[Bf-blender-cvs] [38cdc7bcc1f] master: Fix non-thread safe code in view layer object hash

[Brecht Van Lommel]

Commit: 38cdc7bcc1f2ac7e89578be079e4be0b049a4036
Author: Brecht Van Lommel
Date:   Fri Oct 2 19:30:19 2020 +0200
Branches: master
https://developer.blender.org/rB38cdc7bcc1f2ac7e89578be079e4be0b049a4036

Fix non-thread safe code in view layer object hash

Found as part of D8324, multithreaded Cycles object sync, where it caused
a crash on concurrent access to object holdout state.

===================================================================

M	source/blender/blenkernel/intern/layer.c

===================================================================

diff --git a/source/blender/blenkernel/intern/layer.c b/source/blender/blenkernel/intern/layer.c
index 1d47fb002e6..4ed8a796d5d 100644
--- a/source/blender/blenkernel/intern/layer.c
+++ b/source/blender/blenkernel/intern/layer.c
@@ -358,14 +358,16 @@ static void view_layer_bases_hash_create(ViewLayer *view_layer)
     BLI_mutex_lock(&hash_lock);
 
     if (view_layer->object_bases_hash == NULL) {
-      view_layer->object_bases_hash = BLI_ghash_new(
-          BLI_ghashutil_ptrhash, BLI_ghashutil_ptrcmp, __func__);
+      GHash *hash = BLI_ghash_new(BLI_ghashutil_ptrhash, BLI_ghashutil_ptrcmp, __func__);
 
       LISTBASE_FOREACH (Base *, base, &view_layer->object_bases) {
         if (base->object) {
-          BLI_ghash_insert(view_layer->object_bases_hash, base->object, base);
+          BLI_ghash_insert(hash, base->object, base);
         }
       }
+
+      /* Assign pointer only after hash is complete. */
+      view_layer->object_bases_hash = hash;
     }
 
     BLI_mutex_unlock(&hash_lock);