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;
114 #define WIN32_LEAN_AND_MEAN
117 struct _THREADNAME_INFO
119 DWORD dwType; // must be 0x1000
120 LPCSTR szName; // pointer to name (in user addr space)
121 DWORD dwThreadID; // thread ID (-1=caller thread)
122 DWORD dwFlags; // reserved for future use, must be zero
124 typedef struct _THREADNAME_INFO THREADNAME_INFO;
127 SetThreadName (DWORD dwThreadID, LPCSTR szThreadName)
129 THREADNAME_INFO info;
130 info.dwType = 0x1000;
131 info.szName = szThreadName;
132 info.dwThreadID = dwThreadID;
136 RaiseException (0x406D1388, 0, sizeof (info) / sizeof (DWORD),
137 (const ULONG_PTR *) &info);
139 __except (EXCEPTION_CONTINUE_EXECUTION) {
144 static void gst_task_finalize (GObject * object);
146 static void gst_task_func (GstTask * task);
148 static GMutex pool_lock;
152 GST_DEBUG_CATEGORY_INIT (task_debug, "task", 0, "Processing tasks"); \
155 G_DEFINE_TYPE_WITH_CODE (GstTask, gst_task, GST_TYPE_OBJECT, _do_init);
158 init_klass_pool (GstTaskClass * klass)
160 g_mutex_lock (&pool_lock);
162 gst_task_pool_cleanup (klass->pool);
163 gst_object_unref (klass->pool);
165 klass->pool = gst_task_pool_new ();
166 /* Classes are never destroyed so this ref will never be dropped */
167 GST_OBJECT_FLAG_SET (klass->pool, GST_OBJECT_FLAG_MAY_BE_LEAKED);
168 gst_task_pool_prepare (klass->pool, NULL);
169 g_mutex_unlock (&pool_lock);
173 gst_task_class_init (GstTaskClass * klass)
175 GObjectClass *gobject_class;
177 gobject_class = (GObjectClass *) klass;
179 g_type_class_add_private (klass, sizeof (GstTaskPrivate));
181 gobject_class->finalize = gst_task_finalize;
183 init_klass_pool (klass);
187 gst_task_init (GstTask * task)
191 klass = GST_TASK_GET_CLASS (task);
193 task->priv = GST_TASK_GET_PRIVATE (task);
194 task->running = FALSE;
197 g_cond_init (&task->cond);
198 SET_TASK_STATE (task, GST_TASK_STOPPED);
200 /* use the default klass pool for this task, users can
201 * override this later */
202 g_mutex_lock (&pool_lock);
203 task->priv->pool = gst_object_ref (klass->pool);
204 g_mutex_unlock (&pool_lock);
206 /* clear floating flag */
207 gst_object_ref_sink (task);
211 gst_task_finalize (GObject * object)
213 GstTask *task = GST_TASK (object);
214 GstTaskPrivate *priv = task->priv;
216 GST_DEBUG ("task %p finalize", task);
218 if (priv->enter_notify)
219 priv->enter_notify (priv->enter_user_data);
221 if (priv->leave_notify)
222 priv->leave_notify (priv->leave_user_data);
225 task->notify (task->user_data);
227 gst_object_unref (priv->pool);
229 /* task thread cannot be running here since it holds a ref
230 * to the task so that the finalize could not have happened */
231 g_cond_clear (&task->cond);
233 G_OBJECT_CLASS (gst_task_parent_class)->finalize (object);
236 /* should be called with the object LOCK */
238 gst_task_configure_name (GstTask * task)
240 #if defined(HAVE_SYS_PRCTL_H) && defined(PR_SET_NAME)
242 gchar thread_name[17] = { 0, };
244 GST_OBJECT_LOCK (task);
245 name = GST_OBJECT_NAME (task);
247 /* set the thread name to something easily identifiable */
248 if (!snprintf (thread_name, 17, "%s", GST_STR_NULL (name))) {
249 GST_DEBUG_OBJECT (task, "Could not create thread name for '%s'", name);
251 GST_DEBUG_OBJECT (task, "Setting thread name to '%s'", thread_name);
