summaryrefslogtreecommitdiff
path: root/tests/sys/kqueue/libkqueue/timer.c
blob: 5116aea98b83052daf244ff1ef40f7c2482f5d9f (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
/*
 * Copyright (c) 2009 Mark Heily <mark@heily.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "common.h"
#include <sys/time.h>

#define	MILLION 1000000
#define	THOUSAND 1000
#define	SEC_TO_MS(t) ((t) * THOUSAND)	/* Convert seconds to milliseconds. */
#define	SEC_TO_US(t) ((t) * MILLION)	/* Convert seconds to microseconds. */
#define	MS_TO_US(t)  ((t) * THOUSAND)	/* Convert milliseconds to microseconds. */
#define	US_TO_NS(t)  ((t) * THOUSAND)	/* Convert microseconds to nanoseconds. */


/* Get the current time with microsecond precision. Used for
 * sub-second timing to make some timer tests run faster.
 */
static uint64_t
now(void)
{
    struct timeval tv;

    gettimeofday(&tv, NULL);
    /* Promote potentially 32-bit time_t to uint64_t before conversion. */
    return SEC_TO_US((uint64_t)tv.tv_sec) + tv.tv_usec;
}

/* Sleep for a given number of milliseconds. The timeout is assumed to
 * be less than 1 second.
 */
static void
mssleep(int t)
{
    struct timespec stime = {
        .tv_sec = 0,
        .tv_nsec = US_TO_NS(MS_TO_US(t)),
    };

    nanosleep(&stime, NULL);
}

/* Sleep for a given number of microseconds. The timeout is assumed to
 * be less than 1 second.
 */
static void
ussleep(int t)
{
    struct timespec stime = {
        .tv_sec = 0,
        .tv_nsec = US_TO_NS(t),
    };

    nanosleep(&stime, NULL);
}

static void
test_kevent_timer_add(void)
{
    const char *test_id = "kevent(EVFILT_TIMER, EV_ADD)";
    struct kevent kev;

    test_begin(test_id);

    EV_SET(&kev, 1, EVFILT_TIMER, EV_ADD, 0, 1000, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    success();
}

static void
test_kevent_timer_del(void)
{
    const char *test_id = "kevent(EVFILT_TIMER, EV_DELETE)";
    struct kevent kev;

    test_begin(test_id);

    EV_SET(&kev, 1, EVFILT_TIMER, EV_DELETE, 0, 0, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    test_no_kevents();

    success();
}

static void
test_kevent_timer_get(void)
{
    const char *test_id = "kevent(EVFILT_TIMER, wait)";
    struct kevent kev;

    test_begin(test_id);

    EV_SET(&kev, 1, EVFILT_TIMER, EV_ADD, 0, 1000, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    kev.flags |= EV_CLEAR;
    kev.data = 1; 
    kevent_cmp(&kev, kevent_get(kqfd));

    EV_SET(&kev, 1, EVFILT_TIMER, EV_DELETE, 0, 0, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    success();
}

static void
test_oneshot(void)
{
    const char *test_id = "kevent(EVFILT_TIMER, EV_ONESHOT)";
    struct kevent kev;

    test_begin(test_id);

    test_no_kevents();

    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT, 0, 500,NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Retrieve the event */
    kev.flags = EV_ADD | EV_CLEAR | EV_ONESHOT;
    kev.data = 1; 
    kevent_cmp(&kev, kevent_get(kqfd));

    /* Check if the event occurs again */
    sleep(3);
    test_no_kevents();


    success();
}

static void
test_periodic(void)
{
    const char *test_id = "kevent(EVFILT_TIMER, periodic)";
    struct kevent kev;

    test_begin(test_id);

    test_no_kevents();

    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD, 0, 1000,NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Retrieve the event */
    kev.flags = EV_ADD | EV_CLEAR;
    kev.data = 1; 
    kevent_cmp(&kev, kevent_get(kqfd));

    /* Check if the event occurs again */
    sleep(1);
    kevent_cmp(&kev, kevent_get(kqfd));

    /* Delete the event */
    kev.flags = EV_DELETE;
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    success();
}

static void
test_periodic_modify(void)
{
    const char *test_id = "kevent(EVFILT_TIMER, periodic_modify)";
    struct kevent kev;

    test_begin(test_id);

    test_no_kevents();

    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD, 0, 1000, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Retrieve the event */
    kev.flags = EV_ADD | EV_CLEAR;
    kev.data = 1;
    kevent_cmp(&kev, kevent_get(kqfd));

    /* Check if the event occurs again */
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD, 0, 495, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    kev.flags = EV_ADD | EV_CLEAR;
    sleep(1);
    kev.data = 2;	/* Should have fired twice */

    kevent_cmp(&kev, kevent_get(kqfd));

