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., 59 Temple Place - Suite 330,
19 * Boston, MA 02111-1307, 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.
67 * Last reviewed on 2006-03-12 (0.10.5)
70 #include "gst_private.h"
75 #include <sys/types.h>
82 #define GST_CAT_DEFAULT GST_CAT_BUS
92 static void gst_bus_dispose (GObject * object);
94 static GstObjectClass *parent_class = NULL;
95 static guint gst_bus_signals[LAST_SIGNAL] = { 0 };
99 guint num_sync_message_emitters;
107 G_DEFINE_TYPE (GstBus, gst_bus, GST_TYPE_OBJECT);
109 /* fixme: do something about this */
111 marshal_VOID__MINIOBJECT (GClosure * closure, GValue * return_value,
112 guint n_param_values, const GValue * param_values, gpointer invocation_hint,
113 gpointer marshal_data)
115 typedef void (*marshalfunc_VOID__MINIOBJECT) (gpointer obj, gpointer arg1,
117 register marshalfunc_VOID__MINIOBJECT callback;
118 register GCClosure *cc = (GCClosure *) closure;
119 register gpointer data1, data2;
121 g_return_if_fail (n_param_values == 2);
123 if (G_CCLOSURE_SWAP_DATA (closure)) {
124 data1 = closure->data;
125 data2 = g_value_peek_pointer (param_values + 0);
127 data1 = g_value_peek_pointer (param_values + 0);
128 data2 = closure->data;
131 (marshalfunc_VOID__MINIOBJECT) (marshal_data ? marshal_data :
134 callback (data1, gst_value_get_mini_object (param_values + 1), data2);
138 gst_bus_class_init (GstBusClass * klass)
140 GObjectClass *gobject_class = (GObjectClass *) klass;
142 parent_class = g_type_class_peek_parent (klass);
144 gobject_class->dispose = gst_bus_dispose;
147 * GstBus::sync-message:
148 * @bus: the object which received the signal
149 * @message: the message that has been posted synchronously
151 * A message has been posted on the bus. This signal is emitted from the
152 * thread that posted the message so one has to be careful with locking.
154 * This signal will not be emitted by default, you have to set up
155 * gst_bus_sync_signal_handler() as a sync handler if you want this
156 * signal to be emitted when a message is posted on the bus, like this:
158 * gst_bus_set_sync_handler (bus, gst_bus_sync_signal_handler, yourdata);
161 gst_bus_signals[SYNC_MESSAGE] =
162 g_signal_new ("sync-message", G_TYPE_FROM_CLASS (klass),
163 G_SIGNAL_RUN_LAST | G_SIGNAL_DETAILED,
164 G_STRUCT_OFFSET (GstBusClass, sync_message), NULL, NULL,
165 marshal_VOID__MINIOBJECT, G_TYPE_NONE, 1, GST_TYPE_MESSAGE);
169 * @bus: the object which received the signal
170 * @message: the message that has been posted asynchronously
172 * A message has been posted on the bus. This signal is emitted from a
173 * GSource added to the mainloop. this signal will only be emitted when
174 * there is a mainloop running.
176 gst_bus_signals[ASYNC_MESSAGE] =
177 g_signal_new ("message", G_TYPE_FROM_CLASS (klass),
178 G_SIGNAL_RUN_LAST | G_SIGNAL_DETAILED,
179 G_STRUCT_OFFSET (GstBusClass, message), NULL, NULL,
180 marshal_VOID__MINIOBJECT, G_TYPE_NONE, 1, GST_TYPE_MESSAGE);
182 g_type_class_add_private (klass, sizeof (GstBusPrivate));
186 gst_bus_init (GstBus * bus)
188 bus->queue = gst_atomic_queue_new (32);
189 bus->queue_lock = g_mutex_new ();
191 bus->priv = G_TYPE_INSTANCE_GET_PRIVATE (bus, GST_TYPE_BUS, GstBusPrivate);
192 bus->priv->queue_cond = g_cond_new ();
194 bus->priv->poll = gst_poll_new_timer ();
195 gst_poll_get_read_gpollfd (bus->priv->poll, &bus->priv->pollfd);
197 GST_DEBUG_OBJECT (bus, "created");
201 gst_bus_dispose (GObject * object)
203 GstBus *bus = GST_BUS (object);
208 g_mutex_lock (bus->queue_lock);
210 message = gst_atomic_queue_pop (bus->queue);
212 gst_message_unref (message);
213 } while (message != NULL);
214 gst_atomic_queue_unref (bus->queue);
216 g_mutex_unlock (bus->queue_lock);
217 g_mutex_free (bus->queue_lock);
218 bus->queue_lock = NULL;
219 g_cond_free (bus->priv->queue_cond);
220 bus->priv->queue_cond = NULL;
223 gst_poll_free (bus->priv->poll);
224 bus->priv->poll = NULL;
227 G_OBJECT_CLASS (parent_class)->dispose (object);
233 * Creates a new #GstBus instance.
