* @short_description: Asynchronous message bus subsystem
* @see_also: #GstMessage, #GstElement
*
- * The #GstBus is an object responsible for delivering #GstMessages in
- * a first-in first-out way from the streaming threads to the application.
+ * The #GstBus is an object responsible for delivering #GstMessage packets in
+ * a first-in first-out way from the streaming threads (see #GstTask) to the
+ * application.
*
* Since the application typically only wants to deal with delivery of these
* messages from one thread, the GstBus will marshall the messages between
* convert all bus messages into signal emissions.
*
* A message is posted on the bus with the gst_bus_post() method. With the
- * gst_bus_peek() and gst_bus_pop() methods one can look at or retrieve a previously
- * posted message.
+ * gst_bus_peek() and gst_bus_pop() methods one can look at or retrieve a
+ * previously posted message.
*
* The bus can be polled with the gst_bus_poll() method. This methods blocks
* up to the specified timeout value until one of the specified messages types
- * is posted on the bus. The application can then _pop() the messages from the
- * bus to handle them.
+ * is posted on the bus. The application can then gst_bus_pop() the messages
+ * from the bus to handle them.
* Alternatively the application can register an asynchronous bus function
* using gst_bus_add_watch_full() or gst_bus_add_watch(). This function will
- * receive messages a short while after they have been posted.
+ * install a #GSource in the default glib main loop and will deliver messages
+ * a short while after they have been posted. Note that the main loop should
+ * be running for the asynchronous callbacks.
*
* It is also possible to get messages from the bus without any thread
* marshalling with the gst_bus_set_sync_handler() method. This makes it
* Note that a #GstPipeline will set its bus into flushing state when changing
* from READY to NULL state.
*
- * Last reviewed on 2005-10-28 (0.9.4)
+ * Last reviewed on 2006-03-12 (0.10.5)
*/
+#include "gst_private.h"
#include <errno.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#include <sys/types.h>
-#include "gst_private.h"
#include "gstinfo.h"
#include "gstbus.h"
LAST_SIGNAL
};
-static void gst_bus_class_init (GstBusClass * klass);
-static void gst_bus_init (GstBus * bus);
static void gst_bus_dispose (GObject * object);
-static void gst_bus_set_property (GObject * object, guint prop_id,
- const GValue * value, GParamSpec * pspec);
-static void gst_bus_get_property (GObject * object, guint prop_id,
- GValue * value, GParamSpec * pspec);
+static void gst_bus_set_main_context (GstBus * bus, GMainContext * ctx);
static GstObjectClass *parent_class = NULL;
static guint gst_bus_signals[LAST_SIGNAL] = { 0 };
-/* the context we wakeup when we posted a message on the bus */
-static GMainContext *main_context;
-
-GType
-gst_bus_get_type (void)
-{
- static GType bus_type = 0;
-
- if (!bus_type) {
- static const GTypeInfo bus_info = {
- sizeof (GstBusClass),
- NULL,
- NULL,
- (GClassInitFunc) gst_bus_class_init,
- NULL,
- NULL,
- sizeof (GstBus),
- 0,
- (GInstanceInitFunc) gst_bus_init,
- NULL
- };
-
- bus_type = g_type_register_static (GST_TYPE_OBJECT, "GstBus", &bus_info, 0);
- }
- return bus_type;
-}
+struct _GstBusPrivate
+{
+ guint num_sync_message_emitters;
+ GCond *queue_cond;
+ GSource *watch_id;
+ GMainContext *main_context;
+};
+
+G_DEFINE_TYPE (GstBus, gst_bus, GST_TYPE_OBJECT);
/* fixme: do something about this */
static void
data2 = closure->data;
}
callback =
- (marshalfunc_VOID__MINIOBJECT) (marshal_data ? marshal_data : cc->
- callback);
+ (marshalfunc_VOID__MINIOBJECT) (marshal_data ? marshal_data :
+ cc->callback);
callback (data1, gst_value_get_mini_object (param_values + 1), data2);
}
static void
gst_bus_class_init (GstBusClass * klass)
{
- GObjectClass *gobject_class;
- GstObjectClass *gstobject_class;
-
- gobject_class = (GObjectClass *) klass;
- gstobject_class = (GstObjectClass *) klass;
+ GObjectClass *gobject_class = (GObjectClass *) klass;
parent_class = g_type_class_peek_parent (klass);
- if (!g_thread_supported ())
- g_thread_init (NULL);
-
- gobject_class->dispose = GST_DEBUG_FUNCPTR (gst_bus_dispose);
- gobject_class->set_property = GST_DEBUG_FUNCPTR (gst_bus_set_property);
- gobject_class->get_property = GST_DEBUG_FUNCPTR (gst_bus_get_property);
+ gobject_class->dispose = gst_bus_dispose;
/**
* GstBus::sync-message:
* @message: the message that has been posted synchronously
*
* A message has been posted on the bus. This signal is emitted from the
- * thread that posted the message so one has to be carefull with locking.
