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78 lines
2.3 KiB
C
78 lines
2.3 KiB
C
/* Test sem_trywait with threads.
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Copyright (C) 2024-2025 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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#include <errno.h>
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#include <pthread.h>
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#include <semaphore.h>
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#include <support/check.h>
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#include <support/xthread.h>
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/* The test uses two threads, the main thread and a newly created
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thread to test the operation of sem_trywait in a threaded scenario.
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The intent is to test sem_trywait when it would return EAGAIN, and
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then again after the critical section in the new thread has posted
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to the semaphore and the main thread succeeds in calling
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sem_trywait. It is possible this test fails with a timeout if the
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second thread takes longer than the test timeout to acquire the
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lock, and post. */
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static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
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static sem_t sem;
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static void *
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tf (void *arg)
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{
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xpthread_mutex_lock (&lock);
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sem_post (&sem);
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xpthread_mutex_unlock (&lock);
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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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int ret;
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ret = sem_init (&sem, 0, 0);
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TEST_VERIFY_EXIT (ret == 0);
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xpthread_mutex_lock (&lock);
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pthread_t th = xpthread_create (NULL, tf, NULL);
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errno = 0;
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/* The other thread is waiting on the lock before it calls sem_post,
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so sem_trywait should fail. */
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ret = sem_trywait (&sem);
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TEST_COMPARE (ret, -1);
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TEST_COMPARE (errno, EAGAIN);
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xpthread_mutex_unlock (&lock);
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/* The other thread now takes the lock, calls sem_post and releases
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the lock. */
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for (;;)
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{
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errno = 0;
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ret = sem_trywait (&sem);
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if (ret == 0)
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break;
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TEST_COMPARE (errno, EAGAIN);
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}
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xpthread_join (th);
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return 0;
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}
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#include <support/test-driver.c>
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