File: balancer_test.go

package info (click to toggle)
golang-google-grpc 1.27.1-1
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, experimental, sid
  • size: 5,048 kB
  • sloc: sh: 583; makefile: 66
file content (789 lines) | stat: -rw-r--r-- 24,532 bytes parent folder | download
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
/*
 *
 * Copyright 2016 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 (
	"context"
	"fmt"
	"math"
	"strconv"
	"sync"
	"testing"
	"time"

	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/naming"
	"google.golang.org/grpc/status"
)

func pickFirstBalancerV1(r naming.Resolver) Balancer {
	return &pickFirst{&roundRobin{r: r}}
}

type testWatcher struct {
	// the channel to receives name resolution updates
	update chan *naming.Update
	// the side channel to get to know how many updates in a batch
	side chan int
	// the channel to notify update injector that the update reading is done
	readDone chan int
}

func (w *testWatcher) Next() (updates []*naming.Update, err error) {
	n := <-w.side
	if n == 0 {
		return nil, fmt.Errorf("w.side is closed")
	}
	for i := 0; i < n; i++ {
		u := <-w.update
		if u != nil {
			updates = append(updates, u)
		}
	}
	w.readDone <- 0
	return
}

func (w *testWatcher) Close() {
	close(w.side)
}

// Inject naming resolution updates to the testWatcher.
func (w *testWatcher) inject(updates []*naming.Update) {
	w.side <- len(updates)
	for _, u := range updates {
		w.update <- u
	}
	<-w.readDone
}

type testNameResolver struct {
	w    *testWatcher
	addr string
}

func (r *testNameResolver) Resolve(target string) (naming.Watcher, error) {
	r.w = &testWatcher{
		update:   make(chan *naming.Update, 1),
		side:     make(chan int, 1),
		readDone: make(chan int),
	}
	r.w.side <- 1
	r.w.update <- &naming.Update{
		Op:   naming.Add,
		Addr: r.addr,
	}
	go func() {
		<-r.w.readDone
	}()
	return r.w, nil
}

func startServers(t *testing.T, numServers int, maxStreams uint32) ([]*server, *testNameResolver, func()) {
	var servers []*server
	for i := 0; i < numServers; i++ {
		s := newTestServer()
		servers = append(servers, s)
		go s.start(t, 0, maxStreams)
		s.wait(t, 2*time.Second)
	}
	// Point to server[0]
	addr := "localhost:" + servers[0].port
	return servers, &testNameResolver{
			addr: addr,
		}, func() {
			for i := 0; i < numServers; i++ {
				servers[i].stop()
			}
		}
}

func (s) TestNameDiscovery(t *testing.T) {
	// Start 2 servers on 2 ports.
	numServers := 2
	servers, r, cleanup := startServers(t, numServers, math.MaxUint32)
	defer cleanup()
	cc, err := Dial("passthrough:///foo.bar.com", WithBalancer(RoundRobin(r)), WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	req := "port"
	var reply string
	if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err == nil || errorDesc(err) != servers[0].port {
		t.Fatalf("grpc.Invoke(_, _, _, _, _) = %v, want %s", err, servers[0].port)
	}
	// Inject the name resolution change to remove servers[0] and add servers[1].
	var updates []*naming.Update
	updates = append(updates, &naming.Update{
		Op:   naming.Delete,
		Addr: "localhost:" + servers[0].port,
	})
	updates = append(updates, &naming.Update{
		Op:   naming.Add,
		Addr: "localhost:" + servers[1].port,
	})
	r.w.inject(updates)
	// Loop until the rpcs in flight talks to servers[1].
	for {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err != nil && errorDesc(err) == servers[1].port {
			break
		}
		time.Sleep(10 * time.Millisecond)
	}
}