+ * thread that posted the message so one has to be careful with locking.
+ *
+ * This signal will not be emitted by default, you have to set up
+ * gst_bus_sync_signal_handler() as a sync handler if you want this
+ * signal to be emitted when a message is posted on the bus, like this:
+ * <programlisting>
+ * gst_bus_set_sync_handler (bus, gst_bus_sync_signal_handler, yourdata);
+ * </programlisting>
*/
gst_bus_signals[SYNC_MESSAGE] =
g_signal_new ("sync-message", G_TYPE_FROM_CLASS (klass),
* @message: the message that has been posted asynchronously
*
* A message has been posted on the bus. This signal is emitted from a
- * GSource added to the mainloop.
+ * GSource added to the mainloop. this signal will only be emitted when
+ * there is a mainloop running.
*/
gst_bus_signals[ASYNC_MESSAGE] =
g_signal_new ("message", G_TYPE_FROM_CLASS (klass),
G_STRUCT_OFFSET (GstBusClass, message), NULL, NULL,
marshal_VOID__MINIOBJECT, G_TYPE_NONE, 1, GST_TYPE_MESSAGE);
- main_context = g_main_context_default ();
+ g_type_class_add_private (klass, sizeof (GstBusPrivate));
}
static void
bus->queue = g_queue_new ();
bus->queue_lock = g_mutex_new ();
+ bus->priv = G_TYPE_INSTANCE_GET_PRIVATE (bus, GST_TYPE_BUS, GstBusPrivate);
+ bus->priv->queue_cond = g_cond_new ();
+
GST_DEBUG_OBJECT (bus, "created");
}
static void
gst_bus_dispose (GObject * object)
{
- GstBus *bus;
-
- bus = GST_BUS (object);
+ GstBus *bus = GST_BUS (object);
if (bus->queue) {
GstMessage *message;
g_mutex_unlock (bus->queue_lock);
g_mutex_free (bus->queue_lock);
bus->queue_lock = NULL;
+ g_cond_free (bus->priv->queue_cond);
+ bus->priv->queue_cond = NULL;
+ }
+
+ if (bus->priv->main_context) {
+ g_main_context_unref (bus->priv->main_context);
+ bus->priv->main_context = NULL;
}
G_OBJECT_CLASS (parent_class)->dispose (object);
}
static void
-gst_bus_set_property (GObject * object, guint prop_id,
- const GValue * value, GParamSpec * pspec)
+gst_bus_wakeup_main_context (GstBus * bus)
{
- GstBus *bus;
+ GMainContext *ctx;
- bus = GST_BUS (object);
+ GST_OBJECT_LOCK (bus);
+ if ((ctx = bus->priv->main_context))
+ g_main_context_ref (ctx);
+ GST_OBJECT_UNLOCK (bus);
- switch (prop_id) {
- default:
- G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
- break;
- }
+ g_main_context_wakeup (ctx);
+
+ if (ctx)
+ g_main_context_unref (ctx);
}
static void
-gst_bus_get_property (GObject * object, guint prop_id,
- GValue * value, GParamSpec * pspec)
+gst_bus_set_main_context (GstBus * bus, GMainContext * ctx)
{
- GstBus *bus;
+ GST_OBJECT_LOCK (bus);
- bus = GST_BUS (object);
+ if (bus->priv->main_context != NULL) {
+ g_main_context_unref (bus->priv->main_context);
+ bus->priv->main_context = NULL;
+ }
- switch (prop_id) {
- default:
- G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
- break;
+ if (ctx != NULL) {
+ bus->priv->main_context = g_main_context_ref (ctx);
}
+
+ GST_DEBUG_OBJECT (bus, "setting main context to %p, GLib default context: %p",
+ ctx, g_main_context_default ());
+
+ GST_OBJECT_UNLOCK (bus);
}
/**
*
* Creates a new #GstBus instance.
