Description

   This routine causes a thread to wait until one of the following
   occurs:

   o  The specified condition variable is signaled or broadcast.

   o  The current system clock time is greater than or equal to the
      time specified by the abstime argument.

   This routine is identical to pthread_cond_wait(), except that
   this routine can return before a condition variable is signaled
   or broadcast, specifically, when the specified time expires. For
   more information, see the pthread_cond_wait() description.

   This routine atomically releases the mutex and causes the calling
   thread to wait on the condition. When the thread regains control
   after calling pthread_cond_timedwait(), the mutex is locked and
   the thread is the owner. This is true regardless of why the wait
   ended. If general cancelability is enabled, the thread reacquires
   the mutex (blocking for it if necessary) before the cleanup
   handlers are run (or before the exception is raised).

   If the current time equals or exceeds the expiration time, this
   routine returns immediately, releasing and reacquiring the mutex.
   It might cause the calling thread to yield (see the sched_yield()
   description). Your code should check the return status whenever
   this routine returns and take the appropriate action. Otherwise,
   waiting on the condition variable can become a nonblocking loop.

   Call this routine after you have locked the mutex specified
   in mutex. The results of this routine are unpredictable if
   this routine is called without first locking the mutex. The
   only routines that are supported for use with asynchronous
   cancelability enabled are those that disable asynchronous
   cancelability.