/**
* Waits for a condition variable up to a certain date.
* This works like vlc_cond_wait(), except for the additional time-out.
*
* If the variable was initialized with vlc_cond_init(), the timeout has the
* same arbitrary origin as mdate(). If the variable was initialized with
* vlc_cond_init_daytime(), the timeout is expressed from the Unix epoch.
*
* @param p_condvar condition variable to wait on
* @param p_mutex mutex which is unlocked while waiting,
* then locked again when waking up.
* @param deadline <b>absolute</b> timeout
*
* @return 0 if the condition was signaled, an error code in case of timeout.
*/
int vlc_cond_timedwait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex,
mtime_t deadline)
{
#if defined(__APPLE__) && !defined(__powerpc__) && !defined( __ppc__ ) && !defined( __ppc64__ )
/* mdate() is the monotonic clock, timedwait origin is gettimeofday() which
* isn't monotonic. Use imedwait_relative_np() instead
*/
mtime_t base = mdate();
deadline -= base;
if (deadline < 0)
deadline = 0;
lldiv_t d = lldiv( deadline, CLOCK_FREQ );
struct timespec ts = { d.quot, d.rem * (1000000000 / CLOCK_FREQ) };
int val = pthread_cond_timedwait_relative_np(p_condvar, p_mutex, &ts);
if (val != ETIMEDOUT)
VLC_THREAD_ASSERT ("timed-waiting on condition");
return val;
#else
lldiv_t d = lldiv( deadline, CLOCK_FREQ );
struct timespec ts = { d.quot, d.rem * (1000000000 / CLOCK_FREQ) };
int val = pthread_cond_timedwait (p_condvar, p_mutex, &ts);
if (val != ETIMEDOUT)
VLC_THREAD_ASSERT ("timed-waiting on condition");
return val;
#endif
}
/**
* Increments the value of a semaphore.
*/
int vlc_sem_post (vlc_sem_t *sem)
{
int val = sem_post (sem);
if (val != EOVERFLOW)
VLC_THREAD_ASSERT ("unlocking semaphore");
return val;
}
/* Destroys a condition variable. No threads shall be waiting or signaling the
* condition.
* parameter: p_condvar condition variable to destroy */
void vlc_cond_destroy (vlc_cond_t *p_condvar)
{
int val = pthread_cond_destroy( p_condvar );
/* due to a faulty pthread implementation within Darwin 11 and
* later condition variables cannot be destroyed without
* terminating the application immediately.
* This Darwin kernel issue is still present in version 13
* and might not be resolved prior to Darwin 15.
* radar://12496249
*
* To work-around this, we are just leaking the condition variable
* which is acceptable due to VLC's low number of created variables
* and its usually limited runtime.
* Ideally, we should implement a re-useable pool.
*/
if (val != 0) {
#ifndef NDEBUG
printf("pthread_cond_destroy returned %i\n", val);
#endif
if (val == EBUSY)
return;
}
VLC_THREAD_ASSERT ("destroying condition");
}
/**
* Atomically wait for the semaphore to become non-zero (if needed),
* then decrements it.
*/
void vlc_sem_wait (vlc_sem_t *sem)
{
int val;
do
val = sem_wait (sem);
while (val == EINTR);
VLC_THREAD_ASSERT ("locking semaphore");
}
/**
* Acquires a mutex if and only if it is not currently held by another thread.
* This function never sleeps and can be used in delay-critical code paths.
* This function is not a cancellation-point.
*
* <b>Beware</b>: If this function fails, then the mutex is held... by another
* thread. The calling thread must deal with the error appropriately. That
* typically implies postponing the operations that would have required the
* mutex. If the thread cannot defer those operations, then it must use
* vlc_mutex_lock(). If in doubt, use vlc_mutex_lock() instead.
*
* @param p_mutex mutex initialized with vlc_mutex_init() or
* vlc_mutex_init_recursive()
* @return 0 if the mutex could be acquired, an error code otherwise.
*/
int vlc_mutex_trylock (vlc_mutex_t *p_mutex)
{
int val = pthread_mutex_trylock( p_mutex );
if (val != EBUSY)
VLC_THREAD_ASSERT ("locking mutex");
return val;
}
/**
* Save the current cancellation state (enabled or disabled), then disable
* cancellation for the calling thread.
* This function must be called before entering a piece of code that is not
* cancellation-safe, unless it can be proven that the calling thread will not
* be cancelled.
* @return Previous cancellation state (opaque value for vlc_restorecancel()).
