2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * 2005 Wim Taymans <wim@fluendo.com>
5 * gsttask.c: Streaming tasks
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Library General Public License for more details.
17 * You should have received a copy of the GNU Library General Public
18 * License along with this library; if not, write to the
19 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
20 * Boston, MA 02110-1301, USA.
25 * @short_description: Abstraction of GStreamer streaming threads.
26 * @see_also: #GstElement, #GstPad
28 * #GstTask is used by #GstElement and #GstPad to provide the data passing
29 * threads in a #GstPipeline.
31 * A #GstPad will typically start a #GstTask to push or pull data to/from the
32 * peer pads. Most source elements start a #GstTask to push data. In some cases
33 * a demuxer element can start a #GstTask to pull data from a peer element. This
34 * is typically done when the demuxer can perform random access on the upstream
35 * peer element for improved performance.
37 * Although convenience functions exist on #GstPad to start/pause/stop tasks, it
38 * might sometimes be needed to create a #GstTask manually if it is not related to
41 * Before the #GstTask can be run, it needs a #GRecMutex that can be set with
42 * gst_task_set_lock().
44 * The task can be started, paused and stopped with gst_task_start(), gst_task_pause()
45 * and gst_task_stop() respectively or with the gst_task_set_state() function.
47 * A #GstTask will repeatedly call the #GstTaskFunction with the user data
48 * that was provided when creating the task with gst_task_new(). While calling
49 * the function it will acquire the provided lock. The provided lock is released
50 * when the task pauses or stops.
52 * Stopping a task with gst_task_stop() will not immediately make sure the task is
53 * not running anymore. Use gst_task_join() to make sure the task is completely
54 * stopped and the thread is stopped.
56 * After creating a #GstTask, use gst_object_unref() to free its resources. This can
57 * only be done when the task is not running anymore.
59 * Task functions can send a #GstMessage to send out-of-band data to the
60 * application. The application can receive messages from the #GstBus in its
63 * For debugging purposes, the task will configure its object name as the thread
64 * name on Linux. Please note that the object name should be configured before the
65 * task is started; changing the object name after the task has been started, has
66 * no effect on the thread name.
69 #include "gst_private.h"
73 #include "glib-compat-private.h"
77 #ifdef HAVE_SYS_PRCTL_H
78 #include <sys/prctl.h>
81 #ifdef HAVE_PTHREAD_SETNAME_NP_WITHOUT_TID
85 GST_DEBUG_CATEGORY_STATIC (task_debug);
86 #define GST_CAT_DEFAULT (task_debug)
88 #define SET_TASK_STATE(t,s) (g_atomic_int_set (&GST_TASK_STATE(t), (s)))
89 #define GET_TASK_STATE(t) ((GstTaskState) g_atomic_int_get (&GST_TASK_STATE(t)))
91 #define GST_TASK_GET_PRIVATE(obj) \
92 (G_TYPE_INSTANCE_GET_PRIVATE ((obj), GST_TYPE_TASK, GstTaskPrivate))
94 struct _GstTaskPrivate
96 /* callbacks for managing the thread of this task */
97 GstTaskThreadFunc enter_func;
98 gpointer enter_user_data;
99 GDestroyNotify enter_notify;
101 GstTaskThreadFunc leave_func;
102 gpointer leave_user_data;
103 GDestroyNotify leave_notify;
105 /* configured pool */
108 /* remember the pool and id that is currently running. */
110 GstTaskPool *pool_id;
116 struct _THREADNAME_INFO
118 DWORD dwType; // must be 0x1000
119 LPCSTR szName; // pointer to name (in user addr space)
120 DWORD dwThreadID; // thread ID (-1=caller thread)
121 DWORD dwFlags; // reserved for future use, must be zero
123 typedef struct _THREADNAME_INFO THREADNAME_INFO;
126 SetThreadName (DWORD dwThreadID, LPCSTR szThreadName)
128 THREADNAME_INFO info;
129 info.dwType = 0x1000;
130 info.szName = szThreadName;
131 info.dwThreadID = dwThreadID;
135 RaiseException (0x406D1388, 0, sizeof (info) / sizeof (DWORD),
138 __except (EXCEPTION_CONTINUE_EXECUTION) {
