preallocated slices (#934)

registry/etcd/etcd.go

@@ -341,7 +341,7 @@ func (e *etcdRegistry) GetService(name string) ([]*registry.Service, error) {
 		}
 	}
 
-	var services []*registry.Service
+	services := make([]*registry.Service, 0, len(serviceMap))
 	for _, service := range serviceMap {
 		services = append(services, service)
 	}
@@ -350,7 +350,6 @@ func (e *etcdRegistry) GetService(name string) ([]*registry.Service, error) {
 }
 
 func (e *etcdRegistry) ListServices() ([]*registry.Service, error) {
-	var services []*registry.Service
 	versions := make(map[string]*registry.Service)
 
 	ctx, cancel := context.WithTimeout(context.Background(), e.options.Timeout)
@@ -379,6 +378,7 @@ func (e *etcdRegistry) ListServices() ([]*registry.Service, error) {
 		v.Nodes = append(v.Nodes, sn.Nodes...)
 	}
 
+	services := make([]*registry.Service, 0, len(versions))
 	for _, service := range versions {
 		services = append(services, service)
 	}

registry/mdns_registry.go

@@ -292,7 +292,7 @@ func (m *mdnsRegistry) GetService(service string) ([]*Service, error) {
 	<-done
 
 	// create list and return
-	var services []*Service
+	services := make([]*Service, 0, len(serviceMap))
 
 	for _, service := range serviceMap {
 		services = append(services, service)

registry/memory/memory.go

@@ -111,7 +111,7 @@ func (m *Registry) ttlPrune() {
 }
 
 func (m *Registry) sendEvent(r *registry.Result) {
-	var watchers []*Watcher
+	watchers := make([]*Watcher, 0, len(m.Watchers))
 
 	m.RLock()
 	for _, w := range m.Watchers {

registry/service/util.go

@@ -10,7 +10,7 @@ func values(v []*registry.Value) []*pb.Value {
 		return []*pb.Value{}
 	}
 
-	var vs []*pb.Value
+	vs := make([]*pb.Value, 0, len(v))
 	for _, vi := range v {
 		vs = append(vs, &pb.Value{
 			Name:   vi.Name,
@@ -26,7 +26,7 @@ func toValues(v []*pb.Value) []*registry.Value {
 		return []*registry.Value{}
 	}
 
-	var vs []*registry.Value
+	vs := make([]*registry.Value, 0, len(v))
 	for _, vi := range v {
 		vs = append(vs, &registry.Value{
 			Name:   vi.Name,
@@ -66,7 +66,7 @@ func ToProto(s *registry.Service) *pb.Service {
 		})
 	}
 
-	var nodes []*pb.Node
+	nodes := make([]*pb.Node, 0, len(s.Nodes))
 
 	for _, node := range s.Nodes {
 		nodes = append(nodes, &pb.Node{
@@ -86,7 +86,7 @@ func ToProto(s *registry.Service) *pb.Service {
 }
 
 func ToService(s *pb.Service) *registry.Service {
-	var endpoints []*registry.Endpoint
+	endpoints := make([]*registry.Endpoint, 0, len(s.Endpoints))
 	for _, ep := range s.Endpoints {
 		var request, response *registry.Value
 
@@ -114,7 +114,7 @@ func ToService(s *pb.Service) *registry.Service {
 		})
 	}
 
-	var nodes []*registry.Node
+	nodes := make([]*registry.Node, 0, len(s.Nodes))
 	for _, node := range s.Nodes {
 		nodes = append(nodes, &registry.Node{
 			Id:       node.Id,