pthread_key_delete.c

/*
 * pthread_key_delete.c
 *
 * Description:
 * POSIX thread functions which implement thread-specific data (TSD).
 *
 * --------------------------------------------------------------------------
 *
 *      Pthreads-embedded (PTE) - POSIX Threads Library for embedded systems
 *      Copyright(C) 2008 Jason Schmidlapp
 *
 *      Contact Email: jschmidlapp@users.sourceforge.net
 *
 *
 *      Based upon Pthreads-win32 - POSIX Threads Library for Win32
 *      Copyright(C) 1998 John E. Bossom
 *      Copyright(C) 1999,2005 Pthreads-win32 contributors
 *
 *      Contact Email: rpj@callisto.canberra.edu.au
 *
 *      The original list of contributors to the Pthreads-win32 project
 *      is contained in the file CONTRIBUTORS.ptw32 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.,
 *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#include <stdio.h>
#include <stdlib.h>


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


int
pthread_key_delete (pthread_key_t key)
/*
 * ------------------------------------------------------
 * DOCPUBLIC
 *      This function deletes a thread-specific data key. This
 *      does not change the value of the thread specific data key
 *      for any thread and does not run the key's destructor
 *      in any thread so it should be used with caution.
 *
 * PARAMETERS
 *      key
 *              pointer to an instance of pthread_key_t
 *
 *
 * DESCRIPTION
 *      This function deletes a thread-specific data key. This
 *      does not change the value of the thread specific data key
 *      for any thread and does not run the key's destructor
 *      in any thread so it should be used with caution.
 *
 * RESULTS
 *              0               successfully deleted the key,
 *              EINVAL          key is invalid,
 *
 * ------------------------------------------------------
 */
{
  int result = 0;

  if (key != NULL)
    {
      if (key->threads != NULL &&
          key->destructor != NULL &&
          pthread_mutex_lock (&(key->keyLock)) == 0)
        {
          ThreadKeyAssoc *assoc;
          /*
           * Run through all Thread<-->Key associations
           * for this key.
           *
           * While we hold at least one of the locks guarding
           * the assoc, we know that the assoc pointed to by
           * key->threads is valid.
           */
          while ((assoc = (ThreadKeyAssoc *) key->threads) != NULL)
            {
              pte_thread_t * thread = assoc->thread;

              if (assoc == NULL)
                {
                  /* Finished */
                  break;
                }

              if (pthread_mutex_lock (&(thread->threadLock)) == 0)
                {
                  /*
                   * Since we are starting at the head of the key's threads
                   * chain, this will also point key->threads at the next assoc.
                   * While we hold key->keyLock, no other thread can insert
                   * a new assoc via pthread_setspecific.
                   */
                  pte_tkAssocDestroy (assoc);
                  (void) pthread_mutex_unlock (&(thread->threadLock));
                }
              else
                {
                  /* Thread or lock is no longer valid? */
                  pte_tkAssocDestroy (assoc);
                }
            }
          pthread_mutex_unlock (&(key->keyLock));
        }

      pte_osTlsFree (key->key);
      if (key->destructor != NULL)
        {
          /* A thread could be holding the keyLock */
          while (EBUSY == (result = pthread_mutex_destroy (&(key->keyLock))))
            {
              pte_osYield(); // Ugly.
            }
        }

      free (key);
    }

  return (result);
}