validate: reporter: break cyclic references with reports

My patch fixing monitor leak (15e7f1bbfd)
introduced a ref cycle between GstValidateReporter and
GstValidateReport.

The reports uses its reporter so it needs a ref on it
to ensure it's stay alive. But reports are owned by GstValidateReporter and/or
GstValidateRunner.
The best way I found to break this cycle is to introduce this purge
method. It's not great but the design is a bit tricky.

Reviewed-by: Thibault Saunier <tsaunier@gnome.org>
Differential Revision: https://phabricator.freedesktop.org/D1029

validate/gst/validate/gst-validate-bin-monitor.c

@@ -116,6 +116,15 @@ gst_validate_bin_monitor_get_property (GObject * object, guint prop_id,
   }
 }
 
+static void
+purge_and_unref_reporter (gpointer data)
+{
+  GstValidateReporter *reporter = data;
+
+  gst_validate_reporter_purge_reports (reporter);
+  g_object_unref (reporter);
+}
+
 static void
 gst_validate_bin_monitor_dispose (GObject * object)
 {
@@ -125,10 +134,13 @@ gst_validate_bin_monitor_dispose (GObject * object)
   if (bin && monitor->element_added_id)
     g_signal_handler_disconnect (bin, monitor->element_added_id);
 
-  if (monitor->scenario)
+  if (monitor->scenario) {
+    gst_validate_reporter_purge_reports (GST_VALIDATE_REPORTER
+        (monitor->scenario));
     g_object_unref (monitor->scenario);
+  }
 
-  g_list_free_full (monitor->element_monitors, g_object_unref);
+  g_list_free_full (monitor->element_monitors, purge_and_unref_reporter);
 
   G_OBJECT_CLASS (parent_class)->dispose (object);
 }

validate/gst/validate/gst-validate-element-monitor.c

@@ -98,6 +98,14 @@ gst_validate_element_set_media_descriptor (GstValidateMonitor * monitor,
   gst_iterator_free (iterator);
 }
 
+static void
+purge_and_unref_reporter (gpointer data)
+{
+  GstValidateReporter *reporter = data;
+
+  gst_validate_reporter_purge_reports (reporter);
+  g_object_unref (reporter);
+}
 
 static void
 gst_validate_element_monitor_dispose (GObject * object)
@@ -109,7 +117,7 @@ gst_validate_element_monitor_dispose (GObject * object)
     g_signal_handler_disconnect (GST_VALIDATE_MONITOR_GET_OBJECT (monitor),
         monitor->pad_added_id);
 
-  g_list_free_full (monitor->pad_monitors, g_object_unref);
+  g_list_free_full (monitor->pad_monitors, purge_and_unref_reporter);
 
   G_OBJECT_CLASS (parent_class)->dispose (object);
 }

validate/gst/validate/gst-validate-reporter.c

@@ -436,3 +436,22 @@ gst_validate_reporter_get_reports_count (GstValidateReporter * reporter)
 
   return ret;
 }
+
+/**
+ * gst_validate_reporter_purge_reports:
+ * @reporter: a #GstValidateReporter
+ *
+ * Remove all the #GstValidateReport from @reporter. This should be called
+ * before unreffing the reporter to break cyclic references.
+ */
+void
+gst_validate_reporter_purge_reports (GstValidateReporter * reporter)
+{
+  GstValidateReporterPrivate *priv;
+
+  priv = g_object_get_data (G_OBJECT (reporter), REPORTER_PRIVATE);
+
+  GST_VALIDATE_REPORTER_REPORTS_LOCK (reporter);
+  g_hash_table_remove_all (priv->reports);
+  GST_VALIDATE_REPORTER_REPORTS_UNLOCK (reporter);
+}

validate/gst/validate/gst-validate-reporter.h

@@ -115,5 +115,7 @@ GList * gst_validate_reporter_get_reports (GstValidateReporter * reporter);
 gint gst_validate_reporter_get_reports_count (GstValidateReporter *reporter);
 GstValidateReportingDetails gst_validate_reporter_get_reporting_level (GstValidateReporter *reporter);
 
+void gst_validate_reporter_purge_reports (GstValidateReporter * reporter);
+
 G_END_DECLS
 #endif /* _GST_VALIDATE_REPORTER_ */

validate/gst/validate/media-descriptor-writer.c

@@ -557,6 +557,7 @@ _run_frame_analysis (GstValidateMediaDescriptorWriter * writer,
   writer->priv->loop = NULL;
   gst_bus_remove_signal_watch (bus);
   gst_object_unref (bus);
+  gst_validate_reporter_purge_reports (GST_VALIDATE_REPORTER (monitor));
   g_object_unref (monitor);
 
   return TRUE;

validate/tools/gst-validate-media-check.c

@@ -155,10 +155,14 @@ out:
   g_free (output_file);
   g_free (expected_file);
 
-  if (reference)
+  if (reference) {
+    gst_validate_reporter_purge_reports (GST_VALIDATE_REPORTER (reference));
     gst_object_unref (reference);
-  if (writer)
+  }
+  if (writer) {
+    gst_validate_reporter_purge_reports (GST_VALIDATE_REPORTER (writer));
     gst_object_unref (writer);
+  }
   if (runner)
     gst_object_unref (runner);
   gst_deinit ();

validate/tools/gst-validate-transcoding.c

@@ -978,6 +978,7 @@ exit:
   g_main_loop_unref (mainloop);
   g_clear_object (&encoding_profile);
   g_object_unref (pipeline);
+  gst_validate_reporter_purge_reports (GST_VALIDATE_REPORTER (monitor));
   g_object_unref (monitor);
   g_object_unref (runner);
 

validate/tools/gst-validate.c

@@ -657,6 +657,7 @@ exit:
   g_main_loop_unref (mainloop);
   g_object_unref (pipeline);
   g_object_unref (runner);
+  gst_validate_reporter_purge_reports (GST_VALIDATE_REPORTER (monitor));
   g_object_unref (monitor);
   g_clear_error (&err);
 #ifdef G_OS_UNIX