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Commit 58c0ece0 authored by Rémi Denis-Courmont's avatar Rémi Denis-Courmont
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darwin: remove duplicated and desynched documentation

parent 2ecaf892
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src/darwin/thread.c
View file @ 58c0ece0
......@@ -138,8 +138,6 @@ void vlc_mutex_init( vlc_mutex_t *p_mutex )
pthread_mutexattr_destroy( &attr );
}
/* Initializes a recursive mutex.
* warning: This is strongly discouraged. Please use normal mutexes. */
void vlc_mutex_init_recursive( vlc_mutex_t *p_mutex )
{
pthread_mutexattr_t attr;
......@@ -153,10 +151,6 @@ void vlc_mutex_init_recursive( vlc_mutex_t *p_mutex )
}
/* Destroys a mutex. The mutex must not be locked.
*
* parameter: p_mutex mutex to destroy
* returns: always succeeds */
void vlc_mutex_destroy (vlc_mutex_t *p_mutex)
{
int val = pthread_mutex_destroy( p_mutex );
......@@ -170,7 +164,6 @@ void vlc_mutex_destroy (vlc_mutex_t *p_mutex)
# define RUNNING_ON_VALGRIND (0)
# endif
/* Asserts that a mutex is locked by the calling thread. */
void vlc_assert_locked (vlc_mutex_t *p_mutex)
{
if (RUNNING_ON_VALGRIND > 0)
......@@ -179,33 +172,12 @@ void vlc_assert_locked (vlc_mutex_t *p_mutex)
}
#endif
/* Acquires a mutex. If needed, waits for any other thread to release it.
* Beware of deadlocks when locking multiple mutexes at the same time,
* or when using mutexes from callbacks.
* This function is not a cancellation-point.
*
* parameter: p_mutex mutex initialized with vlc_mutex_init() or
* vlc_mutex_init_recursive()
*/
void vlc_mutex_lock (vlc_mutex_t *p_mutex)
{
int val = pthread_mutex_lock( p_mutex );
VLC_THREAD_ASSERT ("locking mutex");
}
/* 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.
*
* BEWARE: 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.
*
* parameter: p_mutex mutex initialized with vlc_mutex_init() or
* vlc_mutex_init_recursive()
* returns: 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 );
......@@ -215,8 +187,6 @@ int vlc_mutex_trylock (vlc_mutex_t *p_mutex)
return val;
}
/* Release a mutex (or crashes if the mutex is not locked by the caller).
* parameter p_mutex mutex locked with vlc_mutex_lock(). */
void vlc_mutex_unlock (vlc_mutex_t *p_mutex)
{
int val = pthread_mutex_unlock( p_mutex );
......@@ -229,7 +199,6 @@ enum
VLC_CLOCK_REALTIME,
};
/* Initialize a condition variable. */
void vlc_cond_init (vlc_cond_t *p_condvar)
{
if (unlikely(pthread_cond_init (&p_condvar->cond, NULL)))
......@@ -237,9 +206,6 @@ void vlc_cond_init (vlc_cond_t *p_condvar)
p_condvar->clock = VLC_CLOCK_MONOTONIC;
}
/* Initialize a condition variable.
* Contrary to vlc_cond_init(), the wall clock will be used as a reference for
* the vlc_cond_timedwait() time-out parameter. */
void vlc_cond_init_daytime (vlc_cond_t *p_condvar)
{
if (unlikely(pthread_cond_init (&p_condvar->cond, NULL)))
......@@ -248,9 +214,6 @@ void vlc_cond_init_daytime (vlc_cond_t *p_condvar)
}
/* 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->cond);
......@@ -279,69 +242,23 @@ void vlc_cond_destroy (vlc_cond_t *p_condvar)
VLC_THREAD_ASSERT ("destroying condition");
}
/* Wake up one thread waiting on a condition variable, if any.
* parameter: p_condvar condition variable */
void vlc_cond_signal (vlc_cond_t *p_condvar)
{
int val = pthread_cond_signal (&p_condvar->cond);
VLC_THREAD_ASSERT ("signaling condition variable");
}
/* Wake up all threads (if any) waiting on a condition variable.
