2 * Copyright (C) 2004 Wim Taymans <wim@fluendo.com>
4 * gstbus.c: GstBus subsystem
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Library General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Library General Public License for more details.
16 * You should have received a copy of the GNU Library General Public
17 * License along with this library; if not, write to the
18 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
19 * Boston, MA 02110-1301, USA.
24 * @short_description: Asynchronous message bus subsystem
25 * @see_also: #GstMessage, #GstElement
27 * The #GstBus is an object responsible for delivering #GstMessage packets in
28 * a first-in first-out way from the streaming threads (see #GstTask) to the
31 * Since the application typically only wants to deal with delivery of these
32 * messages from one thread, the GstBus will marshall the messages between
33 * different threads. This is important since the actual streaming of media
34 * is done in another thread than the application.
36 * The GstBus provides support for #GSource based notifications. This makes it
37 * possible to handle the delivery in the glib mainloop.
39 * The #GSource callback function gst_bus_async_signal_func() can be used to
40 * convert all bus messages into signal emissions.
42 * A message is posted on the bus with the gst_bus_post() method. With the
43 * gst_bus_peek() and gst_bus_pop() methods one can look at or retrieve a
44 * previously posted message.
46 * The bus can be polled with the gst_bus_poll() method. This methods blocks
47 * up to the specified timeout value until one of the specified messages types
48 * is posted on the bus. The application can then gst_bus_pop() the messages
49 * from the bus to handle them.
50 * Alternatively the application can register an asynchronous bus function
51 * using gst_bus_add_watch_full() or gst_bus_add_watch(). This function will
52 * install a #GSource in the default glib main loop and will deliver messages
53 * a short while after they have been posted. Note that the main loop should
54 * be running for the asynchronous callbacks.
56 * It is also possible to get messages from the bus without any thread
57 * marshalling with the gst_bus_set_sync_handler() method. This makes it
58 * possible to react to a message in the same thread that posted the
59 * message on the bus. This should only be used if the application is able
60 * to deal with messages from different threads.
62 * Every #GstPipeline has one bus.
64 * Note that a #GstPipeline will set its bus into flushing state when changing
65 * from READY to NULL state.
68 #include "gst_private.h"
73 #include <sys/types.h>
75 #include "gstatomicqueue.h"
80 #include "glib-compat-private.h"
82 #define GST_CAT_DEFAULT GST_CAT_BUS
92 #define DEFAULT_ENABLE_ASYNC (TRUE)
100 static void gst_bus_dispose (GObject * object);
101 static void gst_bus_finalize (GObject * object);
103 static guint gst_bus_signals[LAST_SIGNAL] = { 0 };
105 struct _GstBusPrivate
107 GstAtomicQueue *queue;
110 GstBusSyncHandler sync_handler;
111 gpointer sync_handler_data;
112 GDestroyNotify sync_handler_notify;
114 guint num_signal_watchers;
116 guint num_sync_message_emitters;
117 GSource *signal_watch;
119 gboolean enable_async;
124 #define gst_bus_parent_class parent_class
125 G_DEFINE_TYPE (GstBus, gst_bus, GST_TYPE_OBJECT);
128 gst_bus_set_property (GObject * object,
129 guint prop_id, const GValue * value, GParamSpec * pspec)
131 GstBus *bus = GST_BUS_CAST (object);
134 case PROP_ENABLE_ASYNC:
135 bus->priv->enable_async = g_value_get_boolean (value);
138 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
144 gst_bus_constructed (GObject * object)
146 GstBus *bus = GST_BUS_CAST (object);
148 if (bus->priv->enable_async) {
149 bus->priv->poll = gst_poll_new_timer ();
150 gst_poll_get_read_gpollfd (bus->priv->poll, &bus->priv->pollfd);
155 gst_bus_class_init (GstBusClass * klass)
157 GObjectClass *gobject_class = (GObjectClass *) klass;
159 gobject_class->dispose = gst_bus_dispose;
160 gobject_class->finalize = gst_bus_finalize;
161 gobject_class->set_property = gst_bus_set_property;
162 gobject_class->constructed = gst_bus_constructed;
165 * GstBus::enable-async:
167 * Enable async message delivery support for bus watches,
168 * gst_bus_pop() and similar API. Without this only the
169 * synchronous message handlers are called.
171 * This property is used to create the child element buses
174 g_object_class_install_property (gobject_class, PROP_ENABLE_ASYNC,
175 g_param_spec_boolean ("enable-async", "Enable Async",
176 "Enable async message delivery for bus watches and gst_bus_pop()",
177 DEFAULT_ENABLE_ASYNC,
178 G_PARAM_CONSTRUCT_ONLY | G_PARAM_WRITABLE | G_PARAM_STATIC_STRINGS));
181 * GstBus::sync-message:
182 * @bus: the object which received the signal
183 * @message: the message that has been posted synchronously
185 * A message has been posted on the bus. This signal is emitted from the
186 * thread that posted the message so one has to be careful with locking.
188 * This signal will not be emitted by default, you have to call
189 * gst_bus_enable_sync_message_emission() before.
