nle: Use a message based mechanism to detect parent nleobject duration

Recursing up is pretty ugly and will fail when we start using ancillary
pipelines for sources in nle, using a message/event based mechanism is
a common pattern that is much cleaner.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5983>

subprojects/gst-editing-services/plugins/ges/gesdemux.c

@@ -32,6 +32,7 @@
  * uri scheme.
  **/
 
+#include "plugins/shared/nlegesplugin.h"
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
@@ -71,6 +72,10 @@ struct _GESDemux
 G_DEFINE_TYPE (GESDemux, ges_demux, ges_base_bin_get_type ());
 #define GES_DEMUX(obj) ((GESDemux*)obj)
 
+static void
+ges_demux_adapt_timeline_duration (GESDemux * self, GESTimeline * timeline,
+    GstElement * parent);
+
 enum
 {
   PROP_0,
@@ -344,75 +349,61 @@ ges_demux_set_srcpad_probe (GstElement * element, GstPad * pad,
   return TRUE;
 }
 
-static void
-ges_demux_adapt_timeline_duration (GESDemux * self, GESTimeline * timeline)
+void
+ges_demux_adapt_timeline_duration (GESDemux * self, GESTimeline * timeline,
+    GstElement * parent)
 {
-  GType nleobject_type = g_type_from_name ("NleObject");
-  GstObject *parent, *tmpparent;
+  GstClockTime duration, inpoint, timeline_duration;
 
-  parent = gst_object_get_parent (GST_OBJECT (self));
-  while (parent) {
-    if (g_type_is_a (G_OBJECT_TYPE (parent), nleobject_type)) {
-      GstClockTime duration, inpoint, timeline_duration;
+  g_object_get (parent, "duration", &duration, "inpoint", &inpoint, NULL);
+  g_object_get (timeline, "duration", &timeline_duration, NULL);
 
-      g_object_get (parent, "duration", &duration, "inpoint", &inpoint, NULL);
-      g_object_get (timeline, "duration", &timeline_duration, NULL);
+  GST_DEBUG_OBJECT (self, "Adapting duration");
+  if (inpoint + duration > timeline_duration) {
+    GESLayer *layer = ges_timeline_get_layer (timeline, 0);
 
-      if (inpoint + duration > timeline_duration) {
-        GESLayer *layer = ges_timeline_get_layer (timeline, 0);
+    if (layer) {
+      GESClip *clip = GES_CLIP (ges_test_clip_new ());
+      GList *tmp, *tracks = ges_timeline_get_tracks (timeline);
 
-        if (layer) {
-          GESClip *clip = GES_CLIP (ges_test_clip_new ());
-          GList *tmp, *tracks = ges_timeline_get_tracks (timeline);
-
-          g_object_set (clip, "start", timeline_duration, "duration",
-              inpoint + duration, "vpattern", GES_VIDEO_TEST_PATTERN_SMPTE75,
-              NULL);
-          ges_layer_add_clip (layer, clip);
-          for (tmp = tracks; tmp; tmp = tmp->next) {
-            if (GES_IS_VIDEO_TRACK (tmp->data)) {
-              GESEffect *text;
-              GstCaps *caps;
-              gchar *effect_str_full = NULL;
-              const gchar *effect_str =
-                  "textoverlay text=\"Nested timeline too short, please FIX!\" halignment=center valignment=center";
-
-              g_object_get (tmp->data, "restriction-caps", &caps, NULL);
-              if (caps) {
-                gchar *caps_str = gst_caps_to_string (caps);
-                effect_str = effect_str_full =
-                    g_strdup_printf
-                    ("videoconvertscale ! capsfilter caps=\"%s\" ! %s",
-                    caps_str, effect_str);
-                g_free (caps_str);
-                gst_caps_unref (caps);
-              }
-              text = ges_effect_new (effect_str);
-              g_free (effect_str_full);
-
-              if (!ges_container_add (GES_CONTAINER (clip),
-                      GES_TIMELINE_ELEMENT (text))) {
-                GST_ERROR ("Could not add text overlay to ending clip!");
-              }
-            }
+      g_object_set (clip, "start", timeline_duration, "duration",
+          inpoint + duration, "vpattern", GES_VIDEO_TEST_PATTERN_SMPTE75, NULL);
+      ges_layer_add_clip (layer, clip);
+      for (tmp = tracks; tmp; tmp = tmp->next) {
+        if (GES_IS_VIDEO_TRACK (tmp->data)) {
+          GESEffect *text;
+          GstCaps *caps;
+          gchar *effect_str_full = NULL;
+          const gchar *effect_str =
+              "textoverlay text=\"Nested timeline too short, please FIX!\" halignment=center valignment=center";
 
