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 */
51 # include <mach/mach_init.h> /* mach_task_self in semaphores */
55 * Print a backtrace to the standard error for debugging purpose.
57 void vlc_trace (const char *fn
, const char *file
, unsigned line
)
59 fprintf (stderr
, "at %s:%u in %s\n", file
, line
, fn
);
60 fflush (stderr
); /* needed before switch to low-level I/O */
63 int len
= backtrace (stack
, sizeof (stack
) / sizeof (stack
[0]));
64 backtrace_symbols_fd (stack
, len
, 2);
69 static inline unsigned long vlc_threadid (void)
71 #if defined (__linux__)
72 /* glibc does not provide a call for this */
73 return syscall (SYS_gettid
);
76 union { pthread_t th
; unsigned long int i
; } v
= { };
77 v
.th
= pthread_self ();
84 /*****************************************************************************
85 * vlc_thread_fatal: Report an error from the threading layer
86 *****************************************************************************
87 * This is mostly meant for debugging.
88 *****************************************************************************/
90 vlc_thread_fatal (const char *action
, int error
,
91 const char *function
, const char *file
, unsigned line
)
93 int canc
= vlc_savecancel ();
94 fprintf (stderr
, "LibVLC fatal error %s (%d) in thread %lu ",
95 action
, error
, vlc_threadid ());
96 vlc_trace (function
, file
, line
);
98 /* Sometimes strerror_r() crashes too, so make sure we print an error
99 * message before we invoke it */
101 /* Avoid the strerror_r() prototype brain damage in glibc */
103 fprintf (stderr
, " Error message: %m\n");
108 switch (strerror_r (error
, buf
, sizeof (buf
)))
113 case ERANGE
: /* should never happen */
114 msg
= "unknwon (too big to display)";
117 msg
= "unknown (invalid error number)";
120 fprintf (stderr
, " Error message: %s\n", msg
);
124 vlc_restorecancel (canc
);
128 # define VLC_THREAD_ASSERT( action ) \
130 vlc_thread_fatal (action, val, __func__, __FILE__, __LINE__)
132 # define VLC_THREAD_ASSERT( action ) ((void)val)
135 #if defined (__GLIBC__) && (__GLIBC_MINOR__ < 6)
136 /* This is not prototyped under glibc, though it exists. */
137 int pthread_mutexattr_setkind_np( pthread_mutexattr_t
*attr
, int kind
);
140 /*****************************************************************************
141 * vlc_mutex_init: initialize a mutex
142 *****************************************************************************/
143 void vlc_mutex_init( vlc_mutex_t
*p_mutex
)
145 pthread_mutexattr_t attr
;
147 if (unlikely(pthread_mutexattr_init (&attr
)))
150 pthread_mutexattr_settype( &attr
, PTHREAD_MUTEX_NORMAL
);
152 /* Create error-checking mutex to detect problems more easily. */
153 # if defined (__GLIBC__) && (__GLIBC__ == 2) && (__GLIBC_MINOR__ < 6)
154 pthread_mutexattr_setkind_np( &attr
, PTHREAD_MUTEX_ERRORCHECK_NP
);
156 pthread_mutexattr_settype( &attr
, PTHREAD_MUTEX_ERRORCHECK
);
159 if (unlikely(pthread_mutex_init (p_mutex
, &attr
)))
161 pthread_mutexattr_destroy( &attr
);
164 /*****************************************************************************
165 * vlc_mutex_init: initialize a recursive mutex (Do not use)
166 *****************************************************************************/
167 void vlc_mutex_init_recursive( vlc_mutex_t
*p_mutex
)
169 pthread_mutexattr_t attr
;
171 if (unlikely(pthread_mutexattr_init (&attr
)))
173 #if defined (__GLIBC__) && (__GLIBC__ == 2) && (__GLIBC_MINOR__ < 6)
174 pthread_mutexattr_setkind_np( &attr
, PTHREAD_MUTEX_RECURSIVE_NP
);
176 pthread_mutexattr_settype( &attr
, PTHREAD_MUTEX_RECURSIVE
);
178 if (unlikely(pthread_mutex_init (p_mutex
, &attr
)))
180 pthread_mutexattr_destroy( &attr
);
185 * Destroys a mutex. The mutex must not be locked.