func (s) TestEmptyAddrs(t *testing.T) {
	servers, r, cleanup := startServers(t, 1, math.MaxUint32)
	defer cleanup()
	cc, err := Dial("passthrough:///foo.bar.com", WithBalancer(RoundRobin(r)), WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	var reply string
	if err := cc.Invoke(context.Background(), "/foo/bar", &expectedRequest, &reply); err != nil || reply != expectedResponse {
		t.Fatalf("grpc.Invoke(_, _, _, _, _) = %v, reply = %q, want %q, <nil>", err, reply, expectedResponse)
	}
	// Inject name resolution change to remove the server so that there is no address
	// available after that.
	u := &naming.Update{
		Op:   naming.Delete,
		Addr: "localhost:" + servers[0].port,
	}
	r.w.inject([]*naming.Update{u})
	// Loop until the above updates apply.
	for {
		time.Sleep(10 * time.Millisecond)
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)
		if err := cc.Invoke(ctx, "/foo/bar", &expectedRequest, &reply); err != nil {
			cancel()
			break
		}
		cancel()
	}
}

func (s) TestRoundRobin(t *testing.T) {
	// Start 3 servers on 3 ports.
	numServers := 3
	servers, r, cleanup := startServers(t, numServers, math.MaxUint32)
	defer cleanup()
	cc, err := Dial("passthrough:///foo.bar.com", WithBalancer(RoundRobin(r)), WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	// Add servers[1] to the service discovery.
	u := &naming.Update{
		Op:   naming.Add,
		Addr: "localhost:" + servers[1].port,
	}
	r.w.inject([]*naming.Update{u})
	req := "port"
	var reply string
	// Loop until servers[1] is up
	for {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err != nil && errorDesc(err) == servers[1].port {
			break
		}
		time.Sleep(10 * time.Millisecond)
	}
	// Add server2[2] to the service discovery.
	u = &naming.Update{
		Op:   naming.Add,
		Addr: "localhost:" + servers[2].port,
	}
	r.w.inject([]*naming.Update{u})
	// Loop until both servers[2] are up.
	for {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err != nil && errorDesc(err) == servers[2].port {
			break
		}
		time.Sleep(10 * time.Millisecond)
	}
	// Check the incoming RPCs served in a round-robin manner.
	for i := 0; i < 10; i++ {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err == nil || errorDesc(err) != servers[i%numServers].port {
			t.Fatalf("Index %d: Invoke(_, _, _, _, _) = %v, want %s", i, err, servers[i%numServers].port)
		}
	}
}

func (s) TestCloseWithPendingRPC(t *testing.T) {
	servers, r, cleanup := startServers(t, 1, math.MaxUint32)
	defer cleanup()
	cc, err := Dial("passthrough:///foo.bar.com", WithBalancer(RoundRobin(r)), WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	var reply string
	if err := cc.Invoke(context.Background(), "/foo/bar", &expectedRequest, &reply, WaitForReady(true)); err != nil {
		t.Fatalf("grpc.Invoke(_, _, _, _, _) = %v, want %s", err, servers[0].port)
	}
	// Remove the server.
	updates := []*naming.Update{{
		Op:   naming.Delete,
		Addr: "localhost:" + servers[0].port,
	}}
	r.w.inject(updates)
	// Loop until the above update applies.
	for {
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)
		if err := cc.Invoke(ctx, "/foo/bar", &expectedRequest, &reply, WaitForReady(true)); status.Code(err) == codes.DeadlineExceeded {
			cancel()
			break
		}
		time.Sleep(10 * time.Millisecond)
		cancel()
	}
	// Issue 2 RPCs which should be completed with error status once cc is closed.
	var wg sync.WaitGroup
	wg.Add(2)
	go func() {
		defer wg.Done()
		var reply string
		if err := cc.Invoke(context.Background(), "/foo/bar", &expectedRequest, &reply, WaitForReady(true)); err == nil {
			t.Errorf("grpc.Invoke(_, _, _, _, _) = %v, want not nil", err)
		}
	}()
	go func() {
		defer wg.Done()
		var reply string
		time.Sleep(5 * time.Millisecond)
		if err := cc.Invoke(context.Background(), "/foo/bar", &expectedRequest, &reply, WaitForReady(true)); err == nil {
			t.Errorf("grpc.Invoke(_, _, _, _, _) = %v, want not nil", err)
		}
	}()
	time.Sleep(5 * time.Millisecond)
	cc.Close()
	wg.Wait()
}