191 gst_bus_signals[SYNC_MESSAGE] =
192 g_signal_new ("sync-message", G_TYPE_FROM_CLASS (klass),
193 G_SIGNAL_RUN_LAST | G_SIGNAL_DETAILED,
194 G_STRUCT_OFFSET (GstBusClass, sync_message), NULL, NULL,
195 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_MESSAGE);
199 * @bus: the object which received the signal
200 * @message: the message that has been posted asynchronously
202 * A message has been posted on the bus. This signal is emitted from a
203 * GSource added to the mainloop. this signal will only be emitted when
204 * there is a mainloop running.
206 gst_bus_signals[ASYNC_MESSAGE] =
207 g_signal_new ("message", G_TYPE_FROM_CLASS (klass),
208 G_SIGNAL_RUN_LAST | G_SIGNAL_DETAILED,
209 G_STRUCT_OFFSET (GstBusClass, message), NULL, NULL,
210 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_MESSAGE);
212 g_type_class_add_private (klass, sizeof (GstBusPrivate));
216 gst_bus_init (GstBus * bus)
218 bus->priv = G_TYPE_INSTANCE_GET_PRIVATE (bus, GST_TYPE_BUS, GstBusPrivate);
219 bus->priv->enable_async = DEFAULT_ENABLE_ASYNC;
220 g_mutex_init (&bus->priv->queue_lock);
221 bus->priv->queue = gst_atomic_queue_new (32);
223 /* clear floating flag */
224 gst_object_ref_sink (bus);
226 GST_DEBUG_OBJECT (bus, "created");
230 gst_bus_dispose (GObject * object)
232 GstBus *bus = GST_BUS (object);
234 if (bus->priv->queue) {
237 g_mutex_lock (&bus->priv->queue_lock);
239 message = gst_atomic_queue_pop (bus->priv->queue);
241 gst_message_unref (message);
242 } while (message != NULL);
243 gst_atomic_queue_unref (bus->priv->queue);
244 bus->priv->queue = NULL;
245 g_mutex_unlock (&bus->priv->queue_lock);
246 g_mutex_clear (&bus->priv->queue_lock);
249 gst_poll_free (bus->priv->poll);
250 bus->priv->poll = NULL;
253 G_OBJECT_CLASS (parent_class)->dispose (object);
257 gst_bus_finalize (GObject * object)
259 GstBus *bus = GST_BUS (object);
261 if (bus->priv->sync_handler_notify)
262 bus->priv->sync_handler_notify (bus->priv->sync_handler_data);
264 G_OBJECT_CLASS (parent_class)->finalize (object);
270 * Creates a new #GstBus instance.
272 * Returns: (transfer full): a new #GstBus instance
279 result = g_object_newv (gst_bus_get_type (), 0, NULL);
280 GST_DEBUG_OBJECT (result, "created new bus");
287 * @bus: a #GstBus to post on
288 * @message: (transfer full): the #GstMessage to post
290 * Post a message on the given bus. Ownership of the message
291 * is taken by the bus.
293 * Returns: %TRUE if the message could be posted, %FALSE if the bus is flushing.
298 gst_bus_post (GstBus * bus, GstMessage * message)
300 GstBusSyncReply reply = GST_BUS_PASS;
301 GstBusSyncHandler handler;
302 gboolean emit_sync_message;
303 gpointer handler_data;
305 g_return_val_if_fail (GST_IS_BUS (bus), FALSE);
306 g_return_val_if_fail (GST_IS_MESSAGE (message), FALSE);
308 GST_DEBUG_OBJECT (bus, "[msg %p] posting on bus %" GST_PTR_FORMAT, message,
311 /* check we didn't accidentally add a public flag that maps to same value */
312 g_assert (!GST_MINI_OBJECT_FLAG_IS_SET (message,
313 GST_MESSAGE_FLAG_ASYNC_DELIVERY));
315 GST_OBJECT_LOCK (bus);
316 /* check if the bus is flushing */
317 if (GST_OBJECT_FLAG_IS_SET (bus, GST_BUS_FLUSHING))
320 handler = bus->priv->sync_handler;
321 handler_data = bus->priv->sync_handler_data;
322 emit_sync_message = bus->priv->num_sync_message_emitters > 0;
323 GST_OBJECT_UNLOCK (bus);
325 /* first call the sync handler if it is installed */
327 reply = handler (bus, message, handler_data);
329 /* emit sync-message if requested to do so via
330 gst_bus_enable_sync_message_emission. terrible but effective */
331 if (emit_sync_message && reply != GST_BUS_DROP
332 && handler != gst_bus_sync_signal_handler)
333 gst_bus_sync_signal_handler (bus, message, NULL);
335 /* If this is a bus without async message delivery
336 * always drop the message */
337 if (!bus->priv->poll)
338 reply = GST_BUS_DROP;
340 /* now see what we should do with the message */
343 /* drop the message */
344 GST_DEBUG_OBJECT (bus, "[msg %p] dropped", message);
347 /* pass the message to the async queue, refcount passed in the queue */
348 GST_DEBUG_OBJECT (bus, "[msg %p] pushing on async queue", message);
349 gst_atomic_queue_push (bus->priv->queue, message);
350 gst_poll_write_control (bus->priv->poll);
351 GST_DEBUG_OBJECT (bus, "[msg %p] pushed on async queue", message);
356 /* async delivery, we need a mutex and a cond to block
358 GCond *cond = GST_MESSAGE_GET_COND (message);
359 GMutex *lock = GST_MESSAGE_GET_LOCK (message);
364 GST_MINI_OBJECT_FLAG_SET (message, GST_MESSAGE_FLAG_ASYNC_DELIVERY);
366 GST_DEBUG_OBJECT (bus, "[msg %p] waiting for async delivery", message);
368 /* now we lock the message mutex, send the message to the async
369 * queue. When the message is handled by the app and destroyed,