+          g_object_get (tmp->data, "restriction-caps", &caps, NULL);
+          if (caps) {
+            gchar *caps_str = gst_caps_to_string (caps);
+            effect_str = effect_str_full =
+                g_strdup_printf
+                ("videoconvertscale ! capsfilter caps=\"%s\" ! %s", caps_str,
+                effect_str);
+            g_free (caps_str);
+            gst_caps_unref (caps);
+          }
+          text = ges_effect_new (effect_str);
+          g_free (effect_str_full);
+
+          if (!ges_container_add (GES_CONTAINER (clip),
+                  GES_TIMELINE_ELEMENT (text))) {
+            GST_ERROR ("Could not add text overlay to ending clip!");
           }
-          g_list_free_full (tracks, gst_object_unref);
-          GST_INFO_OBJECT (timeline,
-              "Added test clip with duration: %" GST_TIME_FORMAT " - %"
-              GST_TIME_FORMAT " to match parent nleobject duration",
-              GST_TIME_ARGS (timeline_duration),
-              GST_TIME_ARGS (inpoint + duration - timeline_duration));
         }
+
       }
-      gst_object_unref (parent);
-
-      return;
+      g_list_free_full (tracks, gst_object_unref);
+      GST_INFO_OBJECT (timeline,
+          "Added test clip with duration: %" GST_TIME_FORMAT " - %"
+          GST_TIME_FORMAT " to match parent nleobject duration",
+          GST_TIME_ARGS (timeline_duration),
+          GST_TIME_ARGS (inpoint + duration - timeline_duration));
     }
-
-    tmpparent = parent;
-    parent = gst_object_get_parent (GST_OBJECT (parent));
-    gst_object_unref (tmpparent);
   }
 }
 
@@ -450,7 +441,20 @@ ges_demux_create_timeline (GESDemux * self, gchar * uri, GError ** error)
   if (data.error)
     goto done;
 
-  ges_demux_adapt_timeline_duration (self, data.timeline);
+  NleQueryParentNleObject *query_parent =
+      g_atomic_rc_box_new0 (NleQueryParentNleObject);
+  GType query_gtype = g_type_from_name ("NleQueryParentNleObject");
+  gst_element_post_message (GST_ELEMENT (self),
+      gst_message_new_element (GST_OBJECT (self),
+          gst_structure_new (NLE_QUERY_PARENT_NLE_OBJECT, "query",
+              query_gtype, query_parent, NULL)));
+  g_mutex_lock (&query_parent->lock);
+  if (query_parent->nle_object) {
+    ges_demux_adapt_timeline_duration (self, data.timeline,
+        query_parent->nle_object);
+  }
+  g_mutex_unlock (&query_parent->lock);
+  g_boxed_free (query_gtype, query_parent);
 
   query = gst_query_new_uri ();
   if (gst_pad_peer_query (self->sinkpad, query)) {

subprojects/gst-editing-services/plugins/nle/nleobject.c

@@ -24,6 +24,7 @@
 
 #include <string.h>
 #include "nle.h"
+#include "../shared/nlegesplugin.h"
 
 /**
  * SECTION:nleobject
@@ -33,6 +34,22 @@
  * properties provided by all the GNonLin elements.
  */
 
+static void
+nle_query_parent_nle_object_free (NleQueryParentNleObject * query)
+{
+  gst_clear_object (&query->nle_object);
+}
+
+void
+nle_query_parent_nle_object_release (NleQueryParentNleObject * query)
+{
+  g_atomic_rc_box_release_full (query,
+      (GDestroyNotify) nle_query_parent_nle_object_free);
+}
+
+G_DEFINE_BOXED_TYPE (NleQueryParentNleObject,
+    nle_query_parent_nle_object,
+    g_atomic_rc_box_acquire, nle_query_parent_nle_object_release);
 
