78 lines
2.5 KiB
C
78 lines
2.5 KiB
C
/* Copyright (C) 2003, 2004 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <errno.h>
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#include <sysdep.h>
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#include <lowlevellock.h>
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#include <pthreadP.h>
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/* Wait on barrier. */
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int
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pthread_barrier_wait (barrier)
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pthread_barrier_t *barrier;
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{
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struct pthread_barrier *ibarrier = (struct pthread_barrier *) barrier;
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int result = 0;
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/* Make sure we are alone. */
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lll_lock (ibarrier->lock);
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/* One more arrival. */
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--ibarrier->left;
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/* Are these all? */
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if (ibarrier->left == 0)
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{
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/* Yes. Increment the event counter to avoid invalid wake-ups and
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tell the current waiters that it is their turn. */
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++ibarrier->curr_event;
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/* Wake up everybody. */
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lll_futex_wake (&ibarrier->curr_event, INT_MAX);
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/* This is the thread which finished the serialization. */
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result = PTHREAD_BARRIER_SERIAL_THREAD;
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}
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else
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{
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/* The number of the event we are waiting for. The barrier's event
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number must be bumped before we continue. */
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unsigned int event = ibarrier->curr_event;
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/* Before suspending, make the barrier available to others. */
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lll_unlock (ibarrier->lock);
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/* Wait for the event counter of the barrier to change. */
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do
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lll_futex_wait (&ibarrier->curr_event, event);
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while (event == ibarrier->curr_event);
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}
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/* Make sure the init_count is stored locally or in a register. */
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unsigned int init_count = ibarrier->init_count;
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/* If this was the last woken thread, unlock. */
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if (atomic_exchange_and_add (&ibarrier->left, 1) == init_count - 1)
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/* We are done. */
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lll_unlock (ibarrier->lock);
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return result;
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}
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