370 * the cond will be signalled and we can continue */
373 gst_atomic_queue_push (bus->priv->queue, message);
374 gst_poll_write_control (bus->priv->poll);
376 /* now block till the message is freed */
377 g_cond_wait (cond, lock);
379 /* we acquired a new ref from gst_message_dispose() so we can clean up */
380 g_mutex_unlock (lock);
382 GST_DEBUG_OBJECT (bus, "[msg %p] delivered asynchronously", message);
384 GST_MINI_OBJECT_FLAG_UNSET (message, GST_MESSAGE_FLAG_ASYNC_DELIVERY);
386 g_mutex_clear (lock);
389 gst_message_unref (message);
393 g_warning ("invalid return from bus sync handler");
401 GST_DEBUG_OBJECT (bus, "bus is flushing");
402 GST_OBJECT_UNLOCK (bus);
403 gst_message_unref (message);
410 * gst_bus_have_pending:
411 * @bus: a #GstBus to check
413 * Check if there are pending messages on the bus that
416 * Returns: %TRUE if there are messages on the bus to be handled, %FALSE
422 gst_bus_have_pending (GstBus * bus)
426 g_return_val_if_fail (GST_IS_BUS (bus), FALSE);
428 /* see if there is a message on the bus */
429 result = gst_atomic_queue_length (bus->priv->queue) != 0;
435 * gst_bus_set_flushing:
437 * @flushing: whether or not to flush the bus
439 * If @flushing, flush out and unref any messages queued in the bus. Releases
440 * references to the message origin objects. Will flush future messages until
441 * gst_bus_set_flushing() sets @flushing to %FALSE.
446 gst_bus_set_flushing (GstBus * bus, gboolean flushing)
449 GList *message_list = NULL;
451 g_return_if_fail (GST_IS_BUS (bus));
453 GST_OBJECT_LOCK (bus);
456 GST_OBJECT_FLAG_SET (bus, GST_BUS_FLUSHING);
458 GST_DEBUG_OBJECT (bus, "set bus flushing");
460 while ((message = gst_bus_pop (bus)))
461 message_list = g_list_prepend (message_list, message);
463 GST_DEBUG_OBJECT (bus, "unset bus flushing");
464 GST_OBJECT_FLAG_UNSET (bus, GST_BUS_FLUSHING);
467 GST_OBJECT_UNLOCK (bus);
469 g_list_free_full (message_list, (GDestroyNotify) gst_message_unref);
473 * gst_bus_timed_pop_filtered:
474 * @bus: a #GstBus to pop from
475 * @timeout: a timeout in nanoseconds, or GST_CLOCK_TIME_NONE to wait forever
476 * @types: message types to take into account, GST_MESSAGE_ANY for any type
478 * Get a message from the bus whose type matches the message type mask @types,
479 * waiting up to the specified timeout (and discarding any messages that do not
480 * match the mask provided).
482 * If @timeout is 0, this function behaves like gst_bus_pop_filtered(). If
483 * @timeout is #GST_CLOCK_TIME_NONE, this function will block forever until a
484 * matching message was posted on the bus.
486 * Returns: (transfer full) (nullable): a #GstMessage matching the
487 * filter in @types, or %NULL if no matching message was found on
488 * the bus until the timeout expired. The message is taken from
489 * the bus and needs to be unreffed with gst_message_unref() after
495 gst_bus_timed_pop_filtered (GstBus * bus, GstClockTime timeout,
496 GstMessageType types)
500 gboolean first_round = TRUE;
501 GstClockTime elapsed = 0;
503 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
504 g_return_val_if_fail (types != 0, NULL);
505 g_return_val_if_fail (timeout == 0 || bus->priv->poll != NULL, NULL);
507 g_mutex_lock (&bus->priv->queue_lock);
512 GST_LOG_OBJECT (bus, "have %d messages",
513 gst_atomic_queue_length (bus->priv->queue));
515 while ((message = gst_atomic_queue_pop (bus->priv->queue))) {
517 gst_poll_read_control (bus->priv->poll);
519 GST_DEBUG_OBJECT (bus, "got message %p, %s from %s, type mask is %u",
520 message, GST_MESSAGE_TYPE_NAME (message),
521 GST_MESSAGE_SRC_NAME (message), (guint) types);
522 if ((GST_MESSAGE_TYPE (message) & types) != 0) {
523 /* Extra check to ensure extended types don't get matched unless
525 if ((!GST_MESSAGE_TYPE_IS_EXTENDED (message))
526 || (types & GST_MESSAGE_EXTENDED)) {
527 /* exit the loop, we have a message */
532 GST_DEBUG_OBJECT (bus, "discarding message, does not match mask");
533 gst_message_unref (message);
537 /* no need to wait, exit loop */
541 else if (timeout != GST_CLOCK_TIME_NONE) {
543 g_get_current_time (&then);
546 g_get_current_time (&now);
548 elapsed = GST_TIMEVAL_TO_TIME (now) - GST_TIMEVAL_TO_TIME (then);
550 if (elapsed > timeout)
555 /* only here in timeout case */
556 g_assert (bus->priv->poll);
557 g_mutex_unlock (&bus->priv->queue_lock);
558 ret = gst_poll_wait (bus->priv->poll, timeout - elapsed);
559 g_mutex_lock (&bus->priv->queue_lock);
562 GST_INFO_OBJECT (bus, "timed out, breaking loop");
565 GST_INFO_OBJECT (bus, "we got woken up, recheck for message");
571 g_mutex_unlock (&bus->priv->queue_lock);
579 * @bus: a #GstBus to pop
580 * @timeout: a timeout
582 * Get a message from the bus, waiting up to the specified timeout.
