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  */
  28
  29 #include "namespace.h"
  30 #include <machine/tls.h>
  31 #include <errno.h>
  32 #include <stdlib.h>
  33 #include <pthread.h>
  34 #include "un-namespace.h"
  35
  36 #include "thr_private.h"
  37
  38 int
  39 _pthread_barrier_destroy(pthread_barrier_t *barrier)
  40 {
  41         pthread_barrier_t bar;
  42
  43         if (barrier == NULL || *barrier == NULL)
  44                 return (EINVAL);
  45
  46         bar = *barrier;
  47         if (bar->b_waiters > 0)
  48                 return (EBUSY);
  49         *barrier = NULL;
  50         free(bar);
  51         return (0);
  52 }
  53
  54 int
  55 _pthread_barrier_init(pthread_barrier_t * __restrict barrier,
  56     const pthread_barrierattr_t * __restrict attr __unused, unsigned count)
  57 {
  58         pthread_barrier_t bar;
  59
  60         if (barrier == NULL || count == 0 || count > INT_MAX)
  61                 return (EINVAL);
  62
  63         bar = malloc(sizeof(struct pthread_barrier));
  64         if (bar == NULL)
  65                 return (ENOMEM);
  66
  67         _thr_umtx_init(&bar->b_lock);
  68         bar->b_cycle    = 0;
  69         bar->b_waiters  = 0;
  70         bar->b_count    = count;
  71         *barrier        = bar;
  72
  73         return (0);
  74 }
  75
  76 int
  77 _pthread_barrier_wait(pthread_barrier_t *barrier)
  78 {
  79         struct pthread *curthread;
  80         pthread_barrier_t bar;
  81         int64_t cycle;
  82         int ret;
  83
  84         if (barrier == NULL || *barrier == NULL)
  85                 return (EINVAL);
  86
  87         bar = *barrier;
  88         curthread = tls_get_curthread();
  89         THR_UMTX_LOCK(curthread, &bar->b_lock);
  90         if (++bar->b_waiters == bar->b_count) {
  91                 /* Current thread is lastest thread */
  92                 bar->b_waiters = 0;
  93                 bar->b_cycle++;
  94                 _thr_umtx_wake(&bar->b_cycle, 0);
  95                 THR_UMTX_UNLOCK(curthread, &bar->b_lock);
  96                 ret = PTHREAD_BARRIER_SERIAL_THREAD;
  97         } else {
  98                 cycle = bar->b_cycle;
  99                 THR_UMTX_UNLOCK(curthread, &bar->b_lock);
 100                 do {
 101                         _thr_umtx_wait(&bar->b_cycle, cycle, NULL, 0);
 102                         /* test cycle to avoid bogus wakeup */
 103                 } while (cycle == bar->b_cycle);
 104                 ret = 0;
 105         }
 106         return (ret);
 107 }
 108
 109 __strong_reference(_pthread_barrier_init,       pthread_barrier_init);
 110 __strong_reference(_pthread_barrier_wait,       pthread_barrier_wait);
 111 __strong_reference(_pthread_barrier_destroy,    pthread_barrier_destroy);