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/* POSIX barrier implementation for LinuxThreads.

   Copyright (C) 2000 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Kaz Kylheku <kaz@ashi.footprints.net>, 2000.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Library General Public License as

   published by the Free Software Foundation; either version 2 of the

   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public

   License along with the GNU C Library; see the file COPYING.LIB.  If not,

   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,

   Boston, MA 02111-1307, USA.  */

#include <errno.h>

#include "pthread.h"

#include "internals.h"

#include "spinlock.h"

#include "queue.h"

#include "restart.h"

int

pthread_barrier_wait(pthread_barrier_t *barrier)

{

  pthread_descr self = thread_self();

  pthread_descr temp_wake_queue, th;

  int result = 0;

  __pthread_lock(&barrier->__ba_lock, self);

  /* If the required number of threads have achieved rendezvous... */

  if (barrier->__ba_present >= barrier->__ba_required - 1)

    {

      /* ... then this last caller shall be the serial thread */

      result = PTHREAD_BARRIER_SERIAL_THREAD;

      /* Copy and clear wait queue and reset barrier. */

      temp_wake_queue = barrier->__ba_waiting;

      barrier->__ba_waiting = NULL;

      barrier->__ba_present = 0;

    }

  else

    {

      result = 0;

      barrier->__ba_present++;

      enqueue(&barrier->__ba_waiting, self);

    }

  __pthread_unlock(&barrier->__ba_lock);

  if (result == 0)

    {

      /* Non-serial threads have to suspend */

      suspend(self);

      /* We don't bother dealing with cancellation because the POSIX

         spec for barriers doesn't mention that pthread_barrier_wait

         is a cancellation point. */

    }

  else

    {

      /* Serial thread wakes up all others. */

      while ((th = dequeue(&temp_wake_queue)) != NULL)

        restart(th);

    }

  return result;

}

int

pthread_barrier_init(pthread_barrier_t *barrier,

                                const pthread_barrierattr_t *attr,

                                unsigned int count)

{

  if (count == 0)

     return EINVAL;

  __pthread_init_lock(&barrier->__ba_lock);

  barrier->__ba_required = count;

  barrier->__ba_present = 0;

  barrier->__ba_waiting = NULL;

  return 0;

}

int

pthread_barrier_destroy(pthread_barrier_t *barrier)

{

  if (barrier->__ba_waiting != NULL) return EBUSY;

  return 0;

}

int

pthread_barrierattr_init(pthread_barrierattr_t *attr)

{

  attr->__pshared = PTHREAD_PROCESS_PRIVATE;

  return 0;

}

int

pthread_barrierattr_destroy(pthread_barrierattr_t *attr)

{

  return 0;

}

int

__pthread_barrierattr_getpshared(const pthread_barrierattr_t *attr,

                                 int *pshared)

{

  *pshared = attr->__pshared;

  return 0;

}

int

pthread_barrierattr_setpshared(pthread_barrierattr_t *attr, int pshared)

{

  if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED)

    return EINVAL;

  attr->__pshared = pshared;

  return 0;

}