*
- * Returns: a new #GstBus instance
+ * Returns: (transfer full): a new #GstBus instance
*/
GstBus *
gst_bus_new (void)
{
GstBus *result;
- result = g_object_new (gst_bus_get_type (), NULL);
+ result = g_object_newv (gst_bus_get_type (), 0, NULL);
+ GST_DEBUG_OBJECT (result, "created new bus");
return result;
}
/**
* gst_bus_post:
* @bus: a #GstBus to post on
- * @message: The #GstMessage to post
+ * @message: (transfer full): the #GstMessage to post
*
* Post a message on the given bus. Ownership of the message
* is taken by the bus.
{
GstBusSyncReply reply = GST_BUS_PASS;
GstBusSyncHandler handler;
+ gboolean emit_sync_message;
gpointer handler_data;
g_return_val_if_fail (GST_IS_BUS (bus), FALSE);
g_return_val_if_fail (GST_IS_MESSAGE (message), FALSE);
- GST_DEBUG_OBJECT (bus, "[msg %p] posting on bus, type %s",
- message, gst_message_type_get_name (GST_MESSAGE_TYPE (message)));
+ GST_DEBUG_OBJECT (bus, "[msg %p] posting on bus, type %s, %" GST_PTR_FORMAT
+ " from source %" GST_PTR_FORMAT,
+ message, GST_MESSAGE_TYPE_NAME (message), message->structure,
+ message->src);
GST_OBJECT_LOCK (bus);
/* check if the bus is flushing */
handler = bus->sync_handler;
handler_data = bus->sync_handler_data;
+ emit_sync_message = bus->priv->num_sync_message_emitters > 0;
GST_OBJECT_UNLOCK (bus);
/* first call the sync handler if it is installed */
if (handler)
reply = handler (bus, message, handler_data);
+ /* emit sync-message if requested to do so via
+ gst_bus_enable_sync_message_emission. terrible but effective */
+ if (emit_sync_message && reply != GST_BUS_DROP
+ && handler != gst_bus_sync_signal_handler)
+ gst_bus_sync_signal_handler (bus, message, NULL);
+
/* now see what we should do with the message */
switch (reply) {
case GST_BUS_DROP:
GST_DEBUG_OBJECT (bus, "[msg %p] pushing on async queue", message);
g_mutex_lock (bus->queue_lock);
g_queue_push_tail (bus->queue, message);
+ g_cond_broadcast (bus->priv->queue_cond);
g_mutex_unlock (bus->queue_lock);
GST_DEBUG_OBJECT (bus, "[msg %p] pushed on async queue", message);
- /* FIXME cannot assume sources are only in the default context */
- g_main_context_wakeup (main_context);
+ gst_bus_wakeup_main_context (bus);
break;
case GST_BUS_ASYNC:
g_mutex_lock (lock);
g_mutex_lock (bus->queue_lock);
g_queue_push_tail (bus->queue, message);
+ g_cond_broadcast (bus->priv->queue_cond);
g_mutex_unlock (bus->queue_lock);
- /* FIXME cannot assume sources are only in the default context */
- g_main_context_wakeup (main_context);
+ gst_bus_wakeup_main_context (bus);
/* now block till the message is freed */
g_cond_wait (cond, lock);
* Check if there are pending messages on the bus that
* should be handled.
*
- * Returns: TRUE if there are messages on the bus to be handled, FALSE
+ * Returns: TRUE if there are messages on the bus to be handled, FALSE
* otherwise.
*
* MT safe.
GST_OBJECT_UNLOCK (bus);
}
-
/**
- * gst_bus_pop:
- * @bus: a #GstBus to pop
+ * gst_bus_timed_pop_filtered:
+ * @bus: a #GstBus to pop from
+ * @timeout: a timeout in nanoseconds, or GST_CLOCK_TIME_NONE to wait forever
+ * @types: message types to take into account, GST_MESSAGE_ANY for any type
*
- * Get a message from the bus.
+ * Get a message from the bus whose type matches the message type mask @types,
+ * waiting up to the specified timeout (and discarding any messages that do not
+ * match the mask provided).
*
- * Returns: The #GstMessage that is on the bus, or NULL if the bus is empty.
+ * If @timeout is 0, this function behaves like gst_bus_pop_filtered(). If
+ * @timeout is #GST_CLOCK_TIME_NONE, this function will block forever until a
+ * matching message was posted on the bus.
+ *
+ * Returns: (transfer full): a #GstMessage matching the filter in @types,
+ * or NULL if no matching message was found on the bus until the timeout
+ * expired. The message is taken from the bus and needs to be unreffed
+ * with gst_message_unref() after usage.
*
* MT safe.
