aboutsummaryrefslogtreecommitdiff
path: root/vendor/google.golang.org/grpc/server.go
blob: 014c72b3f2834f630d545e3cd66384b9c11d916f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
/*
 *
 * Copyright 2014 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package grpc

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"math"
	"net"
	"net/http"
	"reflect"
	"runtime"
	"strings"
	"sync"
	"time"

	"io/ioutil"

	"golang.org/x/net/context"
	"golang.org/x/net/http2"
	"golang.org/x/net/trace"

	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/credentials"
	"google.golang.org/grpc/encoding"
	"google.golang.org/grpc/encoding/proto"
	"google.golang.org/grpc/grpclog"
	"google.golang.org/grpc/internal"
	"google.golang.org/grpc/internal/channelz"
	"google.golang.org/grpc/keepalive"
	"google.golang.org/grpc/metadata"
	"google.golang.org/grpc/stats"
	"google.golang.org/grpc/status"
	"google.golang.org/grpc/tap"
	"google.golang.org/grpc/transport"
)

const (
	defaultServerMaxReceiveMessageSize = 1024 * 1024 * 4
	defaultServerMaxSendMessageSize    = math.MaxInt32
)

type methodHandler func(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor UnaryServerInterceptor) (interface{}, error)

// MethodDesc represents an RPC service's method specification.
type MethodDesc struct {
	MethodName string
	Handler    methodHandler
}

// ServiceDesc represents an RPC service's specification.
type ServiceDesc struct {
	ServiceName string
	// The pointer to the service interface. Used to check whether the user
	// provided implementation satisfies the interface requirements.
	HandlerType interface{}
	Methods     []MethodDesc
	Streams     []StreamDesc
	Metadata    interface{}
}

// service consists of the information of the server serving this service and
// the methods in this service.
type service struct {
	server interface{} // the server for service methods
	md     map[string]*MethodDesc
	sd     map[string]*StreamDesc
	mdata  interface{}
}

// Server is a gRPC server to serve RPC requests.
type Server struct {
	opts options

	mu     sync.Mutex // guards following
	lis    map[net.Listener]bool
	conns  map[io.Closer]bool
	serve  bool
	drain  bool
	cv     *sync.Cond          // signaled when connections close for GracefulStop
	m      map[string]*service // service name -> service info
	events trace.EventLog

	quit               chan struct{}
	done               chan struct{}
	quitOnce           sync.Once
	doneOnce           sync.Once
	channelzRemoveOnce sync.Once
	serveWG            sync.WaitGroup // counts active Serve goroutines for GracefulStop

	channelzID          int64 // channelz unique identification number
	czmu                sync.RWMutex
	callsStarted        int64
	callsFailed         int64
	callsSucceeded      int64
	lastCallStartedTime time.Time
}

type options struct {
	creds                 credentials.TransportCredentials
	codec                 baseCodec
	cp                    Compressor
	dc                    Decompressor
	unaryInt              UnaryServerInterceptor
	streamInt             StreamServerInterceptor
	inTapHandle           tap.ServerInHandle
	statsHandler          stats.Handler
	maxConcurrentStreams  uint32
	maxReceiveMessageSize int
	maxSendMessageSize    int
	useHandlerImpl        bool // use http.Handler-based server
	unknownStreamDesc     *StreamDesc
	keepaliveParams       keepalive.ServerParameters
	keepalivePolicy       keepalive.EnforcementPolicy
	initialWindowSize     int32
	initialConnWindowSize int32
	writeBufferSize       int
	readBufferSize        int
	connectionTimeout     time.Duration
}

var defaultServerOptions = options{
	maxReceiveMessageSize: defaultServerMaxReceiveMessageSize,
	maxSendMessageSize:    defaultServerMaxSendMessageSize,
	connectionTimeout:     120 * time.Second,
}

// A ServerOption sets options such as credentials, codec and keepalive parameters, etc.
type ServerOption func(*options)

// WriteBufferSize lets you set the size of write buffer, this determines how much data can be batched
// before doing a write on the wire.
func WriteBufferSize(s int) ServerOption {
	return func(o *options) {
		o.writeBufferSize = s
	}
}

// ReadBufferSize lets you set the size of read buffer, this determines how much data can be read at most
// for one read syscall.
func ReadBufferSize(s int) ServerOption {
	return func(o *options) {
		o.readBufferSize = s
	}
}

// InitialWindowSize returns a ServerOption that sets window size for stream.
// The lower bound for window size is 64K and any value smaller than that will be ignored.
func InitialWindowSize(s int32) ServerOption {
	return func(o *options) {
		o.initialWindowSize = s
	}
}

// InitialConnWindowSize returns a ServerOption that sets window size for a connection.
// The lower bound for window size is 64K and any value smaller than that will be ignored.
func InitialConnWindowSize(s int32) ServerOption {
	return func(o *options) {
		o.initialConnWindowSize = s
	}
}

// KeepaliveParams returns a ServerOption that sets keepalive and max-age parameters for the server.
func KeepaliveParams(kp keepalive.ServerParameters) ServerOption {
	return func(o *options) {
		o.keepaliveParams = kp
	}
}

// KeepaliveEnforcementPolicy returns a ServerOption that sets keepalive enforcement policy for the server.
func KeepaliveEnforcementPolicy(kep keepalive.EnforcementPolicy) ServerOption {
	return func(o *options) {
		o.keepalivePolicy = kep
	}
}

// CustomCodec returns a ServerOption that sets a codec for message marshaling and unmarshaling.
//
// This will override any lookups by content-subtype for Codecs registered with RegisterCodec.
func CustomCodec(codec Codec) ServerOption {
	return func(o *options) {
		o.codec = codec
	}
}

// RPCCompressor returns a ServerOption that sets a compressor for outbound
// messages.  For backward compatibility, all outbound messages will be sent
// using this compressor, regardless of incoming message compression.  By
// default, server messages will be sent using the same compressor with which
// request messages were sent.
//
// Deprecated: use encoding.RegisterCompressor instead.
func RPCCompressor(cp Compressor) ServerOption {
	return func(o *options) {
		o.cp = cp
	}
}