187 * @param p_mutex mutex to destroy
188 * @return always succeeds
190 void vlc_mutex_destroy (vlc_mutex_t
*p_mutex
)
192 int val
= pthread_mutex_destroy( p_mutex
);
193 VLC_THREAD_ASSERT ("destroying mutex");
197 # ifdef HAVE_VALGRIND_VALGRIND_H
198 # include <valgrind/valgrind.h>
200 # define RUNNING_ON_VALGRIND (0)
203 void vlc_assert_locked (vlc_mutex_t
*p_mutex
)
205 if (RUNNING_ON_VALGRIND
> 0)
207 assert (pthread_mutex_lock (p_mutex
) == EDEADLK
);
212 * Acquires a mutex. If needed, waits for any other thread to release it.
213 * Beware of deadlocks when locking multiple mutexes at the same time,
214 * or when using mutexes from callbacks.
215 * This function is not a cancellation-point.
217 * @param p_mutex mutex initialized with vlc_mutex_init() or
218 * vlc_mutex_init_recursive()
220 void vlc_mutex_lock (vlc_mutex_t
*p_mutex
)
222 int val
= pthread_mutex_lock( p_mutex
);
223 VLC_THREAD_ASSERT ("locking mutex");
227 * Acquires a mutex if and only if it is not currently held by another thread.
228 * This function never sleeps and can be used in delay-critical code paths.
229 * This function is not a cancellation-point.
231 * <b>Beware</b>: If this function fails, then the mutex is held... by another
232 * thread. The calling thread must deal with the error appropriately. That
233 * typically implies postponing the operations that would have required the
234 * mutex. If the thread cannot defer those operations, then it must use
235 * vlc_mutex_lock(). If in doubt, use vlc_mutex_lock() instead.
237 * @param p_mutex mutex initialized with vlc_mutex_init() or
238 * vlc_mutex_init_recursive()
239 * @return 0 if the mutex could be acquired, an error code otherwise.
241 int vlc_mutex_trylock (vlc_mutex_t
*p_mutex
)
243 int val
= pthread_mutex_trylock( p_mutex
);
246 VLC_THREAD_ASSERT ("locking mutex");
251 * Releases a mutex (or crashes if the mutex is not locked by the caller).
252 * @param p_mutex mutex locked with vlc_mutex_lock().
254 void vlc_mutex_unlock (vlc_mutex_t
*p_mutex
)
256 int val
= pthread_mutex_unlock( p_mutex
);
257 VLC_THREAD_ASSERT ("unlocking mutex");
261 * Initializes a condition variable.
263 void vlc_cond_init (vlc_cond_t
*p_condvar
)
265 pthread_condattr_t attr
;
267 if (unlikely(pthread_condattr_init (&attr
)))
269 #if !defined (_POSIX_CLOCK_SELECTION)
270 /* Fairly outdated POSIX support (that was defined in 2001) */
271 # define _POSIX_CLOCK_SELECTION (-1)
273 #if (_POSIX_CLOCK_SELECTION >= 0)
274 /* NOTE: This must be the same clock as the one in mtime.c */
275 pthread_condattr_setclock (&attr
, CLOCK_MONOTONIC
);
278 if (unlikely(pthread_cond_init (p_condvar
, &attr
)))
280 pthread_condattr_destroy (&attr
);
284 * Initializes a condition variable.
285 * Contrary to vlc_cond_init(), the wall clock will be used as a reference for
286 * the vlc_cond_timedwait() time-out parameter.
288 void vlc_cond_init_daytime (vlc_cond_t
*p_condvar
)
290 if (unlikely(pthread_cond_init (p_condvar
, NULL
)))
295 * Destroys a condition variable. No threads shall be waiting or signaling the
297 * @param p_condvar condition variable to destroy
299 void vlc_cond_destroy (vlc_cond_t
*p_condvar
)
301 int val
= pthread_cond_destroy( p_condvar
);
302 VLC_THREAD_ASSERT ("destroying condition");
306 * Wakes up one thread waiting on a condition variable, if any.