+ *
+ * Since: 0.10.15
*/
GstMessage *
-gst_bus_pop (GstBus * bus)
+gst_bus_timed_pop_filtered (GstBus * bus, GstClockTime timeout,
+ GstMessageType types)
{
GstMessage *message;
+ GTimeVal *timeval, abstimeout;
+ gboolean first_round = TRUE;
g_return_val_if_fail (GST_IS_BUS (bus), NULL);
+ g_return_val_if_fail (types != 0, NULL);
g_mutex_lock (bus->queue_lock);
- message = g_queue_pop_head (bus->queue);
- if (message)
- GST_DEBUG_OBJECT (bus, "pop from bus, have %d messages, got message %p, %s",
- g_queue_get_length (bus->queue) + 1, message,
- gst_message_type_get_name (GST_MESSAGE_TYPE (message)));
- else
- GST_DEBUG_OBJECT (bus, "pop from bus, no messages");
+
+ while (TRUE) {
+ GST_LOG_OBJECT (bus, "have %d messages", g_queue_get_length (bus->queue));
+
+ while ((message = g_queue_pop_head (bus->queue))) {
+ GST_DEBUG_OBJECT (bus, "got message %p, %s from %s, type mask is %u",
+ message, GST_MESSAGE_TYPE_NAME (message),
+ GST_OBJECT_NAME (GST_MESSAGE_SRC (message)), (guint) types);
+ if ((GST_MESSAGE_TYPE (message) & types) != 0) {
+ /* exit the loop, we have a message */
+ goto beach;
+ } else {
+ GST_DEBUG_OBJECT (bus, "discarding message, does not match mask");
+ gst_message_unref (message);
+ message = NULL;
+ }
+ }
+
+ /* no need to wait, exit loop */
+ if (timeout == 0)
+ break;
+
+ if (timeout == GST_CLOCK_TIME_NONE) {
+ /* wait forever */
+ timeval = NULL;
+ } else if (first_round) {
+ glong add = timeout / 1000;
+
+ if (add == 0)
+ /* no need to wait */
+ break;
+
+ /* make timeout absolute */
+ g_get_current_time (&abstimeout);
+ g_time_val_add (&abstimeout, add);
+ timeval = &abstimeout;
+ first_round = FALSE;
+ GST_DEBUG_OBJECT (bus, "blocking for message, timeout %ld", add);
+ } else {
+ /* calculated the absolute end time already, no need to do it again */
+ GST_DEBUG_OBJECT (bus, "blocking for message, again");
+ timeval = &abstimeout; /* fool compiler */
+ }
+ if (!g_cond_timed_wait (bus->priv->queue_cond, bus->queue_lock, timeval)) {
+ GST_INFO_OBJECT (bus, "timed out, breaking loop");
+ break;
+ } else {
+ GST_INFO_OBJECT (bus, "we got woken up, recheck for message");
+ }
+ }
+
+beach:
+
g_mutex_unlock (bus->queue_lock);
return message;
}
+
+/**
+ * gst_bus_timed_pop:
+ * @bus: a #GstBus to pop
+ * @timeout: a timeout
+ *
+ * Get a message from the bus, waiting up to the specified timeout.
+ *
+ * If @timeout is 0, this function behaves like gst_bus_pop(). If @timeout is
+ * #GST_CLOCK_TIME_NONE, this function will block forever until a message was
+ * posted on the bus.
+ *
+ * Returns: (transfer full): the #GstMessage that is on the bus after the
+ * specified timeout or NULL if the bus is empty after the timeout expired.
+ * The message is taken from the bus and needs to be unreffed with
+ * gst_message_unref() after usage.
+ *
+ * MT safe.
+ *
+ * Since: 0.10.12
+ */
+GstMessage *
+gst_bus_timed_pop (GstBus * bus, GstClockTime timeout)
+{
+ g_return_val_if_fail (GST_IS_BUS (bus), NULL);
+
+ return gst_bus_timed_pop_filtered (bus, timeout, GST_MESSAGE_ANY);
+}
+
+/**
+ * gst_bus_pop_filtered:
+ * @bus: a #GstBus to pop
+ * @types: message types to take into account
+ *
+ * Get a message matching @type from the bus. Will discard all messages on
+ * the bus that do not match @type and that have been posted before the first
+ * message that does match @type. If there is no message matching @type on
+ * the bus, all messages will be discarded.
+ *
+ * Returns: (transfer full): the next #GstMessage matching @type that is on
+ * the bus, or NULL if the bus is empty or there is no message matching
+ * @type. The message is taken from the bus and needs to be unreffed with
+ * gst_message_unref() after usage.