// RPCDecompressor returns a ServerOption that sets a decompressor for inbound
// messages.  It has higher priority than decompressors registered via
// encoding.RegisterCompressor.
//
// Deprecated: use encoding.RegisterCompressor instead.
func RPCDecompressor(dc Decompressor) ServerOption {
	return func(o *options) {
		o.dc = dc
	}
}

// MaxMsgSize returns a ServerOption to set the max message size in bytes the server can receive.
// If this is not set, gRPC uses the default limit.
//
// Deprecated: use MaxRecvMsgSize instead.
func MaxMsgSize(m int) ServerOption {
	return MaxRecvMsgSize(m)
}

// MaxRecvMsgSize returns a ServerOption to set the max message size in bytes the server can receive.
// If this is not set, gRPC uses the default 4MB.
func MaxRecvMsgSize(m int) ServerOption {
	return func(o *options) {
		o.maxReceiveMessageSize = m
	}
}

// MaxSendMsgSize returns a ServerOption to set the max message size in bytes the server can send.
// If this is not set, gRPC uses the default 4MB.
func MaxSendMsgSize(m int) ServerOption {
	return func(o *options) {
		o.maxSendMessageSize = m
	}
}

// MaxConcurrentStreams returns a ServerOption that will apply a limit on the number
// of concurrent streams to each ServerTransport.
func MaxConcurrentStreams(n uint32) ServerOption {
	return func(o *options) {
		o.maxConcurrentStreams = n
	}
}

// Creds returns a ServerOption that sets credentials for server connections.
func Creds(c credentials.TransportCredentials) ServerOption {
	return func(o *options) {
		o.creds = c
	}
}

// UnaryInterceptor returns a ServerOption that sets the UnaryServerInterceptor for the
// server. Only one unary interceptor can be installed. The construction of multiple
// interceptors (e.g., chaining) can be implemented at the caller.
func UnaryInterceptor(i UnaryServerInterceptor) ServerOption {
	return func(o *options) {
		if o.unaryInt != nil {
			panic("The unary server interceptor was already set and may not be reset.")
		}
		o.unaryInt = i
	}
}

// StreamInterceptor returns a ServerOption that sets the StreamServerInterceptor for the
// server. Only one stream interceptor can be installed.
func StreamInterceptor(i StreamServerInterceptor) ServerOption {
	return func(o *options) {
		if o.streamInt != nil {
			panic("The stream server interceptor was already set and may not be reset.")
		}
		o.streamInt = i
	}
}

// InTapHandle returns a ServerOption that sets the tap handle for all the server
// transport to be created. Only one can be installed.
func InTapHandle(h tap.ServerInHandle) ServerOption {
	return func(o *options) {
		if o.inTapHandle != nil {
			panic("The tap handle was already set and may not be reset.")
		}
		o.inTapHandle = h
	}
}

// StatsHandler returns a ServerOption that sets the stats handler for the server.
func StatsHandler(h stats.Handler) ServerOption {
	return func(o *options) {
		o.statsHandler = h
	}
}

// UnknownServiceHandler returns a ServerOption that allows for adding a custom
// unknown service handler. The provided method is a bidi-streaming RPC service
// handler that will be invoked instead of returning the "unimplemented" gRPC
// error whenever a request is received for an unregistered service or method.
// The handling function has full access to the Context of the request and the
// stream, and the invocation bypasses interceptors.
func UnknownServiceHandler(streamHandler StreamHandler) ServerOption {
	return func(o *options) {
		o.unknownStreamDesc = &StreamDesc{
			StreamName: "unknown_service_handler",
			Handler:    streamHandler,
			// We need to assume that the users of the streamHandler will want to use both.
			ClientStreams: true,
			ServerStreams: true,
		}
	}
}

// ConnectionTimeout returns a ServerOption that sets the timeout for
// connection establishment (up to and including HTTP/2 handshaking) for all
// new connections.  If this is not set, the default is 120 seconds.  A zero or
// negative value will result in an immediate timeout.
//
// This API is EXPERIMENTAL.
func ConnectionTimeout(d time.Duration) ServerOption {
	return func(o *options) {
		o.connectionTimeout = d
	}
}

// NewServer creates a gRPC server which has no service registered and has not
// started to accept requests yet.
func NewServer(opt ...ServerOption) *Server {
	opts := defaultServerOptions
	for _, o := range opt {
		o(&opts)
	}
	s := &Server{
		lis:   make(map[net.Listener]bool),
		opts:  opts,
		conns: make(map[io.Closer]bool),
		m:     make(map[string]*service),
		quit:  make(chan struct{}),
		done:  make(chan struct{}),
	}
	s.cv = sync.NewCond(&s.mu)
	if EnableTracing {
		_, file, line, _ := runtime.Caller(1)
		s.events = trace.NewEventLog("grpc.Server", fmt.Sprintf("%s:%d", file, line))
	}

	if channelz.IsOn() {
		s.channelzID = channelz.RegisterServer(s, "")
	}
	return s
}

// printf records an event in s's event log, unless s has been stopped.
// REQUIRES s.mu is held.
func (s *Server) printf(format string, a ...interface{}) {
	if s.events != nil {
		s.events.Printf(format, a...)
	}
}

// errorf records an error in s's event log, unless s has been stopped.
// REQUIRES s.mu is held.
func (s *Server) errorf(format string, a ...interface{}) {
	if s.events != nil {
		s.events.Errorf(format, a...)
	}
}

