/*
 * pthread_mutex_consistent.c
 *
 * Description:
 * This translation unit implements mutual exclusion (mutex) 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

/*
 * From the Sun Multi-threaded Programming Guide
 *
 * robustness defines the behavior when the owner of the mutex terminates without unlocking the
 * mutex, usually because its process terminated abnormally. The value of robustness that is
 * defined in pthread.h is PTHREAD_MUTEX_ROBUST or PTHREAD_MUTEX_STALLED. The
 * default value is PTHREAD_MUTEX_STALLED .
 * [] PTHREAD_MUTEX_STALLED
 * When the owner of the mutex terminates without unlocking the mutex, all subsequent calls
 * to pthread_mutex_lock() are blocked from progress in an unspecified manner.
 * [] PTHREAD_MUTEX_ROBUST
 * When the owner of the mutex terminates without unlocking the mutex, the mutex is
 * unlocked. The next owner of this mutex acquires the mutex with an error return of
 * EOWNERDEAD.
 * Note - Your application must always check the return code from pthread_mutex_lock() for
 * a mutex initialized with the PTHREAD_MUTEX_ROBUST attribute.
 * [] The new owner of this mutex should make the state protected by the mutex consistent.
 * This state might have been left inconsistent when the previous owner terminated.
 * [] If the new owner is able to make the state consistent, call
 * pthread_mutex_consistent() for the mutex before unlocking the mutex. This
 * marks the mutex as consistent and subsequent calls to pthread_mutex_lock() and
 * pthread_mutex_unlock() will behave in the normal manner.
 * [] If the new owner is not able to make the state consistent, do not call
 * pthread_mutex_consistent() for the mutex, but unlock the mutex.
 * All waiters are woken up and all subsequent calls to pthread_mutex_lock() fail to
 * acquire the mutex. The return code is ENOTRECOVERABLE. The mutex can be made
 * consistent by calling pthread_mutex_destroy() to uninitialize the mutex, and calling
 * pthread_mutex_int() to reinitialize the mutex.However, the state that was protected
 * by the mutex remains inconsistent and some form of application recovery is required.
 * [] If the thread that acquires the lock with EOWNERDEAD terminates without unlocking the
 * mutex, the next owner acquires the lock with an EOWNERDEAD return code.
 */
#if !defined(_UWIN)
/*#   include <process.h> */
#endif
#include "pthread.h"
#include "implement.h"

INLINE
int
__ptw32_robust_mutex_inherit(pthread_mutex_t * mutex)
{
  int result;
  pthread_mutex_t mx = *mutex;
  __ptw32_robust_node_t* robust = mx->robustNode;

  switch ((LONG)__PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG(
             (__PTW32_INTERLOCKED_LONGPTR)&robust->stateInconsistent,
             (__PTW32_INTERLOCKED_LONG)__PTW32_ROBUST_INCONSISTENT,
             (__PTW32_INTERLOCKED_LONG)-1 /* The terminating thread sets this */))
    {
      case -1L:
          result = EOWNERDEAD;
          break;
      case (LONG)__PTW32_ROBUST_NOTRECOVERABLE:
          result = ENOTRECOVERABLE;
          break;
      default:
          result = 0;
          break;
    }

  return result;
}

/*
 * The next two internal support functions depend on being
 * called only by the thread that owns the robust mutex. This
 * enables us to avoid additional locks.
 * Any mutex currently in the thread's robust mutex list is held
 * by the thread, again eliminating the need for locks.
 * The forward/backward links allow the thread to unlock mutexes
 * in any order, not necessarily the reverse locking order.
 * This is all possible because it is an error if a thread that
 * does not own the [robust] mutex attempts to unlock it.
 */

INLINE
void
__ptw32_robust_mutex_add(pthread_mutex_t* mutex, pthread_t self)
{
  __ptw32_robust_node_t** list;
  pthread_mutex_t mx = *mutex;
  __ptw32_thread_t* tp = (__ptw32_thread_t*)self.p;
  __ptw32_robust_node_t* robust = mx->robustNode;

  list = &tp->robustMxList;
  mx->ownerThread = self;
  if (NULL == *list)
    {
      robust->prev = NULL;
      robust->next = NULL;
      *list = robust;
    }
  else
    {
      robust->prev = NULL;
      robust->next = *list;
      (*list)->prev = robust;
      *list = robust;
    }
}

INLINE
void
__ptw32_robust_mutex_remove(pthread_mutex_t* mutex, __ptw32_thread_t* otp)
{
  __ptw32_robust_node_t** list;
  pthread_mutex_t mx = *mutex;
  __ptw32_robust_node_t* robust = mx->robustNode;

  list = &(((__ptw32_thread_t*)mx->ownerThread.p)->robustMxList);
  mx->ownerThread.p = otp;
  if (robust->next != NULL)
    {
      robust->next->prev = robust->prev;
    }
  if (robust->prev != NULL)
    {
      robust->prev->next = robust->next;
    }
  if (*list == robust)
    {
      *list = robust->next;
    }
}


int
pthread_mutex_consistent (pthread_mutex_t* mutex)
{
  pthread_mutex_t mx = *mutex;
  int result = 0;

  /*
   * Let the system deal with invalid pointers.
   */
  if (mx == NULL)
    {
      return EINVAL;
    }

  if (mx->kind >= 0
        ||  (__PTW32_INTERLOCKED_LONG)__PTW32_ROBUST_INCONSISTENT !=  __PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG(
                                                 (__PTW32_INTERLOCKED_LONGPTR)&mx->robustNode->stateInconsistent,
                                                 (__PTW32_INTERLOCKED_LONG)__PTW32_ROBUST_CONSISTENT,
                                                 (__PTW32_INTERLOCKED_LONG)__PTW32_ROBUST_INCONSISTENT))
    {
      result = EINVAL;
    }

  return (result);
}