+ *
+ * MT safe.
+ *
+ * Since: 0.10.15
+ */
+GstMessage *
+gst_bus_pop_filtered (GstBus * bus, GstMessageType types)
+{
+ g_return_val_if_fail (GST_IS_BUS (bus), NULL);
+ g_return_val_if_fail (types != 0, NULL);
+
+ return gst_bus_timed_pop_filtered (bus, 0, types);
+}
+
+/**
+ * gst_bus_pop:
+ * @bus: a #GstBus to pop
+ *
+ * Get a message from the bus.
+ *
+ * Returns: (transfer full): the #GstMessage that is on the bus, or NULL if the
+ * bus is empty. The message is taken from the bus and needs to be unreffed
+ * with gst_message_unref() after usage.
+ *
+ * MT safe.
+ */
+GstMessage *
+gst_bus_pop (GstBus * bus)
+{
+ g_return_val_if_fail (GST_IS_BUS (bus), NULL);
+
+ return gst_bus_timed_pop_filtered (bus, 0, GST_MESSAGE_ANY);
+}
+
/**
* gst_bus_peek:
* @bus: a #GstBus
* on the bus' message queue. A reference is returned, and needs to be unreffed
* by the caller.
*
- * Returns: The #GstMessage that is on the bus, or NULL if the bus is empty.
+ * Returns: (transfer full): the #GstMessage that is on the bus, or NULL if the
+ * bus is empty.
*
* MT safe.
*/
{
GSource source;
GstBus *bus;
+ gboolean inited;
} GstBusSource;
static gboolean
{
GstBusSource *bsrc = (GstBusSource *) source;
+ /* we do this here now that we know that we're attached to a main context
+ * (we don't support detaching a source from a main context and then
+ * re-attaching it to a different main context) */
+ if (G_UNLIKELY (!bsrc->inited)) {
+ gst_bus_set_main_context (bsrc->bus, g_source_get_context (source));
+ bsrc->inited = TRUE;
+ }
+
*timeout = -1;
return gst_bus_have_pending (bsrc->bus);
}
g_return_val_if_fail (GST_IS_BUS (bus), FALSE);
message = gst_bus_pop (bus);
- g_return_val_if_fail (message != NULL, FALSE);
+
+ /* The message queue might be empty if some other thread or callback set
+ * the bus to flushing between check/prepare and dispatch */
+ if (G_UNLIKELY (message == NULL))
+ return TRUE;
if (!handler)
goto no_handler;
- GST_DEBUG_OBJECT (bus, "source %p calling dispatch with %p", source, message);
+ GST_DEBUG_OBJECT (bus, "source %p calling dispatch with %" GST_PTR_FORMAT,
+ source, message);
keep = handler (bus, message, user_data);
gst_message_unref (message);
no_handler:
{
g_warning ("GstBus watch dispatched without callback\n"
- "You must call g_source_connect().");
+ "You must call g_source_set_callback().");
gst_message_unref (message);
return FALSE;
}
gst_bus_source_finalize (GSource * source)
{
GstBusSource *bsource = (GstBusSource *) source;
+ GstBus *bus;
+ bus = bsource->bus;
+
+ GST_DEBUG_OBJECT (bus, "finalize source %p", source);
+
+ GST_OBJECT_LOCK (bus);
+ if (bus->priv->watch_id == source)
+ bus->priv->watch_id = NULL;
+ GST_OBJECT_UNLOCK (bus);
+
+ gst_bus_set_main_context (bsource->bus, NULL);
gst_object_unref (bsource->bus);
bsource->bus = NULL;
}
* a message is on the bus. After the GSource is dispatched, the
* message is popped off the bus and unreffed.
*
- * Returns: A #GSource that can be added to a mainloop.
+ * Returns: (transfer full): a #GSource that can be added to a mainloop.
