add roundrobin

rpcx/internal/balancer/roundrobin.go

@@ -1,8 +1,11 @@
 package balancer
 
 import (
+	"context"
+
 	"google.golang.org/grpc/balancer"
 	"google.golang.org/grpc/balancer/base"
+	"google.golang.org/grpc/resolver"
 )
 
 const (
@@ -20,6 +23,14 @@ func newBuilder() balancer.Builder {
 	return base.NewBalancerBuilder(Name, new(roundRobinPickerBuilder))
 }
 
-func (b *roundRobinPickerBuilder) Build(info base.PickerBuildInfo) balancer.Picker {
+func (b *roundRobinPickerBuilder) Build(readySCs map[resolver.Address]balancer.SubConn) balancer.Picker {
+	panic("implement me")
+}
+
+type roundRobinPicker struct {
+}
+
+func (p *roundRobinPicker) Pick(ctx context.Context, info balancer.PickInfo) (
+	conn balancer.SubConn, done func(balancer.DoneInfo), err error) {
 	panic("implement me")
 }