* parameter: p_cond condition variable */
void vlc_cond_broadcast (vlc_cond_t *p_condvar)
{
pthread_cond_broadcast (&p_condvar->cond);
}
/* Wait for a condition variable. The calling thread will be suspended until
* another thread calls vlc_cond_signal() or vlc_cond_broadcast() on the same
* condition variable, the thread is cancelled with vlc_cancel(), or the
* system causes a "spurious" unsolicited wake-up.
*
* A mutex is needed to wait on a condition variable. It must <b>not</b> be
* a recursive mutex. Although it is possible to use the same mutex for
* multiple condition, it is not valid to use different mutexes for the same
* condition variable at the same time from different threads.
*
* In case of thread cancellation, the mutex is always locked before
* cancellation proceeds.
*
* The canonical way to use a condition variable to wait for event foobar is:
sample code:
vlc_mutex_lock (&lock);
mutex_cleanup_push (&lock); // release the mutex in case of cancellation
while (!foobar)
vlc_cond_wait (&wait, &lock);
--- foobar is now true, do something about it here --
vlc_cleanup_run (); // release the mutex
*
* 1st parameter: p_condvar condition variable to wait on
* 2nd parameter: p_mutex mutex which is unlocked while waiting,
* then locked again when waking up. */
void vlc_cond_wait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex)
{
int val = pthread_cond_wait (&p_condvar->cond, p_mutex);
VLC_THREAD_ASSERT ("waiting on condition");
}
/* Wait 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.
*
* 1st parameter: p_condvar condition variable to wait on
* 2nd parameter: p_mutex mutex which is unlocked while waiting,
* then locked again when waking up.
* 3rd parameter: deadline <b>absolute</b> timeout
*
* returns 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)
{
......@@ -399,7 +316,6 @@ void vlc_sem_init (vlc_sem_t *sem, unsigned value)
abort ();
}
/* Destroy a semaphore. */
void vlc_sem_destroy (vlc_sem_t *sem)
{
int val;
......@@ -412,8 +328,6 @@ void vlc_sem_destroy (vlc_sem_t *sem)
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;
......@@ -428,8 +342,6 @@ int vlc_sem_post (vlc_sem_t *sem)
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;
......@@ -442,52 +354,36 @@ void vlc_sem_wait (vlc_sem_t *sem)
VLC_THREAD_ASSERT ("locking semaphore");
}
/* Initialize a read/write lock. */
void vlc_rwlock_init (vlc_rwlock_t *lock)
{
if (unlikely(pthread_rwlock_init (lock, NULL)))
abort ();
}
/* Destroy an initialized unused read/write lock. */
void vlc_rwlock_destroy (vlc_rwlock_t *lock)
{
int val = pthread_rwlock_destroy (lock);
VLC_THREAD_ASSERT ("destroying R/W lock");
}
/* Acquire a read/write lock for reading. Recursion is allowed.
* Attention: This function may be a cancellation point. */
void vlc_rwlock_rdlock (vlc_rwlock_t *lock)
{
int val = pthread_rwlock_rdlock (lock);
VLC_THREAD_ASSERT ("acquiring R/W lock for reading");
}
/* Acquire a read/write lock for writing. Recursion is not allowed.
* Attention: This function may be a cancellation point. */
void vlc_rwlock_wrlock (vlc_rwlock_t *lock)
{
int val = pthread_rwlock_wrlock (lock);
VLC_THREAD_ASSERT ("acquiring R/W lock for writing");
}
/* Release a read/write lock. */
void vlc_rwlock_unlock (vlc_rwlock_t *lock)
{
int val = pthread_rwlock_unlock (lock);
VLC_THREAD_ASSERT ("releasing R/W lock");
}
/* Allocates a thread-specific variable.
* 1st parameter: key where to store the thread-specific variable handle
* 2nd parameter: destr a destruction callback. It is called whenever a thread
* exits and the thread-specific variable has a non-NULL value.
* returns 0 on success, a system error code otherwise.
*
* This function can actually fail because there is a fixed limit on the number
* of thread-specific variable in a process on most systems.