*/
GSource *
gst_bus_create_watch (GstBus * bus)
source = (GstBusSource *) g_source_new (&gst_bus_source_funcs,
sizeof (GstBusSource));
- gst_object_ref (bus);
- source->bus = bus;
+
+#if GLIB_CHECK_VERSION(2,26,0)
+ g_source_set_name ((GSource *) source, "GStreamer message bus watch");
+#endif
+
+ source->bus = gst_object_ref (bus);
+ source->inited = FALSE;
return (GSource *) source;
}
+/* must be called with the bus OBJECT LOCK */
+static guint
+gst_bus_add_watch_full_unlocked (GstBus * bus, gint priority,
+ GstBusFunc func, gpointer user_data, GDestroyNotify notify)
+{
+ GMainContext *ctx;
+ guint id;
+ GSource *source;
+
+ if (bus->priv->watch_id) {
+ GST_ERROR_OBJECT (bus,
+ "Tried to add new watch while one was already there");
+ return 0;
+ }
+
+ source = gst_bus_create_watch (bus);
+
+ if (priority != G_PRIORITY_DEFAULT)
+ g_source_set_priority (source, priority);
+
+ g_source_set_callback (source, (GSourceFunc) func, user_data, notify);
+
+ ctx = g_main_context_get_thread_default ();
+ id = g_source_attach (source, ctx);
+ g_source_unref (source);
+
+ if (id) {
+ bus->priv->watch_id = source;
+ }
+
+ GST_DEBUG_OBJECT (bus, "New source %p with id %u", source, id);
+ return id;
+}
+
/**
* gst_bus_add_watch_full:
* @bus: a #GstBus to create the watch for.
* @user_data: user data passed to @func.
* @notify: the function to call when the source is removed.
*
- * Adds a bus watch to the default main context with the given priority.
- * If the func returns FALSE, the source will be removed.
+ * Adds a bus watch to the default main context with the given @priority (e.g.
+ * %G_PRIORITY_DEFAULT). Since 0.10.33 it is also possible to use a non-default
+ * main context set up using g_main_context_push_thread_default() (before
+ * one had to create a bus watch source and attach it to the desired main
+ * context 'manually').
+ *
+ * This function is used to receive asynchronous messages in the main loop.
+ * There can only be a single bus watch per bus, you must remove it before you
+ * can set a new one.
*
- * When the func is called, the message belongs to the caller; if you want to
- * keep a copy of it, call gst_message_ref() before leaving the func.
+ * When @func is called, the message belongs to the caller; if you want to
+ * keep a copy of it, call gst_message_ref() before leaving @func.
*
- * The watch can be removed using #g_source_remove().
+ * The watch can be removed using g_source_remove() or by returning FALSE
+ * from @func.
*
* Returns: The event source id.
*
GstBusFunc func, gpointer user_data, GDestroyNotify notify)
{
guint id;
- GSource *source;
g_return_val_if_fail (GST_IS_BUS (bus), 0);
- source = gst_bus_create_watch (bus);
-
- if (priority != G_PRIORITY_DEFAULT)
- g_source_set_priority (source, priority);
-
- g_source_set_callback (source, (GSourceFunc) func, user_data, notify);
-
- id = g_source_attach (source, NULL);
- g_source_unref (source);
+ GST_OBJECT_LOCK (bus);
+ id = gst_bus_add_watch_full_unlocked (bus, priority, func, user_data, notify);
+ GST_OBJECT_UNLOCK (bus);
- GST_DEBUG_OBJECT (bus, "New source %p", source);
return id;
}
* @func: A function to call when a message is received.
* @user_data: user data passed to @func.
*
- * Adds a bus watch to the default main context with the default priority.
+ * Adds a bus watch to the default main context with the default priority
+ * (%G_PRIORITY_DEFAULT). Since 0.10.33 it is also possible to use a non-default
+ * main context set up using g_main_context_push_thread_default() (before
+ * one had to create a bus watch source and attach it to the desired main
+ * context 'manually').
+ *
+ * This function is used to receive asynchronous messages in the main loop.
+ * There can only be a single bus watch per bus, you must remove it before you
+ * can set a new one.
*
- * The watch can be removed using #g_source_remove().
+ * The watch can be removed using g_source_remove() or by returning FALSE
+ * from @func.
*
* Returns: The event source id.
*
static void
poll_func (GstBus * bus, GstMessage * message, GstBusPollData * poll_data)
{
+ GstMessageType type;
+
if (!g_main_loop_is_running (poll_data->loop)) {
GST_DEBUG ("mainloop %p not running", poll_data->loop);
return;
}
- if (GST_MESSAGE_TYPE (message) & poll_data->events) {
- g_return_if_fail (poll_data->message == NULL);
+ type = GST_MESSAGE_TYPE (message);
+
+ if (type & poll_data->events) {
+ g_assert (poll_data->message == NULL);
/* keep ref to message */
poll_data->message = gst_message_ref (message);
GST_DEBUG ("mainloop %p quit", poll_data->loop);
g_main_loop_quit (poll_data->loop);
+ } else {
+ GST_DEBUG ("type %08x does not match %08x", type, poll_data->events);
}
}
poll_data->source_running = FALSE;
if (!poll_data->timeout_id) {
g_main_loop_unref (poll_data->loop);
- g_free (poll_data);
+ g_slice_free (GstBusPollData, poll_data);
}
}
poll_data->timeout_id = 0;
if (!poll_data->source_running) {
g_main_loop_unref (poll_data->loop);
- g_free (poll_data);
+ g_slice_free (GstBusPollData, poll_data);
}
}
* @bus: a #GstBus
* @events: a mask of #GstMessageType, representing the set of message types to
* poll for.