235 * Returns: (transfer full): a new #GstBus instance
242 result = g_object_newv (gst_bus_get_type (), 0, NULL);
243 GST_DEBUG_OBJECT (result, "created new bus");
250 * @bus: a #GstBus to post on
251 * @message: (transfer full): the #GstMessage to post
253 * Post a message on the given bus. Ownership of the message
254 * is taken by the bus.
256 * Returns: TRUE if the message could be posted, FALSE if the bus is flushing.
261 gst_bus_post (GstBus * bus, GstMessage * message)
263 GstBusSyncReply reply = GST_BUS_PASS;
264 GstBusSyncHandler handler;
265 gboolean emit_sync_message;
266 gpointer handler_data;
268 g_return_val_if_fail (GST_IS_BUS (bus), FALSE);
269 g_return_val_if_fail (GST_IS_MESSAGE (message), FALSE);
271 GST_DEBUG_OBJECT (bus, "[msg %p] posting on bus, type %s, %" GST_PTR_FORMAT
272 " from source %" GST_PTR_FORMAT,
273 message, GST_MESSAGE_TYPE_NAME (message), message->structure,
276 GST_OBJECT_LOCK (bus);
277 /* check if the bus is flushing */
278 if (GST_OBJECT_FLAG_IS_SET (bus, GST_BUS_FLUSHING))
281 handler = bus->sync_handler;
282 handler_data = bus->sync_handler_data;
283 emit_sync_message = bus->priv->num_sync_message_emitters > 0;
284 GST_OBJECT_UNLOCK (bus);
286 /* first call the sync handler if it is installed */
288 reply = handler (bus, message, handler_data);
290 /* emit sync-message if requested to do so via
291 gst_bus_enable_sync_message_emission. terrible but effective */
292 if (emit_sync_message && reply != GST_BUS_DROP
293 && handler != gst_bus_sync_signal_handler)
294 gst_bus_sync_signal_handler (bus, message, NULL);
296 /* now see what we should do with the message */
299 /* drop the message */
300 GST_DEBUG_OBJECT (bus, "[msg %p] dropped", message);
303 /* pass the message to the async queue, refcount passed in the queue */
304 GST_DEBUG_OBJECT (bus, "[msg %p] pushing on async queue", message);
305 gst_atomic_queue_push (bus->queue, message);
307 gst_poll_write_control (bus->priv->poll);
308 GST_DEBUG_OBJECT (bus, "[msg %p] pushed on async queue", message);
313 /* async delivery, we need a mutex and a cond to block
315 GMutex *lock = g_mutex_new ();
316 GCond *cond = g_cond_new ();
318 GST_MESSAGE_COND (message) = cond;
319 GST_MESSAGE_GET_LOCK (message) = lock;
321 GST_DEBUG_OBJECT (bus, "[msg %p] waiting for async delivery", message);
323 /* now we lock the message mutex, send the message to the async
324 * queue. When the message is handled by the app and destroyed,
325 * the cond will be signalled and we can continue */
328 gst_atomic_queue_push (bus->queue, message);
330 gst_poll_write_control (bus->priv->poll);
332 /* now block till the message is freed */
333 g_cond_wait (cond, lock);
334 g_mutex_unlock (lock);
336 GST_DEBUG_OBJECT (bus, "[msg %p] delivered asynchronously", message);
343 g_warning ("invalid return from bus sync handler");
351 GST_DEBUG_OBJECT (bus, "bus is flushing");
352 gst_message_unref (message);
353 GST_OBJECT_UNLOCK (bus);
360 * gst_bus_have_pending:
361 * @bus: a #GstBus to check
363 * Check if there are pending messages on the bus that
366 * Returns: TRUE if there are messages on the bus to be handled, FALSE
372 gst_bus_have_pending (GstBus * bus)
376 g_return_val_if_fail (GST_IS_BUS (bus), FALSE);
378 /* see if there is a message on the bus */
379 result = gst_atomic_queue_length (bus->queue) != 0;
385 * gst_bus_set_flushing:
387 * @flushing: whether or not to flush the bus
389 * If @flushing, flush out and unref any messages queued in the bus. Releases
390 * references to the message origin objects. Will flush future messages until
391 * gst_bus_set_flushing() sets @flushing to #FALSE.
