Refactor access to dependency graph

This change ensures that operators which needs access to evaluated data
first makes sure there is a dependency graph.

Other accesses to the dependency graph made it more explicit about
whether they just need a valid dependency graph pointer or whether they
expect the graph to be already evaluated.

This replaces OPTYPE_USE_EVAL_DATA which is now removed.

Some general rules about usage of accessors:

- Drawing is expected to happen from a fully evaluated dependency graph.
  There is now a function to access it, which will in the future control
  that dependency graph is actually evaluated.

  This check is not yet done because there are some things to be taken
  care about first: for example, post-update hooks might leave scene in
  a state where something is still tagged for update.

- All operators which needs to access evaluated state must use
  CTX_data_ensure_evaluated_depsgraph().

  This function replaces OPTYPE_USE_EVAL_DATA.

  The call is generally to be done in the very beginning of the
  operator, prior other logic (unless this is some comprehensive
  operator which might or might not need access to an evaluated state).

  This call is never to be used from a loop.

  If some utility function requires evaluated state of dependency graph
  the graph is to be passed as an explicit argument. This way it is
  clear that no evaluation happens in a loop or something like this.

- All cases which needs to know dependency graph pointer, but which
  doesn't want to actually evaluate it can use old-style function
  CTX_data_depsgraph_pointer(), assuming that underlying code will
  ensure dependency graph is evaluated prior to accessing it.

- The new functions are replacing OPTYPE_USE_EVAL_DATA, so now it is
  explicit and local about where dependency graph is being ensured.

This commit also contains some fixes of wrong usage of evaluation
functions on original objects. Ideally should be split out, but in
reality with all the APIs being renamed is quite tricky.

Fixes T67454: Blender crash on rapid undo and select

Speculation here is that sometimes undo and selection operators are
sometimes handled in the same event loop iteration, which leaves
non-evaluated dependency graph.

Fixes T67973: Crash on Fix Deforms operator
Fixes T67902: Crash when undo a loop cut

Reviewers: brecht

Reviewed By: brecht

Subscribers: lichtwerk

Maniphest Tasks: T67454

Differential Revision: https://developer.blender.org/D5343

4 files changed, 10 insertions, 6 deletions

diff --git a/source/blender/makesrna/intern/rna_context.c b/source/blender/makesrna/intern/rna_context.c
index 9986b4c1674..735cd1fd923 100644
--- a/source/blender/makesrna/intern/rna_context.c
+++ b/source/blender/makesrna/intern/rna_context.c
@@ -211,7 +211,7 @@ static struct Depsgraph *rna_Context_evaluated_depsgraph_get(bContext *C)
   BPy_BEGIN_ALLOW_THREADS;
 #  endif
 
-  depsgraph = CTX_data_evaluated_depsgraph(C);
+  depsgraph = CTX_data_ensure_evaluated_depsgraph(C);
 
 #  ifdef WITH_PYTHON
   BPy_END_ALLOW_THREADS;
diff --git a/source/blender/makesrna/intern/rna_layer.c b/source/blender/makesrna/intern/rna_layer.c
index 1c0ced060d5..c9b51707759 100644
--- a/source/blender/makesrna/intern/rna_layer.c
+++ b/source/blender/makesrna/intern/rna_layer.c
@@ -178,8 +178,8 @@ static void rna_ViewLayer_update_tagged(ID *id_ptr, ViewLayer *view_layer, Main
 
   Scene *scene = (Scene *)id_ptr;
   Depsgraph *depsgraph = BKE_scene_get_depsgraph(scene, view_layer, true);
-  /* NOTE: This is similar to CTX_data_depsgraph(). Ideally such access would be de-duplicated
-   * across all possible cases, but for now this is safest and easiest way to go.
+  /* NOTE: This is similar to CTX_data_depsgraph_pointer(). Ideally such access would be
+   * de-duplicated across all possible cases, but for now this is safest and easiest way to go.
    *
    * The reason for this is that it's possible to have Python operator which asks view layer to
    * be updated. After re-do of such operator view layer's dependency graph will not be marked
diff --git a/source/blender/makesrna/intern/rna_modifier.c b/source/blender/makesrna/intern/rna_modifier.c
index 6cd4be81a56..a04e0e6422f 100644
--- a/source/blender/makesrna/intern/rna_modifier.c
+++ b/source/blender/makesrna/intern/rna_modifier.c
@@ -1114,8 +1114,6 @@ static const EnumPropertyItem *rna_DataTransferModifier_layers_select_src_itemf(
     return rna_enum_dt_layers_select_src_items;
   }
 
-  Depsgraph *depsgraph = CTX_data_depsgraph(C);
-
   /* No active here! */
   RNA_enum_items_add_value(
       &item, &totitem, rna_enum_dt_layers_select_src_items, DT_LAYERS_ALL_SRC);
@@ -1155,6 +1153,7 @@ static const EnumPropertyItem *rna_DataTransferModifier_layers_select_src_itemf(
       Mesh *me_eval;
       int num_data, i;
 
+      Depsgraph *depsgraph = CTX_data_ensure_evaluated_depsgraph(C);
       Scene *scene_eval = DEG_get_evaluated_scene(depsgraph);
       Object *ob_src_eval = DEG_get_evaluated_object(depsgraph, ob_src);
 
@@ -1180,6 +1179,7 @@ static const EnumPropertyItem *rna_DataTransferModifier_layers_select_src_itemf(
       Mesh *me_eval;
       int num_data, i;
 
+      Depsgraph *depsgraph = CTX_data_ensure_evaluated_depsgraph(C);
       Scene *scene_eval = DEG_get_evaluated_scene(depsgraph);
       Object *ob_src_eval = DEG_get_evaluated_object(depsgraph, ob_src);
 
diff --git a/source/blender/makesrna/intern/rna_object_api.c b/source/blender/makesrna/intern/rna_object_api.c
index c91481931a2..5fb1cae31e3 100644
--- a/source/blender/makesrna/intern/rna_object_api.c
+++ b/source/blender/makesrna/intern/rna_object_api.c
@@ -465,6 +465,8 @@ static int mesh_looptri_to_poly_index(Mesh *me_eval, const MLoopTri *lt)
   return index_mp_to_orig ? index_mp_to_orig[lt->poly] : lt->poly;
 }
 
+/* TOOD(sergey): Make the Python API more clear that evaluation might happen, or requite passing
+ * fully evaluated depsgraph. */
 static Object *eval_object_ensure(Object *ob,
                                   bContext *C,
                                   ReportList *reports,
@@ -474,7 +476,7 @@ static Object *eval_object_ensure(Object *ob,
     Object *ob_orig = ob;
     Depsgraph *depsgraph = rnaptr_depsgraph != NULL ? rnaptr_depsgraph->data : NULL;
     if (depsgraph == NULL) {
-      depsgraph = CTX_data_depsgraph(C);
+      depsgraph = CTX_data_ensure_evaluated_depsgraph(C);
     }
     if (depsgraph != NULL) {
       ob = DEG_get_evaluated_object(depsgraph, ob);
@@ -502,6 +504,8 @@ static void rna_Object_ray_cast(Object *ob,
 {
   bool success = false;
 
+  /* TODO(sergey): This isn't very reliable check. It is possible to have non-NULL pointer but
+   * which is out of date, and possibly dangling one. */
   if (ob->runtime.mesh_eval == NULL &&
       (ob = eval_object_ensure(ob, C, reports, rnaptr_depsgraph)) == NULL) {
     return;