func (s) TestGetOnWaitChannel(t *testing.T) {
	servers, r, cleanup := startServers(t, 1, math.MaxUint32)
	defer cleanup()
	cc, err := Dial("passthrough:///foo.bar.com", WithBalancer(RoundRobin(r)), WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	// Remove all servers so that all upcoming RPCs will block on waitCh.
	updates := []*naming.Update{{
		Op:   naming.Delete,
		Addr: "localhost:" + servers[0].port,
	}}
	r.w.inject(updates)
	for {
		var reply string
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)
		if err := cc.Invoke(ctx, "/foo/bar", &expectedRequest, &reply, WaitForReady(true)); status.Code(err) == codes.DeadlineExceeded {
			cancel()
			break
		}
		cancel()
		time.Sleep(10 * time.Millisecond)
	}
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()
		var reply string
		if err := cc.Invoke(context.Background(), "/foo/bar", &expectedRequest, &reply, WaitForReady(true)); err != nil {
			t.Errorf("grpc.Invoke(_, _, _, _, _) = %v, want <nil>", err)
		}
	}()
	// Add a connected server to get the above RPC through.
	updates = []*naming.Update{{
		Op:   naming.Add,
		Addr: "localhost:" + servers[0].port,
	}}
	r.w.inject(updates)
	// Wait until the above RPC succeeds.
	wg.Wait()
}

func (s) TestOneServerDown(t *testing.T) {
	// Start 2 servers.
	numServers := 2
	servers, r, cleanup := startServers(t, numServers, math.MaxUint32)
	defer cleanup()
	cc, err := Dial("passthrough:///foo.bar.com", WithBalancer(RoundRobin(r)), WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	// Add servers[1] to the service discovery.
	var updates []*naming.Update
	updates = append(updates, &naming.Update{
		Op:   naming.Add,
		Addr: "localhost:" + servers[1].port,
	})
	r.w.inject(updates)
	req := "port"
	var reply string
	// Loop until servers[1] is up
	for {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err != nil && errorDesc(err) == servers[1].port {
			break
		}
		time.Sleep(10 * time.Millisecond)
	}

	var wg sync.WaitGroup
	numRPC := 100
	sleepDuration := 10 * time.Millisecond
	wg.Add(1)
	go func() {
		time.Sleep(sleepDuration)
		// After sleepDuration, kill server[0].
		servers[0].stop()
		wg.Done()
	}()

	// All non-failfast RPCs should not block because there's at least one connection available.
	for i := 0; i < numRPC; i++ {
		wg.Add(1)
		go func() {
			time.Sleep(sleepDuration)
			// After sleepDuration, invoke RPC.
			// server[0] is killed around the same time to make it racy between balancer and gRPC internals.
			cc.Invoke(context.Background(), "/foo/bar", &req, &reply, WaitForReady(true))
			wg.Done()
		}()
	}
	wg.Wait()
}

func (s) TestOneAddressRemoval(t *testing.T) {
	// Start 2 servers.
	numServers := 2
	servers, r, cleanup := startServers(t, numServers, math.MaxUint32)
	defer cleanup()
	cc, err := Dial("passthrough:///foo.bar.com", WithBalancer(RoundRobin(r)), WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	// Add servers[1] to the service discovery.
	var updates []*naming.Update
	updates = append(updates, &naming.Update{
		Op:   naming.Add,
		Addr: "localhost:" + servers[1].port,
	})
	r.w.inject(updates)
	req := "port"
	var reply string
	// Loop until servers[1] is up
	for {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err != nil && errorDesc(err) == servers[1].port {
			break
		}
		time.Sleep(10 * time.Millisecond)
	}

	var wg sync.WaitGroup
	numRPC := 100
	sleepDuration := 10 * time.Millisecond
	wg.Add(1)
	go func() {
		time.Sleep(sleepDuration)
		// After sleepDuration, delete server[0].
		var updates []*naming.Update
		updates = append(updates, &naming.Update{
			Op:   naming.Delete,
			Addr: "localhost:" + servers[0].port,
		})
		r.w.inject(updates)
		wg.Done()
	}()

