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gst/gstbin.c: Cleanup the get_state() function a little, make sure it iterates the same set of elements.

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Original commit message from CVS:
* gst/gstbin.c: (gst_bin_get_state), (gst_bin_iterate_state_order),
(gst_bin_change_state):
Cleanup the get_state() function a little, make sure it
iterates the same set of elements.
Added stub iterate_state_order().
This commit is contained in:
Wim Taymans 2005-06-27 18:11:24 +00:00
parent 0b44c713a7
commit adbd17c378
2 changed files with 91 additions and 26 deletions
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8
ChangeLog
View file

@ -1,3 +1,11 @@
2005-06-27 Wim Taymans <wim@fluendo.com>
* gst/gstbin.c: (gst_bin_get_state), (gst_bin_iterate_state_order),
(gst_bin_change_state):
Cleanup the get_state() function a little, make sure it
iterates the same set of elements.
Added stub iterate_state_order().
2005-06-27 Thomas Vander Stichele <thomas at apestaart dot org>
* docs/gst/gstreamer-docs.sgml:

109
gst/gstbin.c
View file

@ -841,36 +841,58 @@ gst_bin_get_state (GstElement * element, GstElementState * state,
GList *children;
guint32 children_cookie;
gboolean zero_timeout;
gboolean have_no_preroll;
GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "getting state");
zero_timeout = timeout != NULL && timeout->tv_sec == 0
&& timeout->tv_usec == 0;
/* lock bin, no element can be added or removed between going into
* the quick scan and the blocking wait. */
GST_LOCK (bin);
restart:
have_no_preroll = FALSE;
/* if we have a non zero timeout we must make sure not to block
* on the sinks when we have NO_PREROLL elements. This is why we do
* a quick check if there are still NO_PREROLL elements. We also
* catch the error elements this way. */
GST_STATE_LOCK (bin);
if (!zero_timeout) {
GST_LOCK (bin);
GTimeVal tv;
gboolean have_no_preroll = FALSE;
gboolean have_async = FALSE;
GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "checking for NO_PREROLL");
/* use 0 timeout so we don't block on the sinks */
GST_TIME_TO_TIMEVAL (0, tv);
children = bin->children;
children_cookie = bin->children_cookie;
while (children) {
GstElement *child = GST_ELEMENT_CAST (children->data);
gst_object_ref (GST_OBJECT_CAST (child));
/* now we release the lock to enter a non blocking wait. We
* release the lock anyway since we can. */
GST_UNLOCK (bin);
ret = gst_element_get_state (child, NULL, NULL, &tv);
gst_object_unref (GST_OBJECT_CAST (child));
/* now grab the lock to iterate to the next child */
GST_LOCK (bin);
if (G_UNLIKELY (children_cookie != bin->children_cookie)) {
/* child added/removed during state change, restart. We need
* to restart with the quick check as a no-preroll element could
* have been added here and we don't want to block on sinks then.*/
goto restart;
}
switch (ret) {
/* report FAILURE or NO_PREROLL immediatly */
case GST_STATE_FAILURE:
GST_UNLOCK (bin);
goto report;
goto done;
case GST_STATE_NO_PREROLL:
/* we have to continue scanning as there might be
* ERRORS too */
@ -884,47 +906,50 @@ gst_bin_get_state (GstElement * element, GstElementState * state,
}
children = g_list_next (children);
}
GST_UNLOCK (bin);
/* if we get here, we have no FAILURES, check for any NO_PREROLL
* elements then. */
if (have_no_preroll)
goto report;
if (have_no_preroll) {
ret = GST_STATE_NO_PREROLL;
goto done;
}
/* if we get here, no NO_PREROLL elements are in the pipeline */
GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "no NO_PREROLL elements");
GST_STATE_NO_PREROLL (element) = FALSE;
/* if no ASYNC elements exist we don't even have to poll with a
* timeout again */
if (!have_async)
goto report;
if (!have_async) {
ret = GST_STATE_SUCCESS;
goto done;
}
}
/* we have to release the state lock as we might block when querying