// RegisterService registers a service and its implementation to the gRPC
// server. It is 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 (s *Server) register(sd *ServiceDesc, ss interface{}) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.printf("RegisterService(%q)", sd.ServiceName)
	if s.serve {
		grpclog.Fatalf("grpc: Server.RegisterService after Server.Serve for %q", sd.ServiceName)
	}
	if _, ok := s.m[sd.ServiceName]; ok {
		grpclog.Fatalf("grpc: Server.RegisterService found duplicate service registration for %q", sd.ServiceName)
	}
	srv := &service{
		server: ss,
		md:     make(map[string]*MethodDesc),
		sd:     make(map[string]*StreamDesc),
		mdata:  sd.Metadata,
	}
	for i := range sd.Methods {
		d := &sd.Methods[i]
		srv.md[d.MethodName] = d
	}
	for i := range sd.Streams {
		d := &sd.Streams[i]
		srv.sd[d.StreamName] = d
	}
	s.m[sd.ServiceName] = srv
}

// MethodInfo contains the information of an RPC including its method name and type.
type MethodInfo struct {
	// Name is the method name only, without the service name or package name.
	Name string
	// IsClientStream indicates whether the RPC is a client streaming RPC.
	IsClientStream bool
	// IsServerStream indicates whether the RPC is a server streaming RPC.
	IsServerStream bool
}

// ServiceInfo contains unary RPC method info, streaming RPC method info and metadata for a service.
type ServiceInfo struct {
	Methods []MethodInfo
	// Metadata is the metadata specified in ServiceDesc when registering service.
	Metadata interface{}
}

// GetServiceInfo returns a map from service names to ServiceInfo.
// Service names include the package names, in the form of <package>.<service>.
func (s *Server) GetServiceInfo() map[string]ServiceInfo {
	ret := make(map[string]ServiceInfo)
	for n, srv := range s.m {
		methods := make([]MethodInfo, 0, len(srv.md)+len(srv.sd))
		for m := range srv.md {
			methods = append(methods, MethodInfo{
				Name:           m,
				IsClientStream: false,
				IsServerStream: false,
			})
		}
		for m, d := range srv.sd {
			methods = append(methods, MethodInfo{
				Name:           m,
				IsClientStream: d.ClientStreams,
				IsServerStream: d.ServerStreams,
			})
		}

		ret[n] = ServiceInfo{
			Methods:  methods,
			Metadata: srv.mdata,
		}
	}
	return ret
}

// ErrServerStopped indicates that the operation is now illegal because of
// the server being stopped.
var ErrServerStopped = errors.New("grpc: the server has been stopped")

func (s *Server) useTransportAuthenticator(rawConn net.Conn) (net.Conn, credentials.AuthInfo, error) {
	if s.opts.creds == nil {
		return rawConn, nil, nil
	}
	return s.opts.creds.ServerHandshake(rawConn)
}

type listenSocket struct {
	net.Listener
	channelzID int64
}

func (l *listenSocket) ChannelzMetric() *channelz.SocketInternalMetric {
	return &channelz.SocketInternalMetric{
		LocalAddr: l.Listener.Addr(),
	}
}

func (l *listenSocket) Close() error {
	err := l.Listener.Close()
	if channelz.IsOn() {
		channelz.RemoveEntry(l.channelzID)
	}
	return err
}

// Serve accepts incoming connections on the listener lis, creating a new
// ServerTransport and service goroutine for each. The service goroutines
// read gRPC requests and then call the registered handlers to reply to them.
// Serve returns when lis.Accept fails with fatal errors.  lis will be closed when
// this method returns.
// Serve will return a non-nil error unless Stop or GracefulStop is called.
func (s *Server) Serve(lis net.Listener) error {
	s.mu.Lock()
	s.printf("serving")
	s.serve = true
	if s.lis == nil {
		// Serve called after Stop or GracefulStop.
		s.mu.Unlock()
		lis.Close()
		return ErrServerStopped
	}

	s.serveWG.Add(1)
	defer func() {
		s.serveWG.Done()
		select {
		// Stop or GracefulStop called; block until done and return nil.
		case <-s.quit:
			<-s.done
		default:
		}
	}()

	ls := &listenSocket{Listener: lis}
	s.lis[ls] = true

	if channelz.IsOn() {
		ls.channelzID = channelz.RegisterListenSocket(ls, s.channelzID, "")
	}
	s.mu.Unlock()

	defer func() {
		s.mu.Lock()
		if s.lis != nil && s.lis[ls] {
			ls.Close()
			delete(s.lis, ls)
		}
		s.mu.Unlock()
	}()

	var tempDelay time.Duration // how long to sleep on accept failure

	for {
		rawConn, err := lis.Accept()
		if err != nil {
			if ne, ok := err.(interface {
				Temporary() bool
			}); ok && ne.Temporary() {
				if tempDelay == 0 {
					tempDelay = 5 * time.Millisecond
				} else {
					tempDelay *= 2
				}
				if max := 1 * time.Second; tempDelay > max {
					tempDelay = max
				}
				s.mu.Lock()
				s.printf("Accept error: %v; retrying in %v", err, tempDelay)
				s.mu.Unlock()
				timer := time.NewTimer(tempDelay)
				select {
				case <-timer.C:
				case <-s.quit:
					timer.Stop()
					return nil
				}
				continue
			}
			s.mu.Lock()
			s.printf("done serving; Accept = %v", err)
			s.mu.Unlock()

			select {
			case <-s.quit:
				return nil
			default:
			}
			return err
		}
		tempDelay = 0
		// Start a new goroutine to deal with rawConn so we don't stall this Accept
		// loop goroutine.
		//
		// Make sure we account for the goroutine so GracefulStop doesn't nil out
		// s.conns before this conn can be added.
		s.serveWG.Add(1)
		go func() {
			s.handleRawConn(rawConn)
			s.serveWG.Done()
		}()
	}
}