584 * If @timeout is 0, this function behaves like gst_bus_pop(). If @timeout is
585 * #GST_CLOCK_TIME_NONE, this function will block forever until a message was
588 * Returns: (transfer full) (nullable): the #GstMessage that is on the
589 * bus after the specified timeout or %NULL if the bus is empty
590 * after the timeout expired. The message is taken from the bus
591 * and needs to be unreffed with gst_message_unref() after usage.
596 gst_bus_timed_pop (GstBus * bus, GstClockTime timeout)
598 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
600 return gst_bus_timed_pop_filtered (bus, timeout, GST_MESSAGE_ANY);
604 * gst_bus_pop_filtered:
605 * @bus: a #GstBus to pop
606 * @types: message types to take into account
608 * Get a message matching @type from the bus. Will discard all messages on
609 * the bus that do not match @type and that have been posted before the first
610 * message that does match @type. If there is no message matching @type on
611 * the bus, all messages will be discarded. It is not possible to use message
612 * enums beyond #GST_MESSAGE_EXTENDED in the @events mask.
614 * Returns: (transfer full) (nullable): the next #GstMessage matching
615 * @type that is on the bus, or %NULL if the bus is empty or there
616 * is no message matching @type. The message is taken from the bus
617 * and needs to be unreffed with gst_message_unref() after usage.
622 gst_bus_pop_filtered (GstBus * bus, GstMessageType types)
624 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
625 g_return_val_if_fail (types != 0, NULL);
627 return gst_bus_timed_pop_filtered (bus, 0, types);
632 * @bus: a #GstBus to pop
634 * Get a message from the bus.
636 * Returns: (transfer full) (nullable): the #GstMessage that is on the
637 * bus, or %NULL if the bus is empty. The message is taken from
638 * the bus and needs to be unreffed with gst_message_unref() after
644 gst_bus_pop (GstBus * bus)
646 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
648 return gst_bus_timed_pop_filtered (bus, 0, GST_MESSAGE_ANY);
655 * Peek the message on the top of the bus' queue. The message will remain
656 * on the bus' message queue. A reference is returned, and needs to be unreffed
659 * Returns: (transfer full) (nullable): the #GstMessage that is on the
660 * bus, or %NULL if the bus is empty.
665 gst_bus_peek (GstBus * bus)
669 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
671 g_mutex_lock (&bus->priv->queue_lock);
672 message = gst_atomic_queue_peek (bus->priv->queue);
674 gst_message_ref (message);
675 g_mutex_unlock (&bus->priv->queue_lock);
677 GST_DEBUG_OBJECT (bus, "peek on bus, got message %p", message);
683 * gst_bus_set_sync_handler:
684 * @bus: a #GstBus to install the handler on
685 * @func: (allow-none): The handler function to install
686 * @user_data: User data that will be sent to the handler function.
687 * @notify: called when @user_data becomes unused
689 * Sets the synchronous handler on the bus. The function will be called
690 * every time a new message is posted on the bus. Note that the function
691 * will be called in the same thread context as the posting object. This
692 * function is usually only called by the creator of the bus. Applications
693 * should handle messages asynchronously using the gst_bus watch and poll
696 * You cannot replace an existing sync_handler. You can pass %NULL to this
697 * function, which will clear the existing handler.
