lib/libthr/thread/thr_barrier.c

   1 /*-
   2  * Copyright (c) 2003 David Xu <davidxu@freebsd.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD$
  27  */
  28
  29 #include "namespace.h"
  30 #include <errno.h>
  31 #include <stdlib.h>
  32 #include <pthread.h>
  33 #include "un-namespace.h"
  34
  35 #include "thr_private.h"
  36
  37 __weak_reference(_pthread_barrier_init,         pthread_barrier_init);
  38 __weak_reference(_pthread_barrier_wait,         pthread_barrier_wait);
  39 __weak_reference(_pthread_barrier_destroy,      pthread_barrier_destroy);
  40
  41 int
  42 _pthread_barrier_destroy(pthread_barrier_t *barrier)
  43 {
  44         pthread_barrier_t       bar;
  45         struct pthread          *curthread;
  46
  47         if (barrier == NULL || *barrier == NULL)
  48                 return (EINVAL);
  49
  50         curthread = _get_curthread();
  51         bar = *barrier;
  52         THR_UMUTEX_LOCK(curthread, &bar->b_lock);
  53         if (bar->b_destroying) {
  54                 THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
  55                 return (EBUSY);
  56         }
  57         bar->b_destroying = 1;
  58         do {
  59                 if (bar->b_waiters > 0) {
  60                         bar->b_destroying = 0;
  61                         THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
  62                         return (EBUSY);
  63                 }
  64                 if (bar->b_refcount != 0) {
  65                         _thr_ucond_wait(&bar->b_cv, &bar->b_lock, NULL, 0);
  66                         THR_UMUTEX_LOCK(curthread, &bar->b_lock);
  67                 } else
  68                         break;
  69         } while (1);
  70         bar->b_destroying = 0;
  71         THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
  72
  73         *barrier = NULL;
  74         free(bar);
  75         return (0);
  76 }
  77
  78 int
  79 _pthread_barrier_init(pthread_barrier_t *barrier,
  80                       const pthread_barrierattr_t *attr, unsigned count)
  81 {
  82         pthread_barrier_t       bar;
  83
  84         (void)attr;
  85
  86         if (barrier == NULL || count <= 0)
  87                 return (EINVAL);
  88
  89         bar = calloc(1, sizeof(struct pthread_barrier));
  90         if (bar == NULL)
  91                 return (ENOMEM);
  92
  93         _thr_umutex_init(&bar->b_lock);
  94         _thr_ucond_init(&bar->b_cv);
  95         bar->b_count    = count;
  96         *barrier        = bar;
  97
  98         return (0);
  99 }
 100
 101 int
 102 _pthread_barrier_wait(pthread_barrier_t *barrier)
 103 {
 104         struct pthread *curthread = _get_curthread();
 105         pthread_barrier_t bar;
 106         int64_t cycle;
 107         int ret;
 108
 109         if (barrier == NULL || *barrier == NULL)
 110                 return (EINVAL);
 111
 112         bar = *barrier;
 113         THR_UMUTEX_LOCK(curthread, &bar->b_lock);
 114         if (++bar->b_waiters == bar->b_count) {
 115                 /* Current thread is lastest thread */
 116                 bar->b_waiters = 0;
 117                 bar->b_cycle++;
 118                 _thr_ucond_broadcast(&bar->b_cv);
 119                 THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
 120                 ret = PTHREAD_BARRIER_SERIAL_THREAD;
 121         } else {
 122                 cycle = bar->b_cycle;
 123                 bar->b_refcount++;
 124                 do {
 125                         _thr_ucond_wait(&bar->b_cv, &bar->b_lock, NULL, 0);
 126                         THR_UMUTEX_LOCK(curthread, &bar->b_lock);
 127                         /* test cycle to avoid bogus wakeup */
 128                 } while (cycle == bar->b_cycle);
 129                 if (--bar->b_refcount == 0 && bar->b_destroying)
 130                         _thr_ucond_broadcast(&bar->b_cv);
 131                 THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
 132                 ret = 0;
 133         }
 134         return (ret);
 135 }