[Bf-blender-cvs] [d8223bdc382] master: Cleanup: Improvements to Outliner tree writing code, add assert
Julian Eisel
noreply at git.blender.org
Wed Aug 17 20:40:13 CEST 2022
Commit: d8223bdc38202c1ddd8e5cf2a4f3ec6136d9e316
Author: Julian Eisel
Date: Wed Aug 17 19:20:52 2022 +0200
Branches: master
https://developer.blender.org/rBd8223bdc38202c1ddd8e5cf2a4f3ec6136d9e316
Cleanup: Improvements to Outliner tree writing code, add assert
Comments there weren't really helpful, took me a while to get what they
try to say. This attempts to add a better explanation. Also add an
assert for a previous, implicit (but commented) assumption, and some
minor cleanups.
===================================================================
M source/blender/blenkernel/intern/screen.c
===================================================================
diff --git a/source/blender/blenkernel/intern/screen.c b/source/blender/blenkernel/intern/screen.c
index 66ec887b3d4..f1eba64e401 100644
--- a/source/blender/blenkernel/intern/screen.c
+++ b/source/blender/blenkernel/intern/screen.c
@@ -1123,32 +1123,43 @@ static void write_uilist(BlendWriter *writer, uiList *ui_list)
}
}
-static void write_space_outliner(BlendWriter *writer, SpaceOutliner *space_outliner)
+static void write_space_outliner(BlendWriter *writer, const SpaceOutliner *space_outliner)
{
BLI_mempool *ts = space_outliner->treestore;
if (ts) {
- int elems = BLI_mempool_len(ts);
+ const int elems = BLI_mempool_len(ts);
/* linearize mempool to array */
TreeStoreElem *data = elems ? BLI_mempool_as_arrayN(ts, "TreeStoreElem") : NULL;
if (data) {
- /* In this block we use the memory location of the treestore
- * but _not_ its data, the addresses in this case are UUID's,
- * since we can't rely on malloc giving us different values each time.
+ BLO_write_struct(writer, SpaceOutliner, space_outliner);
+
+ /* To store #TreeStore (instead of the mempool), two unique memory addresses are needed,
+ * which can be used to identify the data on read:
+ * 1) One for the #TreeStore data itself.
+ * 2) One for the array of #TreeStoreElem's inside #TreeStore (#TreeStore.data).
+ *
+ * For 1) we just use the mempool's address (#SpaceOutliner::treestore).
+ * For 2) we don't have such a direct choice. We can't just use the array's address from
+ * above, since that may not be unique over all Outliners. So instead use an address relative
+ * to 1).
*/
- TreeStore ts_flat = {0};
+ /* TODO the mempool could be moved to #SpaceOutliner_Runtime so that #SpaceOutliner could
+ * hold the #TreeStore directly. */
- /* we know the treestore is at least as big as a pointer,
- * so offsetting works to give us a UUID. */
+ /* Address relative to the tree-store, as noted above. */
void *data_addr = (void *)POINTER_OFFSET(ts, sizeof(void *));
+ /* There should be plenty of memory addresses within the mempool data that we can point into,
+ * just double-check we don't potentially end up with a memory address that another DNA
+ * struct might use. Assumes BLI_mempool uses the guarded allocator. */
+ BLI_assert(MEM_allocN_len(ts) >= sizeof(void *) * 2);
+ TreeStore ts_flat = {0};
ts_flat.usedelem = elems;
ts_flat.totelem = elems;
ts_flat.data = data_addr;
- BLO_write_struct(writer, SpaceOutliner, space_outliner);
-
BLO_write_struct_at_address(writer, TreeStore, ts, &ts_flat);
BLO_write_struct_array_at_address(writer, TreeStoreElem, elems, data_addr, data);
More information about the Bf-blender-cvs
mailing list