// handleRawConn forks a goroutine to handle a just-accepted connection that
// has not had any I/O performed on it yet.
func (s *Server) handleRawConn(rawConn net.Conn) {
	rawConn.SetDeadline(time.Now().Add(s.opts.connectionTimeout))
	conn, authInfo, err := s.useTransportAuthenticator(rawConn)
	if err != nil {
		s.mu.Lock()
		s.errorf("ServerHandshake(%q) failed: %v", rawConn.RemoteAddr(), err)
		s.mu.Unlock()
		grpclog.Warningf("grpc: Server.Serve failed to complete security handshake from %q: %v", rawConn.RemoteAddr(), err)
		// If serverHandshake returns ErrConnDispatched, keep rawConn open.
		if err != credentials.ErrConnDispatched {
			rawConn.Close()
		}
		rawConn.SetDeadline(time.Time{})
		return
	}

	s.mu.Lock()
	if s.conns == nil {
		s.mu.Unlock()
		conn.Close()
		return
	}
	s.mu.Unlock()

	var serve func()
	c := conn.(io.Closer)
	if s.opts.useHandlerImpl {
		serve = func() { s.serveUsingHandler(conn) }
	} else {
		// Finish handshaking (HTTP2)
		st := s.newHTTP2Transport(conn, authInfo)
		if st == nil {
			return
		}
		c = st
		serve = func() { s.serveStreams(st) }
	}

	rawConn.SetDeadline(time.Time{})
	if !s.addConn(c) {
		return
	}
	go func() {
		serve()
		s.removeConn(c)
	}()
}

// newHTTP2Transport sets up a http/2 transport (using the
// gRPC http2 server transport in transport/http2_server.go).
func (s *Server) newHTTP2Transport(c net.Conn, authInfo credentials.AuthInfo) transport.ServerTransport {
	config := &transport.ServerConfig{
		MaxStreams:            s.opts.maxConcurrentStreams,
		AuthInfo:              authInfo,
		InTapHandle:           s.opts.inTapHandle,
		StatsHandler:          s.opts.statsHandler,
		KeepaliveParams:       s.opts.keepaliveParams,
		KeepalivePolicy:       s.opts.keepalivePolicy,
		InitialWindowSize:     s.opts.initialWindowSize,
		InitialConnWindowSize: s.opts.initialConnWindowSize,
		WriteBufferSize:       s.opts.writeBufferSize,
		ReadBufferSize:        s.opts.readBufferSize,
		ChannelzParentID:      s.channelzID,
	}
	st, err := transport.NewServerTransport("http2", c, config)
	if err != nil {
		s.mu.Lock()
		s.errorf("NewServerTransport(%q) failed: %v", c.RemoteAddr(), err)
		s.mu.Unlock()
		c.Close()
		grpclog.Warningln("grpc: Server.Serve failed to create ServerTransport: ", err)
		return nil
	}

	return st
}

func (s *Server) serveStreams(st transport.ServerTransport) {
	defer st.Close()
	var wg sync.WaitGroup
	st.HandleStreams(func(stream *transport.Stream) {
		wg.Add(1)
		go func() {
			defer wg.Done()
			s.handleStream(st, stream, s.traceInfo(st, stream))
		}()
	}, func(ctx context.Context, method string) context.Context {
		if !EnableTracing {
			return ctx
		}
		tr := trace.New("grpc.Recv."+methodFamily(method), method)
		return trace.NewContext(ctx, tr)
	})
	wg.Wait()
}

var _ http.Handler = (*Server)(nil)

// serveUsingHandler is called from handleRawConn when s is configured
// to handle requests via the http.Handler interface. It sets up a
// net/http.Server to handle the just-accepted conn. The http.Server
// is configured to route all incoming requests (all HTTP/2 streams)
// to ServeHTTP, which creates a new ServerTransport for each stream.
// serveUsingHandler blocks until conn closes.
//
// This codepath is only used when Server.TestingUseHandlerImpl has
// been configured. This lets the end2end tests exercise the ServeHTTP
// method as one of the environment types.
//
// conn is the *tls.Conn that's already been authenticated.
func (s *Server) serveUsingHandler(conn net.Conn) {
	h2s := &http2.Server{
		MaxConcurrentStreams: s.opts.maxConcurrentStreams,
	}
	h2s.ServeConn(conn, &http2.ServeConnOpts{
		Handler: s,
	})
}

// ServeHTTP implements the Go standard library's http.Handler
// interface by responding to the gRPC request r, by looking up
// the requested gRPC method in the gRPC server s.
//
// The provided HTTP request must have arrived on an HTTP/2
// connection. When using the Go standard library's server,
// practically this means that the Request must also have arrived
// over TLS.
//
// To share one port (such as 443 for https) between gRPC and an
// existing http.Handler, use a root http.Handler such as:
//
//   if r.ProtoMajor == 2 && strings.HasPrefix(
//   	r.Header.Get("Content-Type"), "application/grpc") {
//   	grpcServer.ServeHTTP(w, r)
//   } else {
//   	yourMux.ServeHTTP(w, r)
//   }
//
// Note that ServeHTTP uses Go's HTTP/2 server implementation which is totally
// separate from grpc-go's HTTP/2 server. Performance and features may vary
// between the two paths. ServeHTTP does not support some gRPC features
// available through grpc-go's HTTP/2 server, and it is currently EXPERIMENTAL
// and subject to change.
func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	st, err := transport.NewServerHandlerTransport(w, r, s.opts.statsHandler)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	if !s.addConn(st) {
		return
	}
	defer s.removeConn(st)
	s.serveStreams(st)
}

// traceInfo returns a traceInfo and associates it with stream, if tracing is enabled.
// If tracing is not enabled, it returns nil.
func (s *Server) traceInfo(st transport.ServerTransport, stream *transport.Stream) (trInfo *traceInfo) {
	tr, ok := trace.FromContext(stream.Context())
	if !ok {
		return nil
	}

	trInfo = &traceInfo{
		tr: tr,
	}
	trInfo.firstLine.client = false
	trInfo.firstLine.remoteAddr = st.RemoteAddr()

	if dl, ok := stream.Context().Deadline(); ok {
		trInfo.firstLine.deadline = dl.Sub(time.Now())
	}
	return trInfo
}

func (s *Server) addConn(c io.Closer) bool {
	s.mu.Lock()
	defer s.mu.Unlock()
	if s.conns == nil {
		c.Close()
		return false
	}
	if s.drain {
		// Transport added after we drained our existing conns: drain it
		// immediately.
		c.(transport.ServerTransport).Drain()
	}
	s.conns[c] = true
	return true
}

func (s *Server) removeConn(c io.Closer) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if s.conns != nil {
		delete(s.conns, c)
		s.cv.Broadcast()
	}
}

