summaryrefslogtreecommitdiff
path: root/src/pkg/sync/atomic/atomic_test.go
blob: 2229e58d0c72566c85942804a0a4b0a74d4fe064 (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
// Copyright 2011 The Go Authors.  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package atomic_test

import (
	"runtime"
	. "sync/atomic"
	"testing"
	"unsafe"
)

// Tests of correct behavior, without contention.
// (Does the function work as advertised?)
//
// Test that the Add functions add correctly.
// Test that the CompareAndSwap functions actually
// do the comparison and the swap correctly.
//
// The loop over power-of-two values is meant to
// ensure that the operations apply to the full word size.
// The struct fields x.before and x.after check that the
// operations do not extend past the full word size.

const (
	magic32 = 0xdedbeef
	magic64 = 0xdeddeadbeefbeef
)

// Do the 64-bit functions panic?  If so, don't bother testing.
var test64err = func() (err interface{}) {
	defer func() {
		err = recover()
	}()
	var x int64
	AddInt64(&x, 1)
	return nil
}()

func TestAddInt32(t *testing.T) {
	var x struct {
		before int32
		i      int32
		after  int32
	}
	x.before = magic32
	x.after = magic32
	var j int32
	for delta := int32(1); delta+delta > delta; delta += delta {
		k := AddInt32(&x.i, delta)
		j += delta
		if x.i != j || k != j {
			t.Fatalf("delta=%d i=%d j=%d k=%d", delta, x.i, j, k)
		}
	}
	if x.before != magic32 || x.after != magic32 {
		t.Fatalf("wrong magic: %#x _ %#x != %#x _ %#x", x.before, x.after, magic32, magic32)
	}
}

func TestAddUint32(t *testing.T) {
	var x struct {
		before uint32
		i      uint32
		after  uint32
	}
	x.before = magic32
	x.after = magic32
	var j uint32
	for delta := uint32(1); delta+delta > delta; delta += delta {
		k := AddUint32(&x.i, delta)
		j += delta
		if x.i != j || k != j {
			t.Fatalf("delta=%d i=%d j=%d k=%d", delta, x.i, j, k)
		}
	}
	if x.before != magic32 || x.after != magic32 {
		t.Fatalf("wrong magic: %#x _ %#x != %#x _ %#x", x.before, x.after, magic32, magic32)
	}
}

func TestAddInt64(t *testing.T) {
	if test64err != nil {
		t.Logf("Skipping 64-bit tests: %v", test64err)
		return
	}
	var x struct {
		before int64
		i      int64
		after  int64
	}
	x.before = magic64
	x.after = magic64
	var j int64
	for delta := int64(1); delta+delta > delta; delta += delta {
		k := AddInt64(&x.i, delta)
		j += delta
		if x.i != j || k != j {
			t.Fatalf("delta=%d i=%d j=%d k=%d", delta, x.i, j, k)
		}
	}
	if x.before != magic64 || x.after != magic64 {
		t.Fatalf("wrong magic: %#x _ %#x != %#x _ %#x", x.before, x.after, int64(magic64), int64(magic64))
	}
}

func TestAddUint64(t *testing.T) {
	if test64err != nil {
		t.Logf("Skipping 64-bit tests: %v", test64err)
		return
	}
	var x struct {
		before uint64
		i      uint64
		after  uint64
	}
	x.before = magic64
	x.after = magic64
	var j uint64
	for delta := uint64(1); delta+delta > delta; delta += delta {
		k := AddUint64(&x.i, delta)
		j += delta
		if x.i != j || k != j {
			t.Fatalf("delta=%d i=%d j=%d k=%d", delta, x.i, j, k)
		}
	}
	if x.before != magic64 || x.after != magic64 {
		t.Fatalf("wrong magic: %#x _ %#x != %#x _ %#x", x.before, x.after, uint64(magic64), uint64(magic64))
	}
}

func TestAddUintptr(t *testing.T) {
	var x struct {
		before uintptr
		i      uintptr
		after  uintptr
	}
	var m uint64 = magic64
	magicptr := uintptr(m)
	x.before = magicptr
	x.after = magicptr
	var j uintptr
	for delta := uintptr(1); delta+delta > delta; delta += delta {
		k := AddUintptr(&x.i, delta)
		j += delta
		if x.i != j || k != j {
			t.Fatalf("delta=%d i=%d j=%d k=%d", delta, x.i, j, k)
		}
	}
	if x.before != magicptr || x.after != magicptr {
		t.Fatalf("wrong magic: %#x _ %#x != %#x _ %#x", x.before, x.after, magicptr, magicptr)
	}
}

