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
|
// Copyright 2009 The Go Authors. All rights reserved.
// Copyright 2019 The gVisor Authors.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// GOMAXPROCS=10 go test
// Copy/pasted from the standard library's sync/rwmutex_test.go, except for the
// addition of downgradingWriter and the renaming of num_iterations to
// numIterations to shut up Golint.
package sync
import (
"fmt"
"runtime"
"sync/atomic"
"testing"
)
func parallelReader(m *RWMutex, clocked, cunlock, cdone chan bool) {
m.RLock()
clocked <- true
<-cunlock
m.RUnlock()
cdone <- true
}
func doTestParallelReaders(numReaders, gomaxprocs int) {
runtime.GOMAXPROCS(gomaxprocs)
var m RWMutex
clocked := make(chan bool)
cunlock := make(chan bool)
cdone := make(chan bool)
for i := 0; i < numReaders; i++ {
go parallelReader(&m, clocked, cunlock, cdone)
}
// Wait for all parallel RLock()s to succeed.
for i := 0; i < numReaders; i++ {
<-clocked
}
for i := 0; i < numReaders; i++ {
cunlock <- true
}
// Wait for the goroutines to finish.
for i := 0; i < numReaders; i++ {
<-cdone
}
}
func TestParallelReaders(t *testing.T) {
defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(-1))
doTestParallelReaders(1, 4)
doTestParallelReaders(3, 4)
doTestParallelReaders(4, 2)
}
func reader(rwm *RWMutex, numIterations int, activity *int32, cdone chan bool) {
for i := 0; i < numIterations; i++ {
rwm.RLock()
n := atomic.AddInt32(activity, 1)
if n < 1 || n >= 10000 {
panic(fmt.Sprintf("wlock(%d)\n", n))
}
for i := 0; i < 100; i++ {
}
atomic.AddInt32(activity, -1)
rwm.RUnlock()
}
cdone <- true
}
func writer(rwm *RWMutex, numIterations int, activity *int32, cdone chan bool) {
for i := 0; i < numIterations; i++ {
rwm.Lock()
n := atomic.AddInt32(activity, 10000)
if n != 10000 {
panic(fmt.Sprintf("wlock(%d)\n", n))
}
for i := 0; i < 100; i++ {
}
atomic.AddInt32(activity, -10000)
rwm.Unlock()
}
cdone <- true
}
func downgradingWriter(rwm *RWMutex, numIterations int, activity *int32, cdone chan bool) {
for i := 0; i < numIterations; i++ {
rwm.Lock()
n := atomic.AddInt32(activity, 10000)
if n != 10000 {
panic(fmt.Sprintf("wlock(%d)\n", n))
}
for i := 0; i < 100; i++ {
}
atomic.AddInt32(activity, -10000)
rwm.DowngradeLock()
n = atomic.AddInt32(activity, 1)
if n < 1 || n >= 10000 {
panic(fmt.Sprintf("wlock(%d)\n", n))
}
for i := 0; i < 100; i++ {
}
atomic.AddInt32(activity, -1)
rwm.RUnlock()
}
cdone <- true
}
func HammerDowngradableRWMutex(gomaxprocs, numReaders, numIterations int) {
runtime.GOMAXPROCS(gomaxprocs)
// Number of active readers + 10000 * number of active writers.
var activity int32
var rwm RWMutex
cdone := make(chan bool)
go writer(&rwm, numIterations, &activity, cdone)
go downgradingWriter(&rwm, numIterations, &activity, cdone)
var i int
for i = 0; i < numReaders/2; i++ {
go reader(&rwm, numIterations, &activity, cdone)
}
go writer(&rwm, numIterations, &activity, cdone)
go downgradingWriter(&rwm, numIterations, &activity, cdone)
for ; i < numReaders; i++ {
go reader(&rwm, numIterations, &activity, cdone)
}
// Wait for the 4 writers and all readers to finish.
for i := 0; i < 4+numReaders; i++ {
<-cdone
}
}
func TestDowngradableRWMutex(t *testing.T) {
defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(-1))
n := 1000
if testing.Short() {
n = 5
}
HammerDowngradableRWMutex(1, 1, n)
HammerDowngradableRWMutex(1, 3, n)
HammerDowngradableRWMutex(1, 10, n)
HammerDowngradableRWMutex(4, 1, n)
HammerDowngradableRWMutex(4, 3, n)
HammerDowngradableRWMutex(4, 10, n)
HammerDowngradableRWMutex(10, 1, n)
HammerDowngradableRWMutex(10, 3, n)
HammerDowngradableRWMutex(10, 10, n)
HammerDowngradableRWMutex(10, 5, n)
}
func TestRWDoubleTryLock(t *testing.T) {
var rwm RWMutex
if !rwm.TryLock() {
t.Fatal("failed to aquire lock")
}
if rwm.TryLock() {
t.Fatal("unexpectedly succeeded in aquiring locked mutex")
}
}
func TestRWTryLockAfterLock(t *testing.T) {
var rwm RWMutex
rwm.Lock()
if rwm.TryLock() {
t.Fatal("unexpectedly succeeded in aquiring locked mutex")
}
}
func TestRWTryLockUnlock(t *testing.T) {
var rwm RWMutex
if !rwm.TryLock() {
t.Fatal("failed to aquire lock")
}
rwm.Unlock()
if !rwm.TryLock() {
t.Fatal("failed to aquire lock after unlock")
}
}
func TestTryRLockAfterLock(t *testing.T) {
var rwm RWMutex
rwm.Lock()
if rwm.TryRLock() {
t.Fatal("unexpectedly succeeded in aquiring locked mutex")
}
}
func TestTryLockAfterRLock(t *testing.T) {
var rwm RWMutex
rwm.RLock()
if rwm.TryLock() {
t.Fatal("unexpectedly succeeded in aquiring locked mutex")
}
}
func TestDoubleTryRLock(t *testing.T) {
var rwm RWMutex
if !rwm.TryRLock() {
t.Fatal("failed to aquire lock")
}
if !rwm.TryRLock() {
t.Fatal("failed to read aquire read locked lock")
}
}
|