// ChannelzMetric returns ServerInternalMetric of current server.
// This is an EXPERIMENTAL API.
func (s *Server) ChannelzMetric() *channelz.ServerInternalMetric {
	s.czmu.RLock()
	defer s.czmu.RUnlock()
	return &channelz.ServerInternalMetric{
		CallsStarted:             s.callsStarted,
		CallsSucceeded:           s.callsSucceeded,
		CallsFailed:              s.callsFailed,
		LastCallStartedTimestamp: s.lastCallStartedTime,
	}
}

func (s *Server) incrCallsStarted() {
	s.czmu.Lock()
	s.callsStarted++
	s.lastCallStartedTime = time.Now()
	s.czmu.Unlock()
}

func (s *Server) incrCallsSucceeded() {
	s.czmu.Lock()
	s.callsSucceeded++
	s.czmu.Unlock()
}

func (s *Server) incrCallsFailed() {
	s.czmu.Lock()
	s.callsFailed++
	s.czmu.Unlock()
}

func (s *Server) sendResponse(t transport.ServerTransport, stream *transport.Stream, msg interface{}, cp Compressor, opts *transport.Options, comp encoding.Compressor) error {
	data, err := encode(s.getCodec(stream.ContentSubtype()), msg)
	if err != nil {
		grpclog.Errorln("grpc: server failed to encode response: ", err)
		return err
	}
	compData, err := compress(data, cp, comp)
	if err != nil {
		grpclog.Errorln("grpc: server failed to compress response: ", err)
		return err
	}
	hdr, payload := msgHeader(data, compData)
	// TODO(dfawley): should we be checking len(data) instead?
	if len(payload) > s.opts.maxSendMessageSize {
		return status.Errorf(codes.ResourceExhausted, "grpc: trying to send message larger than max (%d vs. %d)", len(payload), s.opts.maxSendMessageSize)
	}
	err = t.Write(stream, hdr, payload, opts)
	if err == nil && s.opts.statsHandler != nil {
		s.opts.statsHandler.HandleRPC(stream.Context(), outPayload(false, msg, data, payload, time.Now()))
	}
	return err
}

func (s *Server) processUnaryRPC(t transport.ServerTransport, stream *transport.Stream, srv *service, md *MethodDesc, trInfo *traceInfo) (err error) {
	if channelz.IsOn() {
		s.incrCallsStarted()
		defer func() {
			if err != nil && err != io.EOF {
				s.incrCallsFailed()
			} else {
				s.incrCallsSucceeded()
			}
		}()
	}
	sh := s.opts.statsHandler
	if sh != nil {
		beginTime := time.Now()
		begin := &stats.Begin{
			BeginTime: beginTime,
		}
		sh.HandleRPC(stream.Context(), begin)
		defer func() {
			end := &stats.End{
				BeginTime: beginTime,
				EndTime:   time.Now(),
			}
			if err != nil && err != io.EOF {
				end.Error = toRPCErr(err)
			}
			sh.HandleRPC(stream.Context(), end)
		}()
	}
	if trInfo != nil {
		defer trInfo.tr.Finish()
		trInfo.firstLine.client = false
		trInfo.tr.LazyLog(&trInfo.firstLine, false)
		defer func() {
			if err != nil && err != io.EOF {
				trInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
				trInfo.tr.SetError()
			}
		}()
	}

	// comp and cp are used for compression.  decomp and dc are used for
	// decompression.  If comp and decomp are both set, they are the same;
	// however they are kept separate to ensure that at most one of the
	// compressor/decompressor variable pairs are set for use later.
	var comp, decomp encoding.Compressor
	var cp Compressor
	var dc Decompressor

	// If dc is set and matches the stream's compression, use it.  Otherwise, try
	// to find a matching registered compressor for decomp.
	if rc := stream.RecvCompress(); s.opts.dc != nil && s.opts.dc.Type() == rc {
		dc = s.opts.dc
	} else if rc != "" && rc != encoding.Identity {
		decomp = encoding.GetCompressor(rc)
		if decomp == nil {
			st := status.Newf(codes.Unimplemented, "grpc: Decompressor is not installed for grpc-encoding %q", rc)
			t.WriteStatus(stream, st)
			return st.Err()
		}
	}

	// If cp is set, use it.  Otherwise, attempt to compress the response using
	// the incoming message compression method.
	//
	// NOTE: this needs to be ahead of all handling, https://github.com/grpc/grpc-go/issues/686.
	if s.opts.cp != nil {
		cp = s.opts.cp
		stream.SetSendCompress(cp.Type())
	} else if rc := stream.RecvCompress(); rc != "" && rc != encoding.Identity {
		// Legacy compressor not specified; attempt to respond with same encoding.
		comp = encoding.GetCompressor(rc)
		if comp != nil {
			stream.SetSendCompress(rc)
		}
	}