func TestCompareAndSwapInt32(t *testing.T) {
	var x struct {
		before int32
		i      int32
		after  int32
	}
	x.before = magic32
	x.after = magic32
	for val := int32(1); val+val > val; val += val {
		x.i = val
		if !CompareAndSwapInt32(&x.i, val, val+1) {
			t.Errorf("should have swapped %#x %#x", val, val+1)
		}
		if x.i != val+1 {
			t.Errorf("wrong x.i after swap: x.i=%#x val+1=%#x", x.i, val+1)
		}
		x.i = val + 1
		if CompareAndSwapInt32(&x.i, val, val+2) {
			t.Errorf("should not have swapped %#x %#x", val, val+2)
		}
		if x.i != val+1 {
			t.Errorf("wrong x.i after swap: x.i=%#x val+1=%#x", x.i, val+1)
		}
	}
	if x.before != magic32 || x.after != magic32 {
		t.Fatalf("wrong magic: %#x _ %#x != %#x _ %#x", x.before, x.after, magic32, magic32)
	}
}

func TestCompareAndSwapUint32(t *testing.T) {
	var x struct {
		before uint32
		i      uint32
		after  uint32
	}
	x.before = magic32
	x.after = magic32
	for val := uint32(1); val+val > val; val += val {
		x.i = val
		if !CompareAndSwapUint32(&x.i, val, val+1) {
			t.Errorf("should have swapped %#x %#x", val, val+1)
		}
		if x.i != val+1 {
			t.Errorf("wrong x.i after swap: x.i=%#x val+1=%#x", x.i, val+1)
		}
		x.i = val + 1
		if CompareAndSwapUint32(&x.i, val, val+2) {
			t.Errorf("should not have swapped %#x %#x", val, val+2)
		}
		if x.i != val+1 {
			t.Errorf("wrong x.i after swap: x.i=%#x val+1=%#x", x.i, val+1)
		}
	}
	if x.before != magic32 || x.after != magic32 {
		t.Fatalf("wrong magic: %#x _ %#x != %#x _ %#x", x.before, x.after, magic32, magic32)
	}
}

func TestCompareAndSwapInt64(t *testing.T) {
	if test64err != nil {
		t.Logf("Skipping 64-bit tests: %v", test64err)
		return
	}
	var x struct {
		before int64
		i      int64
		after  int64
	}
	x.before = magic64
	x.after = magic64
	for val := int64(1); val+val > val; val += val {
		x.i = val
		if !CompareAndSwapInt64(&x.i, val, val+1) {
			t.Errorf("should have swapped %#x %#x", val, val+1)
		}
		if x.i != val+1 {
			t.Errorf("wrong x.i after swap: x.i=%#x val+1=%#x", x.i, val+1)
		}
		x.i = val + 1
		if CompareAndSwapInt64(&x.i, val, val+2) {
			t.Errorf("should not have swapped %#x %#x", val, val+2)
		}
		if x.i != val+1 {
			t.Errorf("wrong x.i after swap: x.i=%#x val+1=%#x", x.i, val+1)
		}
	}
	if x.before != magic64 || x.after != magic64 {
		t.Fatalf("wrong magic: %#x _ %#x != %#x _ %#x", x.before, x.after, uint64(magic64), uint64(magic64))
	}
}

func TestCompareAndSwapUint64(t *testing.T) {
	if test64err != nil {
		t.Logf("Skipping 64-bit tests: %v", test64err)
		return
	}
	var x struct {
		before uint64
		i      uint64
		after  uint64
	}
	x.before = magic64
	x.after = magic64
	for val := uint64(1); val+val > val; val += val {
		x.i = val
		if !CompareAndSwapUint64(&x.i, val, val+1) {
			t.Errorf("should have swapped %#x %#x", val, val+1)
		}
		if x.i != val+1 {
			t.Errorf("wrong x.i after swap: x.i=%#x val+1=%#x", x.i, val+1)
		}
		x.i = val + 1
		if CompareAndSwapUint64(&x.i, val, val+2) {
			t.Errorf("should not have swapped %#x %#x", val, val+2)
		}
		if x.i != val+1 {
			t.Errorf("wrong x.i after swap: x.i=%#x val+1=%#x", x.i, val+1)
		}
	}
	if x.before != magic64 || x.after != magic64 {
		t.Fatalf("wrong magic: %#x _ %#x != %#x _ %#x", x.before, x.after, uint64(magic64), uint64(magic64))
	}
}

