1 /*****************************************************************************
2 * thread.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>
32 #include <vlc_atomic.h>
37 #include <unistd.h> /* fsync() */
44 # include <sys/syscall.h> /* SYS_gettid */
47 #ifdef HAVE_EXECINFO_H
48 # include <execinfo.h>
52 # include <sys/time.h> /* gettimeofday in vlc_cond_timedwait */
53 # include <mach/mach_init.h> /* mach_task_self in semaphores */
54 # include <sys/sysctl.h>
57 #if defined(__OpenBSD__)
58 # include <sys/param.h>
59 # include <sys/sysctl.h>
60 # include <machine/cpu.h>
65 # include <sys/types.h>
66 # include <sys/processor.h>
67 # include <sys/pset.h>
70 #if !defined (_POSIX_TIMERS)
71 # define _POSIX_TIMERS (-1)
73 #if !defined (_POSIX_CLOCK_SELECTION)
74 /* Clock selection was defined in 2001 and became mandatory in 2008. */
75 # define _POSIX_CLOCK_SELECTION (-1)
77 #if !defined (_POSIX_MONOTONIC_CLOCK)
78 # define _POSIX_MONOTONIC_CLOCK (-1)
81 #if (_POSIX_TIMERS > 0)
82 static unsigned vlc_clock_prec;
84 # if (_POSIX_CLOCK_SELECTION > 0)
85 /* POSIX clock selection is needed so that vlc_cond_timewait() is consistent
86 * with mdate() and mwait(). Otherwise, the monotonic clock cannot be used.
87 * Fortunately, clock selection has become mandatory as of 2008 so that really
88 * only broken old systems still lack it. */
90 # if (_POSIX_MONOTONIC_CLOCK > 0)
91 /* Compile-time POSIX monotonic clock support */
92 # define vlc_clock_id (CLOCK_MONOTONIC)
94 # elif (_POSIX_MONOTONIC_CLOCK == 0)
95 /* Run-time POSIX monotonic clock support (see clock_setup() below) */
96 static clockid_t vlc_clock_id;
99 /* No POSIX monotonic clock support */
100 # define vlc_clock_id (CLOCK_REALTIME)
101 # warning Monotonic clock not available. Expect timing issues.
103 # endif /* _POSIX_MONOTONIC_CLOKC */
105 /* No POSIX clock selection. */
106 # define pthread_condattr_setclock(attr, clock) (attr, clock, 0)
107 # warning Clock selection not available. Expect timing issues.
109 # endif /* _POSIX_CLOCK_SELECTION */
111 static void vlc_clock_setup_once (void)
113 # if (_POSIX_MONOTONIC_CLOCK == 0)
114 long val = sysconf (_SC_MONOTONIC_CLOCK);
116 vlc_clock_id = (val < 0) ? CLOCK_REALTIME : CLOCK_MONOTONIC;
120 if (unlikely(clock_getres (vlc_clock_id, &res) != 0 || res.tv_sec != 0))
122 vlc_clock_prec = (res.tv_nsec + 500) / 1000;
125 static pthread_once_t vlc_clock_once = PTHREAD_ONCE_INIT;
127 # define vlc_clock_setup() \
128 pthread_once(&vlc_clock_once, vlc_clock_setup_once)
130 #else /* _POSIX_TIMERS */
132 # include <sys/time.h> /* gettimeofday() */
133 # if defined (HAVE_DECL_NANOSLEEP) && !HAVE_DECL_NANOSLEEP
134 int nanosleep (struct timespec *, struct timespec *);
137 #endif /* _POSIX_TIMERS */
140 * Print a backtrace to the standard error for debugging purpose.
142 void vlc_trace (const char *fn, const char *file, unsigned line)
144 fprintf (stderr, "at %s:%u in %s\n", file, line, fn);
145 fflush (stderr); /* needed before switch to low-level I/O */
146 #ifdef HAVE_BACKTRACE
148 int len = backtrace (stack, sizeof (stack) / sizeof (stack[0]));
149 backtrace_symbols_fd (stack, len, 2);
154 static inline unsigned long vlc_threadid (void)
156 #if defined (__linux__)
157 /* glibc does not provide a call for this */
158 return syscall (SYS_gettid);
161 union { pthread_t th; unsigned long int i; } v = { };
162 v.th = pthread_self ();
169 /*****************************************************************************
170 * vlc_thread_fatal: Report an error from the threading layer
171 *****************************************************************************
172 * This is mostly meant for debugging.