252 if (prctl (PR_SET_NAME, (unsigned long int) thread_name, 0, 0, 0))
253 GST_DEBUG_OBJECT (task, "Failed to set thread name");
255 GST_OBJECT_UNLOCK (task);
256 #elif defined(HAVE_PTHREAD_SETNAME_NP_WITHOUT_TID)
259 GST_OBJECT_LOCK (task);
260 name = GST_OBJECT_NAME (task);
262 /* set the thread name to something easily identifiable */
263 GST_DEBUG_OBJECT (task, "Setting thread name to '%s'", name);
264 if (pthread_setname_np (name))
265 GST_DEBUG_OBJECT (task, "Failed to set thread name");
267 GST_OBJECT_UNLOCK (task);
268 #elif defined (_MSC_VER)
270 name = GST_OBJECT_NAME (task);
272 /* set the thread name to something easily identifiable */
273 GST_DEBUG_OBJECT (task, "Setting thread name to '%s'", name);
274 SetThreadName (-1, name);
279 gst_task_func (GstTask * task)
283 GstTaskPrivate *priv;
287 tself = g_thread_self ();
289 GST_DEBUG ("Entering task %p, thread %p", task, tself);
291 /* we have to grab the lock to get the mutex. We also
292 * mark our state running so that nobody can mess with
294 GST_OBJECT_LOCK (task);
295 if (GET_TASK_STATE (task) == GST_TASK_STOPPED)
297 lock = GST_TASK_GET_LOCK (task);
298 if (G_UNLIKELY (lock == NULL))
300 task->thread = tself;
301 GST_OBJECT_UNLOCK (task);
303 /* fire the enter_func callback when we need to */
304 if (priv->enter_func)
305 priv->enter_func (task, tself, priv->enter_user_data);
307 /* locking order is TASK_LOCK, LOCK */
308 g_rec_mutex_lock (lock);
309 /* configure the thread name now */
310 gst_task_configure_name (task);
312 while (G_LIKELY (GET_TASK_STATE (task) != GST_TASK_STOPPED)) {
313 GST_OBJECT_LOCK (task);
314 while (G_UNLIKELY (GST_TASK_STATE (task) == GST_TASK_PAUSED)) {
315 g_rec_mutex_unlock (lock);
317 GST_TASK_SIGNAL (task);
318 GST_INFO_OBJECT (task, "Task going to paused");
319 GST_TASK_WAIT (task);
320 GST_INFO_OBJECT (task, "Task resume from paused");
321 GST_OBJECT_UNLOCK (task);
322 /* locking order.. */
323 g_rec_mutex_lock (lock);
324 GST_OBJECT_LOCK (task);
327 if (G_UNLIKELY (GET_TASK_STATE (task) == GST_TASK_STOPPED)) {
328 GST_OBJECT_UNLOCK (task);
331 GST_OBJECT_UNLOCK (task);
334 task->func (task->user_data);
337 g_rec_mutex_unlock (lock);
339 GST_OBJECT_LOCK (task);
343 if (priv->leave_func) {
344 /* fire the leave_func callback when we need to. We need to do this before
345 * we signal the task and with the task lock released. */
346 GST_OBJECT_UNLOCK (task);
347 priv->leave_func (task, tself, priv->leave_user_data);
348 GST_OBJECT_LOCK (task);
350 /* now we allow messing with the lock again by setting the running flag to
351 * %FALSE. Together with the SIGNAL this is the sign for the _join() to
353 * Note that we still have not dropped the final ref on the task. We could
354 * check here if there is a pending join() going on and drop the last ref
355 * before releasing the lock as we can be sure that a ref is held by the
356 * caller of the join(). */
357 task->running = FALSE;
358 GST_TASK_SIGNAL (task);
359 GST_OBJECT_UNLOCK (task);
361 GST_DEBUG ("Exit task %p, thread %p", task, g_thread_self ());
363 gst_object_unref (task);
368 g_warning ("starting task without a lock");
374 * gst_task_cleanup_all:
376 * Wait for all tasks to be stopped. This is mainly used internally
377 * to ensure proper cleanup of internal data structures in test suites.