307 * @param p_condvar condition variable
309 void vlc_cond_signal (vlc_cond_t
*p_condvar
)
311 int val
= pthread_cond_signal( p_condvar
);
312 VLC_THREAD_ASSERT ("signaling condition variable");
316 * Wakes up all threads (if any) waiting on a condition variable.
317 * @param p_cond condition variable
319 void vlc_cond_broadcast (vlc_cond_t
*p_condvar
)
321 pthread_cond_broadcast (p_condvar
);
325 * Waits for a condition variable. The calling thread will be suspended until
326 * another thread calls vlc_cond_signal() or vlc_cond_broadcast() on the same
327 * condition variable, the thread is cancelled with vlc_cancel(), or the
328 * system causes a "spurious" unsolicited wake-up.
330 * A mutex is needed to wait on a condition variable. It must <b>not</b> be
331 * a recursive mutex. Although it is possible to use the same mutex for
332 * multiple condition, it is not valid to use different mutexes for the same
333 * condition variable at the same time from different threads.
335 * In case of thread cancellation, the mutex is always locked before
336 * cancellation proceeds.
338 * The canonical way to use a condition variable to wait for event foobar is:
340 vlc_mutex_lock (&lock);
341 mutex_cleanup_push (&lock); // release the mutex in case of cancellation
344 vlc_cond_wait (&wait, &lock);
346 --- foobar is now true, do something about it here --
348 vlc_cleanup_run (); // release the mutex
351 * @param p_condvar condition variable to wait on
352 * @param p_mutex mutex which is unlocked while waiting,
353 * then locked again when waking up.
354 * @param deadline <b>absolute</b> timeout
356 * @return 0 if the condition was signaled, an error code in case of timeout.
358 void vlc_cond_wait (vlc_cond_t
*p_condvar
, vlc_mutex_t
*p_mutex
)
360 int val
= pthread_cond_wait( p_condvar
, p_mutex
);
361 VLC_THREAD_ASSERT ("waiting on condition");
365 * Waits for a condition variable up to a certain date.
366 * This works like vlc_cond_wait(), except for the additional time-out.
368 * If the variable was initialized with vlc_cond_init(), the timeout has the
369 * same arbitrary origin as mdate(). If the variable was initialized with
370 * vlc_cond_init_daytime(), the timeout is expressed from the Unix epoch.
372 * @param p_condvar condition variable to wait on
373 * @param p_mutex mutex which is unlocked while waiting,
374 * then locked again when waking up.
375 * @param deadline <b>absolute</b> timeout
377 * @return 0 if the condition was signaled, an error code in case of timeout.
379 int vlc_cond_timedwait (vlc_cond_t
*p_condvar
, vlc_mutex_t
*p_mutex
,
382 #if defined(__APPLE__) && !defined(__powerpc__) && !defined( __ppc__ ) && !defined( __ppc64__ )
383 /* mdate() is the monotonic clock, timedwait origin is gettimeofday() which
384 * isn't monotonic. Use imedwait_relative_np() instead
386 mtime_t base
= mdate();
390 lldiv_t d
= lldiv( deadline
, CLOCK_FREQ
);
391 struct timespec ts
= { d
.quot
, d
.rem
* (1000000000 / CLOCK_FREQ
) };
393 int val
= pthread_cond_timedwait_relative_np(p_condvar
, p_mutex
, &ts
);
394 if (val
!= ETIMEDOUT
)
395 VLC_THREAD_ASSERT ("timed-waiting on condition");
398 lldiv_t d
= lldiv( deadline
, CLOCK_FREQ
);
399 struct timespec ts
= { d
.quot
, d
.rem
* (1000000000 / CLOCK_FREQ
) };
400 int val
= pthread_cond_timedwait (p_condvar
, p_mutex
, &ts
);
401 if (val
!= ETIMEDOUT
)
402 VLC_THREAD_ASSERT ("timed-waiting on condition");
408 * Initializes a semaphore.
