obs-studio/deps/w32-pthreads/pthread_spin_destroy.c

/*
 * pthread_spin_destroy.c
 *
 * Description:
 * This translation unit implements spin lock primitives.
 *
 * --------------------------------------------------------------------------
 *
 *      Pthreads-win32 - POSIX Threads Library for Win32
 *      Copyright(C) 1998 John E. Bossom
 *      Copyright(C) 1999,2005 Pthreads-win32 contributors
 * 
 *      Contact Email: [email protected]
 * 
 *      The current list of contributors is contained
 *      in the file CONTRIBUTORS included with the source
 *      code distribution. The list can also be seen at the
 *      following World Wide Web location:
 *      http://sources.redhat.com/pthreads-win32/contributors.html
 * 
 *      This 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 of the License, or (at your option) any later version.
 * 
 *      This 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 this library in the file COPYING.LIB;
 *      if not, write to the Free Software Foundation, Inc.,
 *      51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */

#include "pthread.h"
#include "implement.h"


int
pthread_spin_destroy (pthread_spinlock_t * lock)
{
  register pthread_spinlock_t s;
  int result = 0;

  if (lock == NULL || *lock == NULL)
    {
      return EINVAL;
    }

  if ((s = *lock) != PTHREAD_SPINLOCK_INITIALIZER)
    {
      if (s->interlock == PTW32_SPIN_USE_MUTEX)
	{
	  result = pthread_mutex_destroy (&(s->u.mutex));
	}
      else if ((PTW32_INTERLOCKED_LONG) PTW32_SPIN_UNLOCKED !=
	       PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG ((PTW32_INTERLOCKED_LONGPTR) &s->interlock,
						   (PTW32_INTERLOCKED_LONG) PTW32_SPIN_INVALID,
						   (PTW32_INTERLOCKED_LONG) PTW32_SPIN_UNLOCKED))
	{
	  result = EINVAL;
	}

      if (0 == result)
	{
	  /*
	   * We are relying on the application to ensure that all other threads
	   * have finished with the spinlock before destroying it.
	   */
	  *lock = NULL;
	  (void) free (s);
	}
    }
  else
    {
      /*
       * See notes in ptw32_spinlock_check_need_init() above also.
       */
      ptw32_mcs_local_node_t node;

      ptw32_mcs_lock_acquire(&ptw32_spinlock_test_init_lock, &node);

      /*
       * Check again.
       */
      if (*lock == PTHREAD_SPINLOCK_INITIALIZER)
	{
	  /*
	   * This is all we need to do to destroy a statically
	   * initialised spinlock that has not yet been used (initialised).
	   * If we get to here, another thread
	   * waiting to initialise this mutex will get an EINVAL.
	   */
	  *lock = NULL;
	}
      else
	{
	  /*
	   * The spinlock has been initialised while we were waiting
	   * so assume it's in use.
	   */
	  result = EBUSY;
	}

       ptw32_mcs_lock_release(&node);
    }

  return (result);
}