173 *****************************************************************************/
175 vlc_thread_fatal (const char *action, int error,
176 const char *function, const char *file, unsigned line)
178 int canc = vlc_savecancel ();
179 fprintf (stderr, "LibVLC fatal error %s (%d) in thread %lu ",
180 action, error, vlc_threadid ());
181 vlc_trace (function, file, line);
183 /* Sometimes strerror_r() crashes too, so make sure we print an error
184 * message before we invoke it */
186 /* Avoid the strerror_r() prototype brain damage in glibc */
188 fprintf (stderr, " Error message: %m\n");
193 switch (strerror_r (error, buf, sizeof (buf)))
198 case ERANGE: /* should never happen */
199 msg = "unknown (too big to display)";
202 msg = "unknown (invalid error number)";
205 fprintf (stderr, " Error message: %s\n", msg);
209 vlc_restorecancel (canc);
213 # define VLC_THREAD_ASSERT( action ) \
215 vlc_thread_fatal (action, val, __func__, __FILE__, __LINE__)
217 # define VLC_THREAD_ASSERT( action ) ((void)val)
220 #if defined (__GLIBC__) && (__GLIBC_MINOR__ < 6)
221 /* This is not prototyped under glibc, though it exists. */
222 int pthread_mutexattr_setkind_np( pthread_mutexattr_t *attr, int kind );
225 /*****************************************************************************
226 * vlc_mutex_init: initialize a mutex
227 *****************************************************************************/
228 void vlc_mutex_init( vlc_mutex_t *p_mutex )
230 pthread_mutexattr_t attr;
232 if (unlikely(pthread_mutexattr_init (&attr)))
235 pthread_mutexattr_settype( &attr, PTHREAD_MUTEX_NORMAL );
237 /* Create error-checking mutex to detect problems more easily. */
238 # if defined (__GLIBC__) && (__GLIBC__ == 2) && (__GLIBC_MINOR__ < 6)
239 pthread_mutexattr_setkind_np( &attr, PTHREAD_MUTEX_ERRORCHECK_NP );
241 pthread_mutexattr_settype( &attr, PTHREAD_MUTEX_ERRORCHECK );
244 if (unlikely(pthread_mutex_init (p_mutex, &attr)))
246 pthread_mutexattr_destroy( &attr );
249 /*****************************************************************************
250 * vlc_mutex_init: initialize a recursive mutex (Do not use)
251 *****************************************************************************/
252 void vlc_mutex_init_recursive( vlc_mutex_t *p_mutex )
254 pthread_mutexattr_t attr;
256 if (unlikely(pthread_mutexattr_init (&attr)))
258 #if defined (__GLIBC__) && (__GLIBC__ == 2) && (__GLIBC_MINOR__ < 6)
259 pthread_mutexattr_setkind_np( &attr, PTHREAD_MUTEX_RECURSIVE_NP );
261 pthread_mutexattr_settype( &attr, PTHREAD_MUTEX_RECURSIVE );
263 if (unlikely(pthread_mutex_init (p_mutex, &attr)))
265 pthread_mutexattr_destroy( &attr );
270 * Destroys a mutex. The mutex must not be locked.
272 * @param p_mutex mutex to destroy
273 * @return always succeeds
275 void vlc_mutex_destroy (vlc_mutex_t *p_mutex)
277 int val = pthread_mutex_destroy( p_mutex );
278 VLC_THREAD_ASSERT ("destroying mutex");
282 # ifdef HAVE_VALGRIND_VALGRIND_H
283 # include <valgrind/valgrind.h>
285 # define RUNNING_ON_VALGRIND (0)
288 void vlc_assert_locked (vlc_mutex_t *p_mutex)
290 if (RUNNING_ON_VALGRIND > 0)
292 assert (pthread_mutex_lock (p_mutex) == EDEADLK);
297 * Acquires a mutex. If needed, waits for any other thread to release it.
298 * Beware of deadlocks when locking multiple mutexes at the same time,
299 * or when using mutexes from callbacks.
300 * This function is not a cancellation-point.
302 * @param p_mutex mutex initialized with vlc_mutex_init() or
303 * vlc_mutex_init_recursive()
305 void vlc_mutex_lock (vlc_mutex_t *p_mutex)
307 int val = pthread_mutex_lock( p_mutex );
308 VLC_THREAD_ASSERT ("locking mutex");
312 * Acquires a mutex if and only if it is not currently held by another thread.
