Object: Speed up duplication of large selections by doing fewer collection syncs

Previous code was doing N collection syncs when duplicating N objects.
New code avoids all the intermediate syncs by using
BKE_layer_collection_resync_forbid and
BKE_layer_collection_resync_allow, and then does one
BKE_main_collection_sync + BKE_main_collection_sync_remap for the
whole operation. There is some complexity involved where the Base
things of newly duplicated objects can't be found yet, without the
sync, so some work on them (marking them selected, active, ...) has
to be deferred until after the sync.

Timings: scene with 10k cubes, each with unique mesh (Windows, VS2022
Release build, AMD Ryzen 5950X):

- Shift+D duplicate: 13.6s -> 9.2s
- Alt+D duplicate: 4.76s -> 1.53s

Reviewed By: Bastien Montagne
Differential Revision: https://developer.blender.org/D14150

1 files changed, 60 insertions, 25 deletions

diff --git a/source/blender/editors/object/object_add.cc b/source/blender/editors/object/object_add.cc
index 41aaede8d6f..64026f7b06b 100644
--- a/source/blender/editors/object/object_add.cc
+++ b/source/blender/editors/object/object_add.cc
@@ -36,6 +36,7 @@
 #include "BLI_math.h"
 #include "BLI_string.h"
 #include "BLI_utildefines.h"
+#include "BLI_vector.hh"
 
 #include "BLT_translation.h"
 
@@ -3600,7 +3601,8 @@ static Base *object_add_duplicate_internal(Main *bmain,
                                            ViewLayer *view_layer,
                                            Object *ob,
                                            const eDupli_ID_Flags dupflag,
-                                           const eLibIDDuplicateFlags duplicate_options)
+                                           const eLibIDDuplicateFlags duplicate_options,
+                                           Object **r_ob_new)
 {
   Base *base, *basen = nullptr;
   Object *obn;
@@ -3611,6 +3613,9 @@ static Base *object_add_duplicate_internal(Main *bmain,
   else {
     obn = static_cast<Object *>(
         ID_NEW_SET(ob, BKE_object_duplicate(bmain, ob, dupflag, duplicate_options)));
+    if (r_ob_new) {
+      *r_ob_new = obn;
+    }
     DEG_id_tag_update(&obn->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
 
     base = BKE_view_layer_base_find(view_layer, ob);
@@ -3623,7 +3628,7 @@ static Base *object_add_duplicate_internal(Main *bmain,
     }
 
     basen = BKE_view_layer_base_find(view_layer, obn);
-    if (base != nullptr) {
+    if (base != nullptr && basen != nullptr) {
       basen->local_view_bits = base->local_view_bits;
     }
 
@@ -3654,7 +3659,8 @@ Base *ED_object_add_duplicate(
                                         base->object,
                                         dupflag,
                                         LIB_ID_DUPLICATE_IS_SUBPROCESS |
-                                            LIB_ID_DUPLICATE_IS_ROOT_ID);
+                                            LIB_ID_DUPLICATE_IS_ROOT_ID,
+                                        nullptr);
   if (basen == nullptr) {
     return nullptr;
   }
@@ -3687,45 +3693,73 @@ static int duplicate_exec(bContext *C, wmOperator *op)
   ViewLayer *view_layer = CTX_data_view_layer(C);
   const bool linked = RNA_boolean_get(op->ptr, "linked");
   const eDupli_ID_Flags dupflag = (linked) ? (eDupli_ID_Flags)0 : (eDupli_ID_Flags)U.dupflag;
-  bool changed = false;
 
   /* We need to handle that here ourselves, because we may duplicate several objects, in which case
    * we also want to remap pointers between those... */
   BKE_main_id_newptr_and_tag_clear(bmain);
 
+  /* Do not do collection re-syncs for each object; will do it once afterwards.
+   * However this means we can't get to new duplicated Base's immediately, will
+   * have to process them after the sync. */
+  BKE_layer_collection_resync_forbid();
+
+  /* Duplicate the selected objects, remember data needed to process
+   * after the sync (the base of the original object, and the copy of the
+   * original object). */
+  blender::Vector<std::pair<Base *, Object *>> source_bases_new_objects;
+  Object *ob_new_active = nullptr;
+
   CTX_DATA_BEGIN (C, Base *, base, selected_bases) {
-    Base *basen = object_add_duplicate_internal(bmain,
-                                                scene,
-                                                view_layer,
-                                                base->object,
-                                                dupflag,
-                                                LIB_ID_DUPLICATE_IS_SUBPROCESS |
-                                                    LIB_ID_DUPLICATE_IS_ROOT_ID);
+    Object *ob_new = NULL;
+    object_add_duplicate_internal(bmain,
+                                  scene,
+                                  view_layer,
+                                  base->object,
+                                  dupflag,
+                                  LIB_ID_DUPLICATE_IS_SUBPROCESS | LIB_ID_DUPLICATE_IS_ROOT_ID,
+                                  &ob_new);
+    if (ob_new == nullptr) {
+      continue;
+    }
+    source_bases_new_objects.append({base, ob_new});
 
     /* note that this is safe to do with this context iterator,
      * the list is made in advance */
     ED_object_base_select(base, BA_DESELECT);
-    ED_object_base_select(basen, BA_SELECT);
-    changed = true;
-
-    if (basen == nullptr) {
-      continue;
-    }
 
-    /* new object becomes active */
+    /* new object will become active */
     if (BASACT(view_layer) == base) {
-      ED_object_base_activate(C, basen);
-    }
-
-    if (basen->object->data) {
-      DEG_id_tag_update(static_cast<ID *>(basen->object->data), 0);
+      ob_new_active = ob_new;
     }
   }
   CTX_DATA_END;
 
-  if (!changed) {
+  if (source_bases_new_objects.is_empty()) {
     return OPERATOR_CANCELLED;
   }
+  /* Sync the collection now, after everything is duplicated. */
+  BKE_layer_collection_resync_allow();
+  BKE_main_collection_sync(bmain);
+
+  /* After sync we can get to the new Base data, process it here. */
+  for (const auto &item : source_bases_new_objects) {
+    Object *ob_new = item.second;
+    Base *base_source = item.first;
+    Base *base_new = BKE_view_layer_base_find(view_layer, ob_new);
+    if (base_new == nullptr) {
+      continue;
+    }
+    ED_object_base_select(base_new, BA_SELECT);
+    if (ob_new == ob_new_active) {
+      ED_object_base_activate(C, base_new);
+    }
+    if (base_new->object->data) {
+      DEG_id_tag_update(static_cast<ID *>(base_new->object->data), 0);
+    }
+    /* #object_add_duplicate_internal will not have done this, since
+     * before the collection sync it would not have found the new base yet. */
+    base_new->local_view_bits = base_source->local_view_bits;
+  }
 
   /* Note that this will also clear newid pointers and tags. */
   copy_object_set_idnew(C);
@@ -3808,7 +3842,8 @@ static int object_add_named_exec(bContext *C, wmOperator *op)
        * the case here. So we have to do the new-ID relinking ourselves
        * (#copy_object_set_idnew()).
        */
-      LIB_ID_DUPLICATE_IS_SUBPROCESS | LIB_ID_DUPLICATE_IS_ROOT_ID);
+      LIB_ID_DUPLICATE_IS_SUBPROCESS | LIB_ID_DUPLICATE_IS_ROOT_ID,
+      nullptr);
 
   if (basen == nullptr) {
     BKE_report(op->reports, RPT_ERROR, "Object could not be duplicated");