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Diffstat (limited to 'pthread_mutex_timedlock.c')
| -rw-r--r-- | pthread_mutex_timedlock.c | 356 |
1 files changed, 356 insertions, 0 deletions
diff --git a/pthread_mutex_timedlock.c b/pthread_mutex_timedlock.c new file mode 100644 index 0000000..ec1caa9 --- /dev/null +++ b/pthread_mutex_timedlock.c @@ -0,0 +1,356 @@ +/* + * 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); +} |