396 gst_bus_set_flushing (GstBus * bus, gboolean flushing)
400 GST_OBJECT_LOCK (bus);
403 GST_OBJECT_FLAG_SET (bus, GST_BUS_FLUSHING);
405 GST_DEBUG_OBJECT (bus, "set bus flushing");
407 while ((message = gst_bus_pop (bus)))
408 gst_message_unref (message);
410 GST_DEBUG_OBJECT (bus, "unset bus flushing");
411 GST_OBJECT_FLAG_UNSET (bus, GST_BUS_FLUSHING);
414 GST_OBJECT_UNLOCK (bus);
418 * gst_bus_timed_pop_filtered:
419 * @bus: a #GstBus to pop from
420 * @timeout: a timeout in nanoseconds, or GST_CLOCK_TIME_NONE to wait forever
421 * @types: message types to take into account, GST_MESSAGE_ANY for any type
423 * Get a message from the bus whose type matches the message type mask @types,
424 * waiting up to the specified timeout (and discarding any messages that do not
425 * match the mask provided).
427 * If @timeout is 0, this function behaves like gst_bus_pop_filtered(). If
428 * @timeout is #GST_CLOCK_TIME_NONE, this function will block forever until a
429 * matching message was posted on the bus.
431 * Returns: (transfer full): a #GstMessage matching the filter in @types,
432 * or NULL if no matching message was found on the bus until the timeout
433 * expired. The message is taken from the bus and needs to be unreffed
434 * with gst_message_unref() after usage.
441 gst_bus_timed_pop_filtered (GstBus * bus, GstClockTime timeout,
442 GstMessageType types)
446 gboolean first_round = TRUE;
448 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
449 g_return_val_if_fail (types != 0, NULL);
450 g_return_val_if_fail (bus->priv->poll != NULL, NULL);
452 g_mutex_lock (bus->queue_lock);
457 GST_LOG_OBJECT (bus, "have %d messages",
458 gst_atomic_queue_length (bus->queue));
460 while ((message = gst_atomic_queue_pop (bus->queue))) {
461 gst_poll_read_control (bus->priv->poll);
462 GST_DEBUG_OBJECT (bus, "got message %p, %s, type mask is %u",
463 message, GST_MESSAGE_TYPE_NAME (message), (guint) types);
464 if ((GST_MESSAGE_TYPE (message) & types) != 0) {
465 /* exit the loop, we have a message */
468 GST_DEBUG_OBJECT (bus, "discarding message, does not match mask");
469 gst_message_unref (message);
474 /* no need to wait, exit loop */
478 else if (timeout != GST_CLOCK_TIME_NONE) {
480 g_get_current_time (&then);
483 GstClockTime elapsed;
485 g_get_current_time (&now);
487 elapsed = GST_TIMEVAL_TO_TIME (now) - GST_TIMEVAL_TO_TIME (then);
488 if (timeout > elapsed)
495 g_mutex_unlock (bus->queue_lock);
496 ret = gst_poll_wait (bus->priv->poll, timeout);
497 g_mutex_lock (bus->queue_lock);
500 GST_INFO_OBJECT (bus, "timed out, breaking loop");
503 GST_INFO_OBJECT (bus, "we got woken up, recheck for message");
509 g_mutex_unlock (bus->queue_lock);
517 * @bus: a #GstBus to pop
518 * @timeout: a timeout
520 * Get a message from the bus, waiting up to the specified timeout.
522 * If @timeout is 0, this function behaves like gst_bus_pop(). If @timeout is
523 * #GST_CLOCK_TIME_NONE, this function will block forever until a message was
526 * Returns: (transfer full): the #GstMessage that is on the bus after the
527 * specified timeout or NULL if the bus is empty after the timeout expired.
528 * The message is taken from the bus and needs to be unreffed with
529 * gst_message_unref() after usage.
