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Commit 6403d128 authored by Felix Paul Kühne's avatar Felix Paul Kühne
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src/darwin: cleanup threads

parent b85892f9
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Showing with 104 additions and 189 deletions
src/darwin/thread.c
View file @ 6403d128
......@@ -33,21 +33,13 @@
#include <vlc_atomic.h>
#include "libvlc.h"
#include <stdarg.h>
#include <signal.h>
#include <errno.h>
#include <time.h>
#include <assert.h>
#include <sys/types.h>
#include <unistd.h> /* fsync() */
#include <pthread.h>
#include <sched.h>
#include <mach/mach_init.h> /* mach_task_self in semaphores */
#include <execinfo.h>
#include <sys/time.h> /* gettimeofday() */
#define vlc_clock_setup() (void)0
......@@ -61,18 +53,14 @@ static struct timespec mtime_to_ts (mtime_t date)
return ts;
}
/**
* Print a backtrace to the standard error for debugging purpose.
*/
/* Print a backtrace to the standard error for debugging purpose. */
void vlc_trace (const char *fn, const char *file, unsigned line)
{
fprintf (stderr, "at %s:%u in %s\n", file, line, fn);
fflush (stderr); /* needed before switch to low-level I/O */
#ifdef HAVE_BACKTRACE
void *stack[20];
int len = backtrace (stack, sizeof (stack) / sizeof (stack[0]));
backtrace_symbols_fd (stack, len, 2);
#endif
fsync (2);
}
......@@ -84,9 +72,7 @@ static inline unsigned long vlc_threadid (void)
}
#ifndef NDEBUG
/**
* Reports a fatal error from the threading layer, for debugging purposes.
*/
/* Reports a fatal error from the threading layer, for debugging purposes. */
static void
vlc_thread_fatal (const char *action, int error,
const char *function, const char *file, unsigned line)
......@@ -125,9 +111,7 @@ vlc_thread_fatal (const char *action, int error,
# define VLC_THREAD_ASSERT( action ) ((void)val)
#endif
/**
* Initializes a fast mutex.
*/
/* Initializes a fast mutex. */
void vlc_mutex_init( vlc_mutex_t *p_mutex )
{
pthread_mutexattr_t attr;
......@@ -144,10 +128,8 @@ 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.
*/
/* 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;
......@@ -161,12 +143,10 @@ void vlc_mutex_init_recursive( vlc_mutex_t *p_mutex )
}
/**
* Destroys a mutex. The mutex must not be locked.
/* Destroys a mutex. The mutex must not be locked.
*
* @param p_mutex mutex to destroy
* @return always succeeds
*/
* 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 );
......@@ -180,9 +160,7 @@ 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.
*/
/* Asserts that a mutex is locked by the calling thread. */
void vlc_assert_locked (vlc_mutex_t *p_mutex)
{
if (RUNNING_ON_VALGRIND > 0)
......@@ -191,13 +169,12 @@ void vlc_assert_locked (vlc_mutex_t *p_mutex)
}
#endif
/**
* Acquires a mutex. If needed, waits for any other thread to release it.
/* 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.
*
* @param p_mutex mutex initialized with vlc_mutex_init() or
* parameter: p_mutex mutex initialized with vlc_mutex_init() or
* vlc_mutex_init_recursive()
*/
void vlc_mutex_lock (vlc_mutex_t *p_mutex)
......@@ -206,21 +183,19 @@ void vlc_mutex_lock (vlc_mutex_t *p_mutex)
VLC_THREAD_ASSERT ("locking mutex");
}
/**
* Acquires a mutex if and only if it is not currently held by another thread.
/* 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
* 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.
*
* @param p_mutex mutex initialized with vlc_mutex_init() or
* parameter: 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.
*/
* 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 );
......@@ -230,19 +205,15 @@ int vlc_mutex_trylock (vlc_mutex_t *p_mutex)
return val;
}
/**
* Releases a mutex (or crashes if the mutex is not locked by the caller).
* @param p_mutex mutex locked with vlc_mutex_lock().
*/
/* 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 );
VLC_THREAD_ASSERT ("unlocking mutex");
}
/**
* Initializes a condition variable.
*/
/* Initialize a condition variable. */
void vlc_cond_init (vlc_cond_t *p_condvar)
{
pthread_condattr_t attr;
......@@ -255,22 +226,18 @@ void vlc_cond_init (vlc_cond_t *p_condvar)
pthread_condattr_destroy (&attr);
}
/**
* Initializes a condition variable.
/* 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.
