/*
* pthread_mutex_timedlock.c
*
* Description:
* This translation unit implements mutual exclusion (mutex) primitives.
*
* --------------------------------------------------------------------------
*
* Pthreads-win32 - POSIX Threads Library for Win32
* Copyright(C) 1998 John E. Bossom
* Copyright(C) 1999,2002 Pthreads-win32 contributors
*
* Contact Email: rpj@ise.canberra.edu.au
*
* 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:
* http://sources.redhat.com/pthreads-win32/contributors.html
*
* This 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 of the License, or (at your option) any later version.
*
* This 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 this library in the file COPYING.LIB;
* if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#ifndef _UWIN
# include <process.h>
#endif
#ifndef NEED_FTIME
#include <sys/timeb.h>
#endif
#include "pthread.h"
#include "implement.h"
static INLINE int
ptw32_timed_semwait (sem_t * sem, const struct timespec * abstime)
/*
* ------------------------------------------------------
* DESCRIPTION
* This function waits on a POSIX 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 abstime.
* If abstime has passed when this routine is called then
* it returns a result to indicate this.
*
* 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
* 2 abstime has passed already
* 1 abstime timed out while waiting
* 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.
*
* ------------------------------------------------------
*/
{
int result = 0;
#ifdef NEED_FTIME
struct timespec currSysTime;
#else /* NEED_FTIME */
struct _timeb currSysTime;
#endif /* NEED_FTIME */
const DWORD NANOSEC_PER_MILLISEC = 1000000;
const DWORD MILLISEC_PER_SEC = 1000;
DWORD milliseconds;
DWORD status;
if (sem == NULL)
{
result = EINVAL;
}
else
{
if (abstime == NULL)
{
milliseconds = INFINITE;
}
else
{
/*
* Calculate timeout as milliseconds from current system time.
*/
/* get current system time */
#ifdef NEED_FTIME
{
FILETIME ft;
SYSTEMTIME st;
GetSystemTime(&st);
SystemTimeToFileTime(&st, &ft);
/*
* GetSystemTimeAsFileTime(&ft); would be faster,
* but it does not exist on WinCE
*/
ptw32_filetime_to_timespec(&ft, &currSysTime);
}
/*
* subtract current system time from abstime
*/
milliseconds = (abstime->tv_sec - currSysTime.tv_sec) * MILLISEC_PER_SEC;
milliseconds += ((abstime->tv_nsec - currSysTime.tv_nsec)
+ (NANOSEC_PER_MILLISEC/2)) / NANOSEC_PER_MILLISEC;
#else /* NEED_FTIME */
_ftime(&currSysTime);
/*
* subtract current system time from abstime
*/
milliseconds = (abstime->tv_sec - currSysTime.time) * MILLISEC_PER_SEC;
milliseconds += ((abstime->tv_nsec + (NANOSEC_PER_MILLISEC/2)) / NANOSEC_PER_MILLISEC)
- currSysTime.millitm;
#endif /* NEED_FTIME */
if (((int) milliseconds) < 0)
{
return 2;
}
}
#ifdef NEED_SEM
status = WaitForSingleObject( (*sem)->event, milliseconds );
#else /* NEED_SEM */
status = WaitForSingleObject( (*sem)->sem, milliseconds );
#endif
if (status == WAIT_OBJECT_0)
{
#ifdef NEED_SEM
ptw32_decrease_semaphore(sem);
#endif /* NEED_SEM */
return 0;
}
else if (status == WAIT_TIMEOUT)
{
return 1;
}
else
{
result = EINVAL;
}
}
if (result != 0)
{
errno = result;
return -1;
}
return 0;
} /* ptw32_timed_semwait */
int
pthread_mutex_timedlock(pthread_mutex_t *mutex, const struct timespec *abstime)
{
int result = 0;
pthread_mutex_t mx;
#ifdef NEED_SEM
errno = ENOTSUP;
return -1;
#endif
if (mutex == NULL || *mutex == NULL)
{
return EINVAL;
}
/*
* We do a quick check to see if we need to do more work
* to initialise a static mutex. We check
* again inside the guarded section of ptw32_mutex_check_need_init()
* to avoid race conditions.
