb5d601..f893aa6 100644
--- a/watch.go
+++ b/watch.go
@@ -7,11 +7,17 @@ import (
 )
 
 type gossipWatcher struct {
+	wo   registry.WatchOptions
 	next chan *registry.Result
 	stop chan bool
 }
 
-func newGossipWatcher(ch chan *registry.Result, exit chan bool) (registry.Watcher, error) {
+func newGossipWatcher(ch chan *registry.Result, exit chan bool, opts ...registry.WatchOption) (registry.Watcher, error) {
+	var wo registry.WatchOptions
+	for _, o := range opts {
+		o(&wo)
+	}
+
 	stop := make(chan bool)
 
 	go func() {
@@ -20,20 +26,27 @@ func newGossipWatcher(ch chan *registry.Result, exit chan bool) (registry.Watche
 	}()
 
 	return &gossipWatcher{
+		wo:   wo,
 		next: ch,
 		stop: stop,
 	}, nil
 }
 
 func (m *gossipWatcher) Next() (*registry.Result, error) {
-	select {
-	case r, ok := <-m.next:
-		if !ok {
-			return nil, errors.New("result chan closed")
+	for {
+		select {
+		case r, ok := <-m.next:
+			if !ok {
+				return nil, errors.New("result chan closed")
+			}
+			// check watch options
+			if len(m.wo.Service) > 0 && r.Service.Name != m.wo.Service {
+				continue
+			}
+			return r, nil
+		case <-m.stop:
+			return nil, errors.New("watcher stopped")
 		}
-		return r, nil
-	case <-m.stop:
-		return nil, errors.New("watcher stopped")
 	}
 }