382 gst_task_cleanup_all (void)
386 if ((klass = g_type_class_peek (GST_TYPE_TASK))) {
387 init_klass_pool (klass);
390 /* GstElement owns a GThreadPool */
391 _priv_gst_element_cleanup ();
396 * @func: The #GstTaskFunction to use
397 * @user_data: User data to pass to @func
398 * @notify: the function to call when @user_data is no longer needed.
400 * Create a new Task that will repeatedly call the provided @func
401 * with @user_data as a parameter. Typically the task will run in
404 * The function cannot be changed after the task has been created. You
405 * must create a new #GstTask to change the function.
407 * This function will not yet create and start a thread. Use gst_task_start() or
408 * gst_task_pause() to create and start the GThread.
410 * Before the task can be used, a #GRecMutex must be configured using the
411 * gst_task_set_lock() function. This lock will always be acquired while
414 * Returns: (transfer full): A new #GstTask.
419 gst_task_new (GstTaskFunction func, gpointer user_data, GDestroyNotify notify)
423 g_return_val_if_fail (func != NULL, NULL);
425 task = g_object_newv (GST_TYPE_TASK, 0, NULL);
427 task->user_data = user_data;
428 task->notify = notify;
430 GST_DEBUG ("Created task %p", task);
437 * @task: The #GstTask to use
438 * @mutex: The #GRecMutex to use
440 * Set the mutex used by the task. The mutex will be acquired before
441 * calling the #GstTaskFunction.
443 * This function has to be called before calling gst_task_pause() or
449 gst_task_set_lock (GstTask * task, GRecMutex * mutex)
451 g_return_if_fail (GST_IS_TASK (task));
453 GST_OBJECT_LOCK (task);
454 if (G_UNLIKELY (task->running))
456 GST_INFO ("setting stream lock %p on task %p", mutex, task);
457 GST_TASK_GET_LOCK (task) = mutex;
458 GST_OBJECT_UNLOCK (task);
465 GST_OBJECT_UNLOCK (task);
466 g_warning ("cannot call set_lock on a running task");
474 * Get the #GstTaskPool that this task will use for its streaming
479 * Returns: (transfer full): the #GstTaskPool used by @task. gst_object_unref()
483 gst_task_get_pool (GstTask * task)
486 GstTaskPrivate *priv;
488 g_return_val_if_fail (GST_IS_TASK (task), NULL);
492 GST_OBJECT_LOCK (task);
493 result = gst_object_ref (priv->pool);
494 GST_OBJECT_UNLOCK (task);
502 * @pool: (transfer none): a #GstTaskPool
504 * Set @pool as the new GstTaskPool for @task. Any new streaming threads that
505 * will be created by @task will now use @pool.