313 * This function never sleeps and can be used in delay-critical code paths.
314 * This function is not a cancellation-point.
316 * <b>Beware</b>: If this function fails, then the mutex is held... by another
317 * thread. The calling thread must deal with the error appropriately. That
318 * typically implies postponing the operations that would have required the
319 * mutex. If the thread cannot defer those operations, then it must use
320 * vlc_mutex_lock(). If in doubt, use vlc_mutex_lock() instead.
322 * @param p_mutex mutex initialized with vlc_mutex_init() or
323 * vlc_mutex_init_recursive()
324 * @return 0 if the mutex could be acquired, an error code otherwise.
326 int vlc_mutex_trylock (vlc_mutex_t *p_mutex)
328 int val = pthread_mutex_trylock( p_mutex );
331 VLC_THREAD_ASSERT ("locking mutex");
336 * Releases a mutex (or crashes if the mutex is not locked by the caller).
337 * @param p_mutex mutex locked with vlc_mutex_lock().
339 void vlc_mutex_unlock (vlc_mutex_t *p_mutex)
341 int val = pthread_mutex_unlock( p_mutex );
342 VLC_THREAD_ASSERT ("unlocking mutex");
346 * Initializes a condition variable.
348 void vlc_cond_init (vlc_cond_t *p_condvar)
350 pthread_condattr_t attr;
353 if (unlikely(pthread_condattr_init (&attr)))
355 pthread_condattr_setclock (&attr, vlc_clock_id);
357 if (unlikely(pthread_cond_init (p_condvar, &attr)))
359 pthread_condattr_destroy (&attr);
363 * Initializes a condition variable.
364 * Contrary to vlc_cond_init(), the wall clock will be used as a reference for
365 * the vlc_cond_timedwait() time-out parameter.
367 void vlc_cond_init_daytime (vlc_cond_t *p_condvar)
369 if (unlikely(pthread_cond_init (p_condvar, NULL)))
374 * Destroys a condition variable. No threads shall be waiting or signaling the
376 * @param p_condvar condition variable to destroy
378 void vlc_cond_destroy (vlc_cond_t *p_condvar)
380 int val = pthread_cond_destroy( p_condvar );
381 VLC_THREAD_ASSERT ("destroying condition");
385 * Wakes up one thread waiting on a condition variable, if any.
386 * @param p_condvar condition variable
388 void vlc_cond_signal (vlc_cond_t *p_condvar)
390 int val = pthread_cond_signal( p_condvar );
391 VLC_THREAD_ASSERT ("signaling condition variable");
395 * Wakes up all threads (if any) waiting on a condition variable.
396 * @param p_cond condition variable
398 void vlc_cond_broadcast (vlc_cond_t *p_condvar)
400 pthread_cond_broadcast (p_condvar);
404 * Waits for a condition variable. The calling thread will be suspended until
405 * another thread calls vlc_cond_signal() or vlc_cond_broadcast() on the same
406 * condition variable, the thread is cancelled with vlc_cancel(), or the
407 * system causes a "spurious" unsolicited wake-up.
409 * A mutex is needed to wait on a condition variable. It must <b>not</b> be
410 * a recursive mutex. Although it is possible to use the same mutex for
411 * multiple condition, it is not valid to use different mutexes for the same
412 * condition variable at the same time from different threads.
414 * In case of thread cancellation, the mutex is always locked before
415 * cancellation proceeds.
417 * The canonical way to use a condition variable to wait for event foobar is:
419 vlc_mutex_lock (&lock);
420 mutex_cleanup_push (&lock); // release the mutex in case of cancellation
423 vlc_cond_wait (&wait, &lock);
425 --- foobar is now true, do something about it here --
427 vlc_cleanup_run (); // release the mutex
430 * @param p_condvar condition variable to wait on
431 * @param p_mutex mutex which is unlocked while waiting,
432 * then locked again when waking up.
433 * @param deadline <b>absolute</b> timeout
435 void vlc_cond_wait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex)
437 int val = pthread_cond_wait( p_condvar, p_mutex );
438 VLC_THREAD_ASSERT ("waiting on condition");
442 * Waits for a condition variable up to a certain date.
443 * This works like vlc_cond_wait(), except for the additional time-out.
445 * If the variable was initialized with vlc_cond_init(), the timeout has the
446 * same arbitrary origin as mdate(). If the variable was initialized with
447 * vlc_cond_init_daytime(), the timeout is expressed from the Unix epoch.