- * @timeout: the poll timeout, as a #GstClockTimeDiff, or -1 to poll indefinitely.
+ * @timeout: the poll timeout, as a #GstClockTimeDiff, or -1 to poll
+ * indefinitely.
*
* Poll the bus for messages. Will block while waiting for messages to come.
* You can specify a maximum time to poll with the @timeout parameter. If
* This function will run a main loop from the default main context when
* polling.
*
- * Returns: The message that was received, or NULL if the poll timed out.
- * The message is taken from the bus and needs to be unreffed after usage.
+ * You should never use this function, since it is pure evil. This is
+ * especially true for GUI applications based on Gtk+ or Qt, but also for any
+ * other non-trivial application that uses the GLib main loop. As this function
+ * runs a GLib main loop, any callback attached to the default GLib main
+ * context may be invoked. This could be timeouts, GUI events, I/O events etc.;
+ * even if gst_bus_poll() is called with a 0 timeout. Any of these callbacks
+ * may do things you do not expect, e.g. destroy the main application window or
+ * some other resource; change other application state; display a dialog and
+ * run another main loop until the user clicks it away. In short, using this
+ * function may add a lot of complexity to your code through unexpected
+ * re-entrancy and unexpected changes to your application's state.
+ *
+ * For 0 timeouts use gst_bus_pop_filtered() instead of this function; for
+ * other short timeouts use gst_bus_timed_pop_filtered(); everything else is
+ * better handled by setting up an asynchronous bus watch and doing things
+ * from there.
+ *
+ * Returns: (transfer full): the message that was received, or NULL if the
+ * poll timed out. The message is taken from the bus and needs to be
+ * unreffed with gst_message_unref() after usage.
*/
GstMessage *
gst_bus_poll (GstBus * bus, GstMessageType events, GstClockTimeDiff timeout)
GstMessage *ret;
gulong id;
- poll_data = g_new0 (GstBusPollData, 1);
+ poll_data = g_slice_new (GstBusPollData);
poll_data->source_running = TRUE;
poll_data->loop = g_main_loop_new (NULL, FALSE);
poll_data->events = events;
* @message: the #GstMessage received
* @data: user data
*
- * A helper GstBusFunc that can be used to convert all asynchronous messages
+ * A helper #GstBusFunc that can be used to convert all asynchronous messages
* into signals.
*
* Returns: TRUE
}
/**
+ * gst_bus_enable_sync_message_emission:
+ * @bus: a #GstBus on which you want to receive the "sync-message" signal
+ *
+ * Instructs GStreamer to emit the "sync-message" signal after running the bus's
+ * sync handler. This function is here so that code can ensure that they can
+ * synchronously receive messages without having to affect what the bin's sync
+ * handler is.
+ *
+ * This function may be called multiple times. To clean up, the caller is
+ * responsible for calling gst_bus_disable_sync_message_emission() as many times
+ * as this function is called.
+ *
+ * While this function looks similar to gst_bus_add_signal_watch(), it is not
+ * exactly the same -- this function enables <emphasis>synchronous</emphasis> emission of
+ * signals when messages arrive; gst_bus_add_signal_watch() adds an idle callback
+ * to pop messages off the bus <emphasis>asynchronously</emphasis>. The sync-message signal
+ * comes from the thread of whatever object posted the message; the "message"
+ * signal is marshalled to the main thread via the main loop.
+ *
+ * MT safe.
+ */
+void
+gst_bus_enable_sync_message_emission (GstBus * bus)
+{
+ g_return_if_fail (GST_IS_BUS (bus));
+
+ GST_OBJECT_LOCK (bus);
+ bus->priv->num_sync_message_emitters++;
+ GST_OBJECT_UNLOCK (bus);
+}
+
+/**
+ * gst_bus_disable_sync_message_emission:
+ * @bus: a #GstBus on which you previously called
+ * gst_bus_enable_sync_message_emission()
+ *
+ * Instructs GStreamer to stop emitting the "sync-message" signal for this bus.