700 gst_bus_set_sync_handler (GstBus * bus, GstBusSyncHandler func,
701 gpointer user_data, GDestroyNotify notify)
703 GDestroyNotify old_notify;
705 g_return_if_fail (GST_IS_BUS (bus));
707 GST_OBJECT_LOCK (bus);
708 /* Assert if the user attempts to replace an existing sync_handler,
709 * other than to clear it */
710 if (func != NULL && bus->priv->sync_handler != NULL)
713 if ((old_notify = bus->priv->sync_handler_notify)) {
714 gpointer old_data = bus->priv->sync_handler_data;
716 bus->priv->sync_handler_data = NULL;
717 bus->priv->sync_handler_notify = NULL;
718 GST_OBJECT_UNLOCK (bus);
720 old_notify (old_data);
722 GST_OBJECT_LOCK (bus);
724 bus->priv->sync_handler = func;
725 bus->priv->sync_handler_data = user_data;
726 bus->priv->sync_handler_notify = notify;
727 GST_OBJECT_UNLOCK (bus);
733 GST_OBJECT_UNLOCK (bus);
734 g_warning ("cannot replace existing sync handler");
739 /* GSource for the bus
748 gst_bus_source_prepare (GSource * source, gint * timeout)
755 gst_bus_source_check (GSource * source)
757 GstBusSource *bsrc = (GstBusSource *) source;
759 gboolean ret = FALSE;
761 bus = g_weak_ref_get (&bsrc->bus_ref);
763 ret = bus->priv->pollfd.revents & (G_IO_IN | G_IO_HUP | G_IO_ERR);
764 g_object_unref (bus);
771 gst_bus_source_dispatch (GSource * source, GSourceFunc callback,
774 GstBusFunc handler = (GstBusFunc) callback;
775 GstBusSource *bsource = (GstBusSource *) source;
777 gboolean keep = TRUE;
780 g_return_val_if_fail (bsource != NULL, FALSE);
782 bus = g_weak_ref_get (&bsource->bus_ref);
785 g_return_val_if_fail (GST_IS_BUS (bus), FALSE);
787 message = gst_bus_pop (bus);
789 /* The message queue might be empty if some other thread or callback set
790 * the bus to flushing between check/prepare and dispatch */
791 if (G_UNLIKELY (message == NULL))
797 GST_DEBUG_OBJECT (bus, "source %p calling dispatch with %" GST_PTR_FORMAT,
800 keep = handler (bus, message, user_data);
801 gst_message_unref (message);
803 GST_DEBUG_OBJECT (bus, "source %p handler returns %d", source, keep);
804 g_object_unref (bus);
806 GST_WARNING ("GstBusSource without a bus and still attached to a context."
807 " The application is responsible for removing the GstBus"
808 " watch when it isn't needed anymore.");
815 g_warning ("GstBus watch dispatched without callback\n"
816 "You must call g_source_set_callback().");
817 gst_message_unref (message);
823 gst_bus_source_finalize (GSource * source)
825 GstBusSource *bsource = (GstBusSource *) source;
828 bus = g_weak_ref_get (&bsource->bus_ref);
831 GST_DEBUG_OBJECT (bus, "finalize source %p", source);
833 GST_OBJECT_LOCK (bus);
834 if (bus->priv->signal_watch == source)
835 bus->priv->signal_watch = NULL;
836 GST_OBJECT_UNLOCK (bus);
838 g_object_unref (bus);
840 g_weak_ref_clear (&bsource->bus_ref);
843 static GSourceFuncs gst_bus_source_funcs = {
844 gst_bus_source_prepare,
845 gst_bus_source_check,
846 gst_bus_source_dispatch,
847 gst_bus_source_finalize
851 * gst_bus_create_watch:
852 * @bus: a #GstBus to create the watch for
854 * Create watch for this bus. The GSource will be dispatched whenever
855 * a message is on the bus. After the GSource is dispatched, the
856 * message is popped off the bus and unreffed.
858 * Returns: (transfer full): a #GSource that can be added to a mainloop.
861 gst_bus_create_watch (GstBus * bus)
863 GstBusSource *source;
865 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
866 g_return_val_if_fail (bus->priv->poll != NULL, NULL);
868 source = (GstBusSource *) g_source_new (&gst_bus_source_funcs,
869 sizeof (GstBusSource));
871 g_source_set_name ((GSource *) source, "GStreamer message bus watch");
873 g_weak_ref_init (&source->bus_ref, (GObject *) bus);
874 g_source_add_poll ((GSource *) source, &bus->priv->pollfd);
876 return (GSource *) source;
879 /* must be called with the bus OBJECT LOCK */
881 gst_bus_add_watch_full_unlocked (GstBus * bus, gint priority,
882 GstBusFunc func, gpointer user_data, GDestroyNotify notify)
888 if (bus->priv->signal_watch) {
889 GST_ERROR_OBJECT (bus,
890 "Tried to add new watch while one was already there");
894 source = gst_bus_create_watch (bus);
896 if (priority != G_PRIORITY_DEFAULT)
897 g_source_set_priority (source, priority);
899 g_source_set_callback (source, (GSourceFunc) func, user_data, notify);
901 ctx = g_main_context_get_thread_default ();
902 id = g_source_attach (source, ctx);
903 g_source_unref (source);
906 bus->priv->signal_watch = source;
909 GST_DEBUG_OBJECT (bus, "New source %p with id %u", source, id);
914 * gst_bus_add_watch_full: (rename-to gst_bus_add_watch)
915 * @bus: a #GstBus to create the watch for.
916 * @priority: The priority of the watch.
917 * @func: A function to call when a message is received.
918 * @user_data: user data passed to @func.
919 * @notify: the function to call when the source is removed.
921 * Adds a bus watch to the default main context with the given @priority (e.g.
922 * %G_PRIORITY_DEFAULT). It is also possible to use a non-default main
923 * context set up using g_main_context_push_thread_default() (before
924 * one had to create a bus watch source and attach it to the desired main
925 * context 'manually').
927 * This function is used to receive asynchronous messages in the main loop.
