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
|
/* Test program for timedout read/write lock functions.
Copyright (C) 2000 Free Software Foundation, Inc.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2000.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <errno.h>
#include <error.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#define NWRITERS 15
#define WRITETRIES 10
#define NREADERS 15
#define READTRIES 15
#define TIMEOUT 1000000
#define DELAY 1000000
static pthread_rwlock_t lock = PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP;
static void *
writer_thread (void *nr)
{
struct timespec ts;
struct timespec delay;
int n;
ts.tv_sec = 0;
ts.tv_nsec = TIMEOUT;
delay.tv_sec = 0;
delay.tv_nsec = DELAY;
for (n = 0; n < WRITETRIES; ++n)
{
do
{
clock_gettime (CLOCK_REALTIME, &ts);
ts.tv_nsec += 2 * TIMEOUT;
printf ("writer thread %ld tries again\n", (long int) nr);
}
//while (pthread_rwlock_wrlock (&lock), 0);
while (pthread_rwlock_timedwrlock (&lock, &ts) == ETIMEDOUT);
printf ("writer thread %ld succeeded\n", (long int) nr);
nanosleep (&delay, NULL);
pthread_rwlock_unlock (&lock);
printf ("writer thread %ld released\n", (long int) nr);
}
return NULL;
}
static void *
reader_thread (void *nr)
{
struct timespec ts;
struct timespec delay;
int n;
delay.tv_sec = 0;
delay.tv_nsec = DELAY;
for (n = 0; n < READTRIES; ++n)
{
do
{
clock_gettime (CLOCK_REALTIME, &ts);
ts.tv_nsec += TIMEOUT;
printf ("reader thread %ld tries again\n", (long int) nr);
}
//while (pthread_rwlock_rdlock (&lock), 0);
while (pthread_rwlock_timedrdlock (&lock, &ts) == ETIMEDOUT);
printf ("reader thread %ld succeeded\n", (long int) nr);
nanosleep (&delay, NULL);
pthread_rwlock_unlock (&lock);
printf ("reader thread %ld released\n", (long int) nr);
}
return NULL;
}
int
main (void)
{
pthread_t thwr[NWRITERS];
pthread_t thrd[NREADERS];
int n;
void *res;
/* Make standard error the same as standard output. */
dup2 (1, 2);
/* Make sure we see all message, even those on stdout. */
setvbuf (stdout, NULL, _IONBF, 0);
for (n = 0; n < NWRITERS; ++n)
{
int err = pthread_create (&thwr[n], NULL, writer_thread, (void *) n);
if (err != 0)
error (EXIT_FAILURE, err, "cannot create writer thread");
}
for (n = 0; n < NREADERS; ++n)
{
int err = pthread_create (&thrd[n], NULL, reader_thread, (void *) n);
if (err != 0)
error (EXIT_FAILURE, err, "cannot create reader thread");
}
/* Wait for all the threads. */
for (n = 0; n < NWRITERS; ++n)
pthread_join (thwr[n], &res);
for (n = 0; n < NREADERS; ++n)
pthread_join (thrd[n], &res);
return 0;
}
|
