Move Scene's cache management during undo to new system.

Referenced by issue #78608, Memory leak in Material properties: "Data from SCE"
Referenced by issue #78588, Material preview not visible in selection list

source/blender/blenkernel/intern/scene.c

@@ -570,6 +570,20 @@ static void scene_foreach_id(ID *id, LibraryForeachIDData *data)
   }
 }
 
+static void scene_foreach_cache(ID *id,
+                                IDTypeForeachCacheFunctionCallback function_callback,
+                                void *user_data)
+{
+  Scene *scene = (Scene *)id;
+  IDCacheKey key = {
+      .id_session_uuid = id->session_uuid,
+      .offset_in_ID = offsetof(Scene, eevee.light_cache_data),
+      .cache_v = scene->eevee.light_cache_data,
+  };
+
+  function_callback(id, &key, (void **)&scene->eevee.light_cache_data, user_data);
+}
+
 IDTypeInfo IDType_ID_SCE = {
     .id_code = ID_SCE,
     .id_filter = FILTER_ID_SCE,
@@ -587,6 +601,7 @@ IDTypeInfo IDType_ID_SCE = {
      * support all possible corner cases. */
     .make_local = NULL,
     .foreach_id = scene_foreach_id,
+    .foreach_cache = scene_foreach_cache,
 };
 
 const char *RE_engine_id_BLENDER_EEVEE = "BLENDER_EEVEE";

source/blender/blenloader/intern/readblenentry.c

@@ -390,29 +390,26 @@ BlendFileData *BLO_read_from_memfile(Main *oldmain,
       blo_make_old_idmap_from_main(fd, old_mainlist.first);
     }
 
+    /* TODO: Move handling of nodetree caches to new system as well... */
     /* makes lookup of existing images in old main */
     blo_make_image_pointer_map(fd, oldmain);
-
-    /* makes lookup of existing light caches in old main */
-    blo_make_scene_pointer_map(fd, oldmain);
-
     /* makes lookup of existing video clips in old main */
     blo_make_movieclip_pointer_map(fd, oldmain);
 
     /* removed packed data from this trick - it's internal data that needs saves */
 
+    /* Store all existing ID caches pointers into a mapping, to allow restoring them into newly
+     * read IDs whenever possible. */
     blo_cache_storage_init(fd, oldmain);
 
     bfd = blo_read_file_internal(fd, filename);
 
+    /* Ensure relinked caches are not freed together with their old IDs. */
     blo_cache_storage_old_bmain_clear(fd, oldmain);
 
-    /* ensures relinked light caches are not freed */
-    blo_end_scene_pointer_map(fd, oldmain);
-
+    /* TODO: Move handling of nodetree caches to new system as well... */
     /* ensures relinked images are not freed */
     blo_end_image_pointer_map(fd, oldmain);
-
     /* ensures relinked movie clips are not freed */
     blo_end_movieclip_pointer_map(fd, oldmain);
 

source/blender/blenloader/intern/readfile.c

@@ -6942,13 +6942,7 @@ static void direct_link_scene(BlendDataReader *reader, Scene *sce)
   }
 
   if (reader->fd->memfile) {
-    /* If it's undo try to recover the cache. */
-    if (reader->fd->scenemap) {
-      sce->eevee.light_cache_data = newsceadr(reader->fd, sce->eevee.light_cache_data);
-    }
-    else {
-      sce->eevee.light_cache_data = NULL;
-    }
+    /* If it's undo do nothing here, caches are handled by higher-level generic calling code. */
   }
   else {
     /* else try to read the cache from file. */