	// All non-failfast RPCs should not fail because there's at least one connection available.
	for i := 0; i < numRPC; i++ {
		wg.Add(1)
		go func() {
			var reply string
			time.Sleep(sleepDuration)
			// After sleepDuration, invoke RPC.
			// server[0] is removed around the same time to make it racy between balancer and gRPC internals.
			if err := cc.Invoke(context.Background(), "/foo/bar", &expectedRequest, &reply, WaitForReady(true)); err != nil {
				t.Errorf("grpc.Invoke(_, _, _, _, _) = %v, want nil", err)
			}
			wg.Done()
		}()
	}
	wg.Wait()
}

func checkServerUp(t *testing.T, currentServer *server) {
	req := "port"
	port := currentServer.port
	cc, err := Dial("passthrough:///localhost:"+port, WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	var reply string
	for {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err != nil && errorDesc(err) == port {
			break
		}
		time.Sleep(10 * time.Millisecond)
	}
}

func (s) TestPickFirstEmptyAddrs(t *testing.T) {
	servers, r, cleanup := startServers(t, 1, math.MaxUint32)
	defer cleanup()
	cc, err := Dial("passthrough:///foo.bar.com", WithBalancer(pickFirstBalancerV1(r)), WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	var reply string
	if err := cc.Invoke(context.Background(), "/foo/bar", &expectedRequest, &reply); err != nil || reply != expectedResponse {
		t.Fatalf("grpc.Invoke(_, _, _, _, _) = %v, reply = %q, want %q, <nil>", err, reply, expectedResponse)
	}
	// Inject name resolution change to remove the server so that there is no address
	// available after that.
	u := &naming.Update{
		Op:   naming.Delete,
		Addr: "localhost:" + servers[0].port,
	}
	r.w.inject([]*naming.Update{u})
	// Loop until the above updates apply.
	for {
		time.Sleep(10 * time.Millisecond)
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)
		if err := cc.Invoke(ctx, "/foo/bar", &expectedRequest, &reply); err != nil {
			cancel()
			break
		}
		cancel()
	}
}

func (s) TestPickFirstCloseWithPendingRPC(t *testing.T) {
	servers, r, cleanup := startServers(t, 1, math.MaxUint32)
	defer cleanup()
	cc, err := Dial("passthrough:///foo.bar.com", WithBalancer(pickFirstBalancerV1(r)), WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	var reply string
	if err := cc.Invoke(context.Background(), "/foo/bar", &expectedRequest, &reply, WaitForReady(true)); err != nil {
		t.Fatalf("grpc.Invoke(_, _, _, _, _) = %v, want %s", err, servers[0].port)
	}
	// Remove the server.
	updates := []*naming.Update{{
		Op:   naming.Delete,
		Addr: "localhost:" + servers[0].port,
	}}
	r.w.inject(updates)
	// Loop until the above update applies.
	for {
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)
		if err := cc.Invoke(ctx, "/foo/bar", &expectedRequest, &reply, WaitForReady(true)); status.Code(err) == codes.DeadlineExceeded {
			cancel()
			break
		}
		time.Sleep(10 * time.Millisecond)
		cancel()
	}
	// Issue 2 RPCs which should be completed with error status once cc is closed.
	var wg sync.WaitGroup
	wg.Add(2)
	go func() {
		defer wg.Done()
		var reply string
		if err := cc.Invoke(context.Background(), "/foo/bar", &expectedRequest, &reply, WaitForReady(true)); err == nil {
			t.Errorf("grpc.Invoke(_, _, _, _, _) = %v, want not nil", err)
		}
	}()
	go func() {
		defer wg.Done()
		var reply string
		time.Sleep(5 * time.Millisecond)
		if err := cc.Invoke(context.Background(), "/foo/bar", &expectedRequest, &reply, WaitForReady(true)); err == nil {
			t.Errorf("grpc.Invoke(_, _, _, _, _) = %v, want not nil", err)
		}
	}()
	time.Sleep(5 * time.Millisecond)
	cc.Close()
	wg.Wait()
}

func (s) TestPickFirstOrderAllServerUp(t *testing.T) {
	// Start 3 servers on 3 ports.
	numServers := 3
	servers, r, cleanup := startServers(t, numServers, math.MaxUint32)
	defer cleanup()
	cc, err := Dial("passthrough:///foo.bar.com", WithBalancer(pickFirstBalancerV1(r)), WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	// Add servers[1] and [2] to the service discovery.
	u := &naming.Update{
		Op:   naming.Add,
		Addr: "localhost:" + servers[1].port,
	}
	r.w.inject([]*naming.Update{u})

	u = &naming.Update{
		Op:   naming.Add,
		Addr: "localhost:" + servers[2].port,
	}
	r.w.inject([]*naming.Update{u})

