gstelement: protect async state changes against spurious wake ups

When a pipeline is pre-rolling, it waits for all sink elements to report
they have received a buffer before completing the transition to paused.
This async wait is done using a state condition variable. The way this
waits are currently implemented do not protect against spurious conditional
wake ups, which may happen due to external factors in the kernel.

This change implements the wait within a loop that iterates over the protected
variable to reinitiates the wait if the wakeup was spurious. More details in
the [GCond docs](https://docs.gtk.org/glib/struct.Cond.html).

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4086>
This commit is contained in:
Michael Gruner 2023-02-28 11:48:27 -06:00 committed by GStreamer Marge Bot
parent 6ce4a12f0b
commit 53c145a158

View File

@ -2500,11 +2500,19 @@ gst_element_get_state_func (GstElement * element,
{ {
GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE; GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
GstState old_pending; GstState old_pending;
gint64 end_time;
GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %" GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
GST_TIME_FORMAT, GST_TIME_ARGS (timeout)); GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
GST_OBJECT_LOCK (element); GST_OBJECT_LOCK (element);
if (timeout != GST_CLOCK_TIME_NONE) {
/* make timeout absolute */
end_time = g_get_monotonic_time () + (timeout / 1000);
}
do {
ret = GST_STATE_RETURN (element); ret = GST_STATE_RETURN (element);
GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s", GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
gst_element_state_change_return_get_name (ret)); gst_element_state_change_return_get_name (ret));
@ -2523,7 +2531,7 @@ gst_element_get_state_func (GstElement * element,
old_pending = GST_STATE_PENDING (element); old_pending = GST_STATE_PENDING (element);
if (old_pending != GST_STATE_VOID_PENDING) { if (old_pending != GST_STATE_VOID_PENDING) {
gboolean signaled; gboolean signaled = TRUE;
guint32 cookie; guint32 cookie;
/* get cookie to detect state changes during waiting */ /* get cookie to detect state changes during waiting */
@ -2532,11 +2540,9 @@ gst_element_get_state_func (GstElement * element,
GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
"waiting for element to commit state"); "waiting for element to commit state");
/* we have a pending state change, wait for it to complete */ /* we have a pending state change, wait for it to complete or for
an interruption */
if (timeout != GST_CLOCK_TIME_NONE) { if (timeout != GST_CLOCK_TIME_NONE) {
gint64 end_time;
/* make timeout absolute */
end_time = g_get_monotonic_time () + (timeout / 1000);
signaled = GST_STATE_WAIT_UNTIL (element, end_time); signaled = GST_STATE_WAIT_UNTIL (element, end_time);
} else { } else {
GST_STATE_WAIT (element); GST_STATE_WAIT (element);
@ -2547,6 +2553,7 @@ gst_element_get_state_func (GstElement * element,
GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out"); GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
/* timeout triggered */ /* timeout triggered */
ret = GST_STATE_CHANGE_ASYNC; ret = GST_STATE_CHANGE_ASYNC;
goto done;
} else { } else {
if (cookie != element->state_cookie) if (cookie != element->state_cookie)
goto interrupted; goto interrupted;
@ -2566,6 +2573,7 @@ gst_element_get_state_func (GstElement * element,
ret = GST_STATE_CHANGE_SUCCESS; ret = GST_STATE_CHANGE_SUCCESS;
} }
} }
} while (old_pending != GST_STATE (element));
done: done:
if (state) if (state)