    /* Delete the event */
    kev.flags = EV_DELETE;
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    success();
}

#if WITH_NATIVE_KQUEUE_BUGS
static void
test_periodic_to_oneshot(void)
{
    const char *test_id = "kevent(EVFILT_TIMER, period_to_oneshot)";
    struct kevent kev;

    test_begin(test_id);

    test_no_kevents();

    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD, 0, 1000, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Retrieve the event */
    kev.flags = EV_ADD | EV_CLEAR;
    kev.data = 1;
    kevent_cmp(&kev, kevent_get(kqfd));

    /* Check if the event occurs again */
    sleep(1);
    kevent_cmp(&kev, kevent_get(kqfd));

    /* Switch to oneshot */
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT, 0, 500, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);
    kev.flags = EV_ADD | EV_CLEAR | EV_ONESHOT;

    sleep(1);
    kev.data = 1;	/* Should have fired once */

    kevent_cmp(&kev, kevent_get(kqfd));

    success();
}
#endif

static void
test_disable_and_enable(void)
{
    const char *test_id = "kevent(EVFILT_TIMER, EV_DISABLE and EV_ENABLE)";
    struct kevent kev;

    test_begin(test_id);

    test_no_kevents();

    /* Add the watch and immediately disable it */
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT, 0, 2000,NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);
    kev.flags = EV_DISABLE;
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);
    test_no_kevents();

    /* Re-enable and check again */
    kev.flags = EV_ENABLE;
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    kev.flags = EV_ADD | EV_CLEAR | EV_ONESHOT;
    kev.data = 1; 
    kevent_cmp(&kev, kevent_get(kqfd));

    success();
}

static void
test_abstime(void)
{
    const char *test_id = "kevent(EVFILT_TIMER, EV_ONESHOT, NOTE_ABSTIME)";
    struct kevent kev;
    uint64_t end, start, stop;
    const int timeout_sec = 3;

    test_begin(test_id);

    test_no_kevents();

    start = now();
    end = start + SEC_TO_US(timeout_sec);
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT,
      NOTE_ABSTIME | NOTE_USECONDS, end, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Retrieve the event */
    kev.flags = EV_ADD | EV_ONESHOT;
    kev.data = 1;
    kev.fflags = 0;
    kevent_cmp(&kev, kevent_get(kqfd));

    stop = now();
    if (stop < end)
        err(1, "too early %jd %jd", (intmax_t)stop, (intmax_t)end);
    /* Check if the event occurs again */
    sleep(3);
    test_no_kevents();

    success();
}

static void
test_abstime_epoch(void)
{
    const char *test_id = "kevent(EVFILT_TIMER (EPOCH), NOTE_ABSTIME)";
    struct kevent kev;

    test_begin(test_id);

    test_no_kevents();

    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD, NOTE_ABSTIME, 0,
        NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Retrieve the event */
    kev.flags = EV_ADD;
    kev.data = 1;
    kev.fflags = 0;
    kevent_cmp(&kev, kevent_get(kqfd));

    /* Delete the event */
    kev.flags = EV_DELETE;
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    success();
}

static void
test_abstime_preboot(void)
{
    const char *test_id = "kevent(EVFILT_TIMER (PREBOOT), EV_ONESHOT, NOTE_ABSTIME)";
    struct kevent kev;
    struct timespec btp;
    uint64_t end, start, stop;

    test_begin(test_id);

    test_no_kevents();

    /*
     * We'll expire it at just before system boot (roughly) with the hope that
     * we'll get an ~immediate expiration, just as we do for any value specified
     * between system boot and now.
     */
    start = now();
    if (clock_gettime(CLOCK_BOOTTIME, &btp) != 0)
      err(1, "%s", test_id);

    end = start - SEC_TO_US(btp.tv_sec + 1);
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT,
      NOTE_ABSTIME | NOTE_USECONDS, end, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Retrieve the event */
    kev.flags = EV_ADD | EV_ONESHOT;
    kev.data = 1;
    kev.fflags = 0;
    kevent_cmp(&kev, kevent_get(kqfd));

    stop = now();
    if (stop < end)
        err(1, "too early %jd %jd", (intmax_t)stop, (intmax_t)end);
    /* Check if the event occurs again */
    sleep(3);
    test_no_kevents();

    success();
}

static void
test_abstime_postboot(void)
{
    const char *test_id = "kevent(EVFILT_TIMER (POSTBOOT), EV_ONESHOT, NOTE_ABSTIME)";
    struct kevent kev;
    uint64_t end, start, stop;
    const int timeout_sec = 1;

    test_begin(test_id);

    test_no_kevents();