* the children, holding the lock for too long for no reason. */
GST_STATE_UNLOCK (bin);
/* next we poll all children for their state to see if one of them
* is still busy with its state change. */
GST_LOCK (bin);
restart:
* is still busy with its state change. We did not release the bin lock
* yet so the elements are the same as the ones from the quick scan. */
children = bin->children;
children_cookie = bin->children_cookie;
while (children) {
GstElement *child = GST_ELEMENT_CAST (children->data);
gst_object_ref (GST_OBJECT_CAST (child));
/* now we release the lock to enter the potentialy blocking wait */
GST_UNLOCK (bin);
/* ret is ASYNC if some child is still performing the state change */
/* ret is ASYNC if some child is still performing the state change
* ater the timeout. */
ret = gst_element_get_state (child, NULL, NULL, timeout);
gst_object_unref (GST_OBJECT_CAST (child));
/* now grab the lock to iterate to the next child */
GST_LOCK (bin);
if (G_UNLIKELY (children_cookie != bin->children_cookie))
/* child added/removed during state change, restart */
if (G_UNLIKELY (children_cookie != bin->children_cookie)) {
/* child added/removed during state change, restart. We need
* to restart with the quick check as a no-preroll element could
* have been added here and we don't want to block on sinks then.*/
goto restart;
}
switch (ret) {
case GST_STATE_SUCCESS:
@ -945,14 +970,17 @@ restart:
}
children = g_list_next (children);
}
/* if we got here, all elements can to preroll */
GST_STATE_NO_PREROLL (element) = FALSE;
/* if we got here, all elements can do preroll */
have_no_preroll = FALSE;
done:
GST_UNLOCK (bin);
/* now we can take the state lock */
/* now we can take the state lock, it is possible that new elements
* are added now and we still report the old state. No problem though as
* the return is still consistent, the effect is as if the element was
* added after this function completed. */
GST_STATE_LOCK (bin);
report:
switch (ret) {
case GST_STATE_SUCCESS:
/* we can commit the state */
@ -973,6 +1001,8 @@ report:
if (pending)
*pending = GST_STATE_PENDING (element);
GST_STATE_NO_PREROLL (element) = have_no_preroll;
GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
"state current: %s, pending: %s, error: %d, no_preroll: %d, result: %d",
gst_element_state_get_name (GST_STATE (element)),
@ -990,6 +1020,33 @@ append_child (gpointer child, GQueue * queue)
g_queue_push_tail (queue, child);
}
/**
* gst_bin_iterate_state_order:
* @bin: #Gstbin to iterate on
*
* Get an iterator for the elements in this bin in the order
* in which a state change should be performed on them. This
* means that first the sinks and then the other elements will
* be returned.
* Each element will have its refcount increased, so unref
* after use.
*
* MT safe.
*
* Returns: a #GstIterator of #GstElements. gst_iterator_free after use.
*/
GstIterator *
gst_bin_iterate_state_order (GstBin * bin)
{
GstIterator *result;
g_return_val_if_fail (GST_IS_BIN (bin), NULL);
result = NULL;
return result;
}
/* this function is called with the STATE_LOCK held. It works
* as follows:
*
@ -1017,7 +1074,7 @@ gst_bin_change_state (GstElement * element)
guint32 children_cookie;
GQueue *elem_queue; /* list of elements waiting for a state change */
GQueue *semi_queue; /* list of elements with no connected srcpads */
GQueue *temp; /* temp queue of leftovers */
GQueue *temp; /* queue of leftovers */
bin = GST_BIN (element);
@ -1033,7 +1090,7 @@ gst_bin_change_state (GstElement * element)
if (pending == GST_STATE_VOID_PENDING)
return GST_STATE_SUCCESS;
/* all elements added to this queue should have their refcount
/* all elements added to these queues should have their refcount
* incremented */
elem_queue = g_queue_new ();
semi_queue = g_queue_new ();