410 void vlc_sem_init (vlc_sem_t
*sem
, unsigned value
)
412 #if defined(__APPLE__)
413 if (unlikely(semaphore_create(mach_task_self(), sem
, SYNC_POLICY_FIFO
, value
) != KERN_SUCCESS
))
416 if (unlikely(sem_init (sem
, 0, value
)))
422 * Destroys a semaphore.
424 void vlc_sem_destroy (vlc_sem_t
*sem
)
428 #if defined(__APPLE__)
429 if (likely(semaphore_destroy(mach_task_self(), *sem
) == KERN_SUCCESS
))
434 if (likely(sem_destroy (sem
) == 0))
440 VLC_THREAD_ASSERT ("destroying semaphore");
444 * Increments the value of a semaphore.
445 * @return 0 on success, EOVERFLOW in case of integer overflow
447 int vlc_sem_post (vlc_sem_t
*sem
)
451 #if defined(__APPLE__)
452 if (likely(semaphore_signal(*sem
) == KERN_SUCCESS
))
457 if (likely(sem_post (sem
) == 0))
463 if (unlikely(val
!= EOVERFLOW
))
464 VLC_THREAD_ASSERT ("unlocking semaphore");
469 * Atomically wait for the semaphore to become non-zero (if needed),
470 * then decrements it.
472 void vlc_sem_wait (vlc_sem_t
*sem
)
476 #if defined(__APPLE__)
477 if (likely(semaphore_wait(*sem
) == KERN_SUCCESS
))
483 if (likely(sem_wait (sem
) == 0))
485 while ((val
= errno
) == EINTR
);
488 VLC_THREAD_ASSERT ("locking semaphore");
492 * Initializes a read/write lock.
494 void vlc_rwlock_init (vlc_rwlock_t
*lock
)
496 if (unlikely(pthread_rwlock_init (lock
, NULL
)))
501 * Destroys an initialized unused read/write lock.
503 void vlc_rwlock_destroy (vlc_rwlock_t
*lock
)
505 int val
= pthread_rwlock_destroy (lock
);
506 VLC_THREAD_ASSERT ("destroying R/W lock");
510 * Acquires a read/write lock for reading. Recursion is allowed.
512 void vlc_rwlock_rdlock (vlc_rwlock_t
*lock
)
514 int val
= pthread_rwlock_rdlock (lock
);
515 VLC_THREAD_ASSERT ("acquiring R/W lock for reading");
519 * Acquires a read/write lock for writing. Recursion is not allowed.
521 void vlc_rwlock_wrlock (vlc_rwlock_t
*lock
)
523 int val
= pthread_rwlock_wrlock (lock
);
524 VLC_THREAD_ASSERT ("acquiring R/W lock for writing");
528 * Releases a read/write lock.
530 void vlc_rwlock_unlock (vlc_rwlock_t
*lock
)
532 int val
= pthread_rwlock_unlock (lock
);
533 VLC_THREAD_ASSERT ("releasing R/W lock");
537 * Allocates a thread-specific variable.
538 * @param key where to store the thread-specific variable handle
539 * @param destr a destruction callback. It is called whenever a thread exits
540 * and the thread-specific variable has a non-NULL value.
541 * @return 0 on success, a system error code otherwise. This function can
542 * actually fail because there is a fixed limit on the number of
543 * thread-specific variable in a process on most systems.
545 int vlc_threadvar_create (vlc_threadvar_t
*key
, void (*destr
) (void *))
547 return pthread_key_create (key
, destr
);
550 void vlc_threadvar_delete (vlc_threadvar_t
*p_tls
)
552 pthread_key_delete (*p_tls
);
556 * Sets a thread-specific variable.
557 * @param key thread-local variable key (created with vlc_threadvar_create())
558 * @param value new value for the variable for the calling thread
559 * @return 0 on success, a system error code otherwise.