	// Loop until all 3 servers are up
	checkServerUp(t, servers[0])
	checkServerUp(t, servers[1])
	checkServerUp(t, servers[2])

	// Check the incoming RPCs served in server[0]
	req := "port"
	var reply string
	for i := 0; i < 20; i++ {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err == nil || errorDesc(err) != servers[0].port {
			t.Fatalf("Index %d: Invoke(_, _, _, _, _) = %v, want %s", 0, err, servers[0].port)
		}
		time.Sleep(10 * time.Millisecond)
	}

	// Delete server[0] in the balancer, the incoming RPCs served in server[1]
	// For test addrconn, close server[0] instead
	u = &naming.Update{
		Op:   naming.Delete,
		Addr: "localhost:" + servers[0].port,
	}
	r.w.inject([]*naming.Update{u})
	// Loop until it changes to server[1]
	for {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err != nil && errorDesc(err) == servers[1].port {
			break
		}
		time.Sleep(10 * time.Millisecond)
	}
	for i := 0; i < 20; i++ {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err == nil || errorDesc(err) != servers[1].port {
			t.Fatalf("Index %d: Invoke(_, _, _, _, _) = %v, want %s", 1, err, servers[1].port)
		}
		time.Sleep(10 * time.Millisecond)
	}

	// Add server[0] back to the balancer, the incoming RPCs served in server[1]
	// Add is append operation, the order of Notify now is {server[1].port server[2].port server[0].port}
	u = &naming.Update{
		Op:   naming.Add,
		Addr: "localhost:" + servers[0].port,
	}
	r.w.inject([]*naming.Update{u})
	for i := 0; i < 20; i++ {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err == nil || errorDesc(err) != servers[1].port {
			t.Fatalf("Index %d: Invoke(_, _, _, _, _) = %v, want %s", 1, err, servers[1].port)
		}
		time.Sleep(10 * time.Millisecond)
	}

	// Delete server[1] in the balancer, the incoming RPCs served in server[2]
	u = &naming.Update{
		Op:   naming.Delete,
		Addr: "localhost:" + servers[1].port,
	}
	r.w.inject([]*naming.Update{u})
	for {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err != nil && errorDesc(err) == servers[2].port {
			break
		}
		time.Sleep(1 * time.Second)
	}
	for i := 0; i < 20; i++ {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err == nil || errorDesc(err) != servers[2].port {
			t.Fatalf("Index %d: Invoke(_, _, _, _, _) = %v, want %s", 2, err, servers[2].port)
		}
		time.Sleep(10 * time.Millisecond)
	}

	// Delete server[2] in the balancer, the incoming RPCs served in server[0]
	u = &naming.Update{
		Op:   naming.Delete,
		Addr: "localhost:" + servers[2].port,
	}
	r.w.inject([]*naming.Update{u})
	for {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err != nil && errorDesc(err) == servers[0].port {
			break
		}
		time.Sleep(1 * time.Second)
	}
	for i := 0; i < 20; i++ {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err == nil || errorDesc(err) != servers[0].port {
			t.Fatalf("Index %d: Invoke(_, _, _, _, _) = %v, want %s", 0, err, servers[0].port)
		}
		time.Sleep(10 * time.Millisecond)
	}
}

func (s) TestPickFirstOrderOneServerDown(t *testing.T) {
	// Start 3 servers on 3 ports.
	numServers := 3
	servers, r, cleanup := startServers(t, numServers, math.MaxUint32)
	defer cleanup()
	cc, err := Dial("passthrough:///foo.bar.com", WithBalancer(pickFirstBalancerV1(r)), WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	// Add servers[1] and [2] to the service discovery.
	u := &naming.Update{
		Op:   naming.Add,
		Addr: "localhost:" + servers[1].port,
	}
	r.w.inject([]*naming.Update{u})

	u = &naming.Update{
		Op:   naming.Add,
		Addr: "localhost:" + servers[2].port,
	}
	r.w.inject([]*naming.Update{u})

	// Loop until all 3 servers are up
	checkServerUp(t, servers[0])
	checkServerUp(t, servers[1])
	checkServerUp(t, servers[2])