*/
int vlc_threadvar_create (vlc_threadvar_t *key, void (*destr) (void *))
{
return pthread_key_create (key, destr);
......@@ -498,20 +394,11 @@ void vlc_threadvar_delete (vlc_threadvar_t *p_tls)
pthread_key_delete (*p_tls);
}
/* Set a thread-specific variable.
* 1st parameter: key thread-local variable key
* (created with vlc_threadvar_create())
* 2nd parameter: value new value for the variable for the calling thread
* returns 0 on success, a system error code otherwise. */
int vlc_threadvar_set (vlc_threadvar_t key, void *value)
{
return pthread_setspecific (key, value);
}
/* Get the value of a thread-local variable for the calling thread.
* This function cannot fail.
* returns the value associated with the given variable for the calling
* or NULL if there is no value. */
void *vlc_threadvar_get (vlc_threadvar_t key)
{
return pthread_getspecific (key);
......@@ -537,22 +424,11 @@ void vlc_threads_setup (libvlc_int_t *p_libvlc)
vlc_mutex_unlock (&lock);
}
static int vlc_clone_attr (vlc_thread_t *th, pthread_attr_t *attr,
void *(*entry) (void *), void *data, int priority)
{
int ret;
/* Block the signals that signals interface plugin handles.
* If the LibVLC caller wants to handle some signals by itself, it should
* block these before whenever invoking LibVLC. And it must obviously not
* start the VLC signals interface plugin.
*
* LibVLC will normally ignore any interruption caused by an asynchronous
* signal during a system call. But there may well be some buggy cases
* where it fails to handle EINTR (bug reports welcome). Some underlying
* libraries might also not handle EINTR properly.
*/
sigset_t oldset;
{
sigset_t set;
......@@ -568,18 +444,6 @@ static int vlc_clone_attr (vlc_thread_t *th, pthread_attr_t *attr,
(void) priority;
/* The thread stack size.
* The lower the value, the less address space per thread, the highest
* maximum simultaneous threads per process. Too low values will cause
* stack overflows and weird crashes. Set with caution. Also keep in mind
* that 64-bits platforms consume more stack than 32-bits one.
*
* Thanks to on-demand paging, thread stack size only affects address space
* consumption. In terms of memory, threads only use what they need
* (rounded up to the page boundary).
*
* For example, on Linux i386, the default is 2 mega-bytes, which supports
* about 320 threads per processes. */
#define VLC_STACKSIZE (128 * sizeof (void *) * 1024)
#ifdef VLC_STACKSIZE
......@@ -593,17 +457,6 @@ static int vlc_clone_attr (vlc_thread_t *th, pthread_attr_t *attr,
return ret;
}
/* Create and start a new thread.
*
* The thread must be joined with vlc_join() to reclaim resources when it is
* not needed anymore.
*
* 1st parameter: th [OUT] pointer to write the handle of the created thread to
* (mandatory, must be non-NULL)
* 2nd parameter: entry entry point for the thread
* 3rd parameter: data data parameter given to the entry point
* 4th parameter: priority thread priority value
* returns 0 on success, a standard error code on error. */
int vlc_clone (vlc_thread_t *th, void *(*entry) (void *), void *data,
int priority)
{
......@@ -613,50 +466,12 @@ int vlc_clone (vlc_thread_t *th, void *(*entry) (void *), void *data,
return vlc_clone_attr (th, &attr, entry, data, priority);
}
/* Wait for a thread to complete (if needed), then destroys it.
* This is a cancellation point; in case of cancellation, the join does _not_
* occur.
*
* WARNING: A thread cannot join itself (normally VLC will abort if this is
* attempted). Also, a detached thread cannot be joined.
*
* 1st parameter: handle thread handle
* 2nd parameter: p_result - pointer to write the thread return value or NULL
*/
void vlc_join (vlc_thread_t handle, void **result)
{
int val = pthread_join (handle, result);
VLC_THREAD_ASSERT ("joining thread");
}
/* Create and start a new detached thread.