561 int vlc_threadvar_set (vlc_threadvar_t key
, void *value
)
563 return pthread_setspecific (key
, value
);
567 * Gets the value of a thread-local variable for the calling thread.
568 * This function cannot fail.
569 * @return the value associated with the given variable for the calling
570 * or NULL if there is no value.
572 void *vlc_threadvar_get (vlc_threadvar_t key
)
574 return pthread_getspecific (key
);
577 static bool rt_priorities
= false;
578 static int rt_offset
;
580 void vlc_threads_setup (libvlc_int_t
*p_libvlc
)
582 static vlc_mutex_t lock
= VLC_STATIC_MUTEX
;
583 static bool initialized
= false;
585 vlc_mutex_lock (&lock
);
586 /* Initializes real-time priorities before any thread is created,
587 * just once per process. */
591 if (var_InheritBool (p_libvlc
, "rt-priority"))
594 rt_offset
= var_InheritInteger (p_libvlc
, "rt-offset");
595 rt_priorities
= true;
599 vlc_mutex_unlock (&lock
);
603 * Creates and starts new thread.
605 * @param p_handle [OUT] pointer to write the handle of the created thread to
606 * @param entry entry point for the thread
607 * @param data data parameter given to the entry point
608 * @param priority thread priority value
609 * @return 0 on success, a standard error code on error.
611 int vlc_clone (vlc_thread_t
*p_handle
, void * (*entry
) (void *), void *data
,
617 pthread_attr_init (&attr
);
619 /* Block the signals that signals interface plugin handles.
620 * If the LibVLC caller wants to handle some signals by itself, it should
621 * block these before whenever invoking LibVLC. And it must obviously not
622 * start the VLC signals interface plugin.
624 * LibVLC will normally ignore any interruption caused by an asynchronous
625 * signal during a system call. But there may well be some buggy cases
626 * where it fails to handle EINTR (bug reports welcome). Some underlying
627 * libraries might also not handle EINTR properly.
633 sigdelset (&set
, SIGHUP
);
634 sigaddset (&set
, SIGINT
);
635 sigaddset (&set
, SIGQUIT
);
636 sigaddset (&set
, SIGTERM
);
638 sigaddset (&set
, SIGPIPE
); /* We don't want this one, really! */
639 pthread_sigmask (SIG_BLOCK
, &set
, &oldset
);
642 #if defined (_POSIX_PRIORITY_SCHEDULING) && (_POSIX_PRIORITY_SCHEDULING >= 0) \
643 && defined (_POSIX_THREAD_PRIORITY_SCHEDULING) \
644 && (_POSIX_THREAD_PRIORITY_SCHEDULING >= 0)
647 struct sched_param sp
= { .sched_priority
= priority
+ rt_offset
, };
650 if (sp
.sched_priority
<= 0)
651 sp
.sched_priority
+= sched_get_priority_max (policy
= SCHED_OTHER
);
653 sp
.sched_priority
+= sched_get_priority_min (policy
= SCHED_RR
);
655 pthread_attr_setschedpolicy (&attr
, policy
);
656 pthread_attr_setschedparam (&attr
, &sp
);
662 /* The thread stack size.
663 * The lower the value, the less address space per thread, the highest
664 * maximum simultaneous threads per process. Too low values will cause
665 * stack overflows and weird crashes. Set with caution. Also keep in mind
666 * that 64-bits platforms consume more stack than 32-bits one.
668 * Thanks to on-demand paging, thread stack size only affects address space
669 * consumption. In terms of memory, threads only use what they need
670 * (rounded up to the page boundary).