536 gst_bus_timed_pop (GstBus * bus, GstClockTime timeout)
538 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
540 return gst_bus_timed_pop_filtered (bus, timeout, GST_MESSAGE_ANY);
544 * gst_bus_pop_filtered:
545 * @bus: a #GstBus to pop
546 * @types: message types to take into account
548 * Get a message matching @type from the bus. Will discard all messages on
549 * the bus that do not match @type and that have been posted before the first
550 * message that does match @type. If there is no message matching @type on
551 * the bus, all messages will be discarded.
553 * Returns: (transfer full): the next #GstMessage matching @type that is on
554 * the bus, or NULL if the bus is empty or there is no message matching
555 * @type. The message is taken from the bus and needs to be unreffed with
556 * gst_message_unref() after usage.
563 gst_bus_pop_filtered (GstBus * bus, GstMessageType types)
565 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
566 g_return_val_if_fail (types != 0, NULL);
568 return gst_bus_timed_pop_filtered (bus, 0, types);
573 * @bus: a #GstBus to pop
575 * Get a message from the bus.
577 * Returns: (transfer full): the #GstMessage that is on the bus, or NULL if the
578 * bus is empty. The message is taken from the bus and needs to be unreffed
579 * with gst_message_unref() after usage.
584 gst_bus_pop (GstBus * bus)
586 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
588 return gst_bus_timed_pop_filtered (bus, 0, GST_MESSAGE_ANY);
595 * Peek the message on the top of the bus' queue. The message will remain
596 * on the bus' message queue. A reference is returned, and needs to be unreffed
599 * Returns: (transfer full): the #GstMessage that is on the bus, or NULL if the
605 gst_bus_peek (GstBus * bus)
609 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
611 g_mutex_lock (bus->queue_lock);
612 message = gst_atomic_queue_peek (bus->queue);
614 gst_message_ref (message);
615 g_mutex_unlock (bus->queue_lock);
617 GST_DEBUG_OBJECT (bus, "peek on bus, got message %p", message);
623 * gst_bus_set_sync_handler:
624 * @bus: a #GstBus to install the handler on
625 * @func: The handler function to install
626 * @data: User data that will be sent to the handler function.
628 * Sets the synchronous handler on the bus. The function will be called
629 * every time a new message is posted on the bus. Note that the function
630 * will be called in the same thread context as the posting object. This
631 * function is usually only called by the creator of the bus. Applications
632 * should handle messages asynchronously using the gst_bus watch and poll
635 * You cannot replace an existing sync_handler. You can pass NULL to this
636 * function, which will clear the existing handler.
639 gst_bus_set_sync_handler (GstBus * bus, GstBusSyncHandler func, gpointer data)
641 g_return_if_fail (GST_IS_BUS (bus));
643 GST_OBJECT_LOCK (bus);
645 /* Assert if the user attempts to replace an existing sync_handler,
646 * other than to clear it */
647 if (func != NULL && bus->sync_handler != NULL)
650 bus->sync_handler = func;
651 bus->sync_handler_data = data;
652 GST_OBJECT_UNLOCK (bus);
658 GST_OBJECT_UNLOCK (bus);
659 g_warning ("cannot replace existing sync handler");
664 /* GSource for the bus
673 gst_bus_source_prepare (GSource * source, gint * timeout)
680 gst_bus_source_check (GSource * source)
682 GstBusSource *bsrc = (GstBusSource *) source;
684 return bsrc->bus->priv->pollfd.revents & (G_IO_IN | G_IO_HUP | G_IO_ERR);
688 gst_bus_source_dispatch (GSource * source, GSourceFunc callback,
691 GstBusFunc handler = (GstBusFunc) callback;
692 GstBusSource *bsource = (GstBusSource *) source;
697 g_return_val_if_fail (bsource != NULL, FALSE);
701 g_return_val_if_fail (GST_IS_BUS (bus), FALSE);
703 message = gst_bus_pop (bus);
705 /* The message queue might be empty if some other thread or callback set
706 * the bus to flushing between check/prepare and dispatch */
707 if (G_UNLIKELY (message == NULL))
713 GST_DEBUG_OBJECT (bus, "source %p calling dispatch with %p", source, message);
715 keep = handler (bus, message, user_data);
716 gst_message_unref (message);
718 GST_DEBUG_OBJECT (bus, "source %p handler returns %d", source, keep);
724 g_warning ("GstBus watch dispatched without callback\n"
725 "You must call g_source_set_callback().");
726 gst_message_unref (message);
732 gst_bus_source_finalize (GSource * source)
734 GstBusSource *bsource = (GstBusSource *) source;
739 GST_DEBUG_OBJECT (bus, "finalize source %p", source);
741 GST_OBJECT_LOCK (bus);
742 if (bus->priv->watch_id == source)
743 bus->priv->watch_id = NULL;
744 GST_OBJECT_UNLOCK (bus);
746 gst_object_unref (bsource->bus);
750 static GSourceFuncs gst_bus_source_funcs = {
751 gst_bus_source_prepare,
752 gst_bus_source_check,
753 gst_bus_source_dispatch,
754 gst_bus_source_finalize
758 * gst_bus_create_watch:
759 * @bus: a #GstBus to create the watch for
761 * Create watch for this bus. The GSource will be dispatched whenever
762 * a message is on the bus. After the GSource is dispatched, the
763 * message is popped off the bus and unreffed.
