Depsgraph: Remove the "disable-copy-on-write" option completely

After discussion with Sergey and Dalai, we have decided to remove
this option completely. We're getting to the point where it is almost
impossible to really use 2.8 without COW, and keeping the old option
running ends up diverting dev resources away towards tracking down
and fixing problems with a parallel system that will be going away.

14 files changed, 43 insertions, 126 deletions

diff --git a/source/blender/blenkernel/intern/DerivedMesh.c b/source/blender/blenkernel/intern/DerivedMesh.c
index 3c9e0efa12e..8de4b7f741d 100644
--- a/source/blender/blenkernel/intern/DerivedMesh.c
+++ b/source/blender/blenkernel/intern/DerivedMesh.c
@@ -2934,9 +2934,6 @@ static bool calc_modifiers_skip_orco(Depsgraph *depsgraph,
 
 static void mesh_finalize_eval(Object *object)
 {
-	if (!DEG_depsgraph_use_copy_on_write()) {
-		return;
-	}
 	Mesh *mesh = (Mesh *)object->data;
 	Mesh *mesh_eval = object->runtime.mesh_eval;
 	/* Special Tweaks for cases when evaluated mesh came from
diff --git a/source/blender/depsgraph/DEG_depsgraph.h b/source/blender/depsgraph/DEG_depsgraph.h
index d79ee9aa86b..fbd267924a9 100644
--- a/source/blender/depsgraph/DEG_depsgraph.h
+++ b/source/blender/depsgraph/DEG_depsgraph.h
@@ -91,9 +91,6 @@ enum {
 extern "C" {
 #endif
 
-bool DEG_depsgraph_use_copy_on_write(void);
-void DEG_depsgraph_disable_copy_on_write(void);
-
 /* ************************************************ */
 /* Depsgraph API */
 
diff --git a/source/blender/depsgraph/intern/builder/deg_builder.cc b/source/blender/depsgraph/intern/builder/deg_builder.cc
index 2fcad233044..e2fc1efd455 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder.cc
@@ -46,7 +46,6 @@ namespace DEG {
 
 void deg_graph_build_finalize(Main *bmain, Depsgraph *graph)
 {
-	const bool use_copy_on_write = DEG_depsgraph_use_copy_on_write();
 	/* Re-tag IDs for update if it was tagged before the relations
 	 * update tag.
 	 */
@@ -59,9 +58,7 @@ void deg_graph_build_finalize(Main *bmain, Depsgraph *graph)
 		/* TODO(sergey): This is not ideal at all, since this forces
 		 * re-evaluaiton of the whole tree.
 		 */
-		if (use_copy_on_write) {
-			DEG_id_tag_update_ex(bmain, id_node->id_orig, DEG_TAG_COPY_ON_WRITE);
-		}
+		DEG_id_tag_update_ex(bmain, id_node->id_orig, DEG_TAG_COPY_ON_WRITE);
 	}
 }
 
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc b/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
index fbf94293236..677dcfbfb8d 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
@@ -150,9 +150,6 @@ DepsgraphNodeBuilder::~DepsgraphNodeBuilder()
 
 IDDepsNode *DepsgraphNodeBuilder::add_id_node(ID *id)
 {
-	if (!DEG_depsgraph_use_copy_on_write()) {
-		return graph_->add_id_node(id);
-	}
 	IDDepsNode *id_node = NULL;
 	ID *id_cow = (ID *)BLI_ghash_lookup(cow_id_hash_, id);
 	if (id_cow != NULL) {
@@ -324,22 +321,21 @@ ID *DepsgraphNodeBuilder::ensure_cow_id(ID *id_orig)
 
 /* **** Build functions for entity nodes **** */
 
-void DepsgraphNodeBuilder::begin_build() {
-	if (DEG_depsgraph_use_copy_on_write()) {
-		/* Store existing copy-on-write versions of datablock, so we can re-use
-		 * them for new ID nodes.
-		 */
-		cow_id_hash_ = BLI_ghash_ptr_new("Depsgraph id hash");
-		foreach (IDDepsNode *id_node, graph_->id_nodes) {
-			if (deg_copy_on_write_is_expanded(id_node->id_cow)) {
-				if (id_node->id_orig == id_node->id_cow) {
-					continue;
-				}
-				BLI_ghash_insert(cow_id_hash_,
-				                 id_node->id_orig,
-				                 id_node->id_cow);
-				id_node->id_cow = NULL;
+void DepsgraphNodeBuilder::begin_build()
+{
+	/* Store existing copy-on-write versions of datablock, so we can re-use
+	 * them for new ID nodes.
+	 */
+	cow_id_hash_ = BLI_ghash_ptr_new("Depsgraph id hash");
+	foreach (IDDepsNode *id_node, graph_->id_nodes) {
+		if (deg_copy_on_write_is_expanded(id_node->id_cow)) {
+			if (id_node->id_orig == id_node->id_cow) {
+				continue;
 			}
+			BLI_ghash_insert(cow_id_hash_,
+			                 id_node->id_orig,
+			                 id_node->id_cow);
+			id_node->id_cow = NULL;
 		}
 	}
 