143 static void gst_task_finalize (GObject * object);
145 static void gst_task_func (GstTask * task);
147 static GMutex pool_lock;
151 GST_DEBUG_CATEGORY_INIT (task_debug, "task", 0, "Processing tasks"); \
154 G_DEFINE_TYPE_WITH_CODE (GstTask, gst_task, GST_TYPE_OBJECT, _do_init);
157 init_klass_pool (GstTaskClass * klass)
159 g_mutex_lock (&pool_lock);
161 gst_task_pool_cleanup (klass->pool);
162 gst_object_unref (klass->pool);
164 klass->pool = gst_task_pool_new ();
165 gst_task_pool_prepare (klass->pool, NULL);
166 g_mutex_unlock (&pool_lock);
170 gst_task_class_init (GstTaskClass * klass)
172 GObjectClass *gobject_class;
174 gobject_class = (GObjectClass *) klass;
176 g_type_class_add_private (klass, sizeof (GstTaskPrivate));
178 gobject_class->finalize = gst_task_finalize;
180 init_klass_pool (klass);
184 gst_task_init (GstTask * task)
188 klass = GST_TASK_GET_CLASS (task);
190 task->priv = GST_TASK_GET_PRIVATE (task);
191 task->running = FALSE;
194 g_cond_init (&task->cond);
195 SET_TASK_STATE (task, GST_TASK_STOPPED);
197 /* use the default klass pool for this task, users can
198 * override this later */
199 g_mutex_lock (&pool_lock);
200 task->priv->pool = gst_object_ref (klass->pool);
201 g_mutex_unlock (&pool_lock);
203 /* clear floating flag */
204 gst_object_ref_sink (task);
208 gst_task_finalize (GObject * object)
210 GstTask *task = GST_TASK (object);
211 GstTaskPrivate *priv = task->priv;
213 GST_DEBUG ("task %p finalize", task);
215 if (priv->enter_notify)
216 priv->enter_notify (priv->enter_user_data);
218 if (priv->leave_notify)
219 priv->leave_notify (priv->leave_user_data);
222 task->notify (task->user_data);
224 gst_object_unref (priv->pool);
226 /* task thread cannot be running here since it holds a ref
227 * to the task so that the finalize could not have happened */
228 g_cond_clear (&task->cond);
230 G_OBJECT_CLASS (gst_task_parent_class)->finalize (object);
233 /* should be called with the object LOCK */
235 gst_task_configure_name (GstTask * task)
237 #if defined(HAVE_SYS_PRCTL_H) && defined(PR_SET_NAME)
239 gchar thread_name[17] = { 0, };
241 GST_OBJECT_LOCK (task);
242 name = GST_OBJECT_NAME (task);
244 /* set the thread name to something easily identifiable */
245 if (!snprintf (thread_name, 17, "%s", GST_STR_NULL (name))) {
246 GST_DEBUG_OBJECT (task, "Could not create thread name for '%s'", name);
248 GST_DEBUG_OBJECT (task, "Setting thread name to '%s'", thread_name);
249 if (prctl (PR_SET_NAME, (unsigned long int) thread_name, 0, 0, 0))
250 GST_DEBUG_OBJECT (task, "Failed to set thread name");
252 GST_OBJECT_UNLOCK (task);
253 #elif defined(HAVE_PTHREAD_SETNAME_NP_WITHOUT_TID)
256 GST_OBJECT_LOCK (task);
257 name = GST_OBJECT_NAME (task);
259 /* set the thread name to something easily identifiable */
260 GST_DEBUG_OBJECT (task, "Setting thread name to '%s'", name);
261 if (pthread_setname_np (name))
262 GST_DEBUG_OBJECT (task, "Failed to set thread name");
264 GST_OBJECT_UNLOCK (task);
265 #elif defined (_MSC_VER)
267 name = GST_OBJECT_NAME (task);
269 /* set the thread name to something easily identifiable */
270 GST_DEBUG_OBJECT (task, "Setting thread name to '%s'", name);
271 SetThreadName (-1, name);
276 gst_task_func (GstTask * task)
280 GstTaskPrivate *priv;
284 tself = g_thread_self ();
286 GST_DEBUG ("Entering task %p, thread %p", task, tself);
288 /* we have to grab the lock to get the mutex. We also
289 * mark our state running so that nobody can mess with
291 GST_OBJECT_LOCK (task);
292 if (GET_TASK_STATE (task) == GST_TASK_STOPPED)
294 lock = GST_TASK_GET_LOCK (task);
295 if (G_UNLIKELY (lock == NULL))
297 task->thread = tself;
298 GST_OBJECT_UNLOCK (task);
300 /* fire the enter_func callback when we need to */
301 if (priv->enter_func)
302 priv->enter_func (task, tself, priv->enter_user_data);
304 /* locking order is TASK_LOCK, LOCK */
305 g_rec_mutex_lock (lock);
306 /* configure the thread name now */
307 gst_task_configure_name (task);
309 while (G_LIKELY (GET_TASK_STATE (task) != GST_TASK_STOPPED)) {
