some minor fixes

call.go

@@ -132,12 +132,12 @@ func Invoke(ctx context.Context, method string, args, reply interface{}, cc *Cli
 		Last:  true,
 		Delay: false,
 	}
-	var put func()
 	for {
 		var (
 			err    error
 			t      transport.ClientTransport
 			stream *transport.Stream
+			put    func()
 		)
 		// TODO(zhaoq): Need a formal spec of retry strategy for non-failFast rpcs.
 		callHdr := &transport.CallHdr{
@@ -149,6 +149,7 @@ func Invoke(ctx context.Context, method string, args, reply interface{}, cc *Cli
 		}
 		t, put, err = cc.getTransport(ctx)
 		if err != nil {
+			// TODO(zhaoq): Probably revisit the error handling.
 			if err == ErrClientConnClosing {
 				return toRPCErr(err)
 			}

clientconn.go

@@ -384,6 +384,7 @@ func (cc *ClientConn) newAddrConn(addr Address) error {
 			}
 		}
 	}
+	// Insert ac into ac.cc.conns. This needs to be done before any getTransport(...) is called.
 	ac.cc.mu.Lock()
 	if ac.cc.conns == nil {
 		ac.cc.mu.Unlock()
@@ -620,11 +621,11 @@ func (ac *addrConn) resetTransport(closeTransport bool) error {
 		ac.state = Ready
 		ac.stateCV.Broadcast()
 		ac.transport = newTransport
-		ac.down = ac.cc.balancer.Up(ac.addr)
 		if ac.ready != nil {
 			close(ac.ready)
 			ac.ready = nil
 		}
+		ac.down = ac.cc.balancer.Up(ac.addr)
 		ac.mu.Unlock()
 		return nil
 	}

test/end2end_test.go

@@ -340,7 +340,7 @@ func TestReconnectTimeout(t *testing.T) {
 	// Block until reconnect times out.
 	<-waitC
 	if err := conn.Close(); err != nil {
-		t.Fatalf("%v.Close() = %v, want %v", conn, err, grpc.ErrClientConnClosing)
+		t.Fatalf("%v.Close() = %v, want <nil>", conn, err)
 	}
 }
 
@@ -586,6 +586,7 @@ func TestTimeoutOnDeadServer(t *testing.T) {
 
 func testTimeoutOnDeadServer(t *testing.T, e env) {
 	te := newTest(t, e)
+	te.userAgent = testAppUA
 	te.declareLogNoise(
 		"transport: http2Client.notifyError got notified that the client transport was broken EOF",
 		"grpc: Conn.transportMonitor exits due to: grpc: the client connection is closing",
@@ -597,13 +598,16 @@ func testTimeoutOnDeadServer(t *testing.T, e env) {
 
 	cc := te.clientConn()
 	tc := testpb.NewTestServiceClient(cc)
+	if _, err := tc.EmptyCall(context.Background(), &testpb.Empty{}); err != nil {
+		t.Fatalf("TestService/EmptyCall(_, _) = _, %v, want _, <nil>", err)
+	}
 	te.srv.Stop()
 	// Set -1 as the timeout to make sure if transportMonitor gets error
 	// notification in time the failure path of the 1st invoke of
 	// ClientConn.wait hits the deadline exceeded error.
 	ctx, _ := context.WithTimeout(context.Background(), -1)
 	if _, err := tc.EmptyCall(ctx, &testpb.Empty{}); grpc.Code(err) != codes.DeadlineExceeded {
-		t.Fatalf("TestService/EmptyCall(%v, _) = _, error %v, want _, error code: %d", ctx, err, codes.DeadlineExceeded)
+		t.Fatalf("TestService/EmptyCall(%v, _) = _, %v, want _, error code: %d", ctx, err, codes.DeadlineExceeded)
 	}
 	awaitNewConnLogOutput()
 }

transport/transport.go

@@ -392,6 +392,8 @@ type ClientTransport interface {
 	// is called only once.
 	Close() error
 
+	// GracefulClose starts to tear down the transport. It stops accepting
+	// new RPCs and wait the completion of the pending RPCs.
 	GracefulClose() error
 
 	// Write sends the data for the given stream. A nil stream indicates