*/
* the vlc_cond_timedwait() time-out parameter. */
void vlc_cond_init_daytime (vlc_cond_t *p_condvar)
{
if (unlikely(pthread_cond_init (p_condvar, NULL)))
abort ();
}
/**
* Destroys a condition variable. No threads shall be waiting or signaling the
/* Destroys a condition variable. No threads shall be waiting or signaling the
* condition.
* @param p_condvar condition variable to destroy
*/
* parameter: p_condvar condition variable to destroy */
void vlc_cond_destroy (vlc_cond_t *p_condvar)
{
int val = pthread_cond_destroy( p_condvar );
......@@ -299,27 +266,22 @@ void vlc_cond_destroy (vlc_cond_t *p_condvar)
VLC_THREAD_ASSERT ("destroying condition");
}
/**
* Wakes up one thread waiting on a condition variable, if any.
* @param p_condvar condition variable
*/
/* 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 );
VLC_THREAD_ASSERT ("signaling condition variable");
}
/**
* Wakes up all threads (if any) waiting on a condition variable.
* @param p_cond 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);
}
/**
* Waits for a condition variable. The calling thread will be suspended until
/* 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.
......@@ -333,7 +295,7 @@ void vlc_cond_broadcast (vlc_cond_t *p_condvar)
* cancellation proceeds.
*
* The canonical way to use a condition variable to wait for event foobar is:
@code
sample code:
vlc_mutex_lock (&lock);
mutex_cleanup_push (&lock); // release the mutex in case of cancellation
......@@ -343,33 +305,29 @@ void vlc_cond_broadcast (vlc_cond_t *p_condvar)
--- foobar is now true, do something about it here --
vlc_cleanup_run (); // release the mutex
@endcode
*
* @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
*/
* 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, p_mutex );
VLC_THREAD_ASSERT ("waiting on condition");
}
/**
* Waits for a condition variable up to a certain date.
/* 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.
*
* @param p_condvar condition variable to wait on
* @param p_mutex mutex which is unlocked while waiting,
* 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.
* @param deadline <b>absolute</b> timeout
* 3rd parameter: deadline <b>absolute</b> timeout
*
* @return 0 if the condition was signaled, an error code in case of 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)
......@@ -381,18 +339,14 @@ int vlc_cond_timedwait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex,
return val;
}
/**
* Initializes a semaphore.
*/
/* Initialize a semaphore. */
void vlc_sem_init (vlc_sem_t *sem, unsigned value)
{
if (unlikely(semaphore_create(mach_task_self(), sem, SYNC_POLICY_FIFO, value) != KERN_SUCCESS))
abort ();
}
/**
* Destroys a semaphore.
*/
/* Destroy a semaphore. */
void vlc_sem_destroy (vlc_sem_t *sem)
{
int val;
......@@ -405,10 +359,8 @@ void vlc_sem_destroy (vlc_sem_t *sem)
VLC_THREAD_ASSERT ("destroying semaphore");
}
/**
* Increments the value of a semaphore.
* @return 0 on success, EOVERFLOW in case of integer overflow
*/
/* 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;
......@@ -423,10 +375,8 @@ int vlc_sem_post (vlc_sem_t *sem)
return val;
}
/**
* Atomically wait for the semaphore to become non-zero (if needed),
* then decrements it.
*/
/* Atomically wait for the semaphore to become non-zero (if needed),
* then decrements it. */
void vlc_sem_wait (vlc_sem_t *sem)
{
int val;
......@@ -439,61 +389,51 @@ void vlc_sem_wait (vlc_sem_t *sem)
VLC_THREAD_ASSERT ("locking semaphore");
}
/**
* Initializes a read/write lock.
*/
/* Initialize a read/write lock. */
void vlc_rwlock_init (vlc_rwlock_t *lock)
{
if (unlikely(pthread_rwlock_init (lock, NULL)))
abort ();
}
/**
* Destroys an initialized unused read/write lock.
*/
/* 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");
}
/**
* Acquires a read/write lock for reading. Recursion is allowed.
* @note This function may be a point of cancellation.
*/
/* 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");
}
/**
* Acquires a read/write lock for writing. Recursion is not allowed.
* @note This function may be a point of cancellation.
*/
/* 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");
}
/**
* Releases a read/write lock.
*/
/* 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.
* @param key where to store the thread-specific variable handle
* @param destr a destruction callback. It is called whenever a thread exits
* and the thread-specific variable has a non-NULL value.
* @return 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.
/* 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 *))
{
......@@ -505,23 +445,20 @@ void vlc_threadvar_delete (vlc_threadvar_t *p_tls)
pthread_key_delete (*p_tls);
}
/**
* Sets a thread-specific variable.
