Cleanup: split `BKE_scene_get_depsgraph()` into two functions

Split the depsgraph allocation into a separate function
`BKE_scene_ensure_depsgraph()`. Parameters are only passed to those
functions that actually need them. This removes the the "if that boolean
is `false` this pointer is allowed to be `NULL`" logic and more cleanly
decouples code.

No functional changes.

1 files changed, 35 insertions, 19 deletions

diff --git a/source/blender/blenkernel/intern/scene.c b/source/blender/blenkernel/intern/scene.c
index 552076f87ca..d11cc2289c8 100644
--- a/source/blender/blenkernel/intern/scene.c
+++ b/source/blender/blenkernel/intern/scene.c
@@ -1609,7 +1609,7 @@ void BKE_scene_graph_update_for_newframe(Depsgraph *depsgraph)
  */
 void BKE_scene_view_layer_graph_evaluated_ensure(Main *bmain, Scene *scene, ViewLayer *view_layer)
 {
-  Depsgraph *depsgraph = BKE_scene_get_depsgraph(bmain, scene, view_layer, true);
+  Depsgraph *depsgraph = BKE_scene_ensure_depsgraph(bmain, scene, view_layer);
   DEG_make_active(depsgraph);
   BKE_scene_graph_update_tagged(depsgraph, bmain);
 }
@@ -2243,11 +2243,9 @@ void BKE_scene_free_view_layer_depsgraph(Scene *scene, ViewLayer *view_layer)
 
 /* Query depsgraph for a specific contexts. */
 
-static Depsgraph **scene_get_depsgraph_p(Main *bmain,
-                                         Scene *scene,
+static Depsgraph **scene_get_depsgraph_p(Scene *scene,
                                          ViewLayer *view_layer,
-                                         const bool allocate_ghash_entry,
-                                         const bool allocate_depsgraph)
+                                         const bool allocate_ghash_entry)
 {
   /* bmain may be NULL here! */
   BLI_assert(scene != NULL);
@@ -2261,9 +2259,7 @@ static Depsgraph **scene_get_depsgraph_p(Main *bmain,
   if (scene->depsgraph_hash == NULL) {
     return NULL;
   }
-  /* Either ensure item is in the hash or simply return NULL if it's not,
-   * depending on whether caller wants us to create depsgraph or not.
-   */
+
   DepsgraphKey key;
   key.view_layer = view_layer;
 
@@ -2276,20 +2272,35 @@ static Depsgraph **scene_get_depsgraph_p(Main *bmain,
   DepsgraphKey **key_ptr;
   if (BLI_ghash_ensure_p_ex(
           scene->depsgraph_hash, &key, (void ***)&key_ptr, (void ***)&depsgraph_ptr)) {
-    /* Depsgraph was found in the ghash. */
-    return depsgraph_ptr;
-  }
-
-  if (!allocate_depsgraph) {
-    /* Not found and not allowed to allocate. */
-    *depsgraph_ptr = NULL;
     return depsgraph_ptr;
   }
 
+  /* Depsgraph was not found in the ghash, but the key still needs allocating. */
   *key_ptr = MEM_mallocN(sizeof(DepsgraphKey), __func__);
   **key_ptr = key;
 
+  *depsgraph_ptr = NULL;
+  return depsgraph_ptr;
+}
+
+static Depsgraph **scene_ensure_depsgraph_p(Main *bmain, Scene *scene, ViewLayer *view_layer)
+{
+  BLI_assert(bmain != NULL);
+
+  Depsgraph **depsgraph_ptr = scene_get_depsgraph_p(scene, view_layer, true);
+  if (depsgraph_ptr == NULL) {
+    /* The scene has no depsgraph hash. */
+    return NULL;
+  }
+  if (*depsgraph_ptr != NULL) {
+    /* The depsgraph was found, no need to allocate. */
+    return depsgraph_ptr;
+  }
+
+  /* Allocate a new depsgraph. scene_get_depsgraph_p() already ensured that the pointer is stored
+   * in the scene's depsgraph hash. */
   *depsgraph_ptr = DEG_graph_new(bmain, scene, view_layer, DAG_EVAL_VIEWPORT);
+
   /* TODO(sergey): Would be cool to avoid string format print,
    * but is a bit tricky because we can't know in advance whether
    * we will ever enable debug messages for this depsgraph.
@@ -2301,9 +2312,15 @@ static Depsgraph **scene_get_depsgraph_p(Main *bmain,
   return depsgraph_ptr;
 }
 
-Depsgraph *BKE_scene_get_depsgraph(Main *bmain, Scene *scene, ViewLayer *view_layer, bool allocate)
+Depsgraph *BKE_scene_get_depsgraph(Scene *scene, ViewLayer *view_layer)
+{
+  Depsgraph **depsgraph_ptr = scene_get_depsgraph_p(scene, view_layer, false);
+  return (depsgraph_ptr != NULL) ? *depsgraph_ptr : NULL;
+}
+
+Depsgraph *BKE_scene_ensure_depsgraph(Main *bmain, Scene *scene, ViewLayer *view_layer)
 {
-  Depsgraph **depsgraph_ptr = scene_get_depsgraph_p(bmain, scene, view_layer, allocate, allocate);
+  Depsgraph **depsgraph_ptr = scene_ensure_depsgraph_p(bmain, scene, view_layer);
   return (depsgraph_ptr != NULL) ? *depsgraph_ptr : NULL;
 }
 
@@ -2369,8 +2386,7 @@ void BKE_scene_undo_depsgraphs_restore(Main *bmain, GHash *depsgraph_extract)
       }
       BLI_assert(*depsgraph_extract_ptr != NULL);
 
-      Depsgraph **depsgraph_scene_ptr = scene_get_depsgraph_p(
-          bmain, scene, view_layer, true, false);
+      Depsgraph **depsgraph_scene_ptr = scene_get_depsgraph_p(scene, view_layer, true);
       BLI_assert(depsgraph_scene_ptr != NULL);
       BLI_assert(*depsgraph_scene_ptr == NULL);