Geometry Nodes: refactor logging during geometry nodes evaluation

Many ui features for geometry nodes need access to information generated
during evaluation:
* Node warnings.
* Attribute search.
* Viewer node.
* Socket inspection (not in master yet).

The way we logged the required information before had some disadvantages:
* Viewer node used a completely separate system from node warnings and
  attribute search.
* Most of the context of logged information is lost when e.g. the same node
  group is used multiple times.
* A global lock was needed every time something is logged.

This new implementation solves these problems:
* All four mentioned ui features use the same underlying logging system.
* All context information for logged values is kept intact.
* Every thread has its own local logger. The logged informatiton is combined
  in the end.

Differential Revision: https://developer.blender.org/D11785

1 files changed, 4 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_modifier_types.h b/source/blender/makesdna/DNA_modifier_types.h
index 08a38f0652c..1c765d19ce2 100644
--- a/source/blender/makesdna/DNA_modifier_types.h
+++ b/source/blender/makesdna/DNA_modifier_types.h
@@ -2256,6 +2256,10 @@ typedef struct NodesModifierData {
   ModifierData modifier;
   struct bNodeTree *node_group;
   struct NodesModifierSettings settings;
+
+  /* Contains logged information from the last evaluation. This can be used to help the user to
+   * debug a node tree. */
+  void *runtime_eval_log;
 } NodesModifierData;
 
 typedef struct MeshToVolumeModifierData {