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04277e02d7
* All files with FSF copyright notices: Update copyright dates using scripts/update-copyrights. * locale/programs/charmap-kw.h: Regenerated. * locale/programs/locfile-kw.h: Likewise.
183 lines
3.9 KiB
C
183 lines
3.9 KiB
C
/* Copyright (C) 2015-2019 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* This tests that with a reader-preferring rwlock, all readers are woken if
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one reader "steals" lock ownership from a blocked writer. */
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#include <errno.h>
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <semaphore.h>
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#include <unistd.h>
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/* If we strictly prefer writers over readers, a program must not expect
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that, in the presence of concurrent writers, one reader will also acquire
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the lock when another reader has already done so. Thus, use the
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default rwlock type that does not strictly prefer writers. */
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static pthread_rwlock_t r = PTHREAD_RWLOCK_INITIALIZER;
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static pthread_mutex_t m = PTHREAD_MUTEX_INITIALIZER;
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static pthread_cond_t cv = PTHREAD_COND_INITIALIZER;
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/* Avoid using glibc-internal atomic operations. */
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static sem_t stop;
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static int consumer_stop = 0;
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static void *
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writer (void *arg)
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{
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int s;
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do
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{
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if (pthread_rwlock_wrlock (&r) != 0)
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{
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puts ("wrlock failed");
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exit (EXIT_FAILURE);
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}
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if (pthread_rwlock_unlock (&r) != 0)
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{
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puts ("unlock failed");
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exit (EXIT_FAILURE);
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}
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sem_getvalue (&stop, &s);
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}
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while (s == 0);
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return NULL;
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}
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static void *
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reader_producer (void *arg)
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{
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int s;
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do
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{
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if (pthread_rwlock_rdlock (&r) != 0)
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{
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puts ("rdlock reader failed");
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exit (EXIT_FAILURE);
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}
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sem_getvalue (&stop, &s);
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pthread_mutex_lock (&m);
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if (s != 0)
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consumer_stop = 1;
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pthread_cond_signal (&cv);
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pthread_mutex_unlock (&m);
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if (pthread_rwlock_unlock (&r) != 0)
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{
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puts ("unlock reader failed");
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exit (EXIT_FAILURE);
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}
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}
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while (s == 0);
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puts ("producer finished");
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return NULL;
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}
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static void *
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reader_consumer (void *arg)
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{
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int s;
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do
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{
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if (pthread_rwlock_rdlock (&r) != 0)
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{
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puts ("rdlock reader failed");
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exit (EXIT_FAILURE);
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}
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pthread_mutex_lock (&m);
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s = consumer_stop;
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if (s == 0)
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pthread_cond_wait (&cv, &m);
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pthread_mutex_unlock (&m);
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if (pthread_rwlock_unlock (&r) != 0)
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{
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puts ("unlock reader failed");
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exit (EXIT_FAILURE);
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}
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}
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while (s == 0);
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puts ("consumer finished");
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return NULL;
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}
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static int
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do_test (void)
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{
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pthread_t w1, w2, rp, rc;
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if (pthread_create (&w1, NULL, writer, NULL) != 0)
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{
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puts ("create failed");
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return 1;
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}
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if (pthread_create (&w2, NULL, writer, NULL) != 0)
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{
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puts ("create failed");
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return 1;
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}
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if (pthread_create (&rc, NULL, reader_consumer, NULL) != 0)
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{
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puts ("create failed");
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return 1;
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}
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if (pthread_create (&rp, NULL, reader_producer, NULL) != 0)
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{
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puts ("create failed");
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return 1;
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}
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sleep (2);
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sem_post (&stop);
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if (pthread_join (w1, NULL) != 0)
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{
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puts ("w1 join failed");
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return 1;
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}
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if (pthread_join (w2, NULL) != 0)
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{
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puts ("w2 join failed");
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return 1;
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}
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if (pthread_join (rp, NULL) != 0)
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{
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puts ("reader_producer join failed");
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return 1;
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}
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if (pthread_join (rc, NULL) != 0)
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{
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puts ("reader_consumer join failed");
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return 1;
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}
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return 0;
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}
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#define TEST_FUNCTION do_test ()
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#include "../test-skeleton.c"
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