*/
int vlc_savecancel (void)
{
int state;
int val = pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &state);
VLC_THREAD_ASSERT ("saving cancellation");
return state;
}
/**
* Waits for a condition variable up to a certain date.
* This works like vlc_cond_wait(), except for the additional time-out.
*
* If the variable was initialized with vlc_cond_init(), the timeout has the
* same arbitrary origin as mdate(). If the variable was initialized with
* vlc_cond_init_daytime(), the timeout is expressed from the Unix epoch.
*
* @param p_condvar condition variable to wait on
* @param p_mutex mutex which is unlocked while waiting,
* then locked again when waking up.
* @param deadline <b>absolute</b> timeout
*
* @return 0 if the condition was signaled, an error code in case of timeout.
*/
int vlc_cond_timedwait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex,
mtime_t deadline)
{
struct timespec ts = mtime_to_ts (deadline);
int val = pthread_cond_timedwait (p_condvar, p_mutex, &ts);
if (val != ETIMEDOUT)
VLC_THREAD_ASSERT ("timed-waiting on condition");
return val;
}
void vlc_join (vlc_thread_t handle, void **result)
{
vlc_sem_wait (&handle->finished);
vlc_sem_destroy (&handle->finished);
int val = pthread_join (handle->thread, result);
VLC_THREAD_ASSERT ("joining thread");
clean_detached_thread(handle);
}
/**
* Destroys an initialized timer. If needed, the timer is first disarmed.
* This function is undefined if the specified timer is not initialized.
*
* @warning This function <b>must</b> be called before the timer data can be
* freed and before the timer callback function can be unloaded.
*
* @param timer to destroy
*/
void vlc_timer_destroy (vlc_timer_t *id)
{
#ifdef HAVE_POSIX_TIMER
int val = timer_delete (id->handle);
VLC_THREAD_ASSERT ("deleting timer");
#else
timer_not_supported();
#endif
}
void vlc_join (vlc_thread_t handle, void **result)
{
vlc_sem_wait (&handle->finished);
vlc_sem_destroy (&handle->finished);
int val = pthread_join (handle->thread, result);
VLC_THREAD_ASSERT ("joining thread");
vlc_mutex_destroy(&handle->lock);
free(handle);
}
/* Atomically wait for the semaphore to become non-zero (if needed),
* then decrements it. */
void vlc_sem_wait (vlc_sem_t *sem)
{
int val;
if (likely(semaphore_wait(*sem) == KERN_SUCCESS))
return;
val = EINVAL;
VLC_THREAD_ASSERT ("locking semaphore");
}
/* Destroy a semaphore. */
void vlc_sem_destroy (vlc_sem_t *sem)
{
int val;
if (likely(semaphore_destroy(mach_task_self(), *sem) == KERN_SUCCESS))
return;
val = EINVAL;
VLC_THREAD_ASSERT ("destroying semaphore");
}
int vlc_cond_timedwait (vlc_cond_t *condvar, vlc_mutex_t *p_mutex,
mtime_t deadline)
{
struct timespec ts = mtime_to_ts (deadline);
vlc_thread_t th = thread;
int (*cb)(pthread_cond_t *, pthread_mutex_t *, const struct timespec *);
if (th != NULL)
{
vlc_testcancel ();
if (vlc_mutex_trylock (&th->lock) == 0)
{
th->cond = &condvar->cond;
vlc_mutex_unlock (&th->lock);
}
else
{ /* The lock is already held by another thread.
* => That other thread has just cancelled this one. */
vlc_testcancel ();
/* Cancellation did not occur even though this thread is cancelled.
* => Cancellation is disabled. */
th = NULL;
}
}
switch (condvar->clock)
{
case CLOCK_REALTIME:
cb = pthread_cond_timedwait;
break;
case CLOCK_MONOTONIC:
cb = pthread_cond_timedwait_monotonic_np;
break;
default:
assert (0);
}
int val = cb (&condvar->cond, p_mutex, &ts);
if (val != ETIMEDOUT)
VLC_THREAD_ASSERT ("timed-waiting on condition");
if (th != NULL)
{
if (vlc_mutex_trylock (&th->lock) == 0)
{
thread->cond = NULL;
vlc_mutex_unlock (&th->lock);
}
/* Else: This thread was cancelled and is cancellable.
vlc_testcancel() will take of it right there: */
vlc_testcancel();
}
return val;
}
/**
* Atomically wait for the semaphore to become non-zero (if needed),
* then decrements it.