449 * @param p_condvar condition variable to wait on
450 * @param p_mutex mutex which is unlocked while waiting,
451 * then locked again when waking up.
452 * @param deadline <b>absolute</b> timeout
454 * @return 0 if the condition was signaled, an error code in case of timeout.
456 int vlc_cond_timedwait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex,
459 #if defined(__APPLE__) && !defined(__powerpc__) && !defined( __ppc__ ) && !defined( __ppc64__ )
460 /* mdate() is the monotonic clock, timedwait origin is gettimeofday() which
461 * isn't monotonic. Use imedwait_relative_np() instead
463 mtime_t base = mdate();
467 lldiv_t d = lldiv( deadline, CLOCK_FREQ );
468 struct timespec ts = { d.quot, d.rem * (1000000000 / CLOCK_FREQ) };
470 int val = pthread_cond_timedwait_relative_np(p_condvar, p_mutex, &ts);
472 lldiv_t d = lldiv( deadline, CLOCK_FREQ );
473 struct timespec ts = { d.quot, d.rem * (1000000000 / CLOCK_FREQ) };
474 int val = pthread_cond_timedwait (p_condvar, p_mutex, &ts);
476 if (val != ETIMEDOUT)
477 VLC_THREAD_ASSERT ("timed-waiting on condition");
482 * Initializes a semaphore.
484 void vlc_sem_init (vlc_sem_t *sem, unsigned value)
486 #if defined(__APPLE__)
487 if (unlikely(semaphore_create(mach_task_self(), sem, SYNC_POLICY_FIFO, value) != KERN_SUCCESS))
490 if (unlikely(sem_init (sem, 0, value)))
496 * Destroys a semaphore.
498 void vlc_sem_destroy (vlc_sem_t *sem)
502 #if defined(__APPLE__)
503 if (likely(semaphore_destroy(mach_task_self(), *sem) == KERN_SUCCESS))
508 if (likely(sem_destroy (sem) == 0))
514 VLC_THREAD_ASSERT ("destroying semaphore");
518 * Increments the value of a semaphore.
519 * @return 0 on success, EOVERFLOW in case of integer overflow
521 int vlc_sem_post (vlc_sem_t *sem)
525 #if defined(__APPLE__)
526 if (likely(semaphore_signal(*sem) == KERN_SUCCESS))
531 if (likely(sem_post (sem) == 0))
537 if (unlikely(val != EOVERFLOW))
538 VLC_THREAD_ASSERT ("unlocking semaphore");
543 * Atomically wait for the semaphore to become non-zero (if needed),
544 * then decrements it.
546 void vlc_sem_wait (vlc_sem_t *sem)
550 #if defined(__APPLE__)
551 if (likely(semaphore_wait(*sem) == KERN_SUCCESS))
557 if (likely(sem_wait (sem) == 0))
559 while ((val = errno) == EINTR);
562 VLC_THREAD_ASSERT ("locking semaphore");
566 * Initializes a read/write lock.
568 void vlc_rwlock_init (vlc_rwlock_t *lock)
570 if (unlikely(pthread_rwlock_init (lock, NULL)))
575 * Destroys an initialized unused read/write lock.
577 void vlc_rwlock_destroy (vlc_rwlock_t *lock)
579 int val = pthread_rwlock_destroy (lock);
580 VLC_THREAD_ASSERT ("destroying R/W lock");
584 * Acquires a read/write lock for reading. Recursion is allowed.
586 void vlc_rwlock_rdlock (vlc_rwlock_t *lock)
588 int val = pthread_rwlock_rdlock (lock);
589 VLC_THREAD_ASSERT ("acquiring R/W lock for reading");
593 * Acquires a read/write lock for writing. Recursion is not allowed.
595 void vlc_rwlock_wrlock (vlc_rwlock_t *lock)
597 int val = pthread_rwlock_wrlock (lock);
598 VLC_THREAD_ASSERT ("acquiring R/W lock for writing");
602 * Releases a read/write lock.
604 void vlc_rwlock_unlock (vlc_rwlock_t *lock)
606 int val = pthread_rwlock_unlock (lock);
607 VLC_THREAD_ASSERT ("releasing R/W lock");
611 * Allocates a thread-specific variable.
612 * @param key where to store the thread-specific variable handle
613 * @param destr a destruction callback. It is called whenever a thread exits
614 * and the thread-specific variable has a non-NULL value.
