68 lines
2.0 KiB
C
68 lines
2.0 KiB
C
/*
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* Copyright (c) 2014, 2021 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* pthread/pthread_cond_timedwait.c
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* Waits on a condition or until a timeout happens.
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*/
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#include <sys/futex.h>
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#include <errno.h>
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#include <pthread.h>
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int pthread_cond_timedwait(pthread_cond_t* restrict cond,
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pthread_mutex_t* restrict mutex,
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const struct timespec* restrict abstime)
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{
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struct pthread_cond_elem elem;
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pthread_mutex_lock(&cond->lock);
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elem.next = NULL;
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elem.prev = cond->last;
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elem.woken = 0;
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if ( cond->last )
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cond->last->next = &elem;
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if ( !cond->first )
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cond->first = &elem;
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cond->last = &elem;
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pthread_mutex_unlock(&cond->lock);
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pthread_mutex_unlock(mutex);
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int op = FUTEX_WAIT | FUTEX_ABSOLUTE | FUTEX_CLOCK(cond->clock);
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int result = 0;
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while ( !__atomic_load_n(&elem.woken, __ATOMIC_SEQ_CST) &&
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futex(&elem.woken, op, 0, abstime) < 0 )
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{
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if ( errno == EINTR )
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continue;
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if ( errno != EAGAIN )
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result = errno;
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break;
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}
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pthread_mutex_lock(mutex);
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pthread_mutex_lock(&cond->lock);
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if ( !__atomic_load_n(&elem.woken, __ATOMIC_SEQ_CST) )
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{
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if ( elem.next )
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elem.next->prev = elem.prev;
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else
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cond->last = elem.prev;
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if ( elem.prev )
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elem.prev->next = elem.next;
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else
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cond->first = elem.next;
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}
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pthread_mutex_unlock(&cond->lock);
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return result;
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}
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