1 /*****************************************************************************
2 * pthread.c : pthread back-end for LibVLC
3 *****************************************************************************
4 * Copyright (C) 1999-2009 the VideoLAN team
6 * Authors: Jean-Marc Dressler <polux@via.ecp.fr>
7 * Samuel Hocevar <sam@zoy.org>
8 * Gildas Bazin <gbazin@netcourrier.com>
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2 of the License, or
15 * (at your option) any later version.
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
25 *****************************************************************************/
31 #include <vlc_common.h>
36 #include <unistd.h> /* fsync() */
42 # include <sys/syscall.h> /* SYS_gettid */
45 #ifdef HAVE_EXECINFO_H
46 # include <execinfo.h>
50 # include <sys/time.h> /* gettimeofday in vlc_cond_timedwait */
54 * Print a backtrace to the standard error for debugging purpose.
56 void vlc_trace (const char *fn, const char *file, unsigned line)
58 fprintf (stderr, "at %s:%u in %s\n", file, line, fn);
59 fflush (stderr); /* needed before switch to low-level I/O */
62 int len = backtrace (stack, sizeof (stack) / sizeof (stack[0]));
63 backtrace_symbols_fd (stack, len, 2);
68 static inline unsigned long vlc_threadid (void)
70 #if defined (__linux__)
71 /* glibc does not provide a call for this */
72 return syscall (SYS_gettid);
75 union { pthread_t th; unsigned long int i; } v = { };
76 v.th = pthread_self ();
83 /*****************************************************************************
84 * vlc_thread_fatal: Report an error from the threading layer
85 *****************************************************************************
86 * This is mostly meant for debugging.
87 *****************************************************************************/
89 vlc_thread_fatal (const char *action, int error,
90 const char *function, const char *file, unsigned line)
92 int canc = vlc_savecancel ();
93 fprintf (stderr, "LibVLC fatal error %s (%d) in thread %lu ",
94 action, error, vlc_threadid ());
95 vlc_trace (function, file, line);
97 /* Sometimes strerror_r() crashes too, so make sure we print an error
98 * message before we invoke it */
100 /* Avoid the strerror_r() prototype brain damage in glibc */
102 fprintf (stderr, " Error message: %m\n");
107 switch (strerror_r (error, buf, sizeof (buf)))
112 case ERANGE: /* should never happen */
113 msg = "unknwon (too big to display)";
116 msg = "unknown (invalid error number)";
119 fprintf (stderr, " Error message: %s\n", msg);
123 vlc_restorecancel (canc);
127 # define VLC_THREAD_ASSERT( action ) \
129 vlc_thread_fatal (action, val, __func__, __FILE__, __LINE__)
131 # define VLC_THREAD_ASSERT( action ) ((void)val)
134 #if defined (__GLIBC__) && (__GLIBC_MINOR__ < 6)
135 /* This is not prototyped under glibc, though it exists. */
136 int pthread_mutexattr_setkind_np( pthread_mutexattr_t *attr, int kind );
139 /*****************************************************************************
140 * vlc_mutex_init: initialize a mutex
141 *****************************************************************************/
142 void vlc_mutex_init( vlc_mutex_t *p_mutex )
144 pthread_mutexattr_t attr;
146 if (unlikely(pthread_mutexattr_init (&attr)))
149 pthread_mutexattr_settype( &attr, PTHREAD_MUTEX_NORMAL );
151 /* Create error-checking mutex to detect problems more easily. */
152 # if defined (__GLIBC__) && (__GLIBC__ == 2) && (__GLIBC_MINOR__ < 6)
153 pthread_mutexattr_setkind_np( &attr, PTHREAD_MUTEX_ERRORCHECK_NP );
155 pthread_mutexattr_settype( &attr, PTHREAD_MUTEX_ERRORCHECK );
158 if (unlikely(pthread_mutex_init (p_mutex, &attr)))
160 pthread_mutexattr_destroy( &attr );
163 /*****************************************************************************
164 * vlc_mutex_init: initialize a recursive mutex (Do not use)
165 *****************************************************************************/
166 void vlc_mutex_init_recursive( vlc_mutex_t *p_mutex )
168 pthread_mutexattr_t attr;
170 if (unlikely(pthread_mutexattr_init (&attr)))
172 #if defined (__GLIBC__) && (__GLIBC__ == 2) && (__GLIBC_MINOR__ < 6)
173 pthread_mutexattr_setkind_np( &attr, PTHREAD_MUTEX_RECURSIVE_NP );
175 pthread_mutexattr_settype( &attr, PTHREAD_MUTEX_RECURSIVE );
177 if (unlikely(pthread_mutex_init (p_mutex, &attr)))
179 pthread_mutexattr_destroy( &attr );
184 * Destroys a mutex. The mutex must not be locked.