615 * @return 0 on success, a system error code otherwise. This function can
616 * actually fail because there is a fixed limit on the number of
617 * thread-specific variable in a process on most systems.
619 int vlc_threadvar_create (vlc_threadvar_t *key, void (*destr) (void *))
621 return pthread_key_create (key, destr);
624 void vlc_threadvar_delete (vlc_threadvar_t *p_tls)
626 pthread_key_delete (*p_tls);
630 * Sets a thread-specific variable.
631 * @param key thread-local variable key (created with vlc_threadvar_create())
632 * @param value new value for the variable for the calling thread
633 * @return 0 on success, a system error code otherwise.
635 int vlc_threadvar_set (vlc_threadvar_t key, void *value)
637 return pthread_setspecific (key, value);
641 * Gets the value of a thread-local variable for the calling thread.
642 * This function cannot fail.
643 * @return the value associated with the given variable for the calling
644 * or NULL if there is no value.
646 void *vlc_threadvar_get (vlc_threadvar_t key)
648 return pthread_getspecific (key);
651 static bool rt_priorities = false;
652 static int rt_offset;
654 void vlc_threads_setup (libvlc_int_t *p_libvlc)
656 static vlc_mutex_t lock = VLC_STATIC_MUTEX;
657 static bool initialized = false;
659 vlc_mutex_lock (&lock);
660 /* Initializes real-time priorities before any thread is created,
661 * just once per process. */
665 if (var_InheritBool (p_libvlc, "rt-priority"))
668 rt_offset = var_InheritInteger (p_libvlc, "rt-offset");
669 rt_priorities = true;
673 vlc_mutex_unlock (&lock);
677 static int vlc_clone_attr (vlc_thread_t *th, pthread_attr_t *attr,
678 void *(*entry) (void *), void *data, int priority)
682 /* Block the signals that signals interface plugin handles.
683 * If the LibVLC caller wants to handle some signals by itself, it should
684 * block these before whenever invoking LibVLC. And it must obviously not
685 * start the VLC signals interface plugin.
687 * LibVLC will normally ignore any interruption caused by an asynchronous
688 * signal during a system call. But there may well be some buggy cases
689 * where it fails to handle EINTR (bug reports welcome). Some underlying
690 * libraries might also not handle EINTR properly.
696 sigdelset (&set, SIGHUP);
697 sigaddset (&set, SIGINT);
698 sigaddset (&set, SIGQUIT);
699 sigaddset (&set, SIGTERM);
701 sigaddset (&set, SIGPIPE); /* We don't want this one, really! */
702 pthread_sigmask (SIG_BLOCK, &set, &oldset);
705 #if defined (_POSIX_PRIORITY_SCHEDULING) && (_POSIX_PRIORITY_SCHEDULING >= 0) \
706 && defined (_POSIX_THREAD_PRIORITY_SCHEDULING) \
707 && (_POSIX_THREAD_PRIORITY_SCHEDULING >= 0)
710 struct sched_param sp = { .sched_priority = priority + rt_offset, };
713 if (sp.sched_priority <= 0)
714 sp.sched_priority += sched_get_priority_max (policy = SCHED_OTHER);
716 sp.sched_priority += sched_get_priority_min (policy = SCHED_RR);
718 pthread_attr_setschedpolicy (attr, policy);
719 pthread_attr_setschedparam (attr, &sp);
725 /* The thread stack size.
726 * The lower the value, the less address space per thread, the highest
727 * maximum simultaneous threads per process. Too low values will cause
728 * stack overflows and weird crashes. Set with caution. Also keep in mind
729 * that 64-bits platforms consume more stack than 32-bits one.
731 * Thanks to on-demand paging, thread stack size only affects address space
732 * consumption. In terms of memory, threads only use what they need
733 * (rounded up to the page boundary).
735 * For example, on Linux i386, the default is 2 mega-bytes, which supports
736 * about 320 threads per processes. */
737 #define VLC_STACKSIZE (128 * sizeof (void *) * 1024)
740 ret = pthread_attr_setstacksize (attr, VLC_STACKSIZE);
741 assert (ret == 0); /* fails iif VLC_STACKSIZE is invalid */
744 ret = pthread_create (th, attr, entry, data);
745 pthread_sigmask (SIG_SETMASK, &oldset, NULL);
746 pthread_attr_destroy (attr);
751 * Creates and starts new thread.
753 * The thread must be <i>joined</i> with vlc_join() to reclaim resources
754 * when it is not needed anymore.