672 * For example, on Linux i386, the default is 2 mega-bytes, which supports
673 * about 320 threads per processes. */
674 #define VLC_STACKSIZE (128 * sizeof (void *) * 1024)
677 ret
= pthread_attr_setstacksize (&attr
, VLC_STACKSIZE
);
678 assert (ret
== 0); /* fails iif VLC_STACKSIZE is invalid */
681 ret
= pthread_create (p_handle
, &attr
, entry
, data
);
682 pthread_sigmask (SIG_SETMASK
, &oldset
, NULL
);
683 pthread_attr_destroy (&attr
);
688 * Marks a thread as cancelled. Next time the target thread reaches a
689 * cancellation point (while not having disabled cancellation), it will
690 * run its cancellation cleanup handler, the thread variable destructors, and
691 * terminate. vlc_join() must be used afterward regardless of a thread being
694 void vlc_cancel (vlc_thread_t thread_id
)
696 pthread_cancel (thread_id
);
698 pthread_kill (thread_id
, SIGRTMIN
);
703 * Waits for a thread to complete (if needed), then destroys it.
704 * This is a cancellation point; in case of cancellation, the join does _not_
707 * A thread cannot join itself (normally VLC will abort if this is attempted).
708 * Also, a detached thread <b>cannot</b> be joined.
710 * @param handle thread handle
711 * @param p_result [OUT] pointer to write the thread return value or NULL
713 void vlc_join (vlc_thread_t handle
, void **result
)
715 int val
= pthread_join (handle
, result
);
716 VLC_THREAD_ASSERT ("joining thread");
720 * Detaches a thread. When the specified thread completes, it will be
721 * automatically destroyed (in particular, its stack will be reclaimed),
722 * instead of waiting for another thread to call vlc_join(). If the thread has
723 * already completed, it will be destroyed immediately.
725 * When a thread performs some work asynchronously and may complete much
726 * earlier than it can be joined, detaching the thread can save memory.
727 * However, care must be taken that any resources used by a detached thread
728 * remains valid until the thread completes. This will typically involve some
729 * kind of thread-safe signaling.
731 * A thread may detach itself.
733 * @param handle thread handle
735 void vlc_detach (vlc_thread_t handle
)
737 int val
= pthread_detach (handle
);
738 VLC_THREAD_ASSERT ("detaching thread");
742 * Save the current cancellation state (enabled or disabled), then disable
743 * cancellation for the calling thread.
744 * This function must be called before entering a piece of code that is not
745 * cancellation-safe, unless it can be proven that the calling thread will not
747 * @return Previous cancellation state (opaque value for vlc_restorecancel()).
749 int vlc_savecancel (void)
752 int val
= pthread_setcancelstate (PTHREAD_CANCEL_DISABLE
, &state
);
754 VLC_THREAD_ASSERT ("saving cancellation");
759 * Restore the cancellation state for the calling thread.
760 * @param state previous state as returned by vlc_savecancel().
761 * @return Nothing, always succeeds.
763 void vlc_restorecancel (int state
)
768 val
= pthread_setcancelstate (state
, &oldstate
);
769 /* This should fail if an invalid value for given for state */
770 VLC_THREAD_ASSERT ("restoring cancellation");
772 if (unlikely(oldstate
!= PTHREAD_CANCEL_DISABLE
))
773 vlc_thread_fatal ("restoring cancellation while not disabled", EINVAL
,
774 __func__
, __FILE__
, __LINE__
);
776 pthread_setcancelstate (state
, NULL
);
781 * Issues an explicit deferred cancellation point.
782 * This has no effect if thread cancellation is disabled.
783 * This can be called when there is a rather slow non-sleeping operation.
784 * This is also used to force a cancellation point in a function that would
785 * otherwise "not always" be a one (block_FifoGet() is an example).
787 void vlc_testcancel (void)
789 pthread_testcancel ();
792 void vlc_control_cancel (int cmd
, ...)