186 * @param p_mutex mutex to destroy
187 * @return always succeeds
189 void vlc_mutex_destroy (vlc_mutex_t *p_mutex)
191 int val = pthread_mutex_destroy( p_mutex );
192 VLC_THREAD_ASSERT ("destroying mutex");
196 # ifdef HAVE_VALGRIND_VALGRIND_H
197 # include <valgrind/valgrind.h>
199 # define RUNNING_ON_VALGRIND (0)
202 void vlc_assert_locked (vlc_mutex_t *p_mutex)
204 if (RUNNING_ON_VALGRIND > 0)
206 assert (pthread_mutex_lock (p_mutex) == EDEADLK);
211 * Acquires a mutex. If needed, waits for any other thread to release it.
212 * Beware of deadlocks when locking multiple mutexes at the same time,
213 * or when using mutexes from callbacks.
214 * This function is not a cancellation-point.
216 * @param p_mutex mutex initialized with vlc_mutex_init() or
217 * vlc_mutex_init_recursive()
219 void vlc_mutex_lock (vlc_mutex_t *p_mutex)
221 int val = pthread_mutex_lock( p_mutex );
222 VLC_THREAD_ASSERT ("locking mutex");
226 * Acquires a mutex if and only if it is not currently held by another thread.
227 * This function never sleeps and can be used in delay-critical code paths.
228 * This function is not a cancellation-point.
230 * <b>Beware</b>: If this function fails, then the mutex is held... by another
231 * thread. The calling thread must deal with the error appropriately. That
232 * typically implies postponing the operations that would have required the
233 * mutex. If the thread cannot defer those operations, then it must use
234 * vlc_mutex_lock(). If in doubt, use vlc_mutex_lock() instead.
236 * @param p_mutex mutex initialized with vlc_mutex_init() or
237 * vlc_mutex_init_recursive()
238 * @return 0 if the mutex could be acquired, an error code otherwise.
240 int vlc_mutex_trylock (vlc_mutex_t *p_mutex)
242 int val = pthread_mutex_trylock( p_mutex );
245 VLC_THREAD_ASSERT ("locking mutex");
250 * Releases a mutex (or crashes if the mutex is not locked by the caller).
251 * @param p_mutex mutex locked with vlc_mutex_lock().
253 void vlc_mutex_unlock (vlc_mutex_t *p_mutex)
255 int val = pthread_mutex_unlock( p_mutex );
256 VLC_THREAD_ASSERT ("unlocking mutex");
260 * Initializes a condition variable.
262 void vlc_cond_init (vlc_cond_t *p_condvar)
264 pthread_condattr_t attr;
266 if (unlikely(pthread_condattr_init (&attr)))
268 #if !defined (_POSIX_CLOCK_SELECTION)
269 /* Fairly outdated POSIX support (that was defined in 2001) */
270 # define _POSIX_CLOCK_SELECTION (-1)
272 #if (_POSIX_CLOCK_SELECTION >= 0)
273 /* NOTE: This must be the same clock as the one in mtime.c */
274 pthread_condattr_setclock (&attr, CLOCK_MONOTONIC);
277 if (unlikely(pthread_cond_init (p_condvar, &attr)))
279 pthread_condattr_destroy (&attr);
283 * Initializes a condition variable.
284 * Contrary to vlc_cond_init(), the wall clock will be used as a reference for
285 * the vlc_cond_timedwait() time-out parameter.
287 void vlc_cond_init_daytime (vlc_cond_t *p_condvar)
289 if (unlikely(pthread_cond_init (p_condvar, NULL)))
294 * Destroys a condition variable. No threads shall be waiting or signaling the
296 * @param p_condvar condition variable to destroy
298 void vlc_cond_destroy (vlc_cond_t *p_condvar)
300 int val = pthread_cond_destroy( p_condvar );
301 VLC_THREAD_ASSERT ("destroying condition");
305 * Wakes up one thread waiting on a condition variable, if any.
306 * @param p_condvar condition variable
308 void vlc_cond_signal (vlc_cond_t *p_condvar)
310 int val = pthread_cond_signal( p_condvar );
311 VLC_THREAD_ASSERT ("signaling condition variable");
315 * Wakes up all threads (if any) waiting on a condition variable.