756 * @param th [OUT] pointer to write the handle of the created thread to
757 * (mandatory, must be non-NULL)
758 * @param entry entry point for the thread
759 * @param data data parameter given to the entry point
760 * @param priority thread priority value
761 * @return 0 on success, a standard error code on error.
763 int vlc_clone (vlc_thread_t *th, void *(*entry) (void *), void *data,
768 pthread_attr_init (&attr);
769 return vlc_clone_attr (th, &attr, entry, data, priority);
773 * Waits for a thread to complete (if needed), then destroys it.
774 * This is a cancellation point; in case of cancellation, the join does _not_
777 * A thread cannot join itself (normally VLC will abort if this is attempted).
778 * Also, a detached thread <b>cannot</b> be joined.
780 * @param handle thread handle
781 * @param p_result [OUT] pointer to write the thread return value or NULL
783 void vlc_join (vlc_thread_t handle, void **result)
785 int val = pthread_join (handle, result);
786 VLC_THREAD_ASSERT ("joining thread");
790 * Creates and starts new detached thread.
791 * A detached thread cannot be joined. Its resources will be automatically
792 * released whenever the thread exits (in particular, its call stack will be
795 * Detached thread are particularly useful when some work needs to be done
796 * asynchronously, that is likely to be completed much earlier than the thread
797 * can practically be joined. In this case, thread detach can spare memory.
799 * A detached thread may be cancelled, so as to expedite its termination.
800 * Be extremely careful if you do this: while a normal joinable thread can
801 * safely be cancelled after it has already exited, cancelling an already
802 * exited detached thread is undefined: The thread handle would is destroyed
803 * immediately when the detached thread exits. So you need to ensure that the
804 * detached thread is still running before cancellation is attempted.
806 * @warning Care must be taken that any resources used by the detached thread
807 * remains valid until the thread completes.
809 * @note A detached thread must eventually exit just like another other
810 * thread. In practice, LibVLC will wait for detached threads to exit before
811 * it unloads the plugins.
813 * @param th [OUT] pointer to hold the thread handle, or NULL
814 * @param entry entry point for the thread
815 * @param data data parameter given to the entry point
816 * @param priority thread priority value
817 * @return 0 on success, a standard error code on error.
819 int vlc_clone_detach (vlc_thread_t *th, void *(*entry) (void *), void *data,
828 pthread_attr_init (&attr);
829 pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
830 return vlc_clone_attr (th, &attr, entry, data, priority);
833 int vlc_set_priority (vlc_thread_t th, int priority)
835 #if defined (_POSIX_PRIORITY_SCHEDULING) && (_POSIX_PRIORITY_SCHEDULING >= 0) \
836 && defined (_POSIX_THREAD_PRIORITY_SCHEDULING) \
837 && (_POSIX_THREAD_PRIORITY_SCHEDULING >= 0)
840 struct sched_param sp = { .sched_priority = priority + rt_offset, };
843 if (sp.sched_priority <= 0)
844 sp.sched_priority += sched_get_priority_max (policy = SCHED_OTHER);
846 sp.sched_priority += sched_get_priority_min (policy = SCHED_RR);
848 if (pthread_setschedparam (th, policy, &sp))
858 * Marks a thread as cancelled. Next time the target thread reaches a
859 * cancellation point (while not having disabled cancellation), it will
860 * run its cancellation cleanup handler, the thread variable destructors, and
861 * terminate. vlc_join() must be used afterward regardless of a thread being
864 void vlc_cancel (vlc_thread_t thread_id)
866 pthread_cancel (thread_id);
868 pthread_kill (thread_id, SIGRTMIN);
873 * Save the current cancellation state (enabled or disabled), then disable
874 * cancellation for the calling thread.
875 * This function must be called before entering a piece of code that is not
876 * cancellation-safe, unless it can be proven that the calling thread will not
878 * @return Previous cancellation state (opaque value for vlc_restorecancel()).
880 int vlc_savecancel (void)
883 int val = pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &state);
885 VLC_THREAD_ASSERT ("saving cancellation");
890 * Restore the cancellation state for the calling thread.
891 * @param state previous state as returned by vlc_savecancel().
892 * @return Nothing, always succeeds.
