/* Copyright (C) 2003 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <errno.h>
#include <sysdep.h>
#include <lowlevellock.h>
#include <pthreadP.h>


/* Wait on barrier.  */
int
pthread_barrier_wait (barrier)
     pthread_barrier_t *barrier;
{
  struct pthread_barrier *ibarrier = (struct pthread_barrier *) barrier;

  /* Make sure we are alone.  */
  lll_lock (ibarrier->lock);

  /* One more arrival.  */
  --ibarrier->left;

  /* Are these all?  */
  if (ibarrier->left == 0)
    {
      /* Yes.  Restore the barrier to be empty.  */
      ibarrier->left = ibarrier->init_count;

      /* Increment the event counter to avoid invalid wake-ups and
	 tell the current waiters that it is their turn.  */
      ++ibarrier->curr_event;

      /* Wake up everybody.  */
      lll_futex_wake (&ibarrier->curr_event, INT_MAX);

      /* The barrier is open for business again.  */
      lll_unlock (ibarrier->lock);

      /* This is the thread which finished the serialization.  */
      return PTHREAD_BARRIER_SERIAL_THREAD;
    }

  /* The number of the event we are waiting for.  The barrier's event
     number must be bumped before we continue.  */
  unsigned int event = ibarrier->curr_event;
  do
    {
      /* Before suspending, make the barrier available to others.  */
      lll_unlock (ibarrier->lock);

      /* Wait for the event counter of the barrier to change.  */
      lll_futex_wait (&ibarrier->curr_event, event);

      /* We are going to access shared data.  */
      lll_lock (ibarrier->lock);
    }
  while (event == ibarrier->curr_event);

  /* We are done, let others use the barrier.  */
  lll_unlock (ibarrier->lock);

  return 0;
}