316 * @param p_cond condition variable
318 void vlc_cond_broadcast (vlc_cond_t *p_condvar)
320 pthread_cond_broadcast (p_condvar);
324 * Waits for a condition variable. The calling thread will be suspended until
325 * another thread calls vlc_cond_signal() or vlc_cond_broadcast() on the same
326 * condition variable, the thread is cancelled with vlc_cancel(), or the
327 * system causes a "spurious" unsolicited wake-up.
329 * A mutex is needed to wait on a condition variable. It must <b>not</b> be
330 * a recursive mutex. Although it is possible to use the same mutex for
331 * multiple condition, it is not valid to use different mutexes for the same
332 * condition variable at the same time from different threads.
334 * In case of thread cancellation, the mutex is always locked before
335 * cancellation proceeds.
337 * The canonical way to use a condition variable to wait for event foobar is:
339 vlc_mutex_lock (&lock);
340 mutex_cleanup_push (&lock); // release the mutex in case of cancellation
343 vlc_cond_wait (&wait, &lock);
345 --- foobar is now true, do something about it here --
347 vlc_cleanup_run (); // release the mutex
350 * @param p_condvar condition variable to wait on
351 * @param p_mutex mutex which is unlocked while waiting,
352 * then locked again when waking up.
353 * @param deadline <b>absolute</b> timeout
355 * @return 0 if the condition was signaled, an error code in case of timeout.
357 void vlc_cond_wait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex)
359 int val = pthread_cond_wait( p_condvar, p_mutex );
360 VLC_THREAD_ASSERT ("waiting on condition");
364 * Waits for a condition variable up to a certain date.
365 * This works like vlc_cond_wait(), except for the additional time-out.
367 * If the variable was initialized with vlc_cond_init(), the timeout has the
368 * same arbitrary origin as mdate(). If the variable was initialized with
369 * vlc_cond_init_daytime(), the timeout is expressed from the Unix epoch.
371 * @param p_condvar condition variable to wait on
372 * @param p_mutex mutex which is unlocked while waiting,
373 * then locked again when waking up.
374 * @param deadline <b>absolute</b> timeout
376 * @return 0 if the condition was signaled, an error code in case of timeout.
378 int vlc_cond_timedwait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex,
381 #if defined(__APPLE__) && !defined(__powerpc__) && !defined( __ppc__ ) && !defined( __ppc64__ )
382 /* mdate() is mac_absolute_time on OSX, which we must convert to do
383 * the same base than gettimeofday() which pthread_cond_timedwait
385 mtime_t oldbase = mdate();
387 gettimeofday(&tv, NULL);
388 mtime_t newbase = (mtime_t)tv.tv_sec * 1000000 + (mtime_t) tv.tv_usec;
389 deadline = deadline - oldbase + newbase;
391 lldiv_t d = lldiv( deadline, CLOCK_FREQ );
392 struct timespec ts = { d.quot, d.rem * (1000000000 / CLOCK_FREQ) };
394 int val = pthread_cond_timedwait (p_condvar, p_mutex, &ts);
395 if (val != ETIMEDOUT)
396 VLC_THREAD_ASSERT ("timed-waiting on condition");
401 * Initializes a semaphore.
403 void vlc_sem_init (vlc_sem_t *sem, unsigned value)
405 if (unlikely(sem_init (sem, 0, value)))
410 * Destroys a semaphore.
412 void vlc_sem_destroy (vlc_sem_t *sem)
414 if (likely(sem_destroy (sem) == 0))
418 VLC_THREAD_ASSERT ("destroying semaphore");
422 * Increments the value of a semaphore.
423 * @return 0 on success, EOVERFLOW in case of integer overflow
425 int vlc_sem_post (vlc_sem_t *sem)
427 if (likely(sem_post (sem) == 0))
431 if (unlikely(val != EOVERFLOW))
432 VLC_THREAD_ASSERT ("unlocking semaphore");
437 * Atomically wait for the semaphore to become non-zero (if needed),
438 * then decrements it.
440 void vlc_sem_wait (vlc_sem_t *sem)
445 if (likely(sem_wait (sem) == 0))
447 while ((val = errno) == EINTR);
449 VLC_THREAD_ASSERT ("locking semaphore");
453 * Initializes a read/write lock.