* A detached thread cannot be joined. Its resources will be automatically
* released whenever the thread exits (in particular, its call stack will be
* reclaimed).
*
* Detached thread are particularly useful when some work needs to be done
* asynchronously, that is likely to be completed much earlier than the thread
* can practically be joined. In this case, thread detach can spare memory.
*
* A detached thread may be cancelled, so as to expedite its termination.
* Be extremely careful if you do this: while a normal joinable thread can
* safely be cancelled after it has already exited, cancelling an already
* exited detached thread is undefined: The thread handle would is destroyed
* immediately when the detached thread exits. So you need to ensure that the
* detached thread is still running before cancellation is attempted.
*
* WARNING: Care must be taken that any resources used by the detached thread
* remains valid until the thread completes.
*
* Attention: A detached thread must eventually exit just like another other
* thread. In practice, LibVLC will wait for detached threads to exit before
* it unloads the plugins.
*
* 1st parameter: th [OUT] pointer to hold the thread handle, or NULL
* 2nd parameter: entry entry point for the thread
* 3rd parameter: data data parameter given to the entry point
* 4th parameter: priority thread priority value
* returns 0 on success, a standard error code on error. */
int vlc_clone_detach (vlc_thread_t *th, void *(*entry) (void *), void *data,
int priority)
{
......@@ -677,22 +492,11 @@ int vlc_set_priority (vlc_thread_t th, int priority)
return VLC_SUCCESS;
}
/* Marks a thread as cancelled. Next time the target thread reaches a
* cancellation point (while not having disabled cancellation), it will
* run its cancellation cleanup handler, the thread variable destructors, and
* terminate. vlc_join() must be used afterward regardless of a thread being
* cancelled or not. */
void vlc_cancel (vlc_thread_t thread_id)
{
pthread_cancel (thread_id);
}
/* 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.
* returns Previous cancellation state (opaque value for vlc_restorecancel()). */
int vlc_savecancel (void)
{
int state;
......@@ -702,15 +506,12 @@ int vlc_savecancel (void)
return state;
}
/* Restore the cancellation state for the calling thread.
* parameter: previous state as returned by vlc_savecancel(). */
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))
......@@ -721,11 +522,6 @@ void vlc_restorecancel (int state)
#endif
}
/* Issues an explicit deferred cancellation point.
* This has no effect if thread cancellation is disabled.
* This can be called when there is a rather slow non-sleeping operation.
* This is also used to force a cancellation point in a function that would
* otherwise "not always" be a one (block_FifoGet() is an example). */
void vlc_testcancel (void)
{
pthread_testcancel ();
......@@ -737,18 +533,6 @@ void vlc_control_cancel (int cmd, ...)
vlc_assert_unreachable ();
}
/* Precision monotonic clock.
*
* In principles, the clock has a precision of 1 MHz. But the actual resolution
* may be much lower, especially when it comes to sleeping with mwait() or
* msleep(). Most general-purpose operating systems provide a resolution of
* only 100 to 1000 Hz.
*
* WARNING: The origin date (time value "zero") is not specified. It is
* typically the time the kernel started, but this is platform-dependent.
* If you need wall clock time, use gettimeofday() instead.
*
* returns a timestamp in microseconds. */
mtime_t mdate (void)
{
vlc_clock_setup();
......@@ -767,8 +551,6 @@ mtime_t mdate (void)
}
#undef mwait
/* Wait until a deadline (possibly later due to OS scheduling).
* parameter: deadline timestamp to wait for (see mdate()) */
void mwait (mtime_t deadline)
{
deadline -= mdate ();
......@@ -777,8 +559,6 @@ void mwait (mtime_t deadline)
}
#undef msleep
/* Wait for an interval of time.
* parameter: delay how long to wait (in microseconds) */
void msleep (mtime_t delay)
{
struct timespec ts = mtime_to_ts (delay);
......@@ -789,8 +569,6 @@ void msleep (mtime_t delay)
assert (errno == EINTR);
}
/* Count CPUs.
* returns the number of available (logical) CPUs. */
unsigned vlc_GetCPUCount(void)
{
return sysconf(_SC_NPROCESSORS_CONF);
......
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