diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/balancer.go b/vendor/go.etcd.io/etcd/clientv3/balancer/balancer.go
index 3c44e70..d02a7ee 100644
--- a/vendor/go.etcd.io/etcd/clientv3/balancer/balancer.go
+++ b/vendor/go.etcd.io/etcd/clientv3/balancer/balancer.go
@@ -12,24 +12,45 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package balancer implements client balancer.
 package balancer
 
 import (
-	"fmt"
 	"strconv"
 	"sync"
 	"time"
 
+	"go.etcd.io/etcd/clientv3/balancer/connectivity"
 	"go.etcd.io/etcd/clientv3/balancer/picker"
 
 	"go.uber.org/zap"
 	"google.golang.org/grpc/balancer"
-	"google.golang.org/grpc/connectivity"
+	grpcconnectivity "google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/resolver"
 	_ "google.golang.org/grpc/resolver/dns"         // register DNS resolver
 	_ "google.golang.org/grpc/resolver/passthrough" // register passthrough resolver
 )
 
+// Config defines balancer configurations.
+type Config struct {
+	// Policy configures balancer policy.
+	Policy picker.Policy
+
+	// Picker implements gRPC picker.
+	// Leave empty if "Policy" field is not custom.
+	// TODO: currently custom policy is not supported.
+	// Picker picker.Picker
+
+	// Name defines an additional name for balancer.
+	// Useful for balancer testing to avoid register conflicts.
+	// If empty, defaults to policy name.
+	Name string
+
+	// Logger configures balancer logging.
+	// If nil, logs are discarded.
+	Logger *zap.Logger
+}
+
 // RegisterBuilder creates and registers a builder. Since this function calls balancer.Register, it
 // must be invoked at initialization time.
 func RegisterBuilder(cfg Config) {
@@ -54,24 +75,18 @@
 	bb := &baseBalancer{
 		id:     strconv.FormatInt(time.Now().UnixNano(), 36),
 		policy: b.cfg.Policy,
-		name:   b.cfg.Policy.String(),
+		name:   b.cfg.Name,
 		lg:     b.cfg.Logger,
 
 		addrToSc: make(map[resolver.Address]balancer.SubConn),
 		scToAddr: make(map[balancer.SubConn]resolver.Address),
-		scToSt:   make(map[balancer.SubConn]connectivity.State),
+		scToSt:   make(map[balancer.SubConn]grpcconnectivity.State),
 
-		currentConn: nil,
-		csEvltr:     &connectivityStateEvaluator{},
+		currentConn:          nil,
+		connectivityRecorder: connectivity.New(b.cfg.Logger),
 
 		// initialize picker always returns "ErrNoSubConnAvailable"
-		Picker: picker.NewErr(balancer.ErrNoSubConnAvailable),
-	}
-	if b.cfg.Name != "" {
-		bb.name = b.cfg.Name
-	}
-	if bb.lg == nil {
-		bb.lg = zap.NewNop()
+		picker: picker.NewErr(balancer.ErrNoSubConnAvailable),
 	}
 
 	// TODO: support multiple connections
@@ -115,13 +130,12 @@
 
 	addrToSc map[resolver.Address]balancer.SubConn
 	scToAddr map[balancer.SubConn]resolver.Address
-	scToSt   map[balancer.SubConn]connectivity.State
+	scToSt   map[balancer.SubConn]grpcconnectivity.State
 
-	currentConn  balancer.ClientConn
-	currentState connectivity.State
-	csEvltr      *connectivityStateEvaluator
+	currentConn          balancer.ClientConn
+	connectivityRecorder connectivity.Recorder
 
-	picker.Picker
+	picker picker.Picker
 }
 
 // HandleResolvedAddrs implements "grpc/balancer.Balancer" interface.
@@ -131,7 +145,11 @@
 		bb.lg.Warn("HandleResolvedAddrs called with error", zap.String("balancer-id", bb.id), zap.Error(err))
 		return
 	}
-	bb.lg.Info("resolved", zap.String("balancer-id", bb.id), zap.Strings("addresses", addrsToStrings(addrs)))
+	bb.lg.Info("resolved",
+		zap.String("picker", bb.picker.String()),
+		zap.String("balancer-id", bb.id),
+		zap.Strings("addresses", addrsToStrings(addrs)),
+	)
 
 	bb.mu.Lock()
 	defer bb.mu.Unlock()
@@ -142,12 +160,13 @@
 		if _, ok := bb.addrToSc[addr]; !ok {
 			sc, err := bb.currentConn.NewSubConn([]resolver.Address{addr}, balancer.NewSubConnOptions{})
 			if err != nil {
-				bb.lg.Warn("NewSubConn failed", zap.String("balancer-id", bb.id), zap.Error(err), zap.String("address", addr.Addr))
+				bb.lg.Warn("NewSubConn failed", zap.String("picker", bb.picker.String()), zap.String("balancer-id", bb.id), zap.Error(err), zap.String("address", addr.Addr))
 				continue
 			}
+			bb.lg.Info("created subconn", zap.String("address", addr.Addr))
 			bb.addrToSc[addr] = sc
 			bb.scToAddr[sc] = addr
-			bb.scToSt[sc] = connectivity.Idle
+			bb.scToSt[sc] = grpcconnectivity.Idle
 			sc.Connect()
 		}
 	}
@@ -160,6 +179,7 @@
 
 			bb.lg.Info(
 				"removed subconn",
+				zap.String("picker", bb.picker.String()),
 				zap.String("balancer-id", bb.id),
 				zap.String("address", addr.Addr),
 				zap.String("subconn", scToString(sc)),
@@ -174,7 +194,7 @@
 }
 
