xf.li | bdd93d5 | 2023-05-12 07:10:14 -0700 | [diff] [blame^] | 1 | /* Copyright (C) 2015-2016 Free Software Foundation, Inc. |
| 2 | This file is part of the GNU C Library. |
| 3 | |
| 4 | The GNU C Library is free software; you can redistribute it and/or |
| 5 | modify it under the terms of the GNU Lesser General Public |
| 6 | License as published by the Free Software Foundation; either |
| 7 | version 2.1 of the License, or (at your option) any later version. |
| 8 | |
| 9 | The GNU C Library is distributed in the hope that it will be useful, |
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | Lesser General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU Lesser General Public |
| 15 | License along with the GNU C Library; if not, see |
| 16 | <http://www.gnu.org/licenses/>. */ |
| 17 | |
| 18 | /* This tests that with a reader-preferring rwlock, all readers are woken if |
| 19 | one reader "steals" lock ownership from a blocked writer. */ |
| 20 | |
| 21 | #include <errno.h> |
| 22 | #include <pthread.h> |
| 23 | #include <stdio.h> |
| 24 | #include <stdlib.h> |
| 25 | #include <semaphore.h> |
| 26 | #include <unistd.h> |
| 27 | |
| 28 | /* If we strictly prefer writers over readers, a program must not expect |
| 29 | that, in the presence of concurrent writers, one reader will also acquire |
| 30 | the lock when another reader has already done so. Thus, use the |
| 31 | default rwlock type that does not strictly prefer writers. */ |
| 32 | static pthread_rwlock_t r = PTHREAD_RWLOCK_INITIALIZER; |
| 33 | |
| 34 | static pthread_mutex_t m = PTHREAD_MUTEX_INITIALIZER; |
| 35 | static pthread_cond_t cv = PTHREAD_COND_INITIALIZER; |
| 36 | |
| 37 | /* Avoid using glibc-internal atomic operations. */ |
| 38 | static sem_t stop; |
| 39 | static int consumer_stop = 0; |
| 40 | |
| 41 | static void * |
| 42 | writer (void *arg) |
| 43 | { |
| 44 | int s; |
| 45 | |
| 46 | do |
| 47 | { |
| 48 | if (pthread_rwlock_wrlock (&r) != 0) |
| 49 | { |
| 50 | puts ("wrlock failed"); |
| 51 | exit (EXIT_FAILURE); |
| 52 | } |
| 53 | if (pthread_rwlock_unlock (&r) != 0) |
| 54 | { |
| 55 | puts ("unlock failed"); |
| 56 | exit (EXIT_FAILURE); |
| 57 | } |
| 58 | sem_getvalue (&stop, &s); |
| 59 | } |
| 60 | while (s == 0); |
| 61 | return NULL; |
| 62 | } |
| 63 | |
| 64 | static void * |
| 65 | reader_producer (void *arg) |
| 66 | { |
| 67 | int s; |
| 68 | |
| 69 | do |
| 70 | { |
| 71 | if (pthread_rwlock_rdlock (&r) != 0) |
| 72 | { |
| 73 | puts ("rdlock reader failed"); |
| 74 | exit (EXIT_FAILURE); |
| 75 | } |
| 76 | |
| 77 | sem_getvalue (&stop, &s); |
| 78 | |
| 79 | pthread_mutex_lock (&m); |
| 80 | if (s != 0) |
| 81 | consumer_stop = 1; |
| 82 | pthread_cond_signal (&cv); |
| 83 | pthread_mutex_unlock (&m); |
| 84 | |
| 85 | if (pthread_rwlock_unlock (&r) != 0) |
| 86 | { |
| 87 | puts ("unlock reader failed"); |
| 88 | exit (EXIT_FAILURE); |
| 89 | } |
| 90 | } |
| 91 | while (s == 0); |
| 92 | puts ("producer finished"); |
| 93 | return NULL; |
| 94 | } |
| 95 | |
| 96 | static void * |
| 97 | reader_consumer (void *arg) |
| 98 | { |
| 99 | int s; |
| 100 | |
| 101 | do |
| 102 | { |
| 103 | if (pthread_rwlock_rdlock (&r) != 0) |
| 104 | { |
| 105 | puts ("rdlock reader failed"); |
| 106 | exit (EXIT_FAILURE); |
| 107 | } |
| 108 | |
| 109 | pthread_mutex_lock (&m); |
| 110 | s = consumer_stop; |
| 111 | if (s == 0) |
| 112 | pthread_cond_wait (&cv, &m); |
| 113 | pthread_mutex_unlock (&m); |
| 114 | |
| 115 | if (pthread_rwlock_unlock (&r) != 0) |
| 116 | { |
| 117 | puts ("unlock reader failed"); |
| 118 | exit (EXIT_FAILURE); |
| 119 | } |
| 120 | } |
| 121 | while (s == 0); |
| 122 | puts ("consumer finished"); |
| 123 | return NULL; |
| 124 | } |
| 125 | |
| 126 | |
| 127 | static int |
| 128 | do_test (void) |
| 129 | { |
| 130 | pthread_t w1, w2, rp, rc; |
| 131 | |
| 132 | if (pthread_create (&w1, NULL, writer, NULL) != 0) |
| 133 | { |
| 134 | puts ("create failed"); |
| 135 | return 1; |
| 136 | } |
| 137 | if (pthread_create (&w2, NULL, writer, NULL) != 0) |
| 138 | { |
| 139 | puts ("create failed"); |
| 140 | return 1; |
| 141 | } |
| 142 | if (pthread_create (&rc, NULL, reader_consumer, NULL) != 0) |
| 143 | { |
| 144 | puts ("create failed"); |
| 145 | return 1; |
| 146 | } |
| 147 | if (pthread_create (&rp, NULL, reader_producer, NULL) != 0) |
| 148 | { |
| 149 | puts ("create failed"); |
| 150 | return 1; |
| 151 | } |
| 152 | |
| 153 | sleep (2); |
| 154 | sem_post (&stop); |
| 155 | |
| 156 | if (pthread_join (w1, NULL) != 0) |
| 157 | { |
| 158 | puts ("w1 join failed"); |
| 159 | return 1; |
| 160 | } |
| 161 | if (pthread_join (w2, NULL) != 0) |
| 162 | { |
| 163 | puts ("w2 join failed"); |
| 164 | return 1; |
| 165 | } |
| 166 | if (pthread_join (rp, NULL) != 0) |
| 167 | { |
| 168 | puts ("reader_producer join failed"); |
| 169 | return 1; |
| 170 | } |
| 171 | if (pthread_join (rc, NULL) != 0) |
| 172 | { |
| 173 | puts ("reader_consumer join failed"); |
| 174 | return 1; |
| 175 | } |
| 176 | |
| 177 | return 0; |
| 178 | } |
| 179 | |
| 180 | |
| 181 | #define TIMEOUT 3 |
| 182 | #define TEST_FUNCTION do_test () |
| 183 | #include "../test-skeleton.c" |