310 GST_OBJECT_LOCK (task);
311 while (G_UNLIKELY (GST_TASK_STATE (task) == GST_TASK_PAUSED)) {
312 g_rec_mutex_unlock (lock);
314 GST_TASK_SIGNAL (task);
315 GST_INFO_OBJECT (task, "Task going to paused");
316 GST_TASK_WAIT (task);
317 GST_INFO_OBJECT (task, "Task resume from paused");
318 GST_OBJECT_UNLOCK (task);
319 /* locking order.. */
320 g_rec_mutex_lock (lock);
321 GST_OBJECT_LOCK (task);
324 if (G_UNLIKELY (GET_TASK_STATE (task) == GST_TASK_STOPPED)) {
325 GST_OBJECT_UNLOCK (task);
328 GST_OBJECT_UNLOCK (task);
331 task->func (task->user_data);
334 g_rec_mutex_unlock (lock);
336 GST_OBJECT_LOCK (task);
340 if (priv->leave_func) {
341 /* fire the leave_func callback when we need to. We need to do this before
342 * we signal the task and with the task lock released. */
343 GST_OBJECT_UNLOCK (task);
344 priv->leave_func (task, tself, priv->leave_user_data);
345 GST_OBJECT_LOCK (task);
347 /* now we allow messing with the lock again by setting the running flag to
348 * %FALSE. Together with the SIGNAL this is the sign for the _join() to
350 * Note that we still have not dropped the final ref on the task. We could
351 * check here if there is a pending join() going on and drop the last ref
352 * before releasing the lock as we can be sure that a ref is held by the
353 * caller of the join(). */
354 task->running = FALSE;
355 GST_TASK_SIGNAL (task);
356 GST_OBJECT_UNLOCK (task);
358 GST_DEBUG ("Exit task %p, thread %p", task, g_thread_self ());
360 gst_object_unref (task);
365 g_warning ("starting task without a lock");
371 * gst_task_cleanup_all:
373 * Wait for all tasks to be stopped. This is mainly used internally
374 * to ensure proper cleanup of internal data structures in test suites.
379 gst_task_cleanup_all (void)
383 if ((klass = g_type_class_peek (GST_TYPE_TASK))) {
384 init_klass_pool (klass);
390 * @func: The #GstTaskFunction to use
391 * @user_data: User data to pass to @func
392 * @notify: the function to call when @user_data is no longer needed.
394 * Create a new Task that will repeatedly call the provided @func
395 * with @user_data as a parameter. Typically the task will run in
398 * The function cannot be changed after the task has been created. You
399 * must create a new #GstTask to change the function.
401 * This function will not yet create and start a thread. Use gst_task_start() or
402 * gst_task_pause() to create and start the GThread.
404 * Before the task can be used, a #GRecMutex must be configured using the
405 * gst_task_set_lock() function. This lock will always be acquired while
408 * Returns: (transfer full): A new #GstTask.
413 gst_task_new (GstTaskFunction func, gpointer user_data, GDestroyNotify notify)
417 task = g_object_newv (GST_TYPE_TASK, 0, NULL);
419 task->user_data = user_data;
420 task->notify = notify;
422 GST_DEBUG ("Created task %p", task);
429 * @task: The #GstTask to use
430 * @mutex: The #GRecMutex to use
432 * Set the mutex used by the task. The mutex will be acquired before
433 * calling the #GstTaskFunction.
435 * This function has to be called before calling gst_task_pause() or
441 gst_task_set_lock (GstTask * task, GRecMutex * mutex)
443 GST_OBJECT_LOCK (task);
444 if (G_UNLIKELY (task->running))
446 GST_INFO ("setting stream lock %p on task %p", mutex, task);
447 GST_TASK_GET_LOCK (task) = mutex;
448 GST_OBJECT_UNLOCK (task);
455 GST_OBJECT_UNLOCK (task);
456 g_warning ("cannot call set_lock on a running task");
464 * Get the #GstTaskPool that this task will use for its streaming
469 * Returns: (transfer full): the #GstTaskPool used by @task. gst_object_unref()
473 gst_task_get_pool (GstTask * task)
476 GstTaskPrivate *priv;
478 g_return_val_if_fail (GST_IS_TASK (task), NULL);
482 GST_OBJECT_LOCK (task);
483 result = gst_object_ref (priv->pool);
484 GST_OBJECT_UNLOCK (task);
492 * @pool: (transfer none): a #GstTaskPool
494 * Set @pool as the new GstTaskPool for @task. Any new streaming threads that
495 * will be created by @task will now use @pool.