765 * Returns: (transfer full): a #GSource that can be added to a mainloop.
768 gst_bus_create_watch (GstBus * bus)
770 GstBusSource *source;
772 g_return_val_if_fail (GST_IS_BUS (bus), NULL);
773 g_return_val_if_fail (bus->priv->poll != NULL, NULL);
775 source = (GstBusSource *) g_source_new (&gst_bus_source_funcs,
776 sizeof (GstBusSource));
777 source->bus = gst_object_ref (bus);
778 g_source_add_poll ((GSource *) source, &bus->priv->pollfd);
780 return (GSource *) source;
783 /* must be called with the bus OBJECT LOCK */
785 gst_bus_add_watch_full_unlocked (GstBus * bus, gint priority,
786 GstBusFunc func, gpointer user_data, GDestroyNotify notify)
792 if (bus->priv->watch_id) {
793 GST_ERROR_OBJECT (bus,
794 "Tried to add new watch while one was already there");
798 source = gst_bus_create_watch (bus);
800 if (priority != G_PRIORITY_DEFAULT)
801 g_source_set_priority (source, priority);
803 g_source_set_callback (source, (GSourceFunc) func, user_data, notify);
805 ctx = g_main_context_get_thread_default ();
806 id = g_source_attach (source, ctx);
807 g_source_unref (source);
810 bus->priv->watch_id = source;
813 GST_DEBUG_OBJECT (bus, "New source %p with id %u", source, id);
818 * gst_bus_add_watch_full:
819 * @bus: a #GstBus to create the watch for.
820 * @priority: The priority of the watch.
821 * @func: A function to call when a message is received.
822 * @user_data: user data passed to @func.
823 * @notify: the function to call when the source is removed.
825 * Adds a bus watch to the default main context with the given @priority (e.g.
826 * %G_PRIORITY_DEFAULT). Since 0.10.33 it is also possible to use a non-default
827 * main context set up using g_main_context_push_thread_default() (before
828 * one had to create a bus watch source and attach it to the desired main
829 * context 'manually').
831 * This function is used to receive asynchronous messages in the main loop.
832 * There can only be a single bus watch per bus, you must remove it before you
835 * When @func is called, the message belongs to the caller; if you want to
836 * keep a copy of it, call gst_message_ref() before leaving @func.
838 * The watch can be removed using g_source_remove() or by returning FALSE
841 * Returns: The event source id.
846 gst_bus_add_watch_full (GstBus * bus, gint priority,
847 GstBusFunc func, gpointer user_data, GDestroyNotify notify)
851 g_return_val_if_fail (GST_IS_BUS (bus), 0);
853 GST_OBJECT_LOCK (bus);
854 id = gst_bus_add_watch_full_unlocked (bus, priority, func, user_data, notify);
855 GST_OBJECT_UNLOCK (bus);
862 * @bus: a #GstBus to create the watch for
863 * @func: A function to call when a message is received.
864 * @user_data: user data passed to @func.
866 * Adds a bus watch to the default main context with the default priority
867 * (%G_PRIORITY_DEFAULT). Since 0.10.33 it is also possible to use a non-default
868 * main context set up using g_main_context_push_thread_default() (before
869 * one had to create a bus watch source and attach it to the desired main
870 * context 'manually').
872 * This function is used to receive asynchronous messages in the main loop.