 // HandleSubConnStateChange implements "grpc/balancer.Balancer" interface.
-func (bb *baseBalancer) HandleSubConnStateChange(sc balancer.SubConn, s connectivity.State) {
+func (bb *baseBalancer) HandleSubConnStateChange(sc balancer.SubConn, s grpcconnectivity.State) {
 	bb.mu.Lock()
 	defer bb.mu.Unlock()
 
@@ -182,8 +202,10 @@
 	if !ok {
 		bb.lg.Warn(
 			"state change for an unknown subconn",
+			zap.String("picker", bb.picker.String()),
 			zap.String("balancer-id", bb.id),
 			zap.String("subconn", scToString(sc)),
+			zap.Int("subconn-size", len(bb.scToAddr)),
 			zap.String("state", s.String()),
 		)
 		return
@@ -191,9 +213,11 @@
 
 	bb.lg.Info(
 		"state changed",
+		zap.String("picker", bb.picker.String()),
 		zap.String("balancer-id", bb.id),
-		zap.Bool("connected", s == connectivity.Ready),
+		zap.Bool("connected", s == grpcconnectivity.Ready),
 		zap.String("subconn", scToString(sc)),
+		zap.Int("subconn-size", len(bb.scToAddr)),
 		zap.String("address", bb.scToAddr[sc].Addr),
 		zap.String("old-state", old.String()),
 		zap.String("new-state", s.String()),
@@ -201,69 +225,63 @@
 
 	bb.scToSt[sc] = s
 	switch s {
-	case connectivity.Idle:
+	case grpcconnectivity.Idle:
 		sc.Connect()
-	case connectivity.Shutdown:
+	case grpcconnectivity.Shutdown:
 		// When an address was removed by resolver, b called RemoveSubConn but
 		// kept the sc's state in scToSt. Remove state for this sc here.
 		delete(bb.scToAddr, sc)
 		delete(bb.scToSt, sc)
 	}
 
-	oldAggrState := bb.currentState
-	bb.currentState = bb.csEvltr.recordTransition(old, s)
+	oldAggrState := bb.connectivityRecorder.GetCurrentState()
+	bb.connectivityRecorder.RecordTransition(old, s)
 
-	// Regenerate picker when one of the following happens:
+	// Update balancer picker when one of the following happens:
 	//  - this sc became ready from not-ready
 	//  - this sc became not-ready from ready
 	//  - the aggregated state of balancer became TransientFailure from non-TransientFailure
 	//  - the aggregated state of balancer became non-TransientFailure from TransientFailure
-	if (s == connectivity.Ready) != (old == connectivity.Ready) ||
-		(bb.currentState == connectivity.TransientFailure) != (oldAggrState == connectivity.TransientFailure) {
-		bb.regeneratePicker()
+	if (s == grpcconnectivity.Ready) != (old == grpcconnectivity.Ready) ||
+		(bb.connectivityRecorder.GetCurrentState() == grpcconnectivity.TransientFailure) != (oldAggrState == grpcconnectivity.TransientFailure) {
+		bb.updatePicker()
 	}
 
-	bb.currentConn.UpdateBalancerState(bb.currentState, bb.Picker)
-	return
+	bb.currentConn.UpdateBalancerState(bb.connectivityRecorder.GetCurrentState(), bb.picker)
 }
 
-func (bb *baseBalancer) regeneratePicker() {
-	if bb.currentState == connectivity.TransientFailure {
+func (bb *baseBalancer) updatePicker() {
+	if bb.connectivityRecorder.GetCurrentState() == grpcconnectivity.TransientFailure {
+		bb.picker = picker.NewErr(balancer.ErrTransientFailure)
 		bb.lg.Info(
-			"generated transient error picker",
+			"updated picker to transient error picker",
+			zap.String("picker", bb.picker.String()),
 			zap.String("balancer-id", bb.id),
 			zap.String("policy", bb.policy.String()),
 		)
-		bb.Picker = picker.NewErr(balancer.ErrTransientFailure)
 		return
 	}
 
 	// only pass ready subconns to picker
-	scs := make([]balancer.SubConn, 0)
-	addrToSc := make(map[resolver.Address]balancer.SubConn)
 	scToAddr := make(map[balancer.SubConn]resolver.Address)
 	for addr, sc := range bb.addrToSc {
-		if st, ok := bb.scToSt[sc]; ok && st == connectivity.Ready {
-			scs = append(scs, sc)
-			addrToSc[addr] = sc
+		if st, ok := bb.scToSt[sc]; ok && st == grpcconnectivity.Ready {
 			scToAddr[sc] = addr
 		}
 	}
 
-	switch bb.policy {
-	case picker.RoundrobinBalanced:
-		bb.Picker = picker.NewRoundrobinBalanced(bb.lg, scs, addrToSc, scToAddr)
-
-	default:
-		panic(fmt.Errorf("invalid balancer picker policy (%d)", bb.policy))
-	}
-
+	bb.picker = picker.New(picker.Config{
+		Policy:                   bb.policy,
+		Logger:                   bb.lg,
+		SubConnToResolverAddress: scToAddr,
+	})
 	bb.lg.Info(
-		"generated picker",
+		"updated picker",
+		zap.String("picker", bb.picker.String()),
 		zap.String("balancer-id", bb.id),
 		zap.String("policy", bb.policy.String()),
-		zap.Strings("subconn-ready", scsToStrings(addrToSc)),
-		zap.Int("subconn-size", len(addrToSc)),
+		zap.Strings("subconn-ready", scsToStrings(scToAddr)),
+		zap.Int("subconn-size", len(scToAddr)),
 	)
 }