func doCancelAfterFirstResponse(tc testpb.TestServiceClient) {
	ctx, cancel := context.WithCancel(context.Background())
	stream, err := tc.FullDuplexCall(ctx)
	if err != nil {
		grpclog.Fatalf("%v.FullDuplexCall(_) = _, %v", tc, err)
	}
	respParam := []*testpb.ResponseParameters{
		{
			Size: proto.Int32(31415),
		},
	}
	pl := newPayload(testpb.PayloadType_COMPRESSABLE, 27182)
	req := &testpb.StreamingOutputCallRequest{
		ResponseType:       testpb.PayloadType_COMPRESSABLE.Enum(),
		ResponseParameters: respParam,
		Payload:            pl,
	}
	if err := stream.Send(req); err != nil {
		grpclog.Fatalf("%v.Send(%v) = %v", stream, req, err)
	}
	if _, err := stream.Recv(); err != nil {
		grpclog.Fatalf("%v.Recv() = %v", stream, err)
	}
	cancel()
	if _, err := stream.Recv(); grpc.Code(err) != codes.Canceled {
		grpclog.Fatalf("%v compleled with error code %d, want %d", stream, grpc.Code(err), codes.Canceled)
	}
	grpclog.Println("CancelAfterFirstResponse done")
}

func doPerRPCCreds(tc testpb.TestServiceClient) {
	jsonKey := getServiceAccountJSONKey()
	pl := newPayload(testpb.PayloadType_COMPRESSABLE, largeReqSize)
	req := &testpb.SimpleRequest{
		ResponseType:   testpb.PayloadType_COMPRESSABLE.Enum(),
		ResponseSize:   proto.Int32(int32(largeRespSize)),
		Payload:        pl,
		FillUsername:   proto.Bool(true),
		FillOauthScope: proto.Bool(true),
	}
	token := getToken()
	kv := map[string]string{"authorization": token.TokenType + " " + token.AccessToken}
	ctx := metadata.NewContext(context.Background(), metadata.MD{"authorization": []string{kv["authorization"]}})
	reply, err := tc.UnaryCall(ctx, req)
	if err != nil {
		grpclog.Fatal("/TestService/UnaryCall RPC failed: ", err)
	}
	user := reply.GetUsername()
	scope := reply.GetOauthScope()
	if !strings.Contains(string(jsonKey), user) {
		grpclog.Fatalf("Got user name %q which is NOT a substring of %q.", user, jsonKey)
	}
	if !strings.Contains(*oauthScope, scope) {
		grpclog.Fatalf("Got OAuth scope %q which is NOT a substring of %q.", scope, *oauthScope)
	}
	grpclog.Println("PerRPCCreds done")
}

func doClientStreaming(tc testpb.TestServiceClient) {
	stream, err := tc.StreamingInputCall(context.Background())
	if err != nil {
		grpclog.Fatalf("%v.StreamingInputCall(_) = _, %v", tc, err)
	}
	var sum int
	for _, s := range reqSizes {
		pl := newPayload(testpb.PayloadType_COMPRESSABLE, s)
		req := &testpb.StreamingInputCallRequest{
			Payload: pl,
		}
		if err := stream.Send(req); err != nil {
			grpclog.Fatalf("%v.Send(%v) = %v", stream, req, err)
		}
		sum += s
		grpclog.Printf("Sent a request of size %d, aggregated size %d", s, sum)

	}
	reply, err := stream.CloseAndRecv()
	if err != nil {
		grpclog.Fatalf("%v.CloseAndRecv() got error %v, want %v", stream, err, nil)
	}
	if reply.GetAggregatedPayloadSize() != int32(sum) {
		grpclog.Fatalf("%v.CloseAndRecv().GetAggregatePayloadSize() = %v; want %v", stream, reply.GetAggregatedPayloadSize(), sum)
	}
	grpclog.Println("ClientStreaming done")
}

// loadFeatures loads features from a JSON file.
func (s *routeGuideServer) loadFeatures(filePath string) {
	file, err := ioutil.ReadFile(filePath)
	if err != nil {
		grpclog.Fatalf("Failed to load default features: %v", err)
	}
	if err := json.Unmarshal(file, &s.savedFeatures); err != nil {
		grpclog.Fatalf("Failed to load default features: %v", err)
	}
}

func getToken() *oauth2.Token {
	jsonKey := getServiceAccountJSONKey()
	config, err := google.JWTConfigFromJSON(jsonKey, *oauthScope)
	if err != nil {
		grpclog.Fatalf("Failed to get the config: %v", err)
	}
	token, err := config.TokenSource(context.Background()).Token()
	if err != nil {
		grpclog.Fatalf("Failed to get the token: %v", err)
	}
	return token
}

