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
|
/* Copyright (C) 2015-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
/* This tests that with a reader-preferring rwlock, all readers are woken if
one reader "steals" lock ownership from a blocked writer. */
#include <errno.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <semaphore.h>
#include <unistd.h>
/* If we strictly prefer writers over readers, a program must not expect
that, in the presence of concurrent writers, one reader will also acquire
the lock when another reader has already done so. Thus, use the
default rwlock type that does not strictly prefer writers. */
static pthread_rwlock_t r = PTHREAD_RWLOCK_INITIALIZER;
static pthread_mutex_t m = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t cv = PTHREAD_COND_INITIALIZER;
/* Avoid using glibc-internal atomic operations. */
static sem_t stop;
static int consumer_stop = 0;
static void *
writer (void *arg)
{
int s;
do
{
if (pthread_rwlock_wrlock (&r) != 0)
{
puts ("wrlock failed");
exit (EXIT_FAILURE);
}
if (pthread_rwlock_unlock (&r) != 0)
{
puts ("unlock failed");
exit (EXIT_FAILURE);
}
sem_getvalue (&stop, &s);
}
while (s == 0);
return NULL;
}
static void *
reader_producer (void *arg)
{
int s;
do
{
if (pthread_rwlock_rdlock (&r) != 0)
{
puts ("rdlock reader failed");
exit (EXIT_FAILURE);
}
sem_getvalue (&stop, &s);
pthread_mutex_lock (&m);
if (s != 0)
consumer_stop = 1;
pthread_cond_signal (&cv);
pthread_mutex_unlock (&m);
if (pthread_rwlock_unlock (&r) != 0)
{
puts ("unlock reader failed");
exit (EXIT_FAILURE);
}
}
while (s == 0);
puts ("producer finished");
return NULL;
}
static void *
reader_consumer (void *arg)
{
int s;
do
{
if (pthread_rwlock_rdlock (&r) != 0)
{
puts ("rdlock reader failed");
exit (EXIT_FAILURE);
}
pthread_mutex_lock (&m);
s = consumer_stop;
if (s == 0)
pthread_cond_wait (&cv, &m);
pthread_mutex_unlock (&m);
if (pthread_rwlock_unlock (&r) != 0)
{
puts ("unlock reader failed");
exit (EXIT_FAILURE);
}
}
while (s == 0);
puts ("consumer finished");
return NULL;
}
static int
do_test (void)
{
pthread_t w1, w2, rp, rc;
if (pthread_create (&w1, NULL, writer, NULL) != 0)
{
puts ("create failed");
return 1;
}
if (pthread_create (&w2, NULL, writer, NULL) != 0)
{
puts ("create failed");
return 1;
}
if (pthread_create (&rc, NULL, reader_consumer, NULL) != 0)
{
puts ("create failed");
return 1;
}
if (pthread_create (&rp, NULL, reader_producer, NULL) != 0)
{
puts ("create failed");
return 1;
}
sleep (2);
sem_post (&stop);
if (pthread_join (w1, NULL) != 0)
{
puts ("w1 join failed");
return 1;
}
if (pthread_join (w2, NULL) != 0)
{
puts ("w2 join failed");
return 1;
}
if (pthread_join (rp, NULL) != 0)
{
puts ("reader_producer join failed");
return 1;
}
if (pthread_join (rc, NULL) != 0)
{
puts ("reader_consumer join failed");
return 1;
}
return 0;
}
#define TIMEOUT 3
#define TEST_FUNCTION do_test ()
#include "../test-skeleton.c"
|
GitWeb