* @param key thread-local variable key (created with vlc_threadvar_create())
* @param value new value for the variable for the calling thread
* @return 0 on success, a system error code otherwise.
*/
/* 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);
}
/**
* Gets the value of a thread-local variable for the calling thread.
/* Get the value of a thread-local variable for the calling thread.
* This function cannot fail.
* @return the value associated with the given variable for the calling
* or NULL if there is no value.
*/
* 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);
......@@ -603,19 +540,17 @@ static int vlc_clone_attr (vlc_thread_t *th, pthread_attr_t *attr,
return ret;
}
/**
* Creates and starts new thread.
/* Create and start a new thread.
*
* The thread must be <i>joined</i> with vlc_join() to reclaim resources
* when it is not needed anymore.
* The thread must be joined with vlc_join() to reclaim resources when it is
* not needed anymore.
*
* @param th [OUT] pointer to write the handle of the created thread to
* 1st parameter: th [OUT] pointer to write the handle of the created thread to
* (mandatory, must be non-NULL)
* @param entry entry point for the thread
* @param data data parameter given to the entry point
* @param priority thread priority value
* @return 0 on success, a standard error code on error.
*/
* 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)
{
......@@ -625,16 +560,15 @@ int vlc_clone (vlc_thread_t *th, void *(*entry) (void *), void *data,
return vlc_clone_attr (th, &attr, entry, data, priority);
}
/**
* Waits for a thread to complete (if needed), then destroys it.
/* 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 <b>cannot</b> be joined.
*
* WARNING: A thread cannot join itself (normally VLC will abort if this is
* attempted). Also, a detached thread cannot be joined.
*
* @param handle thread handle
* @param p_result [OUT] pointer to write the thread return value or NULL
* 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)
{
......@@ -642,8 +576,7 @@ void vlc_join (vlc_thread_t handle, void **result)
VLC_THREAD_ASSERT ("joining thread");
}
/**
* Creates and starts new detached 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).
......@@ -659,19 +592,18 @@ void vlc_join (vlc_thread_t handle, void **result)
* 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
* WARNING: Care must be taken that any resources used by the detached thread
* remains valid until the thread completes.
*
* @note A detached thread must eventually exit just like another other
* 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.
*
* @param th [OUT] pointer to hold the thread handle, or NULL
* @param entry entry point for the thread
* @param data data parameter given to the entry point
* @param priority thread priority value
* @return 0 on success, a standard error code on error.
*/
* 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)
{
......@@ -692,26 +624,22 @@ 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
/* 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.
*/
* 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
/* 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()).
*/
* returns Previous cancellation state (opaque value for vlc_restorecancel()). */
int vlc_savecancel (void)
{
int state;
......@@ -721,11 +649,8 @@ int vlc_savecancel (void)
return state;
}
/**
* Restore the cancellation state for the calling thread.
* @param state previous state as returned by vlc_savecancel().
* @return Nothing, always succeeds.
*/
/* Restore the cancellation state for the calling thread.
* parameter: previous state as returned by vlc_savecancel(). */
void vlc_restorecancel (int state)
{
#ifndef NDEBUG
......@@ -743,13 +668,11 @@ void vlc_restorecancel (int state)
#endif
}
/**
* Issues an explicit deferred cancellation point.
/* 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).
*/
* otherwise "not always" be a one (block_FifoGet() is an example). */
void vlc_testcancel (void)
{
pthread_testcancel ();
......@@ -761,20 +684,18 @@ void vlc_control_cancel (int cmd, ...)
assert (0);
}
/**
* Precision monotonic clock.
/* 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
* 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.
*
* @return a timestamp in microseconds.
*/
* returns a timestamp in microseconds. */
mtime_t mdate (void)
{
struct timeval tv;
......@@ -785,10 +706,8 @@ mtime_t mdate (void)
}
#undef mwait
/**
* Waits until a deadline (possibly later due to OS scheduling).
* @param deadline timestamp to wait for (see mdate())
*/
/* 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 ();
......@@ -797,10 +716,8 @@ void mwait (mtime_t deadline)
}
#undef msleep
/**
* Waits for an interval of time.
* @param delay how long to wait (in microseconds)
*/
/* 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);
......@@ -810,10 +727,8 @@ void msleep (mtime_t delay)
}
/**
* Count CPUs.
* @return number of available (logical) CPUs.
*/
/* Count CPUs.
* returns the number of available (logical) CPUs. */
unsigned vlc_GetCPUCount(void)
{
return sysconf(_SC_NPROCESSORS_CONF);
......
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