func doCancelAfterBegin(tc testpb.TestServiceClient) {
	ctx, cancel := context.WithCancel(metadata.NewContext(context.Background(), testMetadata))
	stream, err := tc.StreamingInputCall(ctx)
	if err != nil {
		grpclog.Fatalf("%v.StreamingInputCall(_) = _, %v", tc, err)
	}
	cancel()
	_, err = stream.CloseAndRecv()
	if grpc.Code(err) != codes.Canceled {
		grpclog.Fatalf("%v.CloseAndRecv() got error code %d, want %d", stream, grpc.Code(err), codes.Canceled)
	}
	grpclog.Println("CancelAfterBegin done")
}

func doEmptyStream(tc testpb.TestServiceClient) {
	stream, err := tc.FullDuplexCall(context.Background())
	if err != nil {
		grpclog.Fatalf("%v.FullDuplexCall(_) = _, %v", tc, err)
	}
	if err := stream.CloseSend(); err != nil {
		grpclog.Fatalf("%v.CloseSend() got %v, want %v", stream, err, nil)
	}
	if _, err := stream.Recv(); err != io.EOF {
		grpclog.Fatalf("%v failed to complete the empty stream test: %v", stream, err)
	}
	grpclog.Println("Emptystream done")
}

// DoStreamingRoundTrip performs a round trip for a single streaming rpc.
func DoStreamingRoundTrip(tc testpb.TestServiceClient, stream testpb.TestService_StreamingCallClient, reqSize, respSize int) {
	pl := newPayload(testpb.PayloadType_COMPRESSABLE, reqSize)
	req := &testpb.SimpleRequest{
		ResponseType: pl.Type,
		ResponseSize: int32(respSize),
		Payload:      pl,
	}
	if err := stream.Send(req); err != nil {
		grpclog.Fatalf("StreamingCall(_).Send: %v", err)
	}
	if _, err := stream.Recv(); err != nil {
		grpclog.Fatalf("StreamingCall(_).Recv: %v", err)
	}
}

// NewClientConn creates a gRPC client connection to addr.
func NewClientConn(addr string) *grpc.ClientConn {
	conn, err := grpc.Dial(addr, grpc.WithInsecure())
	if err != nil {
		grpclog.Fatalf("NewClientConn(%q) failed to create a ClientConn %v", addr, err)
	}
	return conn
}

func getServiceAccountJSONKey() []byte {
	jsonKey, err := ioutil.ReadFile(*serviceAccountKeyFile)
	if err != nil {
		grpclog.Fatalf("Failed to read the service account key file: %v", err)
	}
	return jsonKey
}

func newPayload(t testpb.PayloadType, size int) *testpb.Payload {
	if size < 0 {
		grpclog.Fatalf("Requested a response with invalid length %d", size)
	}
	body := make([]byte, size)
	switch t {
	case testpb.PayloadType_COMPRESSABLE:
	case testpb.PayloadType_UNCOMPRESSABLE:
		grpclog.Fatalf("PayloadType UNCOMPRESSABLE is not supported")
	default:
		grpclog.Fatalf("Unsupported payload type: %d", t)
	}
	return &testpb.Payload{
		Type: t,
		Body: body,
	}
}

// RegisterService register a service and its implementation to the gRPC
// server. Called from the IDL generated code. This must be called before
// invoking Serve.
func (s *Server) RegisterService(sd *ServiceDesc, ss interface{}) {
	ht := reflect.TypeOf(sd.HandlerType).Elem()
	st := reflect.TypeOf(ss)
	if !st.Implements(ht) {
		grpclog.Fatalf("grpc: Server.RegisterService found the handler of type %v that does not satisfy %v", st, ht)
	}
	s.register(sd, ss)
}

func main() {
	flag.Parse()
	go func() {
		lis, err := net.Listen("tcp", ":0")
		if err != nil {
			grpclog.Fatalf("Failed to listen: %v", err)
		}
		grpclog.Println("Server profiling address: ", lis.Addr().String())
		if err := http.Serve(lis, nil); err != nil {
			grpclog.Fatalf("Failed to serve: %v", err)
		}
	}()
	addr, stopper := benchmark.StartServer(":0") // listen on all interfaces
	grpclog.Println("Server Address: ", addr)
	<-time.After(time.Duration(*duration) * time.Second)
	stopper()
}

func main() {
	flag.Parse()
	lis, err := net.Listen("tcp", fmt.Sprintf(":%d", *port))
	if err != nil {
		grpclog.Fatalf("failed to listen: %v", err)
	}
	var opts []grpc.ServerOption
	if *tls {
		creds, err := credentials.NewServerTLSFromFile(*certFile, *keyFile)
		if err != nil {
			grpclog.Fatalf("Failed to generate credentials %v", err)
		}
		opts = []grpc.ServerOption{grpc.Creds(creds)}
	}
	grpcServer := grpc.NewServer(opts...)
	pb.RegisterRouteGuideServer(grpcServer, newServer())
	grpcServer.Serve(lis)
}