 GST_DEBUG_CATEGORY_STATIC (nleobject_debug);
 #define GST_CAT_DEFAULT nleobject_debug
@@ -103,26 +120,58 @@ static gboolean nle_object_commit_func (NleObject * object, gboolean recurse);
 
 static GstStateChangeReturn nle_object_prepare (NleObject * object);
 
+static void
+nle_bin_handle_message (GstBin * bin, GstMessage * message)
+{
+  if (GST_MESSAGE_TYPE (message) == GST_MESSAGE_ELEMENT) {
+    const GstStructure *s = gst_message_get_structure (message);
+
+    if (gst_structure_has_name (s, NLE_QUERY_PARENT_NLE_OBJECT)) {
+      NleQueryParentNleObject *query;
+
+      gst_structure_get (s, "query", NLE_TYPE_QUERY_PARENT_NLE_OBJECT, &query,
+          NULL);
+      g_assert (query);
+
+      g_mutex_lock (&query->lock);
+      query->nle_object = gst_object_ref (GST_ELEMENT (bin));
+      g_mutex_unlock (&query->lock);
+      nle_query_parent_nle_object_release (query);
+
+      return;
+    }
+  }
+
+  return GST_BIN_CLASS (parent_class)->handle_message (bin, message);
+}
+
 static void
 nle_object_class_init (NleObjectClass * klass)
 {
   GObjectClass *gobject_class;
   GstElementClass *gstelement_class;
+  GstBinClass *gstbin_class;
   NleObjectClass *nleobject_class;
 
   gobject_class = (GObjectClass *) klass;
   gstelement_class = (GstElementClass *) klass;
+  gstbin_class = (GstBinClass *) klass;
   nleobject_class = (NleObjectClass *) klass;
   GST_DEBUG_CATEGORY_INIT (nleobject_debug, "nleobject",
       GST_DEBUG_FG_BLUE | GST_DEBUG_BOLD, "GNonLin object");
   parent_class = g_type_class_ref (GST_TYPE_BIN);
 
+  /* Ensure the NleQueryParentObject GType is registered */
+  GType t = NLE_TYPE_QUERY_PARENT_NLE_OBJECT;
+  g_assert (t);
+
   gobject_class->set_property = GST_DEBUG_FUNCPTR (nle_object_set_property);
   gobject_class->get_property = GST_DEBUG_FUNCPTR (nle_object_get_property);
   gobject_class->constructed = GST_DEBUG_FUNCPTR (nle_object_constructed);
   gobject_class->dispose = GST_DEBUG_FUNCPTR (nle_object_dispose);
 
   gstelement_class->change_state = GST_DEBUG_FUNCPTR (nle_object_change_state);
+  gstbin_class->handle_message = GST_DEBUG_FUNCPTR (nle_bin_handle_message);
 
   nleobject_class->prepare = GST_DEBUG_FUNCPTR (nle_object_prepare_func);
   nleobject_class->cleanup = GST_DEBUG_FUNCPTR (nle_object_cleanup_func);

subprojects/gst-editing-services/plugins/shared/nlegesplugin.h

@@ -0,0 +1,39 @@
+/* GES and NLE plugins shared header
+ *
+ * Copyright (C) 2024 Thibault Saunier <tsaunier@igalia.com>
+ *
+ * nlegesplugin.h
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ *
+ */
+#pragma once
+
+#include <gst/gst.h>
+
+#define NLE_QUERY_PARENT_NLE_OBJECT "nle-query-parent-nle-object"
+typedef struct
+{
+  GMutex lock;
+  GstElement *nle_object;
+} NleQueryParentNleObject;
+
+/* *INDENT-OFF* */
+#define NLE_TYPE_QUERY_PARENT_NLE_OBJECT nle_query_parent_nle_object_get_type ()
+GType nle_query_parent_nle_object_get_type (void) G_GNUC_CONST;
+/* *INDENT-ON* */
+
+void nle_query_parent_nle_object_release (NleQueryParentNleObject * query);