relibc_pthreads-emb/pte_callUserDestroyRoutines.c

/*
 * pte_callUserDestroyRoutines.c
 *
 * Description:
 * This translation unit implements routines which are private to
 * the implementation and may be used throughout it.
 *
 * --------------------------------------------------------------------------
 *
 *      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"

#include <pte_osal.h>

#ifdef __cplusplus
#include <exception>
using std::terminate;
#endif

void
pte_callUserDestroyRoutines (pthread_t thread)
/*
 * -------------------------------------------------------------------
 * DOCPRIVATE
 *
 * This the routine runs through all thread keys and calls
 * the destroy routines on the user's data for the current thread.
 * It simulates the behaviour of POSIX Threads.
 *
 * PARAMETERS
 *              thread
 *                      an instance of pthread_t
 *
 * RETURNS
 *              N/A
 * -------------------------------------------------------------------
 */
{
  ThreadKeyAssoc * assoc;

  if (thread.p != NULL)
    {
      int assocsRemaining;
      int iterations = 0;
      pte_thread_t * sp = (pte_thread_t *) thread.p;

      /*
       * Run through all Thread<-->Key associations
       * for the current thread.
       *
       * Do this process at most PTHREAD_DESTRUCTOR_ITERATIONS times.
       */
      do
        {
          assocsRemaining = 0;
          iterations++;

          (void) pthread_mutex_lock(&(sp->threadLock));
          /*
           * The pointer to the next assoc is stored in the thread struct so that
           * the assoc destructor in pthread_key_delete can adjust it
           * if it deletes this assoc. This can happen if we fail to acquire
           * both locks below, and are forced to release all of our locks,
           * leaving open the opportunity for pthread_key_delete to get in
           * before us.
           */
          sp->nextAssoc = sp->keys;
          (void) pthread_mutex_unlock(&(sp->threadLock));

          for (;;)
            {
              void * value;
              pthread_key_t k;
              void (*destructor) (void *);

              /*
               * First we need to serialise with pthread_key_delete by locking
               * both assoc guards, but in the reverse order to our convention,
               * so we must be careful to avoid deadlock.
               */
              (void) pthread_mutex_lock(&(sp->threadLock));

              if ((assoc = (ThreadKeyAssoc *)sp->nextAssoc) == NULL)
                {
                  /* Finished */
                  pthread_mutex_unlock(&(sp->threadLock));
                  break;
                }
              else
                {
                  /*
                   * assoc->key must be valid because assoc can't change or be
                   * removed from our chain while we hold at least one lock. If
                   * the assoc was on our key chain then the key has not been
                   * deleted yet.
                   *
                   * Now try to acquire the second lock without deadlocking.
                   * If we fail, we need to relinquish the first lock and the
                   * processor and then try to acquire them all again.
                   */
                  if (pthread_mutex_trylock(&(assoc->key->keyLock)) == EBUSY)
                    {
                      pthread_mutex_unlock(&(sp->threadLock));
                      pte_osThreadSleep(1); // Ugly but necessary to avoid priority effects.
                      /*
                       * Go around again.
                       * If pthread_key_delete has removed this assoc in the meantime,
                       * sp->nextAssoc will point to a new assoc.
                       */
                      continue;
                    }
                }

              /* We now hold both locks */

              sp->nextAssoc = assoc->nextKey;

              /*
               * Key still active; pthread_key_delete
               * will block on these same mutexes before
               * it can release actual key; therefore,
               * key is valid and we can call the destroy
               * routine;
               */
              k = assoc->key;
              destructor = k->destructor;
              value = pte_osTlsGetValue(k->key);
              pte_osTlsSetValue (k->key, NULL);

              // Every assoc->key exists and has a destructor
              if (value != NULL && iterations <= PTHREAD_DESTRUCTOR_ITERATIONS)
                {
                  /*
                   * Unlock both locks before the destructor runs.
                   * POSIX says pthread_key_delete can be run from destructors,
                   * and that probably includes with this key as target.
                   * pthread_setspecific can also be run from destructors and
                   * also needs to be able to access the assocs.
                   */
                  (void) pthread_mutex_unlock(&(sp->threadLock));
                  (void) pthread_mutex_unlock(&(k->keyLock));

                  assocsRemaining++;

#ifdef __cplusplus

                  try
                    {
                      /*
                       * Run the caller's cleanup routine.
                       */
                      destructor (value);
                    }
                  catch (...)
                    {
                      /*
                       * A system unexpected exception has occurred
                       * running the user's destructor.
                       * We get control back within this block in case
                       * the application has set up it's own terminate
                       * handler. Since we are leaving the thread we
                       * should not get any internal pthreads
                       * exceptions.
                       */
                      terminate ();
                    }

#else /* __cplusplus */

                  /*
                  * Run the caller's cleanup routine.
                  */
                  destructor (value);

#endif /* __cplusplus */

                }
              else
                {
                  /*
                   * Remove association from both the key and thread chains
                   * and reclaim it's memory resources.
                   */
                  pte_tkAssocDestroy (assoc);
                  (void) pthread_mutex_unlock(&(sp->threadLock));
                  (void) pthread_mutex_unlock(&(k->keyLock));
                }
            }
        }
      while (assocsRemaining);
    }
}				/* pte_callUserDestroyRoutines */