preallocated slices (#917)

router/handler/router.go

@@ -22,7 +22,7 @@ func (r *Router) Lookup(ctx context.Context, req *pb.LookupRequest, resp *pb.Loo
 		return errors.InternalServerError("go.micro.router", "failed to lookup routes: %v", err)
 	}
 
-	var respRoutes []*pb.Route
+	respRoutes := make([]*pb.Route, 0, len(routes))
 	for _, route := range routes {
 		respRoute := &pb.Route{
 			Service: route.Service,

router/service/service.go

@@ -188,7 +188,7 @@ func (s *svc) Advertise() (<-chan *router.Advert, error) {
 
 // Process processes incoming adverts
 func (s *svc) Process(advert *router.Advert) error {
-	var events []*pb.Event
+	events := make([]*pb.Event, 0, len(advert.Events))
 	for _, event := range advert.Events {
 		route := &pb.Route{
 			Service: event.Route.Service,

router/table.go

@@ -194,7 +194,7 @@ func (t *table) Query(q ...QueryOption) ([]Route, error) {
 		return findRoutes(t.routes[opts.Service], opts.Address, opts.Gateway, opts.Network, opts.Router), nil
 	}
 
-	var results []Route
+	results := make([]Route, 0, len(t.routes))
 	// search through all destinations
 	for _, routes := range t.routes {
 		results = append(results, findRoutes(routes, opts.Address, opts.Gateway, opts.Network, opts.Router)...)