mirror of https://github.com/dzavalishin/oskit/
106 lines
2.7 KiB
C
106 lines
2.7 KiB
C
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/*
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* Copyright (c) 1998, 1999 University of Utah and the Flux Group.
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* All rights reserved.
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*
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* This file is part of the Flux OSKit. The OSKit is free software, also known
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* as "open source;" you can redistribute it and/or modify it under the terms
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* of the GNU General Public License (GPL), version 2, as published by the Free
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* Software Foundation (FSF). To explore alternate licensing terms, contact
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* the University of Utah at csl-dist@cs.utah.edu or +1-801-585-3271.
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*
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* The OSKit is distributed in the hope that it will be useful, but WITHOUT ANY
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* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GPL for more details. You should have
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* received a copy of the GPL along with the OSKit; see the file COPYING. If
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* not, write to the FSF, 59 Temple Place #330, Boston, MA 02111-1307, USA.
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*/
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/*
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* Internal mutex implementation.
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*/
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struct pthread_mutex_impl {
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spin_lock_t mlock; /* Actual mutex lock */
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spin_lock_t dlock; /* Lock for this data structure */
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queue_head_t waiters; /* queue for mutex */
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void *holder; /* Opaque to user */
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int count; /* For recursive mutexes */
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int inherit; /* Does priority inheritance */
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int type; /* Mutex type. See below */
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};
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/*
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* Inline mutex functions.
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*
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* NOTE: These assume the spl level is set properly before being called.
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*/
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/*
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* Internal function. Try to lock a mutex. Spinning version.
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*/
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OSKIT_INLINE int
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fast_mutex_spinlock(pthread_mutex_t *m)
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{
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struct pthread_mutex_impl *pimpl = m->impl;
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while (1) {
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pthread_lock(&pimpl->mlock);
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/*
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* Try to get the lock. If successful, set owner and count.
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*/
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if (pimpl->holder == 0) {
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pimpl->holder = (void *) CURPTHREAD();
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pimpl->count = 1;
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pthread_unlock(&pimpl->mlock);
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return 0;
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}
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pthread_unlock(&pimpl->mlock);
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}
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}
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OSKIT_INLINE int
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fast_mutex_lock(pthread_mutex_t *m)
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{
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struct pthread_mutex_impl *pimpl = m->impl;
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pthread_lock(&pimpl->mlock);
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/*
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* Try to get the lock. If successful, set owner and count.
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*/
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if (pimpl->holder == 0) {
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pimpl->holder = (void *) CURPTHREAD();
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pimpl->count = 1;
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pthread_unlock(&pimpl->mlock);
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return 0;
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}
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pthread_unlock(&pimpl->mlock);
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return pthread_mutex_lock(m);
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}
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OSKIT_INLINE int
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fast_mutex_unlock(pthread_mutex_t *m)
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{
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struct pthread_mutex_impl *pimpl = m->impl;
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pthread_lock(&pimpl->mlock);
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/*
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* If the queue is empty, the mutex is free, and the lock can be
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* released.
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*/
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if (queue_empty(&(pimpl->waiters))) {
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pimpl->holder = NULL_THREADPTR;
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pimpl->count = 0;
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pthread_unlock(&pimpl->mlock);
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return 0;
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}
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/*
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* Take the slow boat.
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*/
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pthread_unlock(&pimpl->mlock);
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return pthread_mutex_unlock(m);
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}
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