fix(natsjsregistry): spread load evenly among instances

Signed-off-by: jkoberg <jkoberg@owncloud.com>

ocis-pkg/natsjsregistry/registry.go

@@ -12,6 +12,7 @@ import (
 	"time"
 
 	natsjskv "github.com/go-micro/plugins/v4/store/nats-js-kv"
+	"github.com/google/uuid"
 	"github.com/nats-io/nats.go"
 	"go-micro.dev/v4/registry"
 	"go-micro.dev/v4/store"
@@ -23,6 +24,8 @@ var (
 	_registryAddressEnv  = "MICRO_REGISTRY_ADDRESS"
 	_registryUsernameEnv = "MICRO_REGISTRY_AUTH_USERNAME"
 	_registryPasswordEnv = "MICRO_REGISTRY_AUTH_PASSWORD"
+
+	_serviceDelimiter = "/"
 )
 
 func init() {
@@ -80,71 +83,51 @@ func (n *storeregistry) Register(s *registry.Service, _ ...registry.RegisterOpti
 	if s == nil {
 		return errors.New("wont store nil service")
 	}
+
+	unique := uuid.New().String()
+	if s.Metadata == nil {
+		s.Metadata = make(map[string]string)
+	}
+	s.Metadata["uuid"] = unique
+
 	b, err := json.Marshal(s)
 	if err != nil {
 		return err
 	}
 	return n.store.Write(&store.Record{
-		Key:    s.Name,
+		Key:    s.Name + _serviceDelimiter + unique,
 		Value:  b,
 		Expiry: n.expiry,
 	})
 }
 
-// Deregister removes a service from the registry
+// Deregister removes a service from the registry.
 func (n *storeregistry) Deregister(s *registry.Service, _ ...registry.DeregisterOption) error {
 	n.lock.RLock()
 	defer n.lock.RUnlock()
 
-	return n.store.Delete(s.Name)
+	var unique string
+	if s.Metadata != nil {
+		unique = s.Metadata["uuid"]
+	}
+
+	return n.store.Delete(s.Name + _serviceDelimiter + unique)
 }
 
 // GetService gets a specific service from the registry
 func (n *storeregistry) GetService(s string, _ ...registry.GetOption) ([]*registry.Service, error) {
-	n.lock.RLock()
-	defer n.lock.RUnlock()
-
-	recs, err := n.store.Read(s)
-	if err != nil {
-		return nil, err
-	}
-	svcs := make([]*registry.Service, 0, len(recs))
-	for _, rec := range recs {
-		var s registry.Service
-		if err := json.Unmarshal(rec.Value, &s); err != nil {
-			return nil, err
-		}
-		svcs = append(svcs, &s)
-	}
-	return svcs, nil
+	// avoid listing e.g. `webfinger` when requesting `web` by adding the delimiter to the service name
+	return n.listServices(store.ListPrefix(s + _serviceDelimiter))
 }
 
 // ListServices lists all registered services
 func (n *storeregistry) ListServices(...registry.ListOption) ([]*registry.Service, error) {
-	n.lock.RLock()
-	defer n.lock.RUnlock()
-
-	keys, err := n.store.List()
-	if err != nil {
-		return nil, err
-	}
-
-	var svcs []*registry.Service
-	for _, k := range keys {
-		s, err := n.GetService(k)
-		if err != nil {
-			// TODO: continue ?
-			return nil, err
-		}
-		svcs = append(svcs, s...)
-
-	}
-	return svcs, nil
+	return n.listServices()
 }
 
 // Watch allowes following the changes in the registry if it would be implemented
 func (n *storeregistry) Watch(...registry.WatchOption) (registry.Watcher, error) {
-	return nil, errors.New("watcher not implemented")
+	return NewWatcher(n)
 }
 
 // String returns the name of the registry
@@ -152,6 +135,43 @@ func (n *storeregistry) String() string {
 	return n.typ
 }
 
+func (n *storeregistry) listServices(opts ...store.ListOption) ([]*registry.Service, error) {
+	n.lock.RLock()
+	defer n.lock.RUnlock()
+
+	keys, err := n.store.List(opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	svcs := make([]*registry.Service, 0, len(keys))
+	for _, k := range keys {
+		s, err := n.getService(k)
+		if err != nil {
+			// TODO: continue ?
+			return nil, err
+		}
+		svcs = append(svcs, s)
+
+	}
+	return svcs, nil
+}
+
+func (n *storeregistry) getService(s string) (*registry.Service, error) {
+	recs, err := n.store.Read(s)
+	if err != nil {
+		return nil, err
+	}
+	if len(recs) == 0 {
+		return nil, registry.ErrNotFound
+	}
+	var svc registry.Service
+	if err := json.Unmarshal(recs[0].Value, &svc); err != nil {
+		return nil, err
+	}
+	return &svc, nil
+}
+
 func (n *storeregistry) storeOptions(opts registry.Options) []store.Option {
 	storeoptions := []store.Option{
 		store.Database("service-registry"),

ocis-pkg/natsjsregistry/watcher.go

@@ -0,0 +1,74 @@
+package natsjsregistry
+
+import (
+	"errors"
+
+	"github.com/nats-io/nats.go"
+	"go-micro.dev/v4/registry"
+)
+
+// NatsWatcher is the watcher of the nats interface
+type NatsWatcher interface {
+	Watch(bucket string) (nats.KeyWatcher, error)
+}
+
+// Watcher is used to keep track of changes in the registry
+type Watcher struct {
+	watch   nats.KeyWatcher
+	updates <-chan nats.KeyValueEntry
+	reg     *storeregistry
+}
+
+// NewWatcher returns a new watcher
+func NewWatcher(s *storeregistry) (*Watcher, error) {
+	w, ok := s.store.(NatsWatcher)
+	if !ok {
+		return nil, errors.New("store does not implement watcher interface")
+	}
+
+	watcher, err := w.Watch("service-registry")
+	if err != nil {
+		return nil, err
+	}
+
+	return &Watcher{
+		watch:   watcher,
+		updates: watcher.Updates(),
+		reg:     s,
+	}, nil
+}
+
+// Next returns the next result. It is a blocking call
+func (w *Watcher) Next() (*registry.Result, error) {
+	kve := <-w.updates
+	if kve == nil {
+		return nil, errors.New("watcher stopped")
+	}
+
+	service, err := w.reg.getService(kve.Key())
+	if err != nil {
+		return nil, err
+	}
+
+	var action string
+	switch kve.Operation() {
+	default:
+		action = "create"
+	case nats.KeyValuePut:
+		action = "create"
+	case nats.KeyValueDelete:
+		action = "delete"
+	case nats.KeyValuePurge:
+		action = "delete"
+	}
+
+	return &registry.Result{
+		Service: service,
+		Action:  action,
+	}, nil
+}
+
+// Stop stops the watcher
+func (w *Watcher) Stop() {
+	_ = w.watch.Stop()
+}