873 * There can only be a single bus watch per bus, you must remove it before you
876 * The watch can be removed using g_source_remove() or by returning FALSE
879 * Returns: The event source id.
884 gst_bus_add_watch (GstBus * bus, GstBusFunc func, gpointer user_data)
886 return gst_bus_add_watch_full (bus, G_PRIORITY_DEFAULT, func,
894 gboolean source_running;
895 GstMessageType events;
900 poll_func (GstBus * bus, GstMessage * message, GstBusPollData * poll_data)
904 if (!g_main_loop_is_running (poll_data->loop)) {
905 GST_DEBUG ("mainloop %p not running", poll_data->loop);
909 type = GST_MESSAGE_TYPE (message);
911 if (type & poll_data->events) {
912 g_assert (poll_data->message == NULL);
913 /* keep ref to message */
914 poll_data->message = gst_message_ref (message);
915 GST_DEBUG ("mainloop %p quit", poll_data->loop);
916 g_main_loop_quit (poll_data->loop);
918 GST_DEBUG ("type %08x does not match %08x", type, poll_data->events);
923 poll_timeout (GstBusPollData * poll_data)
925 GST_DEBUG ("mainloop %p quit", poll_data->loop);
926 g_main_loop_quit (poll_data->loop);
928 /* we don't remove the GSource as this would free our poll_data,
929 * which we still need */
934 poll_destroy (GstBusPollData * poll_data, gpointer unused)
936 poll_data->source_running = FALSE;
937 if (!poll_data->timeout_id) {
938 g_main_loop_unref (poll_data->loop);
939 g_slice_free (GstBusPollData, poll_data);
944 poll_destroy_timeout (GstBusPollData * poll_data)
946 poll_data->timeout_id = 0;
947 if (!poll_data->source_running) {
948 g_main_loop_unref (poll_data->loop);
949 g_slice_free (GstBusPollData, poll_data);
956 * @events: a mask of #GstMessageType, representing the set of message types to
958 * @timeout: the poll timeout, as a #GstClockTimeDiff, or -1 to poll
961 * Poll the bus for messages. Will block while waiting for messages to come.
962 * You can specify a maximum time to poll with the @timeout parameter. If
963 * @timeout is negative, this function will block indefinitely.
965 * All messages not in @events will be popped off the bus and will be ignored.
967 * Because poll is implemented using the "message" signal enabled by
968 * gst_bus_add_signal_watch(), calling gst_bus_poll() will cause the "message"
969 * signal to be emitted for every message that poll sees. Thus a "message"
970 * signal handler will see the same messages that this function sees -- neither
971 * will steal messages from the other.
973 * This function will run a main loop from the default main context when
976 * You should never use this function, since it is pure evil. This is
977 * especially true for GUI applications based on Gtk+ or Qt, but also for any
978 * other non-trivial application that uses the GLib main loop. As this function
979 * runs a GLib main loop, any callback attached to the default GLib main
980 * context may be invoked. This could be timeouts, GUI events, I/O events etc.;
981 * even if gst_bus_poll() is called with a 0 timeout. Any of these callbacks
982 * may do things you do not expect, e.g. destroy the main application window or
983 * some other resource; change other application state; display a dialog and
984 * run another main loop until the user clicks it away. In short, using this
985 * function may add a lot of complexity to your code through unexpected
986 * re-entrancy and unexpected changes to your application's state.
988 * For 0 timeouts use gst_bus_pop_filtered() instead of this function; for
989 * other short timeouts use gst_bus_timed_pop_filtered(); everything else is
990 * better handled by setting up an asynchronous bus watch and doing things
993 * Returns: (transfer full): the message that was received, or NULL if the
994 * poll timed out. The message is taken from the bus and needs to be
995 * unreffed with gst_message_unref() after usage.