	p := &parser{r: stream}
	pf, req, err := p.recvMsg(s.opts.maxReceiveMessageSize)
	if err == io.EOF {
		// The entire stream is done (for unary RPC only).
		return err
	}
	if err == io.ErrUnexpectedEOF {
		err = status.Errorf(codes.Internal, io.ErrUnexpectedEOF.Error())
	}
	if err != nil {
		if st, ok := status.FromError(err); ok {
			if e := t.WriteStatus(stream, st); e != nil {
				grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status %v", e)
			}
		} else {
			switch st := err.(type) {
			case transport.ConnectionError:
				// Nothing to do here.
			case transport.StreamError:
				if e := t.WriteStatus(stream, status.New(st.Code, st.Desc)); e != nil {
					grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status %v", e)
				}
			default:
				panic(fmt.Sprintf("grpc: Unexpected error (%T) from recvMsg: %v", st, st))
			}
		}
		return err
	}
	if channelz.IsOn() {
		t.IncrMsgRecv()
	}
	if st := checkRecvPayload(pf, stream.RecvCompress(), dc != nil || decomp != nil); st != nil {
		if e := t.WriteStatus(stream, st); e != nil {
			grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status %v", e)
		}
		return st.Err()
	}
	var inPayload *stats.InPayload
	if sh != nil {
		inPayload = &stats.InPayload{
			RecvTime: time.Now(),
		}
	}
	df := func(v interface{}) error {
		if inPayload != nil {
			inPayload.WireLength = len(req)
		}
		if pf == compressionMade {
			var err error
			if dc != nil {
				req, err = dc.Do(bytes.NewReader(req))
				if err != nil {
					return status.Errorf(codes.Internal, err.Error())
				}
			} else {
				tmp, _ := decomp.Decompress(bytes.NewReader(req))
				req, err = ioutil.ReadAll(tmp)
				if err != nil {
					return status.Errorf(codes.Internal, "grpc: failed to decompress the received message %v", err)
				}
			}
		}
		if len(req) > s.opts.maxReceiveMessageSize {
			// TODO: Revisit the error code. Currently keep it consistent with
			// java implementation.
			return status.Errorf(codes.ResourceExhausted, "grpc: received message larger than max (%d vs. %d)", len(req), s.opts.maxReceiveMessageSize)
		}
		if err := s.getCodec(stream.ContentSubtype()).Unmarshal(req, v); err != nil {
			return status.Errorf(codes.Internal, "grpc: error unmarshalling request: %v", err)
		}
		if inPayload != nil {
			inPayload.Payload = v
			inPayload.Data = req
			inPayload.Length = len(req)
			sh.HandleRPC(stream.Context(), inPayload)
		}
		if trInfo != nil {
			trInfo.tr.LazyLog(&payload{sent: false, msg: v}, true)
		}
		return nil
	}
	ctx := NewContextWithServerTransportStream(stream.Context(), stream)
	reply, appErr := md.Handler(srv.server, ctx, df, s.opts.unaryInt)
	if appErr != nil {
		appStatus, ok := status.FromError(appErr)
		if !ok {
			// Convert appErr if it is not a grpc status error.
			appErr = status.Error(codes.Unknown, appErr.Error())
			appStatus, _ = status.FromError(appErr)
		}
		if trInfo != nil {
			trInfo.tr.LazyLog(stringer(appStatus.Message()), true)
			trInfo.tr.SetError()
		}
		if e := t.WriteStatus(stream, appStatus); e != nil {
			grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status: %v", e)
		}
		return appErr
	}
	if trInfo != nil {
		trInfo.tr.LazyLog(stringer("OK"), false)
	}
	opts := &transport.Options{
		Last:  true,
		Delay: false,
	}

	if err := s.sendResponse(t, stream, reply, cp, opts, comp); err != nil {
		if err == io.EOF {
			// The entire stream is done (for unary RPC only).
			return err
		}
		if s, ok := status.FromError(err); ok {
			if e := t.WriteStatus(stream, s); e != nil {
				grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status: %v", e)
			}
		} else {
			switch st := err.(type) {
			case transport.ConnectionError:
				// Nothing to do here.
			case transport.StreamError:
				if e := t.WriteStatus(stream, status.New(st.Code, st.Desc)); e != nil {
					grpclog.Warningf("grpc: Server.processUnaryRPC failed to write status %v", e)
				}
			default:
				panic(fmt.Sprintf("grpc: Unexpected error (%T) from sendResponse: %v", st, st))
			}
		}
		return err
	}
	if channelz.IsOn() {
		t.IncrMsgSent()
	}
	if trInfo != nil {
		trInfo.tr.LazyLog(&payload{sent: true, msg: reply}, true)
	}
	// TODO: Should we be logging if writing status failed here, like above?
	// Should the logging be in WriteStatus?  Should we ignore the WriteStatus
	// error or allow the stats handler to see it?
	return t.WriteStatus(stream, status.New(codes.OK, ""))
}

func (s *Server) processStreamingRPC(t transport.ServerTransport, stream *transport.Stream, srv *service, sd *StreamDesc, trInfo *traceInfo) (err error) {
	if channelz.IsOn() {
		s.incrCallsStarted()
		defer func() {
			if err != nil && err != io.EOF {
				s.incrCallsFailed()
			} else {
				s.incrCallsSucceeded()
			}
		}()
	}
	sh := s.opts.statsHandler
	if sh != nil {
		beginTime := time.Now()
		begin := &stats.Begin{
			BeginTime: beginTime,
		}
		sh.HandleRPC(stream.Context(), begin)
		defer func() {
			end := &stats.End{
				BeginTime: beginTime,
				EndTime:   time.Now(),
			}
			if err != nil && err != io.EOF {
				end.Error = toRPCErr(err)
			}
			sh.HandleRPC(stream.Context(), end)
		}()
	}
	ctx := NewContextWithServerTransportStream(stream.Context(), stream)
	ss := &serverStream{
		ctx:   ctx,
		t:     t,
		s:     stream,
		p:     &parser{r: stream},
		codec: s.getCodec(stream.ContentSubtype()),
		maxReceiveMessageSize: s.opts.maxReceiveMessageSize,
		maxSendMessageSize:    s.opts.maxSendMessageSize,
		trInfo:                trInfo,
		statsHandler:          sh,
	}