func TestCompareAndSwapUintptr(t *testing.T) {
	var x struct {
		before uintptr
		i      uintptr
		after  uintptr
	}
	var m uint64 = magic64
	magicptr := uintptr(m)
	x.before = magicptr
	x.after = magicptr
	for val := uintptr(1); val+val > val; val += val {
		x.i = val
		if !CompareAndSwapUintptr(&x.i, val, val+1) {
			t.Errorf("should have swapped %#x %#x", val, val+1)
		}
		if x.i != val+1 {
			t.Errorf("wrong x.i after swap: x.i=%#x val+1=%#x", x.i, val+1)
		}
		x.i = val + 1
		if CompareAndSwapUintptr(&x.i, val, val+2) {
			t.Errorf("should not have swapped %#x %#x", val, val+2)
		}
		if x.i != val+1 {
			t.Errorf("wrong x.i after swap: x.i=%#x val+1=%#x", x.i, val+1)
		}
	}
	if x.before != magicptr || x.after != magicptr {
		t.Fatalf("wrong magic: %#x _ %#x != %#x _ %#x", x.before, x.after, magicptr, magicptr)
	}
}

func TestLoadInt32(t *testing.T) {
	var x struct {
		before int32
		i      int32
		after  int32
	}
	x.before = magic32
	x.after = magic32
	for delta := int32(1); delta+delta > delta; delta += delta {
		k := LoadInt32(&x.i)
		if k != x.i {
			t.Fatalf("delta=%d i=%d k=%d", delta, x.i, k)
		}
		x.i += delta
	}
	if x.before != magic32 || x.after != magic32 {
		t.Fatalf("wrong magic: %#x _ %#x != %#x _ %#x", x.before, x.after, magic32, magic32)
	}
}

func TestLoadUint32(t *testing.T) {
	var x struct {
		before uint32
		i      uint32
		after  uint32
	}
	x.before = magic32
	x.after = magic32
	for delta := uint32(1); delta+delta > delta; delta += delta {
		k := LoadUint32(&x.i)
		if k != x.i {
			t.Fatalf("delta=%d i=%d k=%d", delta, x.i, k)
		}
		x.i += delta
	}
	if x.before != magic32 || x.after != magic32 {
		t.Fatalf("wrong magic: %#x _ %#x != %#x _ %#x", x.before, x.after, magic32, magic32)
	}
}

// Tests of correct behavior, with contention.
// (Is the function atomic?)
//
// For each function, we write a "hammer" function that repeatedly
// uses the atomic operation to add 1 to a value.  After running
// multiple hammers in parallel, check that we end with the correct
// total.

var hammer32 = []struct {
	name string
	f    func(*uint32, int)
}{
	{"AddInt32", hammerAddInt32},
	{"AddUint32", hammerAddUint32},
	{"AddUintptr", hammerAddUintptr32},
	{"CompareAndSwapInt32", hammerCompareAndSwapInt32},
	{"CompareAndSwapUint32", hammerCompareAndSwapUint32},
	{"CompareAndSwapUintptr", hammerCompareAndSwapUintptr32},
}

func init() {
	var v uint64 = 1 << 50
	if uintptr(v) != 0 {
		// 64-bit system; clear uintptr tests
		hammer32[2].f = nil
		hammer32[5].f = nil
	}
}

func hammerAddInt32(uval *uint32, count int) {
	val := (*int32)(unsafe.Pointer(uval))
	for i := 0; i < count; i++ {
		AddInt32(val, 1)
	}
}

func hammerAddUint32(val *uint32, count int) {
	for i := 0; i < count; i++ {
		AddUint32(val, 1)
	}
}

func hammerAddUintptr32(uval *uint32, count int) {
	// only safe when uintptr is 32-bit.
	// not called on 64-bit systems.
	val := (*uintptr)(unsafe.Pointer(uval))
	for i := 0; i < count; i++ {
		AddUintptr(val, 1)
	}
}

func hammerCompareAndSwapInt32(uval *uint32, count int) {
	val := (*int32)(unsafe.Pointer(uval))
	for i := 0; i < count; i++ {
		for {
			v := *val
			if CompareAndSwapInt32(val, v, v+1) {
				break
			}
		}
	}
}

func hammerCompareAndSwapUint32(val *uint32, count int) {
	for i := 0; i < count; i++ {
		for {
			v := *val
			if CompareAndSwapUint32(val, v, v+1) {
				break
			}
		}
	}
}

func hammerCompareAndSwapUintptr32(uval *uint32, count int) {
	// only safe when uintptr is 32-bit.
	// not called on 64-bit systems.
	val := (*uintptr)(unsafe.Pointer(uval))
	for i := 0; i < count; i++ {
		for {
			v := *val
			if CompareAndSwapUintptr(val, v, v+1) {
				break
			}
		}
	}
}

func TestHammer32(t *testing.T) {
	const p = 4
	n := 100000
	if testing.Short() {
		n = 1000
	}
	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(p))