998 gst_bus_poll (GstBus * bus, GstMessageType events, GstClockTimeDiff timeout)
1000 GstBusPollData *poll_data;
1004 poll_data = g_slice_new (GstBusPollData);
1005 poll_data->source_running = TRUE;
1006 poll_data->loop = g_main_loop_new (NULL, FALSE);
1007 poll_data->events = events;
1008 poll_data->message = NULL;
1011 poll_data->timeout_id = g_timeout_add_full (G_PRIORITY_DEFAULT_IDLE,
1012 timeout / GST_MSECOND, (GSourceFunc) poll_timeout, poll_data,
1013 (GDestroyNotify) poll_destroy_timeout);
1015 poll_data->timeout_id = 0;
1017 id = g_signal_connect_data (bus, "message", G_CALLBACK (poll_func), poll_data,
1018 (GClosureNotify) poll_destroy, 0);
1020 /* these can be nested, so it's ok */
1021 gst_bus_add_signal_watch (bus);
1023 GST_DEBUG ("running mainloop %p", poll_data->loop);
1024 g_main_loop_run (poll_data->loop);
1025 GST_DEBUG ("mainloop stopped %p", poll_data->loop);
1027 gst_bus_remove_signal_watch (bus);
1030 ret = poll_data->message;
1032 if (poll_data->timeout_id)
1033 g_source_remove (poll_data->timeout_id);
1035 /* poll_data will be freed now */
1036 g_signal_handler_disconnect (bus, id);
1038 GST_DEBUG_OBJECT (bus, "finished poll with message %p", ret);
1044 * gst_bus_async_signal_func:
1046 * @message: the #GstMessage received
1049 * A helper #GstBusFunc that can be used to convert all asynchronous messages
1055 gst_bus_async_signal_func (GstBus * bus, GstMessage * message, gpointer data)
1059 g_return_val_if_fail (GST_IS_BUS (bus), TRUE);
1060 g_return_val_if_fail (message != NULL, TRUE);
1062 detail = gst_message_type_to_quark (GST_MESSAGE_TYPE (message));
1064 g_signal_emit (bus, gst_bus_signals[ASYNC_MESSAGE], detail, message);
1066 /* we never remove this source based on signal emission return values */
1071 * gst_bus_sync_signal_handler:
1073 * @message: the #GstMessage received
1076 * A helper GstBusSyncHandler that can be used to convert all synchronous
1077 * messages into signals.
1079 * Returns: GST_BUS_PASS
1082 gst_bus_sync_signal_handler (GstBus * bus, GstMessage * message, gpointer data)
1086 g_return_val_if_fail (GST_IS_BUS (bus), GST_BUS_DROP);
1087 g_return_val_if_fail (message != NULL, GST_BUS_DROP);
1089 detail = gst_message_type_to_quark (GST_MESSAGE_TYPE (message));
1091 g_signal_emit (bus, gst_bus_signals[SYNC_MESSAGE], detail, message);
1093 return GST_BUS_PASS;
1097 * gst_bus_enable_sync_message_emission:
1098 * @bus: a #GstBus on which you want to receive the "sync-message" signal
1100 * Instructs GStreamer to emit the "sync-message" signal after running the bus's
1101 * sync handler. This function is here so that code can ensure that they can
1102 * synchronously receive messages without having to affect what the bin's sync
1105 * This function may be called multiple times. To clean up, the caller is
1106 * responsible for calling gst_bus_disable_sync_message_emission() as many times
1107 * as this function is called.
1109 * While this function looks similar to gst_bus_add_signal_watch(), it is not
1110 * exactly the same -- this function enables <emphasis>synchronous</emphasis> emission of
1111 * signals when messages arrive; gst_bus_add_signal_watch() adds an idle callback
1112 * to pop messages off the bus <emphasis>asynchronously</emphasis>. The sync-message signal
1113 * comes from the thread of whatever object posted the message; the "message"
1114 * signal is marshalled to the main thread via the main loop.
1119 gst_bus_enable_sync_message_emission (GstBus * bus)
1121 g_return_if_fail (GST_IS_BUS (bus));
1123 GST_OBJECT_LOCK (bus);
1124 bus->priv->num_sync_message_emitters++;
1125 GST_OBJECT_UNLOCK (bus);
1129 * gst_bus_disable_sync_message_emission:
1130 * @bus: a #GstBus on which you previously called
1131 * gst_bus_enable_sync_message_emission()
1133 * Instructs GStreamer to stop emitting the "sync-message" signal for this bus.
1134 * See gst_bus_enable_sync_message_emission() for more information.
