/*      $NetBSD: pthread_barrier.c,v 1.23 2022/02/12 14:59:32 riastradh Exp $   */

/*-
* Copyright (c) 2001, 2003, 2006, 2007, 2009, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Nathan J. Williams, by Jason R. Thorpe, and by Andrew Doran.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

#include <sys/cdefs.h>
__RCSID("$NetBSD: pthread_barrier.c,v 1.23 2022/02/12 14:59:32 riastradh Exp $");

/* Need to use libc-private names for atomic operations. */
#include "../../common/lib/libc/atomic/atomic_op_namespace.h"

#include <errno.h>

#include "pthread.h"
#include "pthread_int.h"

int
pthread_barrier_init(pthread_barrier_t *barrier,
                    const pthread_barrierattr_t *attr, unsigned int count)
{

       pthread__error(EINVAL, "Invalid barrier attribute",
           attr == NULL || attr->ptba_magic == _PT_BARRIERATTR_MAGIC);
       if (count == 0)
               return EINVAL;

       barrier->ptb_magic = _PT_BARRIER_MAGIC;
       PTQ_INIT(&barrier->ptb_waiters);
       barrier->ptb_initcount = count;
       barrier->ptb_curcount = 0;
       barrier->ptb_generation = 0;
       return 0;
}

int
pthread_barrier_destroy(pthread_barrier_t *barrier)
{

       pthread__error(EINVAL, "Invalid barrier",
           barrier->ptb_magic == _PT_BARRIER_MAGIC);
       if (barrier->ptb_curcount != 0)
               return EBUSY;

       barrier->ptb_magic = _PT_BARRIER_DEAD;

       return 0;
}

int
pthread_barrier_wait(pthread_barrier_t *barrier)
{
       pthread_mutex_t *interlock;
       pthread_t self;
       unsigned int gen;

       pthread__error(EINVAL, "Invalid barrier",
           barrier->ptb_magic == _PT_BARRIER_MAGIC);

       /*
        * A single arbitrary thread is supposed to return
        * PTHREAD_BARRIER_SERIAL_THREAD, and everone else
        * is supposed to return 0.  Since pthread_barrier_wait()
        * is not a cancellation point, this is trivial; we
        * simply elect that the thread that causes the barrier
        * to be satisfied gets the special return value.  Note
        * that this final thread does not actually need to block,
        * but instead is responsible for waking everyone else up.
        */
       self = pthread__self();
       interlock = pthread__hashlock(barrier);
       pthread_mutex_lock(interlock);
       if (barrier->ptb_curcount + 1 == barrier->ptb_initcount) {
               barrier->ptb_generation++;
               barrier->ptb_curcount = 0;
               pthread__unpark_all(&barrier->ptb_waiters, self,
                   interlock);
               pthread_mutex_unlock(interlock);
               return PTHREAD_BARRIER_SERIAL_THREAD;
       }
       barrier->ptb_curcount++;
       gen = barrier->ptb_generation;
       for (;;) {
               PTQ_INSERT_TAIL(&barrier->ptb_waiters, self, pt_sleep);
               self->pt_sleepobj = &barrier->ptb_waiters;
               (void)pthread__park(self, interlock, &barrier->ptb_waiters,
                   NULL, 0);
               if (__predict_true(gen != barrier->ptb_generation)) {
                       break;
               }
               pthread_mutex_lock(interlock);
               if (gen != barrier->ptb_generation) {
                       pthread_mutex_unlock(interlock);
                       break;
               }
       }

       return 0;
}

#ifdef _PTHREAD_PSHARED
int
pthread_barrierattr_getpshared(const pthread_barrierattr_t * __restrict attr,
   int * __restrict pshared)
{

       pthread__error(EINVAL, "Invalid barrier attribute",
           attr->ptba_magic == _PT_BARRIERATTR_MAGIC);

       *pshared = PTHREAD_PROCESS_PRIVATE;
       return 0;
}

int
pthread_barrierattr_setpshared(pthread_barrierattr_t *attr, int pshared)
{

       pthread__error(EINVAL, "Invalid barrier attribute",
           attr->ptba_magic == _PT_BARRIERATTR_MAGIC);

       switch(pshared) {
       case PTHREAD_PROCESS_PRIVATE:
               return 0;
       case PTHREAD_PROCESS_SHARED:
               return ENOSYS;
       }
       return EINVAL;
}
#endif

int
pthread_barrierattr_init(pthread_barrierattr_t *attr)
{

       attr->ptba_magic = _PT_BARRIERATTR_MAGIC;
       return 0;
}

int
pthread_barrierattr_destroy(pthread_barrierattr_t *attr)
{

       pthread__error(EINVAL, "Invalid barrier attribute",
           attr->ptba_magic == _PT_BARRIERATTR_MAGIC);
       attr->ptba_magic = _PT_BARRIERATTR_DEAD;
       return 0;
}