500 gst_task_set_pool (GstTask * task, GstTaskPool * pool)
503 GstTaskPrivate *priv;
505 g_return_if_fail (GST_IS_TASK (task));
506 g_return_if_fail (GST_IS_TASK_POOL (pool));
510 GST_OBJECT_LOCK (task);
511 if (priv->pool != pool) {
513 priv->pool = gst_object_ref (pool);
516 GST_OBJECT_UNLOCK (task);
519 gst_object_unref (old);
523 * gst_task_set_enter_callback:
524 * @task: The #GstTask to use
525 * @enter_func: (in): a #GstTaskThreadFunc
526 * @user_data: user data passed to @enter_func
527 * @notify: called when @user_data is no longer referenced
529 * Call @enter_func when the task function of @task is entered. @user_data will
530 * be passed to @enter_func and @notify will be called when @user_data is no
534 gst_task_set_enter_callback (GstTask * task, GstTaskThreadFunc enter_func,
535 gpointer user_data, GDestroyNotify notify)
537 GDestroyNotify old_notify;
539 g_return_if_fail (task != NULL);
540 g_return_if_fail (GST_IS_TASK (task));
542 GST_OBJECT_LOCK (task);
543 if ((old_notify = task->priv->enter_notify)) {
544 gpointer old_data = task->priv->enter_user_data;
546 task->priv->enter_user_data = NULL;
547 task->priv->enter_notify = NULL;
548 GST_OBJECT_UNLOCK (task);
550 old_notify (old_data);
552 GST_OBJECT_LOCK (task);
554 task->priv->enter_func = enter_func;
555 task->priv->enter_user_data = user_data;
556 task->priv->enter_notify = notify;
557 GST_OBJECT_UNLOCK (task);
561 * gst_task_set_leave_callback:
562 * @task: The #GstTask to use
563 * @leave_func: (in): a #GstTaskThreadFunc
564 * @user_data: user data passed to @leave_func
565 * @notify: called when @user_data is no longer referenced
567 * Call @leave_func when the task function of @task is left. @user_data will
568 * be passed to @leave_func and @notify will be called when @user_data is no
572 gst_task_set_leave_callback (GstTask * task, GstTaskThreadFunc leave_func,
573 gpointer user_data, GDestroyNotify notify)
575 GDestroyNotify old_notify;
577 g_return_if_fail (task != NULL);
578 g_return_if_fail (GST_IS_TASK (task));
580 GST_OBJECT_LOCK (task);
581 if ((old_notify = task->priv->leave_notify)) {
582 gpointer old_data = task->priv->leave_user_data;
584 task->priv->leave_user_data = NULL;
585 task->priv->leave_notify = NULL;
586 GST_OBJECT_UNLOCK (task);
588 old_notify (old_data);
590 GST_OBJECT_LOCK (task);
592 task->priv->leave_func = leave_func;
593 task->priv->leave_user_data = user_data;
594 task->priv->leave_notify = notify;
595 GST_OBJECT_UNLOCK (task);
599 * gst_task_get_state:
600 * @task: The #GstTask to query
602 * Get the current state of the task.
604 * Returns: The #GstTaskState of the task
609 gst_task_get_state (GstTask * task)
613 g_return_val_if_fail (GST_IS_TASK (task), GST_TASK_STOPPED);
615 result = GET_TASK_STATE (task);
620 /* make sure the task is running and start a thread if it's not.
621 * This function must be called with the task LOCK. */
623 start_task (GstTask * task)
626 GError *error = NULL;
627 GstTaskPrivate *priv;
631 /* new task, We ref before so that it remains alive while
632 * the thread is running. */
633 gst_object_ref (task);
634 /* mark task as running so that a join will wait until we schedule
635 * and exit the task function. */
636 task->running = TRUE;
638 /* push on the thread pool, we remember the original pool because the user
639 * could change it later on and then we join to the wrong pool. */
640 priv->pool_id = gst_object_ref (priv->pool);
642 gst_task_pool_push (priv->pool_id, (GstTaskPoolFunction) gst_task_func,
646 g_warning ("failed to create thread: %s", error->message);
647 g_error_free (error);
655 * gst_task_set_state:
657 * @state: the new task state
659 * Sets the state of @task to @state.