1136 * In the event that multiple pieces of code have called
1137 * gst_bus_enable_sync_message_emission(), the sync-message emissions will only
1138 * be stopped after all calls to gst_bus_enable_sync_message_emission() were
1139 * "cancelled" by calling this function. In this way the semantics are exactly
1140 * the same as gst_object_ref() that which calls enable should also call
1146 gst_bus_disable_sync_message_emission (GstBus * bus)
1148 g_return_if_fail (GST_IS_BUS (bus));
1149 g_return_if_fail (bus->num_signal_watchers == 0);
1151 GST_OBJECT_LOCK (bus);
1152 bus->priv->num_sync_message_emitters--;
1153 GST_OBJECT_UNLOCK (bus);
1157 * gst_bus_add_signal_watch_full:
1158 * @bus: a #GstBus on which you want to receive the "message" signal
1159 * @priority: The priority of the watch.
1161 * Adds a bus signal watch to the default main context with the given @priority
1162 * (e.g. %G_PRIORITY_DEFAULT). Since 0.10.33 it is also possible to use a
1163 * non-default main context set up using g_main_context_push_thread_default()
1164 * (before one had to create a bus watch source and attach it to the desired
1165 * main context 'manually').
1167 * After calling this statement, the bus will emit the "message" signal for each
1168 * message posted on the bus when the main loop is running.
1170 * This function may be called multiple times. To clean up, the caller is
1171 * responsible for calling gst_bus_remove_signal_watch() as many times as this
1172 * function is called.
1174 * There can only be a single bus watch per bus, you most remove all signal watch
1175 * before you can set another type of watch.
1180 gst_bus_add_signal_watch_full (GstBus * bus, gint priority)
1182 g_return_if_fail (GST_IS_BUS (bus));
1184 /* I know the callees don't take this lock, so go ahead and abuse it */
1185 GST_OBJECT_LOCK (bus);
1187 if (bus->num_signal_watchers > 0)
1190 /* this should not fail because the counter above takes care of it */
1191 g_assert (bus->signal_watch_id == 0);
1193 bus->signal_watch_id =
1194 gst_bus_add_watch_full_unlocked (bus, priority, gst_bus_async_signal_func,
1197 if (G_UNLIKELY (bus->signal_watch_id == 0))
1202 bus->num_signal_watchers++;
1204 GST_OBJECT_UNLOCK (bus);
1210 g_critical ("Could not add signal watch to bus %s", GST_OBJECT_NAME (bus));
1211 GST_OBJECT_UNLOCK (bus);
1217 * gst_bus_add_signal_watch:
1218 * @bus: a #GstBus on which you want to receive the "message" signal
1220 * Adds a bus signal watch to the default main context with the default priority
1221 * (%G_PRIORITY_DEFAULT). Since 0.10.33 it is also possible to use a non-default
1222 * main context set up using g_main_context_push_thread_default() (before
1223 * one had to create a bus watch source and attach it to the desired main
1224 * context 'manually').
1226 * After calling this statement, the bus will emit the "message" signal for each
1227 * message posted on the bus.
1229 * This function may be called multiple times. To clean up, the caller is
1230 * responsible for calling gst_bus_remove_signal_watch() as many times as this
1231 * function is called.
1236 gst_bus_add_signal_watch (GstBus * bus)
1238 gst_bus_add_signal_watch_full (bus, G_PRIORITY_DEFAULT);
1242 * gst_bus_remove_signal_watch:
1243 * @bus: a #GstBus you previously added a signal watch to
1245 * Removes a signal watch previously added with gst_bus_add_signal_watch().
1250 gst_bus_remove_signal_watch (GstBus * bus)
1254 g_return_if_fail (GST_IS_BUS (bus));
1256 /* I know the callees don't take this lock, so go ahead and abuse it */
1257 GST_OBJECT_LOCK (bus);
1259 if (bus->num_signal_watchers == 0)
1262 bus->num_signal_watchers--;
1264 if (bus->num_signal_watchers > 0)
1267 id = bus->signal_watch_id;
1268 bus->signal_watch_id = 0;
1270 GST_DEBUG_OBJECT (bus, "removing signal watch %u", id);
1273 GST_OBJECT_UNLOCK (bus);
1276 g_source_remove (id);
1283 g_critical ("Bus %s has no signal watches attached", GST_OBJECT_NAME (bus));
1284 GST_OBJECT_UNLOCK (bus);
1289 /* Secret API used by GstBin to set the bus in child bus mode
1290 * without sockets and everything. See bug #646624.
1293 _priv_gst_bus_set_child_mode (GstBus * bus)
1295 if (bus->priv->poll)
1296 gst_poll_free (bus->priv->poll);
1297 bus->priv->poll = NULL;