func doServerStreaming(tc testpb.TestServiceClient) {
	respParam := make([]*testpb.ResponseParameters, len(respSizes))
	for i, s := range respSizes {
		respParam[i] = &testpb.ResponseParameters{
			Size: proto.Int32(int32(s)),
		}
	}
	req := &testpb.StreamingOutputCallRequest{
		ResponseType:       testpb.PayloadType_COMPRESSABLE.Enum(),
		ResponseParameters: respParam,
	}
	stream, err := tc.StreamingOutputCall(context.Background(), req)
	if err != nil {
		grpclog.Fatalf("%v.StreamingOutputCall(_) = _, %v", tc, err)
	}
	var rpcStatus error
	var respCnt int
	var index int
	for {
		reply, err := stream.Recv()
		if err != nil {
			rpcStatus = err
			break
		}
		t := reply.GetPayload().GetType()
		if t != testpb.PayloadType_COMPRESSABLE {
			grpclog.Fatalf("Got the reply of type %d, want %d", t, testpb.PayloadType_COMPRESSABLE)
		}
		size := len(reply.GetPayload().GetBody())
		if size != int(respSizes[index]) {
			grpclog.Fatalf("Got reply body of length %d, want %d", size, respSizes[index])
		}
		index++
		respCnt++
	}
	if rpcStatus != io.EOF {
		grpclog.Fatalf("Failed to finish the server streaming rpc: %v", err)
	}
	if respCnt != len(respSizes) {
		grpclog.Fatalf("Got %d reply, want %d", len(respSizes), respCnt)
	}
	grpclog.Println("ServerStreaming done")
}

func doEmptyUnaryCall(tc testpb.TestServiceClient) {
	reply, err := tc.EmptyCall(context.Background(), &testpb.Empty{})
	if err != nil {
		grpclog.Fatal("/TestService/EmptyCall RPC failed: ", err)
	}
	if !proto.Equal(&testpb.Empty{}, reply) {
		grpclog.Fatalf("/TestService/EmptyCall receives %v, want %v", reply, testpb.Empty{})
	}
	grpclog.Println("EmptyUnaryCall done")
}

func main() {
	flag.Parse()
	p := strconv.Itoa(*port)
	lis, err := net.Listen("tcp", ":"+p)
	if err != nil {
		grpclog.Fatalf("failed to listen: %v", err)
	}
	var opts []grpc.ServerOption
	if *useTLS {
		creds, err := credentials.NewServerTLSFromFile(*certFile, *keyFile)
		if err != nil {
			grpclog.Fatalf("Failed to generate credentials %v", err)
		}
		opts = []grpc.ServerOption{grpc.Creds(creds)}
	}
	server := grpc.NewServer(opts...)
	testpb.RegisterTestServiceServer(server, &testServer{})
	server.Serve(lis)
}

// StartServer starts a gRPC server serving a benchmark service on the given
// address, which may be something like "localhost:0". It returns its listen
// address and a function to stop the server.
func StartServer(addr string) (string, func()) {
	lis, err := net.Listen("tcp", addr)
	if err != nil {
		grpclog.Fatalf("Failed to listen: %v", err)
	}
	s := grpc.NewServer(grpc.MaxConcurrentStreams(math.MaxUint32))
	testpb.RegisterTestServiceServer(s, &testServer{})
	go s.Serve(lis)
	return lis.Addr().String(), func() {
		s.Stop()
	}
}

func doTimeoutOnSleepingServer(tc testpb.TestServiceClient) {
	ctx, _ := context.WithTimeout(context.Background(), 1*time.Millisecond)
	stream, err := tc.FullDuplexCall(ctx)
	if err != nil {
		if grpc.Code(err) == codes.DeadlineExceeded {
			grpclog.Println("TimeoutOnSleepingServer done")
			return
		}
		grpclog.Fatalf("%v.FullDuplexCall(_) = _, %v", tc, err)
	}
	pl := newPayload(testpb.PayloadType_COMPRESSABLE, 27182)
	req := &testpb.StreamingOutputCallRequest{
		ResponseType: testpb.PayloadType_COMPRESSABLE.Enum(),
		Payload:      pl,
	}
	if err := stream.Send(req); err != nil {
		grpclog.Fatalf("%v.Send(%v) = %v", stream, req, err)
	}
	if _, err := stream.Recv(); grpc.Code(err) != codes.DeadlineExceeded {
		grpclog.Fatalf("%v.Recv() = _, %v, want error code %d", stream, err, codes.DeadlineExceeded)
	}
	grpclog.Println("TimeoutOnSleepingServer done")
}

// SendHeader sends header metadata. It may be called at most once from a unary
// RPC handler. The ctx is the RPC handler's Context or one derived from it.
func SendHeader(ctx context.Context, md metadata.MD) error {
	if md.Len() == 0 {
		return nil
	}
	stream, ok := transport.StreamFromContext(ctx)
	if !ok {
		return fmt.Errorf("grpc: failed to fetch the stream from the context %v", ctx)
	}
	t := stream.ServerTransport()
	if t == nil {
		grpclog.Fatalf("grpc: SendHeader: %v has no ServerTransport to send header metadata.", stream)
	}
	return t.WriteHeader(stream, md)
}