	// If dc is set and matches the stream's compression, use it.  Otherwise, try
	// to find a matching registered compressor for decomp.
	if rc := stream.RecvCompress(); s.opts.dc != nil && s.opts.dc.Type() == rc {
		ss.dc = s.opts.dc
	} else if rc != "" && rc != encoding.Identity {
		ss.decomp = encoding.GetCompressor(rc)
		if ss.decomp == nil {
			st := status.Newf(codes.Unimplemented, "grpc: Decompressor is not installed for grpc-encoding %q", rc)
			t.WriteStatus(ss.s, st)
			return st.Err()
		}
	}

	// If cp is set, use it.  Otherwise, attempt to compress the response using
	// the incoming message compression method.
	//
	// NOTE: this needs to be ahead of all handling, https://github.com/grpc/grpc-go/issues/686.
	if s.opts.cp != nil {
		ss.cp = s.opts.cp
		stream.SetSendCompress(s.opts.cp.Type())
	} else if rc := stream.RecvCompress(); rc != "" && rc != encoding.Identity {
		// Legacy compressor not specified; attempt to respond with same encoding.
		ss.comp = encoding.GetCompressor(rc)
		if ss.comp != nil {
			stream.SetSendCompress(rc)
		}
	}

	if trInfo != nil {
		trInfo.tr.LazyLog(&trInfo.firstLine, false)
		defer func() {
			ss.mu.Lock()
			if err != nil && err != io.EOF {
				ss.trInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
				ss.trInfo.tr.SetError()
			}
			ss.trInfo.tr.Finish()
			ss.trInfo.tr = nil
			ss.mu.Unlock()
		}()
	}
	var appErr error
	var server interface{}
	if srv != nil {
		server = srv.server
	}
	if s.opts.streamInt == nil {
		appErr = sd.Handler(server, ss)
	} else {
		info := &StreamServerInfo{
			FullMethod:     stream.Method(),
			IsClientStream: sd.ClientStreams,
			IsServerStream: sd.ServerStreams,
		}
		appErr = s.opts.streamInt(server, ss, info, sd.Handler)
	}
	if appErr != nil {
		appStatus, ok := status.FromError(appErr)
		if !ok {
			switch err := appErr.(type) {
			case transport.StreamError:
				appStatus = status.New(err.Code, err.Desc)
			default:
				appStatus = status.New(codes.Unknown, appErr.Error())
			}
			appErr = appStatus.Err()
		}
		if trInfo != nil {
			ss.mu.Lock()
			ss.trInfo.tr.LazyLog(stringer(appStatus.Message()), true)
			ss.trInfo.tr.SetError()
			ss.mu.Unlock()
		}
		t.WriteStatus(ss.s, appStatus)
		// TODO: Should we log an error from WriteStatus here and below?
		return appErr
	}
	if trInfo != nil {
		ss.mu.Lock()
		ss.trInfo.tr.LazyLog(stringer("OK"), false)
		ss.mu.Unlock()
	}
	return t.WriteStatus(ss.s, status.New(codes.OK, ""))
}

func (s *Server) handleStream(t transport.ServerTransport, stream *transport.Stream, trInfo *traceInfo) {
	sm := stream.Method()
	if sm != "" && sm[0] == '/' {
		sm = sm[1:]
	}
	pos := strings.LastIndex(sm, "/")
	if pos == -1 {
		if trInfo != nil {
			trInfo.tr.LazyLog(&fmtStringer{"Malformed method name %q", []interface{}{sm}}, true)
			trInfo.tr.SetError()
		}
		errDesc := fmt.Sprintf("malformed method name: %q", stream.Method())
		if err := t.WriteStatus(stream, status.New(codes.ResourceExhausted, errDesc)); err != nil {
			if trInfo != nil {
				trInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
				trInfo.tr.SetError()
			}
			grpclog.Warningf("grpc: Server.handleStream failed to write status: %v", err)
		}
		if trInfo != nil {
			trInfo.tr.Finish()
		}
		return
	}
	service := sm[:pos]
	method := sm[pos+1:]
	srv, ok := s.m[service]
	if !ok {
		if unknownDesc := s.opts.unknownStreamDesc; unknownDesc != nil {
			s.processStreamingRPC(t, stream, nil, unknownDesc, trInfo)
			return
		}
		if trInfo != nil {
			trInfo.tr.LazyLog(&fmtStringer{"Unknown service %v", []interface{}{service}}, true)
			trInfo.tr.SetError()
		}
		errDesc := fmt.Sprintf("unknown service %v", service)
		if err := t.WriteStatus(stream, status.New(codes.Unimplemented, errDesc)); err != nil {
			if trInfo != nil {
				trInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
				trInfo.tr.SetError()
			}
			grpclog.Warningf("grpc: Server.handleStream failed to write status: %v", err)
		}
		if trInfo != nil {
			trInfo.tr.Finish()
		}
		return
	}
	// Unary RPC or Streaming RPC?
	if md, ok := srv.md[method]; ok {
		s.processUnaryRPC(t, stream, srv, md, trInfo)
		return
	}
	if sd, ok := srv.sd[method]; ok {
		s.processStreamingRPC(t, stream, srv, sd, trInfo)
		return
	}
	if trInfo != nil {
		trInfo.tr.LazyLog(&fmtStringer{"Unknown method %v", []interface{}{method}}, true)
		trInfo.tr.SetError()
	}
	if unknownDesc := s.opts.unknownStreamDesc; unknownDesc != nil {
		s.processStreamingRPC(t, stream, nil, unknownDesc, trInfo)
		return
	}
	errDesc := fmt.Sprintf("unknown method %v", method)
	if err := t.WriteStatus(stream, status.New(codes.Unimplemented, errDesc)); err != nil {
		if trInfo != nil {
			trInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
			trInfo.tr.SetError()
		}
		grpclog.Warningf("grpc: Server.handleStream failed to write status: %v", err)
	}
	if trInfo != nil {
		trInfo.tr.Finish()
	}
}