928 * There can only be a single bus watch per bus, you must remove it before you
931 * The bus watch will only work if a GLib main loop is being run.
933 * When @func is called, the message belongs to the caller; if you want to
934 * keep a copy of it, call gst_message_ref() before leaving @func.
936 * The watch can be removed using gst_bus_remove_watch() or by returning %FALSE
937 * from @func. If the watch was added to the default main context it is also
938 * possible to remove the watch using g_source_remove().
942 * Returns: The event source id or 0 if @bus already got an event source.
945 gst_bus_add_watch_full (GstBus * bus, gint priority,
946 GstBusFunc func, gpointer user_data, GDestroyNotify notify)
950 g_return_val_if_fail (GST_IS_BUS (bus), 0);
952 GST_OBJECT_LOCK (bus);
953 id = gst_bus_add_watch_full_unlocked (bus, priority, func, user_data, notify);
954 GST_OBJECT_UNLOCK (bus);
960 * gst_bus_add_watch: (skip)
961 * @bus: a #GstBus to create the watch for
962 * @func: A function to call when a message is received.
963 * @user_data: user data passed to @func.
965 * Adds a bus watch to the default main context with the default priority
966 * (%G_PRIORITY_DEFAULT). It is also possible to use a non-default main
967 * context set up using g_main_context_push_thread_default() (before
968 * one had to create a bus watch source and attach it to the desired main
969 * context 'manually').
971 * This function is used to receive asynchronous messages in the main loop.
972 * There can only be a single bus watch per bus, you must remove it before you
975 * The bus watch will only work if a GLib main loop is being run.
977 * The watch can be removed using gst_bus_remove_watch() or by returning %FALSE
978 * from @func. If the watch was added to the default main context it is also
979 * possible to remove the watch using g_source_remove().
981 * Returns: The event source id or 0 if @bus already got an event source.
986 gst_bus_add_watch (GstBus * bus, GstBusFunc func, gpointer user_data)
988 return gst_bus_add_watch_full (bus, G_PRIORITY_DEFAULT, func,
993 * gst_bus_remove_watch:
994 * @bus: a #GstBus to remove the watch from.
996 * Removes an installed bus watch from @bus.
998 * Returns: %TRUE on success or %FALSE if @bus has no event source.
1004 gst_bus_remove_watch (GstBus * bus)
1008 g_return_val_if_fail (GST_IS_BUS (bus), FALSE);
1010 GST_OBJECT_LOCK (bus);
1012 if (bus->priv->signal_watch == NULL) {
1013 GST_ERROR_OBJECT (bus, "no bus watch was present");
1017 watch_id = bus->priv->signal_watch;
1019 GST_OBJECT_UNLOCK (bus);
1021 g_source_destroy (watch_id);
1026 GST_OBJECT_UNLOCK (bus);
1035 gboolean source_running;
1036 GstMessageType events;
1037 GstMessage *message;
1041 poll_func (GstBus * bus, GstMessage * message, GstBusPollData * poll_data)
1043 GstMessageType type;
1045 if (!g_main_loop_is_running (poll_data->loop)) {
1046 GST_DEBUG ("mainloop %p not running", poll_data->loop);
1050 type = GST_MESSAGE_TYPE (message);
1052 if (type & poll_data->events) {
1053 g_assert (poll_data->message == NULL);
1054 /* keep ref to message */
1055 poll_data->message = gst_message_ref (message);
1056 GST_DEBUG ("mainloop %p quit", poll_data->loop);
1057 g_main_loop_quit (poll_data->loop);
1059 GST_DEBUG ("type %08x does not match %08x", type, poll_data->events);
1064 poll_timeout (GstBusPollData * poll_data)
1066 GST_DEBUG ("mainloop %p quit", poll_data->loop);
1067 g_main_loop_quit (poll_data->loop);
1069 /* we don't remove the GSource as this would free our poll_data,
1070 * which we still need */
1075 poll_destroy (GstBusPollData * poll_data, gpointer unused)
1077 poll_data->source_running = FALSE;
1078 if (!poll_data->timeout_id) {
1079 g_main_loop_unref (poll_data->loop);
1080 g_slice_free (GstBusPollData, poll_data);
1085 poll_destroy_timeout (GstBusPollData * poll_data)
1087 poll_data->timeout_id = 0;
1088 if (!poll_data->source_running) {
1089 g_main_loop_unref (poll_data->loop);
1090 g_slice_free (GstBusPollData, poll_data);
1097 * @events: a mask of #GstMessageType, representing the set of message types to
1098 * poll for (note special handling of extended message types below)
1099 * @timeout: the poll timeout, as a #GstClockTime, or #GST_CLOCK_TIME_NONE to poll
1102 * Poll the bus for messages. Will block while waiting for messages to come.
1103 * You can specify a maximum time to poll with the @timeout parameter. If
1104 * @timeout is negative, this function will block indefinitely.
1106 * All messages not in @events will be popped off the bus and will be ignored.
1107 * It is not possible to use message enums beyond #GST_MESSAGE_EXTENDED in the
1110 * Because poll is implemented using the "message" signal enabled by
1111 * gst_bus_add_signal_watch(), calling gst_bus_poll() will cause the "message"
1112 * signal to be emitted for every message that poll sees. Thus a "message"
1113 * signal handler will see the same messages that this function sees -- neither
1114 * will steal messages from the other.
