1 files changed, 11 insertions, 0 deletions
diff --git a/source/blender/depsgraph/intern/eval/deg_eval_runtime_backup.h b/source/blender/depsgraph/intern/eval/deg_eval_runtime_backup.h
index c818c1f7064..d1a30652b36 100644
--- a/source/blender/depsgraph/intern/eval/deg_eval_runtime_backup.h
+++ b/source/blender/depsgraph/intern/eval/deg_eval_runtime_backup.h
@@ -46,6 +46,17 @@ class RuntimeBackup {
   /* Restore fields to the given ID. */
   void restore_to_id(ID *id);
 
+  /* Denotes whether init_from_id did put anything into the backup storage.
+   * This will not be the case when init_from_id() is called for an ID which has never been
+   * copied-on-write. In this case there is no need to backup or restore anything.
+   *
+   * It also allows to have restore() logic to be symmetrical to init() without need to worry
+   * that init() might not have happenned.
+   *
+   * In practice this is used by audio system to lock audio while scene is going through
+   * copy-on-write mechanism. */
+  bool have_backup;
+
   AnimationBackup animation_backup;
   SceneBackup scene_backup;
   SoundBackup sound_backup;