455 void vlc_rwlock_init (vlc_rwlock_t *lock)
457 if (unlikely(pthread_rwlock_init (lock, NULL)))
462 * Destroys an initialized unused read/write lock.
464 void vlc_rwlock_destroy (vlc_rwlock_t *lock)
466 int val = pthread_rwlock_destroy (lock);
467 VLC_THREAD_ASSERT ("destroying R/W lock");
471 * Acquires a read/write lock for reading. Recursion is allowed.
473 void vlc_rwlock_rdlock (vlc_rwlock_t *lock)
475 int val = pthread_rwlock_rdlock (lock);
476 VLC_THREAD_ASSERT ("acquiring R/W lock for reading");
480 * Acquires a read/write lock for writing. Recursion is not allowed.
482 void vlc_rwlock_wrlock (vlc_rwlock_t *lock)
484 int val = pthread_rwlock_wrlock (lock);
485 VLC_THREAD_ASSERT ("acquiring R/W lock for writing");
489 * Releases a read/write lock.
491 void vlc_rwlock_unlock (vlc_rwlock_t *lock)
493 int val = pthread_rwlock_unlock (lock);
494 VLC_THREAD_ASSERT ("releasing R/W lock");
498 * Allocates a thread-specific variable.
499 * @param key where to store the thread-specific variable handle
500 * @param destr a destruction callback. It is called whenever a thread exits
501 * and the thread-specific variable has a non-NULL value.
502 * @return 0 on success, a system error code otherwise. This function can
503 * actually fail because there is a fixed limit on the number of
504 * thread-specific variable in a process on most systems.
506 int vlc_threadvar_create (vlc_threadvar_t *key, void (*destr) (void *))
508 return pthread_key_create (key, destr);
511 void vlc_threadvar_delete (vlc_threadvar_t *p_tls)
513 pthread_key_delete (*p_tls);
517 * Sets a thread-specific variable.
518 * @param key thread-local variable key (created with vlc_threadvar_create())
519 * @param value new value for the variable for the calling thread
520 * @return 0 on success, a system error code otherwise.
522 int vlc_threadvar_set (vlc_threadvar_t key, void *value)
524 return pthread_setspecific (key, value);
528 * Gets the value of a thread-local variable for the calling thread.
529 * This function cannot fail.
530 * @return the value associated with the given variable for the calling
531 * or NULL if there is no value.
533 void *vlc_threadvar_get (vlc_threadvar_t key)
535 return pthread_getspecific (key);
538 static bool rt_priorities = false;
539 static int rt_offset;
541 void vlc_threads_setup (libvlc_int_t *p_libvlc)
543 static vlc_mutex_t lock = VLC_STATIC_MUTEX;
544 static bool initialized = false;
546 vlc_mutex_lock (&lock);
547 /* Initializes real-time priorities before any thread is created,
548 * just once per process. */
552 if (var_InheritBool (p_libvlc, "rt-priority"))
555 rt_offset = var_InheritInteger (p_libvlc, "rt-offset");
556 rt_priorities = true;
560 vlc_mutex_unlock (&lock);
564 * Creates and starts new thread.
566 * @param p_handle [OUT] pointer to write the handle of the created thread to
567 * @param entry entry point for the thread
568 * @param data data parameter given to the entry point
569 * @param priority thread priority value
570 * @return 0 on success, a standard error code on error.
572 int vlc_clone (vlc_thread_t *p_handle, void * (*entry) (void *), void *data,
578 pthread_attr_init (&attr);
580 /* Block the signals that signals interface plugin handles.
581 * If the LibVLC caller wants to handle some signals by itself, it should
582 * block these before whenever invoking LibVLC. And it must obviously not
583 * start the VLC signals interface plugin.
585 * LibVLC will normally ignore any interruption caused by an asynchronous
586 * signal during a system call. But there may well be some buggy cases
587 * where it fails to handle EINTR (bug reports welcome). Some underlying
588 * libraries might also not handle EINTR properly.
594 sigdelset (&set, SIGHUP);
595 sigaddset (&set, SIGINT);
596 sigaddset (&set, SIGQUIT);
597 sigaddset (&set, SIGTERM);
599 sigaddset (&set, SIGPIPE); /* We don't want this one, really! */
600 pthread_sigmask (SIG_BLOCK, &set, &oldset);
603 #if defined (_POSIX_PRIORITY_SCHEDULING) && (_POSIX_PRIORITY_SCHEDULING >= 0) \
604 && defined (_POSIX_THREAD_PRIORITY_SCHEDULING) \
605 && (_POSIX_THREAD_PRIORITY_SCHEDULING >= 0)
608 struct sched_param sp = { .sched_priority = priority + rt_offset, };
611 if (sp.sched_priority <= 0)
612 sp.sched_priority += sched_get_priority_max (policy = SCHED_OTHER);
614 sp.sched_priority += sched_get_priority_min (policy = SCHED_RR);
616 pthread_attr_setschedpolicy (&attr, policy);
617 pthread_attr_setschedparam (&attr, &sp);
623 /* The thread stack size.