1116 * This function will run a main loop from the default main context when
1119 * You should never use this function, since it is pure evil. This is
1120 * especially true for GUI applications based on Gtk+ or Qt, but also for any
1121 * other non-trivial application that uses the GLib main loop. As this function
1122 * runs a GLib main loop, any callback attached to the default GLib main
1123 * context may be invoked. This could be timeouts, GUI events, I/O events etc.;
1124 * even if gst_bus_poll() is called with a 0 timeout. Any of these callbacks
1125 * may do things you do not expect, e.g. destroy the main application window or
1126 * some other resource; change other application state; display a dialog and
1127 * run another main loop until the user clicks it away. In short, using this
1128 * function may add a lot of complexity to your code through unexpected
1129 * re-entrancy and unexpected changes to your application's state.
1131 * For 0 timeouts use gst_bus_pop_filtered() instead of this function; for
1132 * other short timeouts use gst_bus_timed_pop_filtered(); everything else is
1133 * better handled by setting up an asynchronous bus watch and doing things
1136 * Returns: (transfer full) (nullable): the message that was received,
1137 * or %NULL if the poll timed out. The message is taken from the
1138 * bus and needs to be unreffed with gst_message_unref() after
1142 gst_bus_poll (GstBus * bus, GstMessageType events, GstClockTime timeout)
1144 GstBusPollData *poll_data;
1148 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
1150 poll_data = g_slice_new (GstBusPollData);
1151 poll_data->source_running = TRUE;
1152 poll_data->loop = g_main_loop_new (NULL, FALSE);
1153 poll_data->events = events;
1154 poll_data->message = NULL;
1156 if (timeout != GST_CLOCK_TIME_NONE)
1157 poll_data->timeout_id = g_timeout_add_full (G_PRIORITY_DEFAULT_IDLE,
1158 timeout / GST_MSECOND, (GSourceFunc) poll_timeout, poll_data,
1159 (GDestroyNotify) poll_destroy_timeout);
1161 poll_data->timeout_id = 0;
1163 id = g_signal_connect_data (bus, "message", G_CALLBACK (poll_func), poll_data,
1164 (GClosureNotify) poll_destroy, 0);
1166 /* these can be nested, so it's ok */
1167 gst_bus_add_signal_watch (bus);
1169 GST_DEBUG ("running mainloop %p", poll_data->loop);
1170 g_main_loop_run (poll_data->loop);
1171 GST_DEBUG ("mainloop stopped %p", poll_data->loop);
1173 gst_bus_remove_signal_watch (bus);
1176 ret = poll_data->message;
1178 if (poll_data->timeout_id)
1179 g_source_remove (poll_data->timeout_id);
1181 /* poll_data will be freed now */
1182 g_signal_handler_disconnect (bus, id);
1184 GST_DEBUG_OBJECT (bus, "finished poll with message %p", ret);
1190 * gst_bus_async_signal_func:
1192 * @message: the #GstMessage received
1195 * A helper #GstBusFunc that can be used to convert all asynchronous messages
1201 gst_bus_async_signal_func (GstBus * bus, GstMessage * message, gpointer data)
1205 g_return_val_if_fail (GST_IS_BUS (bus), TRUE);
1206 g_return_val_if_fail (message != NULL, TRUE);
1208 detail = gst_message_type_to_quark (GST_MESSAGE_TYPE (message));
1210 g_signal_emit (bus, gst_bus_signals[ASYNC_MESSAGE], detail, message);
1212 /* we never remove this source based on signal emission return values */
1217 * gst_bus_sync_signal_handler:
1219 * @message: the #GstMessage received
1222 * A helper GstBusSyncHandler that can be used to convert all synchronous
1223 * messages into signals.
1225 * Returns: GST_BUS_PASS
1228 gst_bus_sync_signal_handler (GstBus * bus, GstMessage * message, gpointer data)
1232 g_return_val_if_fail (GST_IS_BUS (bus), GST_BUS_DROP);
1233 g_return_val_if_fail (message != NULL, GST_BUS_DROP);
1235 detail = gst_message_type_to_quark (GST_MESSAGE_TYPE (message));
1237 g_signal_emit (bus, gst_bus_signals[SYNC_MESSAGE], detail, message);
1239 return GST_BUS_PASS;
1243 * gst_bus_enable_sync_message_emission:
1244 * @bus: a #GstBus on which you want to receive the "sync-message" signal
1246 * Instructs GStreamer to emit the "sync-message" signal after running the bus's
1247 * sync handler. This function is here so that code can ensure that they can
1248 * synchronously receive messages without having to affect what the bin's sync
1251 * This function may be called multiple times. To clean up, the caller is
1252 * responsible for calling gst_bus_disable_sync_message_emission() as many times
1253 * as this function is called.
1255 * While this function looks similar to gst_bus_add_signal_watch(), it is not
1256 * exactly the same -- this function enables <emphasis>synchronous</emphasis> emission of
1257 * signals when messages arrive; gst_bus_add_signal_watch() adds an idle callback
1258 * to pop messages off the bus <emphasis>asynchronously</emphasis>. The sync-message signal
1259 * comes from the thread of whatever object posted the message; the "message"
1260 * signal is marshalled to the main thread via the main loop.
