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/*
* -------------------------------------------------------------
*
* Module: sem_timedwait.c
*
* Purpose:
* Semaphores aren't actually part of the PThreads standard.
* They are defined by the POSIX Standard:
*
* POSIX 1003.1b-1993 (POSIX.1b)
*
* -------------------------------------------------------------
*
* --------------------------------------------------------------------------
*
* 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 "semaphore.h"
#include "implement.h"
typedef struct {
sem_t sem;
int * resultPtr;
} sem_timedwait_cleanup_args_t;
static void PTW32_CDECL
ptw32_sem_timedwait_cleanup (void * args)
{
ptw32_mcs_local_node_t node;
sem_timedwait_cleanup_args_t * a = (sem_timedwait_cleanup_args_t *)args;
sem_t s = a->sem;
ptw32_mcs_lock_acquire(&s->lock, &node);
/*
* We either timed out or were cancelled.
* If someone has posted between then and now we try to take the semaphore.
* Otherwise the semaphore count may be wrong after we
* return. In the case of a cancellation, it is as if we
* were cancelled just before we return (after taking the semaphore)
* which is ok.
*/
if (WaitForSingleObject(s->sem, 0) == WAIT_OBJECT_0)
{
/* We got the semaphore on the second attempt */
*(a->resultPtr) = 0;
}
else
{
/* Indicate we're no longer waiting */
s->value++;
#if defined(NEED_SEM)
if (s->value > 0)
{
s->leftToUnblock = 0;
}
#else
/*
* Don't release the W32 sema, it doesn't need adjustment
* because it doesn't record the number of waiters.
*/
#endif
}
ptw32_mcs_lock_release(&node);
}
int
sem_timedwait (sem_t * sem, const struct timespec *abstime)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function waits on a semaphore possibly until
* 'abstime' time.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* abstime
* pointer to an instance of struct timespec
*
* DESCRIPTION
* This function waits on a semaphore. If the
* semaphore value is greater than zero, it decreases
* its value by one. If the semaphore value is zero, then
* the calling thread (or process) is blocked until it can
* successfully decrease the value or until interrupted by
* a signal.
*
* If 'abstime' is a NULL pointer then this function will
* block until it can successfully decrease the value or
* until interrupted by a signal.
*
* RESULTS
* 0 successfully decreased semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS semaphores are not supported,
* EINTR the function was interrupted by a signal,
* EDEADLK a deadlock condition was detected.
* ETIMEDOUT abstime elapsed before success.
*
* ------------------------------------------------------
*/
{
ptw32_mcs_local_node_t node;
DWORD milliseconds;
int v;
int result = 0;
sem_t s = *sem;
pthread_testcancel();
if (abstime == NULL)
{
milliseconds = INFINITE;
}
else
{
/*
* Calculate timeout as milliseconds from current system time.
*/
milliseconds = ptw32_relmillisecs (abstime);
}
ptw32_mcs_lock_acquire(&s->lock, &node);
v = --s->value;
ptw32_mcs_lock_release(&node);
if (v < 0)
{
#if defined(NEED_SEM)
int timedout;
#endif
sem_timedwait_cleanup_args_t cleanup_args;
cleanup_args.sem = s;
cleanup_args.resultPtr = &result;
#if defined(PTW32_CONFIG_MSVC7)
#pragma inline_depth(0)
#endif
/* Must wait */
pthread_cleanup_push(ptw32_sem_timedwait_cleanup, (void *) &cleanup_args);
#if defined(NEED_SEM)
timedout =
#endif
result = pthreadCancelableTimedWait (s->sem, milliseconds);
pthread_cleanup_pop(result);
#if defined(PTW32_CONFIG_MSVC7)
#pragma inline_depth()
#endif
#if defined(NEED_SEM)
if (!timedout)
{
ptw32_mcs_lock_acquire(&s->lock, &node);
if (s->leftToUnblock > 0)
{
--s->leftToUnblock;
SetEvent(s->sem);
}
ptw32_mcs_lock_release(&node);
}
#endif /* NEED_SEM */
}
if (result != 0)
{
PTW32_SET_ERRNO(result);
return -1;
}
return 0;
} /* sem_timedwait */
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