	for _, tt := range hammer32 {
		if tt.f == nil {
			continue
		}
		c := make(chan int)
		var val uint32
		for i := 0; i < p; i++ {
			go func() {
				tt.f(&val, n)
				c <- 1
			}()
		}
		for i := 0; i < p; i++ {
			<-c
		}
		if val != uint32(n)*p {
			t.Errorf("%s: val=%d want %d", tt.name, val, n*p)
		}
	}
}

var hammer64 = []struct {
	name string
	f    func(*uint64, int)
}{
	{"AddInt64", hammerAddInt64},
	{"AddUint64", hammerAddUint64},
	{"AddUintptr", hammerAddUintptr64},
	{"CompareAndSwapInt64", hammerCompareAndSwapInt64},
	{"CompareAndSwapUint64", hammerCompareAndSwapUint64},
	{"CompareAndSwapUintptr", hammerCompareAndSwapUintptr64},
}

func init() {
	var v uint64 = 1 << 50
	if uintptr(v) == 0 {
		// 32-bit system; clear uintptr tests
		hammer64[2].f = nil
		hammer64[5].f = nil
	}
}

func hammerAddInt64(uval *uint64, count int) {
	val := (*int64)(unsafe.Pointer(uval))
	for i := 0; i < count; i++ {
		AddInt64(val, 1)
	}
}

func hammerAddUint64(val *uint64, count int) {
	for i := 0; i < count; i++ {
		AddUint64(val, 1)
	}
}

func hammerAddUintptr64(uval *uint64, count int) {
	// only safe when uintptr is 64-bit.
	// not called on 32-bit systems.
	val := (*uintptr)(unsafe.Pointer(uval))
	for i := 0; i < count; i++ {
		AddUintptr(val, 1)
	}
}

func hammerCompareAndSwapInt64(uval *uint64, count int) {
	val := (*int64)(unsafe.Pointer(uval))
	for i := 0; i < count; i++ {
		for {
			v := *val
			if CompareAndSwapInt64(val, v, v+1) {
				break
			}
		}
	}
}

func hammerCompareAndSwapUint64(val *uint64, count int) {
	for i := 0; i < count; i++ {
		for {
			v := *val
			if CompareAndSwapUint64(val, v, v+1) {
				break
			}
		}
	}
}

func hammerCompareAndSwapUintptr64(uval *uint64, count int) {
	// only safe when uintptr is 64-bit.
	// not called on 32-bit systems.
	val := (*uintptr)(unsafe.Pointer(uval))
	for i := 0; i < count; i++ {
		for {
			v := *val
			if CompareAndSwapUintptr(val, v, v+1) {
				break
			}
		}
	}
}

func TestHammer64(t *testing.T) {
	if test64err != nil {
		t.Logf("Skipping 64-bit tests: %v", test64err)
		return
	}
	const p = 4
	n := 100000
	if testing.Short() {
		n = 1000
	}
	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(p))

	for _, tt := range hammer64 {
		if tt.f == nil {
			continue
		}
		c := make(chan int)
		var val uint64
		for i := 0; i < p; i++ {
			go func() {
				tt.f(&val, n)
				c <- 1
			}()
		}
		for i := 0; i < p; i++ {
			<-c
		}
		if val != uint64(n)*p {
			t.Errorf("%s: val=%d want %d", tt.name, val, n*p)
		}
	}
}

func hammerLoadInt32(t *testing.T, uval *uint32) {
	val := (*int32)(unsafe.Pointer(uval))
	for {
		v := LoadInt32(val)
		vlo := v & ((1 << 16) - 1)
		vhi := v >> 16
		if vlo != vhi {
			t.Fatalf("LoadInt32: %#x != %#x", vlo, vhi)
		}
		new := v + 1 + 1<<16
		if vlo == 1e4 {
			new = 0
		}
		if CompareAndSwapInt32(val, v, new) {
			break
		}
	}
}

func hammerLoadUint32(t *testing.T, val *uint32) {
	for {
		v := LoadUint32(val)
		vlo := v & ((1 << 16) - 1)
		vhi := v >> 16
		if vlo != vhi {
			t.Fatalf("LoadUint32: %#x != %#x", vlo, vhi)
		}
		new := v + 1 + 1<<16
		if vlo == 1e4 {
			new = 0
		}
		if CompareAndSwapUint32(val, v, new) {
			break
		}
	}
}

func TestHammerLoad(t *testing.T) {
	tests := [...]func(*testing.T, *uint32){hammerLoadInt32, hammerLoadUint32}
	n := 100000
	if testing.Short() {
		n = 10000
	}
	const procs = 8
	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(procs))
	for _, tt := range tests {
		c := make(chan int)
		var val uint32
		for p := 0; p < procs; p++ {
			go func() {
				for i := 0; i < n; i++ {
					tt(t, &val)
				}
				c <- 1
			}()
		}
		for p := 0; p < procs; p++ {
			<-c
		}
	}
}