*/
void vlc_sem_wait (vlc_sem_t *sem)
{
int val;
do
if (likely(sem_wait (sem) == 0))
return;
while ((val = errno) == EINTR);
VLC_THREAD_ASSERT ("locking semaphore");
}
/**
* Destroys a semaphore.
*/
void vlc_sem_destroy (vlc_sem_t *sem)
{
int val;
if (likely(sem_destroy (sem) == 0))
return;
val = errno;
VLC_THREAD_ASSERT ("destroying semaphore");
}
/* Increment the value of a semaphore.
* returns 0 on success, EOVERFLOW in case of integer overflow */
int vlc_sem_post (vlc_sem_t *sem)
{
int val;
if (likely(semaphore_signal(*sem) == KERN_SUCCESS))
return 0;
val = EINVAL;
if (unlikely(val != EOVERFLOW))
VLC_THREAD_ASSERT ("unlocking semaphore");
return val;
}
/**
* Increments the value of a semaphore.
* @return 0 on success, EOVERFLOW in case of integer overflow
*/
int vlc_sem_post (vlc_sem_t *sem)
{
int val;
if (likely(sem_post (sem) == 0))
return 0;
val = errno;
if (unlikely(val != EOVERFLOW))
VLC_THREAD_ASSERT ("unlocking semaphore");
return val;
}
/*****************************************************************************
* vlc_cond_destroy: destroy a condition, inner version
*****************************************************************************/
void __vlc_cond_destroy( const char * psz_file, int i_line, vlc_cond_t *p_condvar )
{
#if defined( LIBVLC_USE_PTHREAD )
int val = pthread_cond_destroy( p_condvar );
VLC_THREAD_ASSERT ("destroying condition");
#elif defined( UNDER_CE ) || defined( WIN32 )
VLC_UNUSED( psz_file); VLC_UNUSED( i_line );
CloseHandle( *p_condvar );
#elif defined( HAVE_KERNEL_SCHEDULER_H )
p_condvar->init = 0;
#endif
}
/**
* Restore the cancellation state for the calling thread.
* @param state previous state as returned by vlc_savecancel().
* @return Nothing, always succeeds.
*/
void vlc_restorecancel (int state)
{
#ifndef NDEBUG
int oldstate, val;
val = pthread_setcancelstate (state, &oldstate);
/* This should fail if an invalid value for given for state */
VLC_THREAD_ASSERT ("restoring cancellation");
if (unlikely(oldstate != PTHREAD_CANCEL_DISABLE))
vlc_thread_fatal ("restoring cancellation while not disabled", EINVAL,
__func__, __FILE__, __LINE__);
#else
pthread_setcancelstate (state, NULL);
#endif
}
/**
* Atomically wait for the semaphore to become non-zero (if needed),
* then decrements it.
*/
void vlc_sem_wait (vlc_sem_t *sem)
{
int val;
#if defined(__APPLE__)
if (likely(semaphore_wait(*sem) == KERN_SUCCESS))
return;
val = EINVAL;
#else
do
if (likely(sem_wait (sem) == 0))
return;
while ((val = errno) == EINTR);
#endif
VLC_THREAD_ASSERT ("locking semaphore");
}
/**
* Destroys a semaphore.
*/
void vlc_sem_destroy (vlc_sem_t *sem)
{
int val;
#if defined(__APPLE__)
if (likely(semaphore_destroy(mach_task_self(), *sem) == KERN_SUCCESS))
return;
val = EINVAL;
#else
if (likely(sem_destroy (sem) == 0))
return;
val = errno;
#endif
VLC_THREAD_ASSERT ("destroying semaphore");
}
/**
* Increments the value of a semaphore.
* @return 0 on success, EOVERFLOW in case of integer overflow
*/
int vlc_sem_post (vlc_sem_t *sem)
{
int val;
#if defined(__APPLE__)
if (likely(semaphore_signal(*sem) == KERN_SUCCESS))
return 0;
val = EINVAL;
#else
if (likely(sem_post (sem) == 0))
return 0;
val = errno;
#endif
if (unlikely(val != EOVERFLOW))
VLC_THREAD_ASSERT ("unlocking semaphore");
return val;
}
/**
* Waits for a condition variable up to a certain date.
* This works like vlc_cond_wait(), except for the additional time-out.
*
* If the variable was initialized with vlc_cond_init(), the timeout has the
* same arbitrary origin as mdate(). If the variable was initialized with
* vlc_cond_init_daytime(), the timeout is expressed from the Unix epoch.
*
* @param p_condvar condition variable to wait on
* @param p_mutex mutex which is unlocked while waiting,
* then locked again when waking up.