// The key to save ServerTransportStream in the context.
type streamKey struct{}

// NewContextWithServerTransportStream creates a new context from ctx and
// attaches stream to it.
//
// This API is EXPERIMENTAL.
func NewContextWithServerTransportStream(ctx context.Context, stream ServerTransportStream) context.Context {
	return context.WithValue(ctx, streamKey{}, stream)
}

// ServerTransportStream is a minimal interface that a transport stream must
// implement. This can be used to mock an actual transport stream for tests of
// handler code that use, for example, grpc.SetHeader (which requires some
// stream to be in context).
//
// See also NewContextWithServerTransportStream.
//
// This API is EXPERIMENTAL.
type ServerTransportStream interface {
	Method() string
	SetHeader(md metadata.MD) error
	SendHeader(md metadata.MD) error
	SetTrailer(md metadata.MD) error
}

// ServerTransportStreamFromContext returns the ServerTransportStream saved in
// ctx. Returns nil if the given context has no stream associated with it
// (which implies it is not an RPC invocation context).
//
// This API is EXPERIMENTAL.
func ServerTransportStreamFromContext(ctx context.Context) ServerTransportStream {
	s, _ := ctx.Value(streamKey{}).(ServerTransportStream)
	return s
}

// Stop stops the gRPC server. It immediately closes all open
// connections and listeners.
// It cancels all active RPCs on the server side and the corresponding
// pending RPCs on the client side will get notified by connection
// errors.
func (s *Server) Stop() {
	s.quitOnce.Do(func() {
		close(s.quit)
	})

	defer func() {
		s.serveWG.Wait()
		s.doneOnce.Do(func() {
			close(s.done)
		})
	}()

	s.channelzRemoveOnce.Do(func() {
		if channelz.IsOn() {
			channelz.RemoveEntry(s.channelzID)
		}
	})

	s.mu.Lock()
	listeners := s.lis
	s.lis = nil
	st := s.conns
	s.conns = nil
	// interrupt GracefulStop if Stop and GracefulStop are called concurrently.
	s.cv.Broadcast()
	s.mu.Unlock()

	for lis := range listeners {
		lis.Close()
	}
	for c := range st {
		c.Close()
	}

	s.mu.Lock()
	if s.events != nil {
		s.events.Finish()
		s.events = nil
	}
	s.mu.Unlock()
}

// GracefulStop stops the gRPC server gracefully. It stops the server from
// accepting new connections and RPCs and blocks until all the pending RPCs are
// finished.
func (s *Server) GracefulStop() {
	s.quitOnce.Do(func() {
		close(s.quit)
	})

	defer func() {
		s.doneOnce.Do(func() {
			close(s.done)
		})
	}()

	s.channelzRemoveOnce.Do(func() {
		if channelz.IsOn() {
			channelz.RemoveEntry(s.channelzID)
		}
	})
	s.mu.Lock()
	if s.conns == nil {
		s.mu.Unlock()
		return
	}

	for lis := range s.lis {
		lis.Close()
	}
	s.lis = nil
	if !s.drain {
		for c := range s.conns {
			c.(transport.ServerTransport).Drain()
		}
		s.drain = true
	}

	// Wait for serving threads to be ready to exit.  Only then can we be sure no
	// new conns will be created.
	s.mu.Unlock()
	s.serveWG.Wait()
	s.mu.Lock()

	for len(s.conns) != 0 {
		s.cv.Wait()
	}
	s.conns = nil
	if s.events != nil {
		s.events.Finish()
		s.events = nil
	}
	s.mu.Unlock()
}

func init() {
	internal.TestingUseHandlerImpl = func(arg interface{}) {
		arg.(*Server).opts.useHandlerImpl = true
	}
}

// contentSubtype must be lowercase
// cannot return nil
func (s *Server) getCodec(contentSubtype string) baseCodec {
	if s.opts.codec != nil {
		return s.opts.codec
	}
	if contentSubtype == "" {
		return encoding.GetCodec(proto.Name)
	}
	codec := encoding.GetCodec(contentSubtype)
	if codec == nil {
		return encoding.GetCodec(proto.Name)
	}
	return codec
}

// SetHeader sets the header metadata.
// When called multiple times, all the provided metadata will be merged.
// All the metadata will be sent out when one of the following happens:
//  - grpc.SendHeader() is called;
//  - The first response is sent out;
//  - An RPC status is sent out (error or success).
func SetHeader(ctx context.Context, md metadata.MD) error {
	if md.Len() == 0 {
		return nil
	}
	stream := ServerTransportStreamFromContext(ctx)
	if stream == nil {
		return status.Errorf(codes.Internal, "grpc: failed to fetch the stream from the context %v", ctx)
	}
	return stream.SetHeader(md)
}

// SendHeader sends header metadata. It may be called at most once.
// The provided md and headers set by SetHeader() will be sent.
func SendHeader(ctx context.Context, md metadata.MD) error {
	stream := ServerTransportStreamFromContext(ctx)
	if stream == nil {
		return status.Errorf(codes.Internal, "grpc: failed to fetch the stream from the context %v", ctx)
	}
	if err := stream.SendHeader(md); err != nil {
		return toRPCErr(err)
	}
	return nil
}

// SetTrailer sets the trailer metadata that will be sent when an RPC returns.
// When called more than once, all the provided metadata will be merged.
func SetTrailer(ctx context.Context, md metadata.MD) error {
	if md.Len() == 0 {
		return nil
	}
	stream := ServerTransportStreamFromContext(ctx)
	if stream == nil {
		return status.Errorf(codes.Internal, "grpc: failed to fetch the stream from the context %v", ctx)
	}
	return stream.SetTrailer(md)
}

// Method returns the method string for the server context.  The returned
// string is in the format of "/service/method".
func Method(ctx context.Context) (string, bool) {
	s := ServerTransportStreamFromContext(ctx)
	if s == nil {
		return "", false
	}
	return s.Method(), true
}