*/
if (*mutex == PTHREAD_MUTEX_INITIALIZER)
{
if ((result = ptw32_mutex_check_need_init(mutex)) != 0)
{
return(result);
}
}
mx = *mutex;
if( 0 == InterlockedIncrement( &mx->lock_idx ) )
{
mx->recursive_count = 1;
mx->ownerThread = (mx->kind != PTHREAD_MUTEX_FAST_NP
? pthread_self()
: (pthread_t) PTW32_MUTEX_OWNER_ANONYMOUS);
}
else
{
if( mx->kind != PTHREAD_MUTEX_FAST_NP &&
pthread_equal( mx->ownerThread, pthread_self() ) )
{
(void) InterlockedDecrement( &mx->lock_idx );
if( mx->kind == PTHREAD_MUTEX_RECURSIVE_NP )
{
mx->recursive_count++;
}
else
{
result = EDEADLK;
}
}
else
{
if (abstime == NULL)
{
result = EINVAL;
}
else
{
switch (ptw32_timed_semwait( &mx->wait_sema, abstime ))
{
case 0: /* We got the mutex. */
{
mx->recursive_count = 1;
mx->ownerThread = (mx->kind != PTHREAD_MUTEX_FAST_NP
? pthread_self()
: (pthread_t) PTW32_MUTEX_OWNER_ANONYMOUS);
break;
}
case 1: /* Timedout, try a second grab. */
{
EnterCriticalSection(&mx->wait_cs);
/*
* If we timeout, it is up to us to adjust lock_idx to say
* we're no longer waiting. If the mutex was also unlocked
* while we were timing out, and we simply return ETIMEDOUT,
* then wait_sema would be left in a state that is not consistent
* with the state of lock_idx.
*
* We must check to see if wait_sema has just been posted
* but we can't just call sem_getvalue - we must compete for
* the semaphore using sem_trywait(), otherwise we would need
* additional critical sections elsewhere, which would make the
* logic too inefficient.
*
* If sem_trywait returns EAGAIN then either wait_sema
* was given directly to another waiting thread or
* another thread has called sem_*wait() before us and
* taken the lock. Then we MUST decrement lock_idx and return
* ETIMEDOUT.
*
* Otherwise we MUST return success (because we have effectively
* acquired the lock that would have been ours had we not
* timed out), and NOT decrement lock_idx.
*
* We can almost guarrantee that EAGAIN is the only
* possible error, so no need to test errno.
*/
if ( -1 == sem_trywait( &mx->wait_sema ) )
{
(void) InterlockedDecrement( &mx->lock_idx );
result = ETIMEDOUT;
}
LeaveCriticalSection(&mx->wait_cs);
break;
}
case 2: /* abstime passed before we started to wait. */
{
/*
* If we timeout, it is up to us to adjust lock_idx to say
* we're no longer waiting.
*
* The owner thread may still have posted wait_sema thinking
* we were waiting. I believe we must check but then NOT do any
* programmed work if we have acquired the mutex because
* we don't how long ago abstime was. We MUST just release it
* immediately.
*/
EnterCriticalSection(&mx->wait_cs);
result = ETIMEDOUT;
if ( -1 == sem_trywait( &mx->wait_sema ) )
{
(void) InterlockedDecrement( &mx->lock_idx );
}
else
{
if ( InterlockedDecrement( &mx->lock_idx ) >= 0 )
{
/* Someone else is waiting on that mutex */
if ( sem_post( &mx->wait_sema ) != 0 )
{
result = errno;
}
}
}
LeaveCriticalSection(&mx->wait_cs);
break;
}
default:
{
result = errno;
break;
}
}
}
}
}
return(result);
}