	// Check the incoming RPCs served in server[0]
	req := "port"
	var reply string
	for i := 0; i < 20; i++ {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err == nil || errorDesc(err) != servers[0].port {
			t.Fatalf("Index %d: Invoke(_, _, _, _, _) = %v, want %s", 0, err, servers[0].port)
		}
		time.Sleep(10 * time.Millisecond)
	}

	// server[0] down, incoming RPCs served in server[1], but the order of Notify still remains
	// {server[0] server[1] server[2]}
	servers[0].stop()
	// Loop until it changes to server[1]
	for {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err != nil && errorDesc(err) == servers[1].port {
			break
		}
		time.Sleep(10 * time.Millisecond)
	}
	for i := 0; i < 20; i++ {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err == nil || errorDesc(err) != servers[1].port {
			t.Fatalf("Index %d: Invoke(_, _, _, _, _) = %v, want %s", 1, err, servers[1].port)
		}
		time.Sleep(10 * time.Millisecond)
	}

	// up the server[0] back, the incoming RPCs served in server[1]
	p, _ := strconv.Atoi(servers[0].port)
	servers[0] = newTestServer()
	go servers[0].start(t, p, math.MaxUint32)
	defer servers[0].stop()
	servers[0].wait(t, 2*time.Second)
	checkServerUp(t, servers[0])

	for i := 0; i < 20; i++ {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err == nil || errorDesc(err) != servers[1].port {
			t.Fatalf("Index %d: Invoke(_, _, _, _, _) = %v, want %s", 1, err, servers[1].port)
		}
		time.Sleep(10 * time.Millisecond)
	}

	// Delete server[1] in the balancer, the incoming RPCs served in server[0]
	u = &naming.Update{
		Op:   naming.Delete,
		Addr: "localhost:" + servers[1].port,
	}
	r.w.inject([]*naming.Update{u})
	for {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err != nil && errorDesc(err) == servers[0].port {
			break
		}
		time.Sleep(1 * time.Second)
	}
	for i := 0; i < 20; i++ {
		if err := cc.Invoke(context.Background(), "/foo/bar", &req, &reply); err == nil || errorDesc(err) != servers[0].port {
			t.Fatalf("Index %d: Invoke(_, _, _, _, _) = %v, want %s", 0, err, servers[0].port)
		}
		time.Sleep(10 * time.Millisecond)
	}
}

func (s) TestPickFirstOneAddressRemoval(t *testing.T) {
	// Start 2 servers.
	numServers := 2
	servers, r, cleanup := startServers(t, numServers, math.MaxUint32)
	defer cleanup()
	cc, err := Dial("passthrough:///localhost:"+servers[0].port, WithBalancer(pickFirstBalancerV1(r)), WithBlock(), WithInsecure(), WithCodec(testCodec{}))
	if err != nil {
		t.Fatalf("Failed to create ClientConn: %v", err)
	}
	defer cc.Close()
	// Add servers[1] to the service discovery.
	var updates []*naming.Update
	updates = append(updates, &naming.Update{
		Op:   naming.Add,
		Addr: "localhost:" + servers[1].port,
	})
	r.w.inject(updates)

	// Create a new cc to Loop until servers[1] is up
	checkServerUp(t, servers[0])
	checkServerUp(t, servers[1])

	var wg sync.WaitGroup
	numRPC := 100
	sleepDuration := 10 * time.Millisecond
	wg.Add(1)
	go func() {
		time.Sleep(sleepDuration)
		// After sleepDuration, delete server[0].
		var updates []*naming.Update
		updates = append(updates, &naming.Update{
			Op:   naming.Delete,
			Addr: "localhost:" + servers[0].port,
		})
		r.w.inject(updates)
		wg.Done()
	}()

	// All non-failfast RPCs should not fail because there's at least one connection available.
	for i := 0; i < numRPC; i++ {
		wg.Add(1)
		go func() {
			var reply string
			time.Sleep(sleepDuration)
			// After sleepDuration, invoke RPC.
			// server[0] is removed around the same time to make it racy between balancer and gRPC internals.
			if err := cc.Invoke(context.Background(), "/foo/bar", &expectedRequest, &reply, WaitForReady(true)); err != nil {
				t.Errorf("grpc.Invoke(_, _, _, _, _) = %v, want nil", err)
			}
			wg.Done()
		}()
	}
	wg.Wait()
}