    /*
     * Set a timer for 1 second ago, it should fire immediately rather than
     * being rejected.
     */
    start = now();
    end = start - SEC_TO_US(timeout_sec);
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT,
      NOTE_ABSTIME | NOTE_USECONDS, end, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Retrieve the event */
    kev.flags = EV_ADD | EV_ONESHOT;
    kev.data = 1;
    kev.fflags = 0;
    kevent_cmp(&kev, kevent_get(kqfd));

    stop = now();
    if (stop < end)
        err(1, "too early %jd %jd", (intmax_t)stop, (intmax_t)end);
    /* Check if the event occurs again */
    sleep(3);
    test_no_kevents();

    success();
}

static void
test_update(void)
{
    const char *test_id = "kevent(EVFILT_TIMER (UPDATE), EV_ADD | EV_ONESHOT)";
    struct kevent kev;
    long elapsed;
    uint64_t start;

    test_begin(test_id);

    test_no_kevents();

    /* First set the timer to 1 second */
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT,
        NOTE_USECONDS, SEC_TO_US(1), (void *)1);
    start = now();
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Now reduce the timer to 1 ms */
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT,
        NOTE_USECONDS, MS_TO_US(1), (void *)2);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Wait for the event */
    kev.flags |= EV_CLEAR;
    kev.fflags &= ~NOTE_USECONDS;
    kev.data = 1;
    kevent_cmp(&kev, kevent_get(kqfd));
    elapsed = now() - start;

    /* Check that the timer expired after at least 1 ms, but less than
     * 1 second. This check is to make sure that the original 1 second
     * timeout was not used.
     */
    printf("timer expired after %ld us\n", elapsed);
    if (elapsed < MS_TO_US(1))
        errx(1, "early timer expiration: %ld us", elapsed);
    if (elapsed > SEC_TO_US(1))
        errx(1, "late timer expiration: %ld us", elapsed);

    success();
}

static void
test_update_equal(void)
{
    const char *test_id = "kevent(EVFILT_TIMER (UPDATE=), EV_ADD | EV_ONESHOT)";
    struct kevent kev;
    long elapsed;
    uint64_t start;

    test_begin(test_id);

    test_no_kevents();

    /* First set the timer to 1 ms */
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT,
        NOTE_USECONDS, MS_TO_US(1), NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Sleep for a significant fraction of the timeout. */
    ussleep(600);
    
    /* Now re-add the timer with the same parameters */
    start = now();
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Wait for the event */
    kev.flags |= EV_CLEAR;
    kev.fflags &= ~NOTE_USECONDS;
    kev.data = 1;
    kevent_cmp(&kev, kevent_get(kqfd));
    elapsed = now() - start;

    /* Check that the timer expired after at least 1 ms. This check is
     * to make sure that the timer re-started and that the event is
     * not from the original add of the timer.
     */
    printf("timer expired after %ld us\n", elapsed);
    if (elapsed < MS_TO_US(1))
        errx(1, "early timer expiration: %ld us", elapsed);

    success();
}

static void
test_update_expired(void)
{
    const char *test_id = "kevent(EVFILT_TIMER (UPDATE EXP), EV_ADD | EV_ONESHOT)";
    struct kevent kev;
    long elapsed;
    uint64_t start;

    test_begin(test_id);

    test_no_kevents();

    /* Set the timer to 1ms */
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT,
        NOTE_USECONDS, MS_TO_US(1), NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Wait for 2 ms to give the timer plenty of time to expire. */
    mssleep(2);
    
    /* Now re-add the timer */
    start = now();
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Wait for the event */
    kev.flags |= EV_CLEAR;
    kev.fflags &= ~NOTE_USECONDS;
    kev.data = 1;
    kevent_cmp(&kev, kevent_get(kqfd));
    elapsed = now() - start;
    
    /* Check that the timer expired after at least 1 ms.  This check
     * is to make sure that the timer re-started and that the event is
     * not from the original add (and expiration) of the timer.
     */
    printf("timer expired after %ld us\n", elapsed);
    if (elapsed < MS_TO_US(1))
        errx(1, "early timer expiration: %ld us", elapsed);

    /* Make sure the re-added timer does not fire. In other words,
     * test that the event received above was the only event from the
     * add and re-add of the timer.
     */
    mssleep(2);
    test_no_kevents();

    success();
}

static void
test_update_periodic(void)
{
    const char *test_id = "kevent(EVFILT_TIMER (UPDATE), periodic)";
    struct kevent kev;
    long elapsed;
    uint64_t start, stop;

    test_begin(test_id);

    test_no_kevents();