* @param deadline <b>absolute</b> timeout
*
* @return 0 if the condition was signaled, an error code in case of timeout.
*/
int vlc_cond_timedwait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex,
mtime_t deadline)
{
#if defined(__APPLE__) && !defined(__powerpc__) && !defined( __ppc__ ) && !defined( __ppc64__ )
/* mdate() is mac_absolute_time on OSX, which we must convert to do
* the same base than gettimeofday() which pthread_cond_timedwait
* relies on. */
mtime_t oldbase = mdate();
struct timeval tv;
gettimeofday(&tv, NULL);
mtime_t newbase = (mtime_t)tv.tv_sec * 1000000 + (mtime_t) tv.tv_usec;
deadline = deadline - oldbase + newbase;
#endif
lldiv_t d = lldiv( deadline, CLOCK_FREQ );
struct timespec ts = { d.quot, d.rem * (1000000000 / CLOCK_FREQ) };
int val = pthread_cond_timedwait (p_condvar, p_mutex, &ts);
if (val != ETIMEDOUT)
VLC_THREAD_ASSERT ("timed-waiting on condition");
return val;
}
void vlc_cond_wait (vlc_cond_t *condvar, vlc_mutex_t *p_mutex)
{
vlc_thread_t th = thread;
if (th != NULL)
{
vlc_testcancel ();
if (vlc_mutex_trylock (&th->lock) == 0)
{
th->cond = &condvar->cond;
vlc_mutex_unlock (&th->lock);
}
else
{ /* The lock is already held by another thread.
* => That other thread has just cancelled this one. */
vlc_testcancel ();
/* Cancellation did not occur even though this thread is cancelled.
* => Cancellation is disabled. */
th = NULL;
}
}
int val = pthread_cond_wait (&condvar->cond, p_mutex);
VLC_THREAD_ASSERT ("waiting on condition");
if (th != NULL)
{
if (vlc_mutex_trylock (&th->lock) == 0)
{
thread->cond = NULL;
vlc_mutex_unlock (&th->lock);
}
/* Else: This thread was cancelled and is cancellable.
vlc_testcancel() will take of it right there: */
vlc_testcancel();
}
}
/*****************************************************************************
* vlc_mutex_destroy: destroy a mutex, inner version
*****************************************************************************/
void __vlc_mutex_destroy( const char * psz_file, int i_line, vlc_mutex_t *p_mutex )
{
#if defined( LIBVLC_USE_PTHREAD )
int val = pthread_mutex_destroy( p_mutex );
VLC_THREAD_ASSERT ("destroying mutex");
#elif defined( UNDER_CE )
VLC_UNUSED( psz_file); VLC_UNUSED( i_line );
DeleteCriticalSection( &p_mutex->csection );
#elif defined( WIN32 )
VLC_UNUSED( psz_file); VLC_UNUSED( i_line );
CloseHandle( *p_mutex );
#elif defined( HAVE_KERNEL_SCHEDULER_H )
if( p_mutex->init == 9999 )
delete_sem( p_mutex->lock );
p_mutex->init = 0;
#endif
}
void vlc_rwlock_unlock(vlc_rwlock_t* lock) {
const int val = pthread_rwlock_unlock(lock);
VLC_THREAD_ASSERT("releasing R/W lock");
}
void vlc_rwlock_wrlock(vlc_rwlock_t* lock) {
const int val = pthread_rwlock_wrlock(lock);
VLC_THREAD_ASSERT("acquiring R/W lock for writing");
}
void vlc_rwlock_destroy(vlc_rwlock_t* lock) {
const int val = pthread_rwlock_destroy(lock);
VLC_THREAD_ASSERT("destroying R/W lock");
}
void vlc_rwlock_init(vlc_rwlock_t* lock) {
const int val = pthread_rwlock_init(lock, NULL);
VLC_THREAD_ASSERT("initializing R/W lock");
}
/**
* Detaches a thread. When the specified thread completes, it will be
* automatically destroyed (in particular, its stack will be reclaimed),
* instead of waiting for another thread to call vlc_join(). If the thread has
* already completed, it will be destroyed immediately.
*
* When a thread performs some work asynchronously and may complete much
* earlier than it can be joined, detaching the thread can save memory.
* However, care must be taken that any resources used by a detached thread
* remains valid until the thread completes. This will typically involve some
* kind of thread-safe signaling.
*
* A thread may detach itself.
*
* @param handle thread handle
*/
void vlc_detach (vlc_thread_t handle)
{
int val = pthread_detach (handle);
VLC_THREAD_ASSERT ("detaching thread");
}