510 gst_task_set_pool (GstTask * task, GstTaskPool * pool)
513 GstTaskPrivate *priv;
515 g_return_if_fail (GST_IS_TASK (task));
516 g_return_if_fail (GST_IS_TASK_POOL (pool));
520 GST_OBJECT_LOCK (task);
521 if (priv->pool != pool) {
523 priv->pool = gst_object_ref (pool);
526 GST_OBJECT_UNLOCK (task);
529 gst_object_unref (old);
533 * gst_task_set_enter_callback:
534 * @task: The #GstTask to use
535 * @enter_func: (in): a #GstTaskThreadFunc
536 * @user_data: user data passed to @enter_func
537 * @notify: called when @user_data is no longer referenced
539 * Call @enter_func when the task function of @task is entered. @user_data will
540 * be passed to @enter_func and @notify will be called when @user_data is no
544 gst_task_set_enter_callback (GstTask * task, GstTaskThreadFunc enter_func,
545 gpointer user_data, GDestroyNotify notify)
547 GDestroyNotify old_notify;
549 g_return_if_fail (task != NULL);
550 g_return_if_fail (GST_IS_TASK (task));
552 GST_OBJECT_LOCK (task);
553 if ((old_notify = task->priv->enter_notify)) {
554 gpointer old_data = task->priv->enter_user_data;
556 task->priv->enter_user_data = NULL;
557 task->priv->enter_notify = NULL;
558 GST_OBJECT_UNLOCK (task);
560 old_notify (old_data);
562 GST_OBJECT_LOCK (task);
564 task->priv->enter_func = enter_func;
565 task->priv->enter_user_data = user_data;
566 task->priv->enter_notify = notify;
567 GST_OBJECT_UNLOCK (task);
571 * gst_task_set_leave_callback:
572 * @task: The #GstTask to use
573 * @leave_func: (in): a #GstTaskThreadFunc
574 * @user_data: user data passed to @leave_func
575 * @notify: called when @user_data is no longer referenced
577 * Call @leave_func when the task function of @task is left. @user_data will
578 * be passed to @leave_func and @notify will be called when @user_data is no
582 gst_task_set_leave_callback (GstTask * task, GstTaskThreadFunc leave_func,
583 gpointer user_data, GDestroyNotify notify)
585 GDestroyNotify old_notify;
587 g_return_if_fail (task != NULL);
588 g_return_if_fail (GST_IS_TASK (task));
590 GST_OBJECT_LOCK (task);
591 if ((old_notify = task->priv->leave_notify)) {
592 gpointer old_data = task->priv->leave_user_data;
594 task->priv->leave_user_data = NULL;
595 task->priv->leave_notify = NULL;
596 GST_OBJECT_UNLOCK (task);
598 old_notify (old_data);
600 GST_OBJECT_LOCK (task);
602 task->priv->leave_func = leave_func;
603 task->priv->leave_user_data = user_data;
604 task->priv->leave_notify = notify;
605 GST_OBJECT_UNLOCK (task);
609 * gst_task_get_state:
610 * @task: The #GstTask to query
612 * Get the current state of the task.
614 * Returns: The #GstTaskState of the task
619 gst_task_get_state (GstTask * task)
623 g_return_val_if_fail (GST_IS_TASK (task), GST_TASK_STOPPED);
625 result = GET_TASK_STATE (task);
630 /* make sure the task is running and start a thread if it's not.
631 * This function must be called with the task LOCK. */
633 start_task (GstTask * task)
636 GError *error = NULL;
637 GstTaskPrivate *priv;
641 /* new task, We ref before so that it remains alive while
642 * the thread is running. */
643 gst_object_ref (task);
644 /* mark task as running so that a join will wait until we schedule
645 * and exit the task function. */
646 task->running = TRUE;
648 /* push on the thread pool, we remember the original pool because the user
649 * could change it later on and then we join to the wrong pool. */
650 priv->pool_id = gst_object_ref (priv->pool);
652 gst_task_pool_push (priv->pool_id, (GstTaskPoolFunction) gst_task_func,
656 g_warning ("failed to create thread: %s", error->message);
657 g_error_free (error);
665 * gst_task_set_state:
667 * @state: the new task state
669 * Sets the state of @task to @state.
671 * The @task must have a lock associated with it using
672 * gst_task_set_lock() when going to GST_TASK_STARTED or GST_TASK_PAUSED or
673 * this function will return %FALSE.
677 * Returns: %TRUE if the state could be changed.