624 * The lower the value, the less address space per thread, the highest
625 * maximum simultaneous threads per process. Too low values will cause
626 * stack overflows and weird crashes. Set with caution. Also keep in mind
627 * that 64-bits platforms consume more stack than 32-bits one.
629 * Thanks to on-demand paging, thread stack size only affects address space
630 * consumption. In terms of memory, threads only use what they need
631 * (rounded up to the page boundary).
633 * For example, on Linux i386, the default is 2 mega-bytes, which supports
634 * about 320 threads per processes. */
635 #define VLC_STACKSIZE (128 * sizeof (void *) * 1024)
638 ret = pthread_attr_setstacksize (&attr, VLC_STACKSIZE);
639 assert (ret == 0); /* fails iif VLC_STACKSIZE is invalid */
642 ret = pthread_create (p_handle, &attr, entry, data);
643 pthread_sigmask (SIG_SETMASK, &oldset, NULL);
644 pthread_attr_destroy (&attr);
649 * Marks a thread as cancelled. Next time the target thread reaches a
650 * cancellation point (while not having disabled cancellation), it will
651 * run its cancellation cleanup handler, the thread variable destructors, and
652 * terminate. vlc_join() must be used afterward regardless of a thread being
655 void vlc_cancel (vlc_thread_t thread_id)
657 pthread_cancel (thread_id);
661 * Waits for a thread to complete (if needed), then destroys it.
662 * This is a cancellation point; in case of cancellation, the join does _not_
665 * A thread cannot join itself (normally VLC will abort if this is attempted).
666 * Also, a detached thread <b>cannot</b> be joined.
668 * @param handle thread handle
669 * @param p_result [OUT] pointer to write the thread return value or NULL
671 void vlc_join (vlc_thread_t handle, void **result)
673 int val = pthread_join (handle, result);
674 VLC_THREAD_ASSERT ("joining thread");
678 * Detaches a thread. When the specified thread completes, it will be
679 * automatically destroyed (in particular, its stack will be reclaimed),
680 * instead of waiting for another thread to call vlc_join(). If the thread has
681 * already completed, it will be destroyed immediately.
683 * When a thread performs some work asynchronously and may complete much
684 * earlier than it can be joined, detaching the thread can save memory.
685 * However, care must be taken that any resources used by a detached thread
686 * remains valid until the thread completes. This will typically involve some
687 * kind of thread-safe signaling.
689 * A thread may detach itself.
691 * @param handle thread handle
693 void vlc_detach (vlc_thread_t handle)
695 int val = pthread_detach (handle);
696 VLC_THREAD_ASSERT ("detaching thread");
700 * Save the current cancellation state (enabled or disabled), then disable
701 * cancellation for the calling thread.
702 * This function must be called before entering a piece of code that is not
703 * cancellation-safe, unless it can be proven that the calling thread will not
705 * @return Previous cancellation state (opaque value for vlc_restorecancel()).
707 int vlc_savecancel (void)
710 int val = pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &state);
712 VLC_THREAD_ASSERT ("saving cancellation");
717 * Restore the cancellation state for the calling thread.
718 * @param state previous state as returned by vlc_savecancel().
719 * @return Nothing, always succeeds.
721 void vlc_restorecancel (int state)
726 val = pthread_setcancelstate (state, &oldstate);
727 /* This should fail if an invalid value for given for state */
728 VLC_THREAD_ASSERT ("restoring cancellation");
730 if (unlikely(oldstate != PTHREAD_CANCEL_DISABLE))
731 vlc_thread_fatal ("restoring cancellation while not disabled", EINVAL,
732 __func__, __FILE__, __LINE__);
734 pthread_setcancelstate (state, NULL);
739 * Issues an explicit deferred cancellation point.
740 * This has no effect if thread cancellation is disabled.
741 * This can be called when there is a rather slow non-sleeping operation.
