remove WithBalancerBuilder

clientconn.go

@@ -210,9 +210,9 @@ func WithBalancer(b Balancer) DialOption {
 	}
 }
 
-// WithBalancerBuilder is for testing only. Users using custom balancers should
+// withBalancerBuilder is for testing only. Users using custom balancers should
 // register their balancer and use service config to choose the balancer to use.
-func WithBalancerBuilder(b balancer.Builder) DialOption {
+func withBalancerBuilder(b balancer.Builder) DialOption {
 	// TODO(bar) remove this when switching balancer is done.
 	return func(o *dialOptions) {
 		o.balancerBuilder = b
@@ -225,6 +225,8 @@ func WithBalancerBuilder(b balancer.Builder) DialOption {
 //
 // The balancer cannot be overridden by balancer option specified by service
 // config.
+//
+// This is an EXPERIMENTAL API.
 func WithBalancerName(balancerName string) DialOption {
 	return func(o *dialOptions) {
 		o.balancerName = balancerName

grpclb.go

@@ -82,9 +82,12 @@ func (x *balanceLoadClientStream) Recv() (*lbpb.LoadBalanceResponse, error) {
 	return m, nil
 }
 
-// NewLBBuilder creates a builder for grpclb. For testing only.
-func NewLBBuilder() balancer.Builder {
-	// TODO(bar grpclb) this function is exported for testing only, remove it when resolver supports selecting grpclb.
+func init() {
+	balancer.Register(newLBBuilder())
+}
+
+// newLBBuilder creates a builder for grpclb. For testing only.
+func newLBBuilder() balancer.Builder {
 	return NewLBBuilderWithFallbackTimeout(defaultFallbackTimeout)
 }
 

grpclb/grpclb_test.go

@@ -37,6 +37,7 @@ import (
 
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/balancer"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/credentials"
 	lbmpb "google.golang.org/grpc/grpclb/grpc_lb_v1/messages"
@@ -344,7 +345,7 @@ func TestGRPCLB(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 	cc, err := grpc.DialContext(ctx, r.Scheme()+":///"+beServerName,
-		grpc.WithBalancerBuilder(grpc.NewLBBuilder()),
+		grpc.WithBalancerName("grpclb"),
 		grpc.WithTransportCredentials(&creds), grpc.WithDialer(fakeNameDialer))
 	if err != nil {
 		t.Fatalf("Failed to dial to the backend %v", err)
@@ -396,7 +397,7 @@ func TestGRPCLBWeighted(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 	cc, err := grpc.DialContext(ctx, r.Scheme()+":///"+beServerName,
-		grpc.WithBalancerBuilder(grpc.NewLBBuilder()),
+		grpc.WithBalancerName("grpclb"),
 		grpc.WithTransportCredentials(&creds), grpc.WithDialer(fakeNameDialer))
 	if err != nil {
 		t.Fatalf("Failed to dial to the backend %v", err)
@@ -462,7 +463,7 @@ func TestDropRequest(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 	cc, err := grpc.DialContext(ctx, r.Scheme()+":///"+beServerName,
-		grpc.WithBalancerBuilder(grpc.NewLBBuilder()),
+		grpc.WithBalancerName("grpclb"),
 		grpc.WithTransportCredentials(&creds), grpc.WithDialer(fakeNameDialer))
 	if err != nil {
 		t.Fatalf("Failed to dial to the backend %v", err)
@@ -537,7 +538,7 @@ func TestBalancerDisconnects(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 	cc, err := grpc.DialContext(ctx, r.Scheme()+":///"+beServerName,
-		grpc.WithBalancerBuilder(grpc.NewLBBuilder()),
+		grpc.WithBalancerName("grpclb"),
 		grpc.WithTransportCredentials(&creds), grpc.WithDialer(fakeNameDialer))
 	if err != nil {
 		t.Fatalf("Failed to dial to the backend %v", err)
@@ -578,6 +579,24 @@ func TestBalancerDisconnects(t *testing.T) {
 	t.Fatalf("No RPC sent to second backend after 1 second")
 }
 
+type customGRPCLBBuilder struct {
+	balancer.Builder
+	name string
+}
+
+func (b *customGRPCLBBuilder) Name() string {
+	return b.name
+}
+
+const grpclbCustomFallbackName = "grpclb_with_custom_fallback_timeout"
+
+func init() {
+	balancer.Register(&customGRPCLBBuilder{
+		Builder: grpc.NewLBBuilderWithFallbackTimeout(100 * time.Millisecond),
+		name:    grpclbCustomFallbackName,
+	})
+}
+
 func TestFallback(t *testing.T) {
 	defer leakcheck.Check(t)
 
@@ -616,7 +635,7 @@ func TestFallback(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 	cc, err := grpc.DialContext(ctx, r.Scheme()+":///"+beServerName,
-		grpc.WithBalancerBuilder(grpc.NewLBBuilderWithFallbackTimeout(100*time.Millisecond)),
+		grpc.WithBalancerName(grpclbCustomFallbackName),
 		grpc.WithTransportCredentials(&creds), grpc.WithDialer(fakeNameDialer))
 	if err != nil {
 		t.Fatalf("Failed to dial to the backend %v", err)
@@ -710,7 +729,7 @@ func runAndGetStats(t *testing.T, dropForLoadBalancing, dropForRateLimiting bool
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 	cc, err := grpc.DialContext(ctx, r.Scheme()+":///"+beServerName,
-		grpc.WithBalancerBuilder(grpc.NewLBBuilder()),
+		grpc.WithBalancerName("grpclb"),
 		grpc.WithTransportCredentials(&creds),
 		grpc.WithPerRPCCredentials(failPreRPCCred{}),
 		grpc.WithDialer(fakeNameDialer))

test/end2end_test.go

@@ -46,8 +46,7 @@ import (
 	"golang.org/x/net/http2"
 	spb "google.golang.org/genproto/googleapis/rpc/status"
 	"google.golang.org/grpc"
-	"google.golang.org/grpc/balancer"
-	_ "google.golang.org/grpc/balancer/roundrobin"
+	"google.golang.org/grpc/balancer/roundrobin"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/credentials"
@@ -693,11 +692,7 @@ func (te *test) clientConn() *grpc.ClientConn {
 	case "v1":
 		opts = append(opts, grpc.WithBalancer(grpc.RoundRobin(nil)))
 	case "round_robin":
-		rr := balancer.Get("round_robin")
-		if rr == nil {
-			te.t.Fatalf("got nil when trying to get roundrobin balancer builder")
-		}
-		opts = append(opts, grpc.WithBalancerBuilder(rr))
+		opts = append(opts, grpc.WithBalancerName(roundrobin.Name))
 	}
 	if te.clientInitialWindowSize > 0 {
 		opts = append(opts, grpc.WithInitialWindowSize(te.clientInitialWindowSize))