/* Wait on a condition.  Generic version.

   Copyright (C) 2000-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C 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 2.1 of the License, or (at your option) any later version.

   The GNU C 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 the GNU C Library;  if not, see

   <http://www.gnu.org/licenses/>.  */

#include <pthread.h>

#include <pt-internal.h>

#include <pthreadP.h>

extern int __pthread_cond_timedwait_internal (pthread_cond_t *cond,

					      pthread_mutex_t *mutex,

					      const struct timespec *abstime);

int

__pthread_cond_timedwait (pthread_cond_t *cond,

			  pthread_mutex_t *mutex,

			  const struct timespec *abstime)

{

  return __pthread_cond_timedwait_internal (cond, mutex, abstime);

}

strong_alias (__pthread_cond_timedwait, pthread_cond_timedwait);

struct cancel_ctx

{

  struct __pthread *wakeup;

  pthread_cond_t *cond;

};

static void

cancel_hook (void *arg)

{

  struct cancel_ctx *ctx = arg;

  struct __pthread *wakeup = ctx->wakeup;

  pthread_cond_t *cond = ctx->cond;

  int unblock;

  __pthread_spin_lock (&cond->__lock);

  /* The thread only needs to be awaken if it's blocking or about to block.

     If it was already unblocked, it's not queued any more.  */

  unblock = wakeup->prevp != NULL;

  if (unblock)

    __pthread_dequeue (wakeup);

  __pthread_spin_unlock (&cond->__lock);

  if (unblock)

    __pthread_wakeup (wakeup);

}

/* Block on condition variable COND until ABSTIME.  As a GNU

   extension, if ABSTIME is NULL, then wait forever.  MUTEX should be

   held by the calling thread.  On return, MUTEX will be held by the

   calling thread.  */

int

__pthread_cond_timedwait_internal (pthread_cond_t *cond,

				   pthread_mutex_t *mutex,

				   const struct timespec *abstime)

{

  error_t err;

  int cancelled, oldtype, drain;

  clockid_t clock_id = __pthread_default_condattr.__clock;

  if (abstime && (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000))

    return EINVAL;

  struct __pthread *self = _pthread_self ();

  struct cancel_ctx ctx;

  ctx.wakeup = self;

  ctx.cond = cond;

  /* Test for a pending cancellation request, switch to deferred mode for

     safer resource handling, and prepare the hook to call in case we're

     cancelled while blocking.  Once CANCEL_LOCK is released, the cancellation

     hook can be called by another thread at any time.  Whatever happens,

     this function must exit with MUTEX locked.

     This function contains inline implementations of pthread_testcancel and

     pthread_setcanceltype to reduce locking overhead.  */

  __pthread_mutex_lock (&self->cancel_lock);

  cancelled = (self->cancel_state == PTHREAD_CANCEL_ENABLE)

      && self->cancel_pending;

  if (!cancelled)

    {

      self->cancel_hook = cancel_hook;

      self->cancel_hook_arg = &ctx;

      oldtype = self->cancel_type;

      if (oldtype != PTHREAD_CANCEL_DEFERRED)

	self->cancel_type = PTHREAD_CANCEL_DEFERRED;

      /* Add ourselves to the list of waiters.  This is done while setting

         the cancellation hook to simplify the cancellation procedure, i.e.

         if the thread is queued, it can be cancelled, otherwise it is

         already unblocked, progressing on the return path.  */

      __pthread_spin_lock (&cond->__lock);

      __pthread_enqueue (&cond->__queue, self);

      if (cond->__attr != NULL)

	clock_id = cond->__attr->__clock;

      __pthread_spin_unlock (&cond->__lock);

    }

  __pthread_mutex_unlock (&self->cancel_lock);

  if (cancelled)

    __pthread_exit (PTHREAD_CANCELED);

  /* Release MUTEX before blocking.  */

  __pthread_mutex_unlock (mutex);

  /* Block the thread.  */

  if (abstime != NULL)

    err = __pthread_timedblock (self, abstime, clock_id);

  else

    {

      err = 0;

      __pthread_block (self);

    }

  __pthread_spin_lock (&cond->__lock);

  if (self->prevp == NULL)

    {

      /* Another thread removed us from the list of waiters, which means a

         wakeup message has been sent.  It was either consumed while we were

         blocking, or queued after we timed out and before we acquired the

         condition lock, in which case the message queue must be drained.  */

      if (!err)

	drain = 0;

      else

	{

	  assert (err == ETIMEDOUT);

	  drain = 1;

	}

    }

  else

    {

      /* We're still in the list of waiters.  Noone attempted to wake us up,

         i.e. we timed out.  */

      assert (err == ETIMEDOUT);

      __pthread_dequeue (self);

      drain = 0;

    }

  __pthread_spin_unlock (&cond->__lock);

  if (drain)

    __pthread_block (self);

  /* We're almost done.  Remove the unblock hook, restore the previous

     cancellation type, and check for a pending cancellation request.  */

  __pthread_mutex_lock (&self->cancel_lock);

  self->cancel_hook = NULL;

  self->cancel_hook_arg = NULL;

  self->cancel_type = oldtype;

  cancelled = (self->cancel_state == PTHREAD_CANCEL_ENABLE)

      && self->cancel_pending;

  __pthread_mutex_unlock (&self->cancel_lock);

  /* Reacquire MUTEX before returning/cancelling.  */

  __pthread_mutex_lock (mutex);

  if (cancelled)

    __pthread_exit (PTHREAD_CANCELED);

  return err;

}