preallocated slices (#917)

client/selector/router/router.go

@@ -101,7 +101,7 @@ func (r *routerSelector) getRoutes(service string) ([]router.Route, error) {
 		return nil, selector.ErrNoneAvailable
 	}
 
-	var routes []router.Route
+	routes := make([]router.Route, 0, len(pbRoutes.Routes))
 
 	// convert from pb to []*router.Route
 	for _, r := range pbRoutes.Routes {

client/selector/strategy.go

@@ -14,7 +14,7 @@ func init() {
 
 // Random is a random strategy algorithm for node selection
 func Random(services []*registry.Service) Next {
-	var nodes []*registry.Node
+	nodes := make([]*registry.Node, 0, len(services))
 
 	for _, service := range services {
 		nodes = append(nodes, service.Nodes...)

config/source/etcd/etcd.go

@@ -38,7 +38,7 @@ func (c *etcd) Read() (*source.ChangeSet, error) {
 		return nil, fmt.Errorf("source not found: %s", c.prefix)
 	}
 
-	var kvs []*mvccpb.KeyValue
+	kvs := make([]*mvccpb.KeyValue, 0, len(rsp.Kvs))
 	for _, v := range rsp.Kvs {
 		kvs = append(kvs, (*mvccpb.KeyValue)(v))
 	}

network/node.go

@@ -282,7 +282,7 @@ func (n *node) Peers() []Node {
 	n.RLock()
 	defer n.RUnlock()
 
-	var peers []Node
+	peers := make([]Node, 0, len(n.peers))
 	for _, nodePeer := range n.peers {
 		peer := nodePeer.getTopology(MaxDepth)
 		peers = append(peers, peer)

registry/service/util.go

@@ -38,7 +38,7 @@ func toValues(v []*pb.Value) []*registry.Value {
 }
 
 func ToProto(s *registry.Service) *pb.Service {
-	var endpoints []*pb.Endpoint
+	endpoints := make([]*pb.Endpoint, 0, len(s.Endpoints))
 	for _, ep := range s.Endpoints {
 		var request, response *pb.Value
 

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)...)

runtime/kubernetes/kubernetes.go

@@ -139,7 +139,7 @@ func (k *kubernetes) Update(s *runtime.Service) error {
 func (k *kubernetes) List() ([]*runtime.Service, error) {
 	// TODO: this should list the k8s deployments
 	// but for now we return in-memory tracked services
-	var services []*runtime.Service
+	services := make([]*runtime.Service, 0, len(k.services))
 	k.RLock()
 	defer k.RUnlock()
 

server/rpc_server.go

@@ -490,7 +490,7 @@ func (s *rpcServer) Register() error {
 		return subscriberList[i].topic > subscriberList[j].topic
 	})
 
-	var endpoints []*registry.Endpoint
+	endpoints := make([]*registry.Endpoint, 0, len(handlerList)+len(subscriberList))
 	for _, n := range handlerList {
 		endpoints = append(endpoints, s.handlers[n].Endpoints()...)
 	}