+ * See gst_bus_enable_sync_message_emission() for more information.
+ *
+ * In the event that multiple pieces of code have called
+ * gst_bus_enable_sync_message_emission(), the sync-message emissions will only
+ * be stopped after all calls to gst_bus_enable_sync_message_emission() were
+ * "cancelled" by calling this function. In this way the semantics are exactly
+ * the same as gst_object_ref() that which calls enable should also call
+ * disable.
+ *
+ * MT safe.
+ */
+void
+gst_bus_disable_sync_message_emission (GstBus * bus)
+{
+ g_return_if_fail (GST_IS_BUS (bus));
+ g_return_if_fail (bus->num_signal_watchers == 0);
+
+ GST_OBJECT_LOCK (bus);
+ bus->priv->num_sync_message_emitters--;
+ GST_OBJECT_UNLOCK (bus);
+}
+
+/**
* gst_bus_add_signal_watch_full:
- * @bus: a #GstBus on which you want to recieve the "message" signal
+ * @bus: a #GstBus on which you want to receive the "message" signal
* @priority: The priority of the watch.
*
- * Adds a bus signal watch to the default main context with the given priority.
- * After calling this statement, the bus will emit the message signal for each
- * message posted on the bus.
+ * Adds a bus signal watch to the default main context with the given @priority
+ * (e.g. %G_PRIORITY_DEFAULT). Since 0.10.33 it is also possible to use a
+ * non-default main context set up using g_main_context_push_thread_default()
+ * (before one had to create a bus watch source and attach it to the desired
+ * main context 'manually').
+ *
+ * After calling this statement, the bus will emit the "message" signal for each
+ * message posted on the bus when the main loop is running.
*
* This function may be called multiple times. To clean up, the caller is
* responsible for calling gst_bus_remove_signal_watch() as many times as this
* function is called.
*
+ * There can only be a single bus watch per bus, you must remove any signal
+ * watch before you can set another type of watch.
+ *
* MT safe.
*/
void
if (bus->num_signal_watchers > 0)
goto done;
+ /* this should not fail because the counter above takes care of it */
g_assert (bus->signal_watch_id == 0);
bus->signal_watch_id =
- gst_bus_add_watch_full (bus, priority, gst_bus_async_signal_func, NULL,
- NULL);
+ gst_bus_add_watch_full_unlocked (bus, priority, gst_bus_async_signal_func,
+ NULL, NULL);
+
+ if (G_UNLIKELY (bus->signal_watch_id == 0))
+ goto add_failed;
done:
bus->num_signal_watchers++;
GST_OBJECT_UNLOCK (bus);
+ return;
+
+ /* ERRORS */
+add_failed:
+ {
+ g_critical ("Could not add signal watch to bus %s", GST_OBJECT_NAME (bus));
+ GST_OBJECT_UNLOCK (bus);
+ return;
+ }
}
/**
* gst_bus_add_signal_watch:
- * @bus: a #GstBus on which you want to recieve the "message" signal
+ * @bus: a #GstBus on which you want to receive the "message" signal
*
- * Adds a bus signal watch to the default main context with the default priority.
- * After calling this statement, the bus will emit the message signal for each
+ * Adds a bus signal watch to the default main context with the default priority
+ * (%G_PRIORITY_DEFAULT). Since 0.10.33 it is also possible to use a non-default
+ * main context set up using g_main_context_push_thread_default() (before
+ * one had to create a bus watch source and attach it to the desired main
+ * context 'manually').
+ *
+ * After calling this statement, the bus will emit the "message" signal for each
* message posted on the bus.
*
* This function may be called multiple times. To clean up, the caller is
void
gst_bus_remove_signal_watch (GstBus * bus)
{
+ guint id = 0;
+
g_return_if_fail (GST_IS_BUS (bus));
/* I know the callees don't take this lock, so go ahead and abuse it */
if (bus->num_signal_watchers > 0)
goto done;
- g_source_remove (bus->signal_watch_id);
+ id = bus->signal_watch_id;
bus->signal_watch_id = 0;
+ GST_DEBUG_OBJECT (bus, "removing signal watch %u", id);
+
done:
GST_OBJECT_UNLOCK (bus);
+
+ if (id)
+ g_source_remove (id);
+
return;
+ /* ERRORS */
error:
{
g_critical ("Bus %s has no signal watches attached", GST_OBJECT_NAME (bus));
projects / platform / upstream / gstreamer.git / blobdiff