lib/libthread_xu/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: src/lib/libpthread/thread/thr_barrier.c,v 1.1 2003/09/04 14:06:43 davidxu Exp $
  27  * $DragonFly: src/lib/libthread_xu/thread/thr_barrier.c,v 1.6 2006/04/06 13:03:09 davidxu Exp $
  28  */
  29
  30 #include "namespace.h"
  31 #include <machine/tls.h>
  32
  33 #include <errno.h>
  34 #include <stdlib.h>
  35 #include <pthread.h>
  36 #include "un-namespace.h"
  37
  38 #include "thr_private.h"
  39
  40 int
  41 _pthread_barrier_destroy(pthread_barrier_t *barrier)
  42 {
  43         pthread_barrier_t       bar;
  44
  45         if (barrier == NULL || *barrier == NULL)
  46                 return (EINVAL);
  47
  48         bar = *barrier;
  49         if (bar->b_waiters > 0)
  50                 return (EBUSY);
  51         *barrier = NULL;
  52         free(bar);
  53         return (0);
  54 }
  55
  56 int
  57 _pthread_barrier_init(pthread_barrier_t *barrier,
  58         const pthread_barrierattr_t *attr __unused, unsigned count)
  59 {
  60         pthread_barrier_t       bar;
  61
  62         if (barrier == NULL || count <= 0)
  63                 return (EINVAL);
  64
  65         bar = malloc(sizeof(struct pthread_barrier));
  66         if (bar == NULL)
  67                 return (ENOMEM);
  68
  69         _thr_umtx_init(&bar->b_lock);
  70         bar->b_cycle    = 0;
  71         bar->b_waiters  = 0;
  72         bar->b_count    = count;
  73         *barrier        = bar;
  74
  75         return (0);
  76 }
  77
  78 int
  79 _pthread_barrier_wait(pthread_barrier_t *barrier)
  80 {
  81         struct pthread *curthread = tls_get_curthread();
  82         pthread_barrier_t bar;
  83         long cycle;
  84         int ret;
  85
  86         if (barrier == NULL || *barrier == NULL)
  87                 return (EINVAL);
  88
  89         bar = *barrier;
  90         THR_UMTX_LOCK(curthread, &bar->b_lock);
  91         if (++bar->b_waiters == bar->b_count) {
  92                 /* Current thread is lastest thread */
  93                 bar->b_waiters = 0;
  94                 bar->b_cycle++;
  95                 _thr_umtx_wake(&bar->b_cycle, bar->b_count);
  96                 THR_UMTX_UNLOCK(curthread, &bar->b_lock);
  97                 ret = PTHREAD_BARRIER_SERIAL_THREAD;
  98         } else {
  99                 cycle = bar->b_cycle;
 100                 THR_UMTX_UNLOCK(curthread, &bar->b_lock);
 101                 do {
 102                         _thr_umtx_wait(&bar->b_cycle, cycle, NULL, 0);
 103                         /* test cycle to avoid bogus wakeup */
 104                 } while (cycle == bar->b_cycle);
 105                 ret = 0;
 106         }
 107         return (ret);
 108 }
 109
 110 __strong_reference(_pthread_barrier_init,       pthread_barrier_init);
 111 __strong_reference(_pthread_barrier_wait,       pthread_barrier_wait);
 112 __strong_reference(_pthread_barrier_destroy,    pthread_barrier_destroy);