1265 gst_bus_enable_sync_message_emission (GstBus * bus)
1267 g_return_if_fail (GST_IS_BUS (bus));
1269 GST_OBJECT_LOCK (bus);
1270 bus->priv->num_sync_message_emitters++;
1271 GST_OBJECT_UNLOCK (bus);
1275 * gst_bus_disable_sync_message_emission:
1276 * @bus: a #GstBus on which you previously called
1277 * gst_bus_enable_sync_message_emission()
1279 * Instructs GStreamer to stop emitting the "sync-message" signal for this bus.
1280 * See gst_bus_enable_sync_message_emission() for more information.
1282 * In the event that multiple pieces of code have called
1283 * gst_bus_enable_sync_message_emission(), the sync-message emissions will only
1284 * be stopped after all calls to gst_bus_enable_sync_message_emission() were
1285 * "cancelled" by calling this function. In this way the semantics are exactly
1286 * the same as gst_object_ref() that which calls enable should also call
1292 gst_bus_disable_sync_message_emission (GstBus * bus)
1294 g_return_if_fail (GST_IS_BUS (bus));
1295 g_return_if_fail (bus->priv->num_sync_message_emitters > 0);
1297 GST_OBJECT_LOCK (bus);
1298 bus->priv->num_sync_message_emitters--;
1299 GST_OBJECT_UNLOCK (bus);
1303 * gst_bus_add_signal_watch_full:
1304 * @bus: a #GstBus on which you want to receive the "message" signal
1305 * @priority: The priority of the watch.
1307 * Adds a bus signal watch to the default main context with the given @priority
1308 * (e.g. %G_PRIORITY_DEFAULT). It is also possible to use a non-default main
1309 * context set up using g_main_context_push_thread_default()
1310 * (before one had to create a bus watch source and attach it to the desired
1311 * main context 'manually').
1313 * After calling this statement, the bus will emit the "message" signal for each
1314 * message posted on the bus when the main loop is running.
1316 * This function may be called multiple times. To clean up, the caller is
1317 * responsible for calling gst_bus_remove_signal_watch() as many times as this
1318 * function is called.
1320 * There can only be a single bus watch per bus, you must remove any signal
1321 * watch before you can set another type of watch.
1326 gst_bus_add_signal_watch_full (GstBus * bus, gint priority)
1328 g_return_if_fail (GST_IS_BUS (bus));
1330 /* I know the callees don't take this lock, so go ahead and abuse it */
1331 GST_OBJECT_LOCK (bus);
1333 if (bus->priv->num_signal_watchers > 0)
1336 /* this should not fail because the counter above takes care of it */
1337 g_assert (!bus->priv->signal_watch);
1339 gst_bus_add_watch_full_unlocked (bus, priority, gst_bus_async_signal_func,
1342 if (G_UNLIKELY (!bus->priv->signal_watch))
1347 bus->priv->num_signal_watchers++;
1349 GST_OBJECT_UNLOCK (bus);
1355 g_critical ("Could not add signal watch to bus %s", GST_OBJECT_NAME (bus));
1356 GST_OBJECT_UNLOCK (bus);
1362 * gst_bus_add_signal_watch:
1363 * @bus: a #GstBus on which you want to receive the "message" signal
1365 * Adds a bus signal watch to the default main context with the default priority
1366 * (%G_PRIORITY_DEFAULT). It is also possible to use a non-default
1367 * main context set up using g_main_context_push_thread_default() (before
1368 * one had to create a bus watch source and attach it to the desired main
1369 * context 'manually').
1371 * After calling this statement, the bus will emit the "message" signal for each
1372 * message posted on the bus.
1374 * This function may be called multiple times. To clean up, the caller is
1375 * responsible for calling gst_bus_remove_signal_watch() as many times as this
1376 * function is called.
1381 gst_bus_add_signal_watch (GstBus * bus)
1383 gst_bus_add_signal_watch_full (bus, G_PRIORITY_DEFAULT);
1387 * gst_bus_remove_signal_watch:
1388 * @bus: a #GstBus you previously added a signal watch to
1390 * Removes a signal watch previously added with gst_bus_add_signal_watch().
1395 gst_bus_remove_signal_watch (GstBus * bus)
1397 GSource *source = NULL;
1399 g_return_if_fail (GST_IS_BUS (bus));
1401 /* I know the callees don't take this lock, so go ahead and abuse it */
1402 GST_OBJECT_LOCK (bus);
1404 if (bus->priv->num_signal_watchers == 0)
1407 bus->priv->num_signal_watchers--;
1409 if (bus->priv->num_signal_watchers > 0)
1412 GST_DEBUG_OBJECT (bus, "removing signal watch %u",
1413 g_source_get_id (bus->priv->signal_watch));
1415 source = bus->priv->signal_watch;
1418 GST_OBJECT_UNLOCK (bus);
1421 g_source_destroy (source);
1428 g_critical ("Bus %s has no signal watches attached", GST_OBJECT_NAME (bus));
1429 GST_OBJECT_UNLOCK (bus);