Add an session-wise uuid integer to IDs.

"session-wise" here mean while editing a same .blend file. So creating
or opening a new one will reset the uuid counter. This should avoid any
overflow in practice.

Only IDs added to Main database get an uuid, runtime-only ones are not
affected.

This is intended to provide undo with a way to find IDs across several
'memory realms' (undo speedup project).

No behavior change is expected from this commit itself.

Part of T60695.

Differential Revision: https://developer.blender.org/D7007

2 files changed, 14 insertions, 1 deletions

diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 3107de38ff7..4d46435eea0 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -8056,7 +8056,8 @@ void blo_lib_link_restore(Main *oldmain,
                           Scene *curscene,
                           ViewLayer *cur_view_layer)
 {
-  struct IDNameLib_Map *id_map = BKE_main_idmap_create(newmain, true, oldmain);
+  struct IDNameLib_Map *id_map = BKE_main_idmap_create(
+      newmain, true, oldmain, MAIN_IDMAP_TYPE_NAME);
 
   for (WorkSpace *workspace = newmain->workspaces.first; workspace;
        workspace = workspace->id.next) {
@@ -8801,6 +8802,8 @@ static ID *create_placeholder(Main *mainvar, const short idcode, const char *idn
   BLI_addtail(lb, ph_id);
   id_sort_by_name(lb, ph_id, NULL);
 
+  BKE_lib_libblock_session_uuid_ensure(ph_id);
+
   return ph_id;
 }
 
@@ -9013,6 +9016,14 @@ static BHead *read_libblock(FileData *fd,
       oldnewmap_insert(fd->libmap, bhead->old, id, bhead->code);
 
       BLI_addtail(lb, id);
+
+      if (fd->memfile == NULL) {
+        /* When actually reading a file , we do want to reset/re-generate session uuids.
+         * In unod case, we want to re-use existing ones. */
+        id->session_uuid = MAIN_ID_SESSION_UUID_UNSET;
+      }
+
+      BKE_lib_libblock_session_uuid_ensure(id);
     }
     else {
       /* unknown ID type */
diff --git a/source/blender/blenloader/intern/versioning_250.c b/source/blender/blenloader/intern/versioning_250.c
index a4b51f91be4..cf4924eeb6d 100644
--- a/source/blender/blenloader/intern/versioning_250.c
+++ b/source/blender/blenloader/intern/versioning_250.c
@@ -446,6 +446,8 @@ static void versions_gpencil_add_main(ListBase *lb, ID *id, const char *name)
   BKE_id_new_name_validate(lb, id, name);
   /* alphabetic insertion: is in BKE_id_new_name_validate */
 
+  BKE_lib_libblock_session_uuid_ensure(id);
+
   if (G.debug & G_DEBUG) {
     printf("Converted GPencil to ID: %s\n", id->name + 2);
   }