    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD, 0, SEC_TO_MS(1), NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Retrieve the event */
    kev.flags = EV_ADD | EV_CLEAR;
    kev.data = 1; 
    kevent_cmp(&kev, kevent_get(kqfd));

    /* Check if the event occurs again */
    sleep(1);
    kevent_cmp(&kev, kevent_get(kqfd));

    /* Re-add with new timeout. */
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD, 0, SEC_TO_MS(2), NULL);
    start = now();
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Retrieve the event */
    kev.flags = EV_ADD | EV_CLEAR;
    kev.data = 1; 
    kevent_cmp(&kev, kevent_get(kqfd));

    stop = now();
    elapsed = stop - start;

    /* Check that the timer expired after at least 2 ms.
     */
    printf("timer expired after %ld us\n", elapsed);
    if (elapsed < MS_TO_US(2))
        errx(1, "early timer expiration: %ld us", elapsed);

    /* Delete the event */
    kev.flags = EV_DELETE;
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    success();
}

static void
test_update_timing(void)
{
#define	MIN_SLEEP 500
#define	MAX_SLEEP 1500
    const char *test_id = "kevent(EVFILT_TIMER (UPDATE TIMING), EV_ADD | EV_ONESHOT)";
    struct kevent kev;
    int iteration;
    int sleeptime;
    long elapsed;
    uint64_t start, stop;

    test_begin(test_id);

    test_no_kevents();

    /* Re-try the update tests with a variety of delays between the
     * original timer activation and the update of the timer. The goal
     * is to show that in all cases the only timer event that is
     * received is from the update and not the original timer add.
     */
    for (sleeptime = MIN_SLEEP, iteration = 1;
         sleeptime < MAX_SLEEP;
         ++sleeptime, ++iteration) {

        /* First set the timer to 1 ms */
        EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT,
            NOTE_USECONDS, MS_TO_US(1), NULL);
        if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
            err(1, "%s", test_id);

        /* Delay; the delay ranges from less than to greater than the
         * timer period.
         */
        ussleep(sleeptime);
    
        /* Now re-add the timer with the same parameters */
        start = now();
        if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
            err(1, "%s", test_id);

        /* Wait for the event */
        kev.flags |= EV_CLEAR;
        kev.fflags &= ~NOTE_USECONDS;
        kev.data = 1;
        kevent_cmp(&kev, kevent_get(kqfd));
        stop = now();
        elapsed = stop - start;

        /* Check that the timer expired after at least 1 ms. This
         * check is to make sure that the timer re-started and that
         * the event is not from the original add of the timer.
         */
        if (elapsed < MS_TO_US(1))
            errx(1, "early timer expiration: %ld us", elapsed);

        /* Make sure the re-added timer does not fire. In other words,
         * test that the event received above was the only event from
         * the add and re-add of the timer.
         */
        mssleep(2);
        test_no_kevents_quietly();
    }

    success();
}

static void
test_dispatch(void)
{
    const char *test_id = "kevent(EVFILT_TIMER, EV_ADD | EV_DISPATCH)";
    struct kevent kev;

    test_no_kevents();

    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_DISPATCH, 0, 200, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);

    /* Get one event */
    kev.flags = EV_ADD | EV_CLEAR | EV_DISPATCH;
    kev.data = 1;
    kevent_cmp(&kev, kevent_get(kqfd));

    /* Confirm that the knote is disabled due to EV_DISPATCH */
    usleep(500000);
    test_no_kevents();

    /* Enable the knote and make sure no events are pending */
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ENABLE | EV_DISPATCH, 0, 200, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);
    test_no_kevents();

    /* Get the next event */
    usleep(1100000); /* 1100 ms */
    kev.flags = EV_ADD | EV_CLEAR | EV_DISPATCH;
    kev.data = 5;
    kevent_cmp(&kev, kevent_get(kqfd));

    /* Remove the knote and ensure the event no longer fires */
    EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_DELETE, 0, 0, NULL);
    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
        err(1, "%s", test_id);
    usleep(500000); /* 500ms */
    test_no_kevents();

    success();
}

void
test_evfilt_timer(void)
{
    kqfd = kqueue();
    test_kevent_timer_add();
    test_kevent_timer_del();
    test_kevent_timer_get();
    test_oneshot();
    test_periodic();
    test_periodic_modify();
#if WITH_NATIVE_KQUEUE_BUGS
    test_periodic_to_oneshot();
#endif
    test_abstime();
    test_abstime_epoch();
    test_abstime_preboot();
    test_abstime_postboot();
    test_update();
    test_update_equal();
    test_update_expired();
    test_update_timing();
    test_update_periodic();
    test_disable_and_enable();
    test_dispatch();
    close(kqfd);
}