109 lines
3.8 KiB
C
109 lines
3.8 KiB
C
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/*
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* pthread_timechange_handler_np.c
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*
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* Description:
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* This translation unit implements miscellaneous thread functions.
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*
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* --------------------------------------------------------------------------
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*
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* Pthreads-win32 - POSIX Threads Library for Win32
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* Copyright(C) 1998 John E. Bossom
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* Copyright(C) 1999,2005 Pthreads-win32 contributors
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*
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* Contact Email: rpj@callisto.canberra.edu.au
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*
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* The current list of contributors is contained
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* in the file CONTRIBUTORS included with the source
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* code distribution. The list can also be seen at the
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* following World Wide Web location:
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* http://sources.redhat.com/pthreads-win32/contributors.html
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library in the file COPYING.LIB;
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* if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include "pthread.h"
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#include "implement.h"
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/*
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* Notes on handling system time adjustments (especially negative ones).
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* ---------------------------------------------------------------------
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*
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* This solution was suggested by Alexander Terekhov, but any errors
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* in the implementation are mine - [Ross Johnson]
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*
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* 1) The problem: threads doing a timedwait on a CV may expect to timeout
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* at a specific absolute time according to a system timer. If the
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* system clock is adjusted backwards then those threads sleep longer than
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* expected. Also, pthreads-win32 converts absolute times to intervals in
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* order to make use of the underlying Win32, and so waiting threads may
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* awake before their proper abstimes.
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*
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* 2) We aren't able to distinquish between threads on timed or untimed waits,
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* so we wake them all at the time of the adjustment so that they can
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* re-evaluate their conditions and re-compute their timeouts.
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*
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* 3) We rely on correctly written applications for this to work. Specifically,
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* they must be able to deal properly with spurious wakeups. That is,
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* they must re-test their condition upon wakeup and wait again if
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* the condition is not satisfied.
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*/
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void *
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pthread_timechange_handler_np (void *arg)
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/*
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* ------------------------------------------------------
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* DOCPUBLIC
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* Broadcasts all CVs to force re-evaluation and
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* new timeouts if required.
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*
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* PARAMETERS
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* NONE
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*
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*
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* DESCRIPTION
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* Broadcasts all CVs to force re-evaluation and
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* new timeouts if required.
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*
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* This routine may be passed directly to pthread_create()
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* as a new thread in order to run asynchronously.
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*
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*
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* RESULTS
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* 0 successfully broadcast all CVs
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* EAGAIN Not all CVs were broadcast
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*
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* ------------------------------------------------------
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*/
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{
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int result = 0;
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pthread_cond_t cv;
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ptw32_mcs_local_node_t node;
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ptw32_mcs_lock_acquire(&ptw32_cond_list_lock, &node);
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cv = ptw32_cond_list_head;
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while (cv != NULL && 0 == result)
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{
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result = pthread_cond_broadcast (&cv);
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cv = cv->next;
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}
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ptw32_mcs_lock_release(&node);
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return (void *) (size_t) (result != 0 ? EAGAIN : 0);
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}
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