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160 lines
3.6 KiB
C
160 lines
3.6 KiB
C
/* Test rwlocks.
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Copyright (C) 2000-2020 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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<https://www.gnu.org/licenses/>. */
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#define _GNU_SOURCE
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#include <pthread.h>
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#include <assert.h>
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#include <error.h>
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#include <errno.h>
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#define THREADS 1
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int a;
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int b;
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/* Get a read lock and assert that a == b. */
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void *
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test1 (void *arg)
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{
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error_t err;
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pthread_rwlock_t *lock = arg;
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int i;
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for (i = 0; i < 200; i++)
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{
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err = pthread_rwlock_rdlock (lock);
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assert (err == 0);
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assert (a == b);
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sched_yield ();
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assert (a == b);
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err = pthread_rwlock_unlock (lock);
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assert (err == 0);
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}
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return 0;
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}
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int
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main (int argc, char **argv)
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{
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error_t err;
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pthread_rwlockattr_t attr;
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pthread_rwlock_t lock;
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int pshared;
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int i;
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pthread_t tid[THREADS];
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void *ret;
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err = pthread_rwlockattr_init (&attr);
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if (err)
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error (1, err, "pthread_rwlockattr_init");
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err = pthread_rwlockattr_getpshared (&attr, &pshared);
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if (err)
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error (1, err, "pthread_rwlockattr_getpshared");
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/* Assert the default state as mandated by POSIX. */
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assert (pshared == PTHREAD_PROCESS_PRIVATE);
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err = pthread_rwlockattr_setpshared (&attr, pshared);
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if (err)
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error (1, err, "pthread_rwlockattr_setpshared");
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err = pthread_rwlock_init (&lock, &attr);
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if (err)
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error (1, err, "pthread_rwlock_init");
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err = pthread_rwlockattr_destroy (&attr);
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if (err)
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error (1, err, "pthread_rwlockattr_destroy");
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/* Now test the lock. */
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for (i = 0; i < THREADS; i++)
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{
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err = pthread_create (&tid[i], 0, test1, &lock);
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if (err)
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error (1, err, "pthread_create");
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}
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for (i = 0; i < 10; i++)
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{
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sched_yield ();
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/* Get a write lock. */
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pthread_rwlock_wrlock (&lock);
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/* Increment a and b giving other threads a chance to run in
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between. */
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sched_yield ();
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a++;
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sched_yield ();
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b++;
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sched_yield ();
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/* Unlock. */
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pthread_rwlock_unlock (&lock);
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}
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for (i = 0; i < THREADS; i++)
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{
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err = pthread_join (tid[i], &ret);
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if (err)
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error (1, err, "pthread_join");
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}
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/* Read lock it. */
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err = pthread_rwlock_tryrdlock (&lock);
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assert (err == 0);
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/* Try to write lock it. It should fail with EBUSY. */
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err = pthread_rwlock_trywrlock (&lock);
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assert (err == EBUSY);
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/* Drop the read lock. */
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err = pthread_rwlock_unlock (&lock);
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assert (err == 0);
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/* Get a write lock. */
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err = pthread_rwlock_trywrlock (&lock);
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assert (err == 0);
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/* Fail trying to acquire another write lock. */
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err = pthread_rwlock_trywrlock (&lock);
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assert (err == EBUSY);
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/* Try to get a read lock which should also fail. */
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err = pthread_rwlock_tryrdlock (&lock);
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assert (err == EBUSY);
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/* Unlock it. */
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err = pthread_rwlock_unlock (&lock);
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assert (err == 0);
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err = pthread_rwlock_destroy (&lock);
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if (err)
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error (1, err, "pthread_rwlock_destroy");
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return 0;
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}
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