804 void (*func
) (void *);
806 mtime_t value
, interval
;
811 static void *vlc_timer_do (void *data
)
813 struct vlc_timer
*timer
= data
;
815 timer
->func (timer
->data
);
817 vlc_mutex_lock (&timer
->lock
);
818 assert (timer
->users
> 0);
819 if (--timer
->users
== 0)
820 vlc_cond_signal (&timer
->wait
);
821 vlc_mutex_unlock (&timer
->lock
);
825 static void *vlc_timer_thread (void *data
)
827 struct vlc_timer
*timer
= data
;
828 mtime_t value
, interval
;
830 vlc_mutex_lock (&timer
->lock
);
831 value
= timer
->value
;
832 interval
= timer
->interval
;
833 vlc_mutex_unlock (&timer
->lock
);
841 vlc_mutex_lock (&timer
->lock
);
842 if (vlc_clone (&th
, vlc_timer_do
, timer
, VLC_THREAD_PRIORITY_INPUT
))
849 vlc_mutex_unlock (&timer
->lock
);
859 * Initializes an asynchronous timer.
860 * @warning Asynchronous timers are processed from an unspecified thread.
861 * Also, multiple occurences of an interval timer can run concurrently.
863 * @param id pointer to timer to be initialized
864 * @param func function that the timer will call
865 * @param data parameter for the timer function
866 * @return 0 on success, a system error code otherwise.
868 int vlc_timer_create (vlc_timer_t
*id
, void (*func
) (void *), void *data
)
870 struct vlc_timer
*timer
= malloc (sizeof (*timer
));
872 if (unlikely(timer
== NULL
))
874 vlc_mutex_init (&timer
->lock
);
875 vlc_cond_init (&timer
->wait
);
888 * Destroys an initialized timer. If needed, the timer is first disarmed.
889 * This function is undefined if the specified timer is not initialized.
891 * @warning This function <b>must</b> be called before the timer data can be
892 * freed and before the timer callback function can be unloaded.
894 * @param timer timer to destroy
896 void vlc_timer_destroy (vlc_timer_t timer
)
898 vlc_timer_schedule (timer
, false, 0, 0);
899 vlc_mutex_lock (&timer
->lock
);
900 while (timer
->users
!= 0)
901 vlc_cond_wait (&timer
->wait
, &timer
->lock
);
902 vlc_mutex_unlock (&timer
->lock
);
904 vlc_cond_destroy (&timer
->wait
);
905 vlc_mutex_destroy (&timer
->lock
);
910 * Arm or disarm an initialized timer.
911 * This functions overrides any previous call to itself.
913 * @note A timer can fire later than requested due to system scheduling
914 * limitations. An interval timer can fail to trigger sometimes, either because
915 * the system is busy or suspended, or because a previous iteration of the
916 * timer is still running. See also vlc_timer_getoverrun().
918 * @param timer initialized timer
919 * @param absolute the timer value origin is the same as mdate() if true,
920 * the timer value is relative to now if false.
921 * @param value zero to disarm the timer, otherwise the initial time to wait
922 * before firing the timer.
923 * @param interval zero to fire the timer just once, otherwise the timer
924 * repetition interval.
926 void vlc_timer_schedule (vlc_timer_t timer
, bool absolute
,
927 mtime_t value
, mtime_t interval
)
929 static vlc_mutex_t lock
= VLC_STATIC_MUTEX
;
931 vlc_mutex_lock (&lock
);
932 vlc_mutex_lock (&timer
->lock
);
935 vlc_mutex_unlock (&timer
->lock
);
936 vlc_cancel (timer
->thread
);
937 vlc_join (timer
->thread
, NULL
);
938 vlc_mutex_lock (&timer
->lock
);
942 && (vlc_clone (&timer
->thread
, vlc_timer_thread
, timer
,
943 VLC_THREAD_PRIORITY_INPUT
) == 0))
945 timer
->value
= (absolute
? 0 : mdate ()) + value
;
946 timer
->interval
= interval
;
948 vlc_mutex_unlock (&timer
->lock
);
949 vlc_mutex_unlock (&lock
);
953 * Fetch and reset the overrun counter for a timer.
954 * @param timer initialized timer
955 * @return the timer overrun counter, i.e. the number of times that the timer
956 * should have run but did not since the last actual run. If all is well, this
959 unsigned vlc_timer_getoverrun (vlc_timer_t timer
)
963 vlc_mutex_lock (&timer
->lock
);
964 ret
= timer
->overruns
;
966 vlc_mutex_unlock (&timer
->lock
);