680 gst_task_set_state (GstTask * task, GstTaskState state)
685 g_return_val_if_fail (GST_IS_TASK (task), FALSE);
687 GST_DEBUG_OBJECT (task, "Changing task %p to state %d", task, state);
689 GST_OBJECT_LOCK (task);
690 if (state != GST_TASK_STOPPED)
691 if (G_UNLIKELY (GST_TASK_GET_LOCK (task) == NULL))
694 /* if the state changed, do our thing */
695 old = GET_TASK_STATE (task);
697 SET_TASK_STATE (task, state);
699 case GST_TASK_STOPPED:
700 /* If the task already has a thread scheduled we don't have to do
702 if (G_UNLIKELY (!task->running))
703 res = start_task (task);
705 case GST_TASK_PAUSED:
706 /* when we are paused, signal to go to the new state */
707 GST_TASK_SIGNAL (task);
709 case GST_TASK_STARTED:
710 /* if we were started, we'll go to the new state after the next
715 GST_OBJECT_UNLOCK (task);
722 GST_WARNING_OBJECT (task, "state %d set on task without a lock", state);
723 GST_OBJECT_UNLOCK (task);
724 g_warning ("task without a lock can't be set to state %d", state);
731 * @task: The #GstTask to start
733 * Starts @task. The @task must have a lock associated with it using
734 * gst_task_set_lock() or this function will return %FALSE.
736 * Returns: %TRUE if the task could be started.
741 gst_task_start (GstTask * task)
743 return gst_task_set_state (task, GST_TASK_STARTED);
748 * @task: The #GstTask to stop
750 * Stops @task. This method merely schedules the task to stop and
751 * will not wait for the task to have completely stopped. Use
752 * gst_task_join() to stop and wait for completion.
754 * Returns: %TRUE if the task could be stopped.
759 gst_task_stop (GstTask * task)
761 return gst_task_set_state (task, GST_TASK_STOPPED);
766 * @task: The #GstTask to pause
768 * Pauses @task. This method can also be called on a task in the
769 * stopped state, in which case a thread will be started and will remain
770 * in the paused state. This function does not wait for the task to complete
773 * Returns: %TRUE if the task could be paused.
778 gst_task_pause (GstTask * task)
780 return gst_task_set_state (task, GST_TASK_PAUSED);
785 * @task: The #GstTask to join
787 * Joins @task. After this call, it is safe to unref the task
788 * and clean up the lock set with gst_task_set_lock().
790 * The task will automatically be stopped with this call.
792 * This function cannot be called from within a task function as this
793 * would cause a deadlock. The function will detect this and print a
796 * Returns: %TRUE if the task could be joined.
801 gst_task_join (GstTask * task)
804 GstTaskPrivate *priv;
806 GstTaskPool *pool = NULL;
808 g_return_val_if_fail (GST_IS_TASK (task), FALSE);
812 tself = g_thread_self ();
814 GST_DEBUG_OBJECT (task, "Joining task %p, thread %p", task, tself);
816 /* we don't use a real thread join here because we are using
818 GST_OBJECT_LOCK (task);
819 if (G_UNLIKELY (tself == task->thread))
821 SET_TASK_STATE (task, GST_TASK_STOPPED);
822 /* signal the state change for when it was blocked in PAUSED. */
823 GST_TASK_SIGNAL (task);
824 /* we set the running flag when pushing the task on the thread pool.
825 * This means that the task function might not be called when we try
826 * to join it here. */
827 while (G_LIKELY (task->running))
828 GST_TASK_WAIT (task);
829 /* clean the thread */
831 /* get the id and pool to join */
832 pool = priv->pool_id;
834 priv->pool_id = NULL;
836 GST_OBJECT_UNLOCK (task);
840 gst_task_pool_join (pool, id);
841 gst_object_unref (pool);
844 GST_DEBUG_OBJECT (task, "Joined task %p", task);
851 GST_WARNING_OBJECT (task, "trying to join task from its thread");
852 GST_OBJECT_UNLOCK (task);
853 g_warning ("\nTrying to join task %p from its thread would deadlock.\n"
854 "You cannot change the state of an element from its streaming\n"
855 "thread. Use g_idle_add() or post a GstMessage on the bus to\n"
856 "schedule the state change from the main thread.\n", task);