661 * The @task must have a lock associated with it using
662 * gst_task_set_lock() when going to GST_TASK_STARTED or GST_TASK_PAUSED or
663 * this function will return %FALSE.
667 * Returns: %TRUE if the state could be changed.
670 gst_task_set_state (GstTask * task, GstTaskState state)
675 g_return_val_if_fail (GST_IS_TASK (task), FALSE);
677 GST_DEBUG_OBJECT (task, "Changing task %p to state %d", task, state);
679 GST_OBJECT_LOCK (task);
680 if (state != GST_TASK_STOPPED)
681 if (G_UNLIKELY (GST_TASK_GET_LOCK (task) == NULL))
684 /* if the state changed, do our thing */
685 old = GET_TASK_STATE (task);
687 SET_TASK_STATE (task, state);
689 case GST_TASK_STOPPED:
690 /* If the task already has a thread scheduled we don't have to do
692 if (G_UNLIKELY (!task->running))
693 res = start_task (task);
695 case GST_TASK_PAUSED:
696 /* when we are paused, signal to go to the new state */
697 GST_TASK_SIGNAL (task);
699 case GST_TASK_STARTED:
700 /* if we were started, we'll go to the new state after the next
705 GST_OBJECT_UNLOCK (task);
712 GST_WARNING_OBJECT (task, "state %d set on task without a lock", state);
713 GST_OBJECT_UNLOCK (task);
714 g_warning ("task without a lock can't be set to state %d", state);
721 * @task: The #GstTask to start
723 * Starts @task. The @task must have a lock associated with it using
724 * gst_task_set_lock() or this function will return %FALSE.
726 * Returns: %TRUE if the task could be started.
731 gst_task_start (GstTask * task)
733 return gst_task_set_state (task, GST_TASK_STARTED);
738 * @task: The #GstTask to stop
740 * Stops @task. This method merely schedules the task to stop and
741 * will not wait for the task to have completely stopped. Use
742 * gst_task_join() to stop and wait for completion.
744 * Returns: %TRUE if the task could be stopped.
749 gst_task_stop (GstTask * task)
751 return gst_task_set_state (task, GST_TASK_STOPPED);
756 * @task: The #GstTask to pause
758 * Pauses @task. This method can also be called on a task in the
759 * stopped state, in which case a thread will be started and will remain
760 * in the paused state. This function does not wait for the task to complete
763 * Returns: %TRUE if the task could be paused.
768 gst_task_pause (GstTask * task)
770 return gst_task_set_state (task, GST_TASK_PAUSED);
775 * @task: The #GstTask to join
777 * Joins @task. After this call, it is safe to unref the task
778 * and clean up the lock set with gst_task_set_lock().
780 * The task will automatically be stopped with this call.
782 * This function cannot be called from within a task function as this
783 * would cause a deadlock. The function will detect this and print a
786 * Returns: %TRUE if the task could be joined.
791 gst_task_join (GstTask * task)
794 GstTaskPrivate *priv;
796 GstTaskPool *pool = NULL;
800 g_return_val_if_fail (GST_IS_TASK (task), FALSE);
802 tself = g_thread_self ();
804 GST_DEBUG_OBJECT (task, "Joining task %p, thread %p", task, tself);
806 /* we don't use a real thread join here because we are using
808 GST_OBJECT_LOCK (task);
809 if (G_UNLIKELY (tself == task->thread))
811 SET_TASK_STATE (task, GST_TASK_STOPPED);
812 /* signal the state change for when it was blocked in PAUSED. */
813 GST_TASK_SIGNAL (task);
814 /* we set the running flag when pushing the task on the thread pool.
815 * This means that the task function might not be called when we try
816 * to join it here. */
817 while (G_LIKELY (task->running))
818 GST_TASK_WAIT (task);
819 /* clean the thread */
821 /* get the id and pool to join */
822 pool = priv->pool_id;
824 priv->pool_id = NULL;
826 GST_OBJECT_UNLOCK (task);
830 gst_task_pool_join (pool, id);
831 gst_object_unref (pool);
834 GST_DEBUG_OBJECT (task, "Joined task %p", task);
841 GST_WARNING_OBJECT (task, "trying to join task from its thread");
842 GST_OBJECT_UNLOCK (task);
843 g_warning ("\nTrying to join task %p from its thread would deadlock.\n"
844 "You cannot change the state of an element from its streaming\n"
845 "thread. Use g_idle_add() or post a GstMessage on the bus to\n"
846 "schedule the state change from the main thread.\n", task);