Moved to google.golang.org/genproto/googleapis/api/annotations

Fixes #52

vendor/github.com/go-kit/kit/sd/zk/subscriber.go

@@ -0,0 +1,86 @@
+package zk
+
+import (
+	"github.com/samuel/go-zookeeper/zk"
+
+	"github.com/go-kit/kit/endpoint"
+	"github.com/go-kit/kit/log"
+	"github.com/go-kit/kit/sd"
+	"github.com/go-kit/kit/sd/cache"
+)
+
+// Subscriber yield endpoints stored in a certain ZooKeeper path. Any kind of
+// change in that path is watched and will update the Subscriber endpoints.
+type Subscriber struct {
+	client Client
+	path   string
+	cache  *cache.Cache
+	logger log.Logger
+	quitc  chan struct{}
+}
+
+var _ sd.Subscriber = &Subscriber{}
+
+// NewSubscriber returns a ZooKeeper subscriber. ZooKeeper will start watching
+// the given path for changes and update the Subscriber endpoints.
+func NewSubscriber(c Client, path string, factory sd.Factory, logger log.Logger) (*Subscriber, error) {
+	s := &Subscriber{
+		client: c,
+		path:   path,
+		cache:  cache.New(factory, logger),
+		logger: logger,
+		quitc:  make(chan struct{}),
+	}
+
+	err := s.client.CreateParentNodes(s.path)
+	if err != nil {
+		return nil, err
+	}
+
+	instances, eventc, err := s.client.GetEntries(s.path)
+	if err != nil {
+		logger.Log("path", s.path, "msg", "failed to retrieve entries", "err", err)
+		return nil, err
+	}
+	logger.Log("path", s.path, "instances", len(instances))
+	s.cache.Update(instances)
+
+	go s.loop(eventc)
+
+	return s, nil
+}
+
+func (s *Subscriber) loop(eventc <-chan zk.Event) {
+	var (
+		instances []string
+		err       error
+	)
+	for {
+		select {
+		case <-eventc:
+			// We received a path update notification. Call GetEntries to
+			// retrieve child node data, and set a new watch, as ZK watches are
+			// one-time triggers.
+			instances, eventc, err = s.client.GetEntries(s.path)
+			if err != nil {
+				s.logger.Log("path", s.path, "msg", "failed to retrieve entries", "err", err)
+				continue
+			}
+			s.logger.Log("path", s.path, "instances", len(instances))
+			s.cache.Update(instances)
+
+		case <-s.quitc:
+			return
+		}
+	}
+}
+
+// Endpoints implements the Subscriber interface.
+func (s *Subscriber) Endpoints() ([]endpoint.Endpoint, error) {
+	return s.cache.Endpoints(), nil
+}
+
+// Stop terminates the Subscriber.
+func (s *Subscriber) Stop() {
+	close(s.quitc)
+}