pthread_spin_init.c

/*
 * pthread_spin_init.c
 *
 * Description:
 * This translation unit implements spin lock primitives.
 *
 * --------------------------------------------------------------------------
 *
 *      Pthreads4w - POSIX Threads for Windows
 *      Copyright 1998 John E. Bossom
 *      Copyright 1999-2018, Pthreads4w contributors
 *
 *      Homepage: https://sourceforge.net/projects/pthreads4w/
 *
 *      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:
 *
 *      https://sourceforge.net/p/pthreads4w/wiki/Contributors/
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

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


int
pthread_spin_init (pthread_spinlock_t * lock, int pshared)
{
  pthread_spinlock_t s;
  int cpus = 0;
  int result = 0;

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

  if (0 != __ptw32_getprocessors (&cpus))
    {
      cpus = 1;
    }

  if (cpus > 1)
    {
      if (pshared == PTHREAD_PROCESS_SHARED)
	{
	  /*
	   * Creating spinlock that can be shared between
	   * processes.
	   */
#if _POSIX_THREAD_PROCESS_SHARED >= 0

	  /*
	   * Not implemented yet.
	   */

#error ERROR [__FILE__, line __LINE__]: Process shared spin locks are not supported yet.

#else

	  return ENOSYS;

#endif /* _POSIX_THREAD_PROCESS_SHARED */

	}
    }

  s = (pthread_spinlock_t) calloc (1, sizeof (*s));

  if (s == NULL)
    {
      return ENOMEM;
    }

  if (cpus > 1)
    {
      s->u.cpus = cpus;
      s->interlock =  __PTW32_SPIN_UNLOCKED;
    }
  else
    {
      pthread_mutexattr_t ma;
      result = pthread_mutexattr_init (&ma);

      if (0 == result)
	{
	  ma->pshared = pshared;
	  result = pthread_mutex_init (&(s->u.mutex), &ma);
	  if (0 == result)
	    {
	      s->interlock =  __PTW32_SPIN_USE_MUTEX;
	    }
	}
      (void) pthread_mutexattr_destroy (&ma);
    }

  if (0 == result)
    {
      *lock = s;
    }
  else
    {
      (void) free (s);
      *lock = NULL;
    }

  return (result);
}