894 void vlc_restorecancel (int state)
899 val = pthread_setcancelstate (state, &oldstate);
900 /* This should fail if an invalid value for given for state */
901 VLC_THREAD_ASSERT ("restoring cancellation");
903 if (unlikely(oldstate != PTHREAD_CANCEL_DISABLE))
904 vlc_thread_fatal ("restoring cancellation while not disabled", EINVAL,
905 __func__, __FILE__, __LINE__);
907 pthread_setcancelstate (state, NULL);
912 * Issues an explicit deferred cancellation point.
913 * This has no effect if thread cancellation is disabled.
914 * This can be called when there is a rather slow non-sleeping operation.
915 * This is also used to force a cancellation point in a function that would
916 * otherwise "not always" be a one (block_FifoGet() is an example).
918 void vlc_testcancel (void)
920 pthread_testcancel ();
923 void vlc_control_cancel (int cmd, ...)
930 * Precision monotonic clock.
932 * In principles, the clock has a precision of 1 MHz. But the actual resolution
933 * may be much lower, especially when it comes to sleeping with mwait() or
934 * msleep(). Most general-purpose operating systems provide a resolution of
935 * only 100 to 1000 Hz.
937 * @warning The origin date (time value "zero") is not specified. It is
938 * typically the time the kernel started, but this is platform-dependent.
939 * If you need wall clock time, use gettimeofday() instead.
941 * @return a timestamp in microseconds.
945 #if (_POSIX_TIMERS > 0)
949 if (unlikely(clock_gettime (vlc_clock_id, &ts) != 0))
952 return (INT64_C(1000000) * ts.tv_sec) + (ts.tv_nsec / 1000);
957 if (unlikely(gettimeofday (&tv, NULL) != 0))
959 return (INT64_C(1000000) * tv.tv_sec) + tv.tv_nsec;
966 * Waits until a deadline (possibly later due to OS scheduling).
967 * @param deadline timestamp to wait for (see mdate())
969 void mwait (mtime_t deadline)
971 #if (_POSIX_TIMERS > 0)
973 /* If the deadline is already elapsed, or within the clock precision,
974 * do not even bother the system timer. */
975 deadline -= vlc_clock_prec;
977 lldiv_t d = lldiv (deadline, 1000000);
978 struct timespec ts = { d.quot, d.rem * 1000 };
980 while (clock_nanosleep (vlc_clock_id, TIMER_ABSTIME, &ts, NULL) == EINTR);
983 deadline -= mdate ();
992 * Waits for an interval of time.
993 * @param delay how long to wait (in microseconds)
995 void msleep (mtime_t delay)
999 lldiv_t d = lldiv (delay, 1000000);
1000 struct timespec ts = { d.quot, d.rem * 1000 };
1002 #if (_POSIX_TIMERS > 0)
1003 while (clock_nanosleep (vlc_clock_id, 0, &ts, &ts) == EINTR);
1006 while (nanosleep (&ts, &ts) == -1)
1007 assert (errno == EINTR);
1015 vlc_thread_t thread;
1016 vlc_cond_t reschedule;
1018 void (*func) (void *);
1020 mtime_t value, interval;
1021 vlc_atomic_t overruns;
1024 static void *vlc_timer_thread (void *data)
1026 struct vlc_timer *timer = data;
1028 vlc_mutex_lock (&timer->lock);
1029 mutex_cleanup_push (&timer->lock);
1033 while (timer->value == 0)
1034 vlc_cond_wait (&timer->reschedule, &timer->lock);
1036 if (vlc_cond_timedwait (&timer->reschedule, &timer->lock,
1039 if (timer->interval == 0)
1040 timer->value = 0; /* disarm */
1041 vlc_mutex_unlock (&timer->lock);
1043 int canc = vlc_savecancel ();
1044 timer->func (timer->data);
1045 vlc_restorecancel (canc);
1047 mtime_t now = mdate ();
1050 vlc_mutex_lock (&timer->lock);
1051 if (timer->interval == 0)
1054 misses = (now - timer->value) / timer->interval;
1055 timer->value += timer->interval;
1056 /* Try to compensate for one miss (mwait() will return immediately)
1057 * but no more. Otherwise, we might busy loop, after extended periods
1058 * without scheduling (suspend, SIGSTOP, RT preemption, ...). */
1062 timer->value += misses * timer->interval;
1063 vlc_atomic_add (&timer->overruns, misses);
1072 * Initializes an asynchronous timer.
1073 * @warning Asynchronous timers are processed from an unspecified thread.
