playsink: Complete reconfiguration on pad release.

Requesting a new pad can start a reconfiguration cycle, where
playsink will block all input pads and wait for data on them
before doing internal reconfiguration. If a pad is released,
that reconfiguration might never trigger because it's now waiting
for a pad that doesn't exist any more.

In that case, complete the reconfiguration on pad release.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1940>

subprojects/gst-plugins-base/gst/playback/gstplaysink.c

@@ -194,6 +194,7 @@ struct _GstPlaySink
 
   gboolean async_pending;
   gboolean need_async_start;
+  gboolean reconfigure_pending;
 
   GstPlayFlags flags;
 
@@ -412,6 +413,8 @@ static void gst_play_sink_navigation_init (gpointer g_iface,
 static void gst_play_sink_colorbalance_init (gpointer g_iface,
     gpointer g_iface_data);
 
+static gboolean is_raw_pad (GstPad * pad);
+
 static void
 _do_init_type (GType type)
 {
@@ -3231,6 +3234,19 @@ gst_play_sink_do_reconfigure (GstPlaySink * playsink)
     need_text = TRUE;
   }
 
+  if (playsink->video_pad) {
+    playsink->video_pad_raw = is_raw_pad (playsink->video_pad);
+    GST_DEBUG_OBJECT (playsink, "Video pad is raw: %d",
+        playsink->video_pad_raw);
+  }
+
+  if (playsink->audio_pad) {
+    playsink->audio_pad_raw = is_raw_pad (playsink->audio_pad);
+    GST_DEBUG_OBJECT (playsink, "Audio pad is raw: %d",
+        playsink->audio_pad_raw);
+  }
+
+
   if (((flags & GST_PLAY_FLAG_VIDEO)
           || (flags & GST_PLAY_FLAG_NATIVE_VIDEO)) && playsink->video_pad) {
     /* we have video and we are requested to show it */
@@ -3881,6 +3897,9 @@ gst_play_sink_do_reconfigure (GstPlaySink * playsink)
   update_av_offset (playsink);
   update_text_offset (playsink);
   do_async_done (playsink);
+
+  playsink->reconfigure_pending = FALSE;
+
   GST_PLAY_SINK_UNLOCK (playsink);
 
   return TRUE;
@@ -4333,11 +4352,39 @@ gst_play_sink_reconfigure (GstPlaySink * playsink)
   video_set_blocked (playsink, TRUE);
   audio_set_blocked (playsink, TRUE);
   text_set_blocked (playsink, TRUE);
+  playsink->reconfigure_pending = TRUE;
   GST_PLAY_SINK_UNLOCK (playsink);
 
   return TRUE;
 }
 
+/* Called with PLAY_SINK_LOCK */
+static gboolean
+gst_play_sink_ready_to_reconfigure_locked (GstPlaySink * playsink)
+{
+  /* We reconfigure when for ALL streams:
+   * * there isn't a pad
+   * * OR the pad is blocked
+   * * OR there are no pending blocks on that pad
+   */
+  if (playsink->reconfigure_pending == FALSE)
+    return FALSE;
+
+  if (playsink->video_pad && !playsink->video_pad_blocked
+      && PENDING_VIDEO_BLOCK (playsink))
+    return FALSE;
+
+  if (playsink->audio_pad && !playsink->audio_pad_blocked
+      && PENDING_AUDIO_BLOCK (playsink))
+    return FALSE;
+
+  if (playsink->text_pad && !playsink->text_pad_blocked
+      && PENDING_TEXT_BLOCK (playsink))
+    return FALSE;
+
+  return TRUE;
+}
+
 static GstPadProbeReturn
 sinkpad_blocked_cb (GstPad * blockedpad, GstPadProbeInfo * info,
     gpointer user_data)
@@ -4365,31 +4412,9 @@ sinkpad_blocked_cb (GstPad * blockedpad, GstPadProbeInfo * info,
     GST_DEBUG_OBJECT (pad, "Text pad blocked");
   }
 
-  /* We reconfigure when for ALL streams:
+  if (gst_play_sink_ready_to_reconfigure_locked (playsink)) {
-   * * there isn't a pad
-   * * OR the pad is blocked
-   * * OR there are no pending blocks on that pad
-   */
-
-  if ((!playsink->video_pad || playsink->video_pad_blocked
-          || !PENDING_VIDEO_BLOCK (playsink)) && (!playsink->audio_pad
-          || playsink->audio_pad_blocked || !PENDING_AUDIO_BLOCK (playsink))
-      && (!playsink->text_pad || playsink->text_pad_blocked
-          || !PENDING_TEXT_BLOCK (playsink))) {
     GST_DEBUG_OBJECT (playsink, "All pads blocked -- reconfiguring");
 
-    if (playsink->video_pad) {
-      playsink->video_pad_raw = is_raw_pad (playsink->video_pad);
-      GST_DEBUG_OBJECT (playsink, "Video pad is raw: %d",
-          playsink->video_pad_raw);
-    }
-
-    if (playsink->audio_pad) {
-      playsink->audio_pad_raw = is_raw_pad (playsink->audio_pad);
-      GST_DEBUG_OBJECT (playsink, "Audio pad is raw: %d",
-          playsink->audio_pad_raw);
-    }
-
     gst_play_sink_do_reconfigure (playsink);
 
     video_set_blocked (playsink, FALSE);
@@ -4681,6 +4706,7 @@ gst_play_sink_release_pad (GstPlaySink * playsink, GstPad * pad)
     res = &pad;
     untarget = FALSE;
   }
+
   GST_PLAY_SINK_UNLOCK (playsink);
 
   if (*res) {
@@ -4694,6 +4720,23 @@ gst_play_sink_release_pad (GstPlaySink * playsink, GstPad * pad)
     gst_element_remove_pad (GST_ELEMENT_CAST (playsink), *res);
     *res = NULL;
   }
+
+  GST_PLAY_SINK_LOCK (playsink);
+
+  /* If we have a pending reconfigure, we might have met the conditions
+   * to reconfigure now */
+  if (gst_play_sink_ready_to_reconfigure_locked (playsink)) {
+    GST_DEBUG_OBJECT (playsink,
+        "All pads ready after release -- reconfiguring");
+
+    gst_play_sink_do_reconfigure (playsink);
+
+    video_set_blocked (playsink, FALSE);
+    audio_set_blocked (playsink, FALSE);
+    text_set_blocked (playsink, FALSE);
+  }
+
+  GST_PLAY_SINK_UNLOCK (playsink);
 }
 
 static void