/*
 * pthread_timechange_handler_np.c
 *
 * Description:
 * This translation unit implements miscellaneous thread functions.
 *
 * --------------------------------------------------------------------------
 *
 *      Pthreads4w - POSIX Threads Library for Win32
 *      Copyright(C) 1998 John E. Bossom
 *      Copyright(C) 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/
 *
 * This file is part of Pthreads4w.
 *
 *    Pthreads4w is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    Pthreads4w 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 General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with Pthreads4w.  If not, see <http://www.gnu.org/licenses/>. *
 */

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

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

/*
 * Notes on handling system time adjustments (especially negative ones).
 * ---------------------------------------------------------------------
 *
 * This solution was suggested by Alexander Terekhov, but any errors
 * in the implementation are mine - [Ross Johnson]
 *
 * 1) The problem: threads doing a timedwait on a CV may expect to timeout
 *    at a specific absolute time according to a system timer. If the
 *    system clock is adjusted backwards then those threads sleep longer than
 *    expected. Also, Pthreads4w converts absolute times to intervals in
 *    order to make use of the underlying Win32, and so waiting threads may
 *    awake before their proper abstimes.
 *
 * 2) We aren't able to distinquish between threads on timed or untimed waits,
 *    so we wake them all at the time of the adjustment so that they can
 *    re-evaluate their conditions and re-compute their timeouts.
 *
 * 3) We rely on correctly written applications for this to work. Specifically,
 *    they must be able to deal properly with spurious wakeups. That is,
 *    they must re-test their condition upon wakeup and wait again if
 *    the condition is not satisfied.
 */

void *
pthread_timechange_handler_np (void *arg)
     /*
      * ------------------------------------------------------
      * DOCPUBLIC
      *      Broadcasts all CVs to force re-evaluation and
      *      new timeouts if required.
      *
      * PARAMETERS
      *      NONE
      *
      *
      * DESCRIPTION
      *      Broadcasts all CVs to force re-evaluation and
      *      new timeouts if required.
      *
      *      This routine may be passed directly to pthread_create()
      *      as a new thread in order to run asynchronously.
      *
      *
      * RESULTS
      *              0               successfully broadcast all CVs
      *              EAGAIN          Not all CVs were broadcast
      *
      * ------------------------------------------------------
      */
{
  int result = 0;
  pthread_cond_t cv;
  ptw32_mcs_local_node_t node;

  ptw32_mcs_lock_acquire(&ptw32_cond_list_lock, &node);

  cv = ptw32_cond_list_head;

  while (cv != NULL && 0 == result)
    {
      result = pthread_cond_broadcast (&cv);
      cv = cv->next;
    }

  ptw32_mcs_lock_release(&node);

  return (void *) (size_t) (result != 0 ? EAGAIN : 0);
}