1074 * Multiple occurences of a single interval timer are serialized; they cannot
1077 * @param id pointer to timer to be initialized
1078 * @param func function that the timer will call
1079 * @param data parameter for the timer function
1080 * @return 0 on success, a system error code otherwise.
1082 int vlc_timer_create (vlc_timer_t *id, void (*func) (void *), void *data)
1084 struct vlc_timer *timer = malloc (sizeof (*timer));
1086 if (unlikely(timer == NULL))
1088 vlc_mutex_init (&timer->lock);
1089 vlc_cond_init (&timer->reschedule);
1094 timer->interval = 0;
1095 vlc_atomic_set(&timer->overruns, 0);
1097 if (vlc_clone (&timer->thread, vlc_timer_thread, timer,
1098 VLC_THREAD_PRIORITY_INPUT))
1100 vlc_cond_destroy (&timer->reschedule);
1101 vlc_mutex_destroy (&timer->lock);
1111 * Destroys an initialized timer. If needed, the timer is first disarmed.
1112 * This function is undefined if the specified timer is not initialized.
1114 * @warning This function <b>must</b> be called before the timer data can be
1115 * freed and before the timer callback function can be unloaded.
1117 * @param timer timer to destroy
1119 void vlc_timer_destroy (vlc_timer_t timer)
1121 vlc_cancel (timer->thread);
1122 vlc_join (timer->thread, NULL);
1123 vlc_cond_destroy (&timer->reschedule);
1124 vlc_mutex_destroy (&timer->lock);
1129 * Arm or disarm an initialized timer.
1130 * This functions overrides any previous call to itself.
1132 * @note A timer can fire later than requested due to system scheduling
1133 * limitations. An interval timer can fail to trigger sometimes, either because
1134 * the system is busy or suspended, or because a previous iteration of the
1135 * timer is still running. See also vlc_timer_getoverrun().
1137 * @param timer initialized timer
1138 * @param absolute the timer value origin is the same as mdate() if true,
1139 * the timer value is relative to now if false.
1140 * @param value zero to disarm the timer, otherwise the initial time to wait
1141 * before firing the timer.
1142 * @param interval zero to fire the timer just once, otherwise the timer
1143 * repetition interval.
1145 void vlc_timer_schedule (vlc_timer_t timer, bool absolute,
1146 mtime_t value, mtime_t interval)
1148 if (!absolute && value != 0)
1151 vlc_mutex_lock (&timer->lock);
1152 timer->value = value;
1153 timer->interval = interval;
1154 vlc_cond_signal (&timer->reschedule);
1155 vlc_mutex_unlock (&timer->lock);
1159 * Fetch and reset the overrun counter for a timer.
1160 * @param timer initialized timer
1161 * @return the timer overrun counter, i.e. the number of times that the timer
1162 * should have run but did not since the last actual run. If all is well, this
1165 unsigned vlc_timer_getoverrun (vlc_timer_t timer)
1167 return vlc_atomic_swap (&timer->overruns, 0);
1173 * @return number of available (logical) CPUs.
1175 unsigned vlc_GetCPUCount(void)
1177 #if defined(HAVE_SCHED_GETAFFINITY)
1181 if (sched_getaffinity (getpid(), sizeof (cpu), &cpu) < 0)
1184 return CPU_COUNT (&cpu);
1186 #elif defined(__APPLE__)
1188 size_t size = sizeof(count) ;
1190 if (sysctlbyname ("hw.ncpu", &count, &size, NULL, 0))
1191 return 1; /* Failure */
1194 #elif defined(__OpenBSD__)
1195 int selectors[2] = { CTL_HW, HW_NCPU };
1197 size_t size = sizeof(count);
1199 if (sysctl (selectors, 2, &count, &size, NULL, 0))
1200 return 1; /* Failure */
1203 #elif defined(__SunOS)
1207 processor_info_t cpuinfo;
1209 processorid_t *cpulist = malloc (sizeof (*cpulist) * sysconf(_SC_NPROCESSORS_MAX));
1210 if (unlikely(cpulist == NULL))
1213 if (pset_info(PS_MYID, &type, &numcpus, cpulist) == 0)
1215 for (u_int i = 0; i < numcpus; i++)
1216 if (processor_info (cpulist[i], &cpuinfo) == 0)
1217 count += (cpuinfo.pi_state == P_ONLINE);
1220 count = sysconf (_SC_NPROCESSORS_ONLN);
1222 return count ? count : 1;
1225 # warning "vlc_GetCPUCount is not implemented for your platform"