[Bf-blender-cvs] [8a73b03fddb] readfile-rework-refcount-handling: Fix crash on undo case.

[Bastien Montagne]

Commit: 8a73b03fddbcb822433621015546d5e8e8402932
Author: Bastien Montagne
Date:   Fri Feb 14 14:53:46 2020 +0100
Branches: readfile-rework-refcount-handling
https://developer.blender.org/rB8a73b03fddbcb822433621015546d5e8e8402932

Fix crash on undo case.

We cannot use libquery too early in undo case, because of all the black
magic we perform over our data-blocks there...

===================================================================

M	source/blender/blenkernel/intern/blendfile.c
M	source/blender/blenloader/intern/readfile.c

===================================================================

diff --git a/source/blender/blenkernel/intern/blendfile.c b/source/blender/blenkernel/intern/blendfile.c
index 5cbcb09f293..efab2039dc3 100644
--- a/source/blender/blenkernel/intern/blendfile.c
+++ b/source/blender/blenkernel/intern/blendfile.c
@@ -364,6 +364,16 @@ static void setup_app_data(bContext *C,
     /* TODO(sergey): Can this be also move above? */
     RE_FreeAllPersistentData();
   }
+
+  if (mode == LOAD_UNDO) {
+    /* In undo/redo case, we do a whole lot of magic tricks to avoid having to re-read linked
+     * data-blocks from libraries (since those are not supposed to change). Unfortunately, that
+     * means that we do not reset their user count, however we do increase that one when doing
+     * lib_link on local IDs using linked ones.
+     * There is no real way to predict amount of changes here, so we have to fully redo
+     * refcounting . */
+    BKE_main_id_refcount_recompute(bmain, false);
+  }
 }
 
 static void setup_app_blend_file_data(bContext *C,
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 9a9611e6542..d3e1eaa3801 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -9527,7 +9527,11 @@ static void lib_link_all(FileData *fd, Main *bmain)
   FOREACH_MAIN_ID_END;
 
   TIMEIT_START(readfile_refcount_recomp);
-  BKE_main_id_refcount_recompute(bmain, false);
+  /* We cannot do that here in undo case, we play too much with IDs from different memory realms,
+   * and Main database is in pretty bad state currently. */
+  if (fd->memfile == NULL) {
+    BKE_main_id_refcount_recompute(bmain, false);
+  }
   TIMEIT_END(readfile_refcount_recomp);
 
   /* Check for possible cycles in scenes' 'set' background property. */