742 * This is also used to force a cancellation point in a function that would
743 * otherwise "not always" be a one (block_FifoGet() is an example).
745 void vlc_testcancel (void)
747 pthread_testcancel ();
750 void vlc_control_cancel (int cmd, ...)
762 void (*func) (void *);
764 mtime_t value, interval;
769 static void *vlc_timer_do (void *data)
771 struct vlc_timer *timer = data;
773 timer->func (timer->data);
775 vlc_mutex_lock (&timer->lock);
776 assert (timer->users > 0);
777 if (--timer->users == 0)
778 vlc_cond_signal (&timer->wait);
779 vlc_mutex_unlock (&timer->lock);
783 static void *vlc_timer_thread (void *data)
785 struct vlc_timer *timer = data;
786 mtime_t value, interval;
788 vlc_mutex_lock (&timer->lock);
789 value = timer->value;
790 interval = timer->interval;
791 vlc_mutex_unlock (&timer->lock);
799 vlc_mutex_lock (&timer->lock);
800 if (vlc_clone (&th, vlc_timer_do, timer, VLC_THREAD_PRIORITY_INPUT))
807 vlc_mutex_unlock (&timer->lock);
817 * Initializes an asynchronous timer.
818 * @warning Asynchronous timers are processed from an unspecified thread.
819 * Also, multiple occurences of an interval timer can run concurrently.
821 * @param id pointer to timer to be initialized
822 * @param func function that the timer will call
823 * @param data parameter for the timer function
824 * @return 0 on success, a system error code otherwise.
826 int vlc_timer_create (vlc_timer_t *id, void (*func) (void *), void *data)
828 struct vlc_timer *timer = malloc (sizeof (*timer));
830 if (unlikely(timer == NULL))
832 vlc_mutex_init (&timer->lock);
833 vlc_cond_init (&timer->wait);
846 * Destroys an initialized timer. If needed, the timer is first disarmed.
847 * This function is undefined if the specified timer is not initialized.
849 * @warning This function <b>must</b> be called before the timer data can be
850 * freed and before the timer callback function can be unloaded.
852 * @param timer timer to destroy
854 void vlc_timer_destroy (vlc_timer_t timer)
856 vlc_timer_schedule (timer, false, 0, 0);
857 vlc_mutex_lock (&timer->lock);
858 while (timer->users != 0)
859 vlc_cond_wait (&timer->wait, &timer->lock);
860 vlc_mutex_unlock (&timer->lock);
862 vlc_cond_destroy (&timer->wait);
863 vlc_mutex_destroy (&timer->lock);
868 * Arm or disarm an initialized timer.
869 * This functions overrides any previous call to itself.
871 * @note A timer can fire later than requested due to system scheduling
872 * limitations. An interval timer can fail to trigger sometimes, either because
873 * the system is busy or suspended, or because a previous iteration of the
874 * timer is still running. See also vlc_timer_getoverrun().
876 * @param timer initialized timer
877 * @param absolute the timer value origin is the same as mdate() if true,
878 * the timer value is relative to now if false.
879 * @param value zero to disarm the timer, otherwise the initial time to wait
880 * before firing the timer.
881 * @param interval zero to fire the timer just once, otherwise the timer
882 * repetition interval.
884 void vlc_timer_schedule (vlc_timer_t timer, bool absolute,
885 mtime_t value, mtime_t interval)
887 static vlc_mutex_t lock = VLC_STATIC_MUTEX;
889 vlc_mutex_lock (&lock);
890 vlc_mutex_lock (&timer->lock);
893 vlc_mutex_unlock (&timer->lock);
894 vlc_cancel (timer->thread);
895 vlc_join (timer->thread, NULL);
896 vlc_mutex_lock (&timer->lock);
900 && (vlc_clone (&timer->thread, vlc_timer_thread, timer,
901 VLC_THREAD_PRIORITY_INPUT) == 0))
903 timer->value = (absolute ? 0 : mdate ()) + value;
904 timer->interval = interval;
906 vlc_mutex_unlock (&timer->lock);
907 vlc_mutex_unlock (&lock);
911 * Fetch and reset the overrun counter for a timer.
912 * @param timer initialized timer
913 * @return the timer overrun counter, i.e. the number of times that the timer
914 * should have run but did not since the last actual run. If all is well, this
917 unsigned vlc_timer_getoverrun (vlc_timer_t timer)
921 vlc_mutex_lock (&timer->lock);
922 ret = timer->overruns;
924 vlc_mutex_unlock (&timer->lock);