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes.h b/source/blender/depsgraph/intern/builder/deg_builder_nodes.h
index 8b9d2d1a010..b7c5a33f2c0 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes.h
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes.h
@@ -33,7 +33,7 @@
 #include "intern/builder/deg_builder_map.h"
 #include "intern/depsgraph_types.h"
 
-#include "DEG_depsgraph.h"  /* used for DEG_depsgraph_use_copy_on_write() */
+#include "DEG_depsgraph.h"
 
 struct Base;
 struct CacheFile;
@@ -92,12 +92,7 @@ struct DepsgraphNodeBuilder {
 	/* For a given COW datablock get corresponding original one. */
 	template<typename T>
 	T *get_orig_datablock(const T *cow) const {
-		if (DEG_depsgraph_use_copy_on_write()) {
-			return (T *)cow->id.orig_id;
-		}
-		else {
-			return (T *)cow;
-		}
+		return (T *)cow->id.orig_id;
 	}
 
 	void begin_build();
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes_rig.cc b/source/blender/depsgraph/intern/builder/deg_builder_nodes_rig.cc
index c48381481f5..d3c4ce01674 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes_rig.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes_rig.cc
@@ -145,16 +145,8 @@ void DepsgraphNodeBuilder::build_splineik_pose(Object *object,
 void DepsgraphNodeBuilder::build_rig(Object *object)
 {
 	bArmature *armature = (bArmature *)object->data;
-	Scene *scene_cow;
-	Object *object_cow;
-	if (DEG_depsgraph_use_copy_on_write()) {
-		scene_cow = get_cow_datablock(scene_);
-		object_cow = get_cow_datablock(object);
-	}
-	else {
-		scene_cow = scene_;
-		object_cow = object;
-	}
+	Scene *scene_cow = get_cow_datablock(scene_);
+	Object *object_cow = get_cow_datablock(object);
 	OperationDepsNode *op_node;
 
 	/* Animation and/or drivers linking posebones to base-armature used to
@@ -324,13 +316,7 @@ void DepsgraphNodeBuilder::build_proxy_rig(Object *object)
 {
 	bArmature *arm = (bArmature *)object->data;
 	OperationDepsNode *op_node;
-	Object *object_cow;
-	if (DEG_depsgraph_use_copy_on_write()) {
-		object_cow = get_cow_datablock(object);
-	}
-	else {
-		object_cow = object;
-	}
+	Object *object_cow = get_cow_datablock(object);
 	/* Sanity check. */
 	BLI_assert(object->pose != NULL);
 	/* Animation. */
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes_view_layer.cc b/source/blender/depsgraph/intern/builder/deg_builder_nodes_view_layer.cc
index fd4b975e53f..3fc97ee3fcf 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes_view_layer.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes_view_layer.cc
@@ -96,13 +96,7 @@ void DepsgraphNodeBuilder::build_view_layer(
 	scene_ = scene;
 	view_layer_ = view_layer;
 	/* Get pointer to a CoW version of scene ID. */
-	Scene *scene_cow;
-	if (DEG_depsgraph_use_copy_on_write()) {
-		scene_cow = get_cow_datablock(scene);
-	}
-	else {
-		scene_cow = scene;
-	}
+	Scene *scene_cow = get_cow_datablock(scene);
 	/* Scene objects. */
 	int select_color = 1;
 	/* NOTE: Base is used for function bindings as-is, so need to pass CoW base,
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
index c4be03eee8c..a422de5b9a4 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
@@ -1028,14 +1028,12 @@ void DepsgraphRelationBuilder::build_animdata_curves_targets(
 		/* It is possible that animation is writing to a nested ID datablock,
 		 * need to make sure animation is evaluated after target ID is copied.
 		 */
-		if (DEG_depsgraph_use_copy_on_write()) {
-			const IDDepsNode *id_node_from = operation_from->owner->owner;
-			const IDDepsNode *id_node_to = operation_to->owner->owner;
-			if (id_node_from != id_node_to) {
-				ComponentKey cow_key(id_node_to->id_orig,
-				                     DEG_NODE_TYPE_COPY_ON_WRITE);
-				add_relation(cow_key, adt_key, "Target CoW -> Animation", true);
-			}
+		const IDDepsNode *id_node_from = operation_from->owner->owner;
+		const IDDepsNode *id_node_to = operation_to->owner->owner;
+		if (id_node_from != id_node_to) {
+			ComponentKey cow_key(id_node_to->id_orig,
+			                     DEG_NODE_TYPE_COPY_ON_WRITE);
+			add_relation(cow_key, adt_key, "Target CoW -> Animation", true);
 		}
 	}
 }
@@ -1209,7 +1207,7 @@ void DepsgraphRelationBuilder::build_driver_data(ID *id, FCurve *fcu)
 		 * datablock, which means driver execution should wait for that
 		 * datablock to be copied.
 		 */
-		if (DEG_depsgraph_use_copy_on_write()) {
+		{
 			PointerRNA id_ptr;
 			PointerRNA ptr;
 			RNA_id_pointer_create(id, &id_ptr);
@@ -1886,18 +1884,16 @@ void DepsgraphRelationBuilder::build_lamp(Object *object)
 		build_nested_nodetree(&lamp->id, lamp->nodetree);
 	}
 
-	if (DEG_depsgraph_use_copy_on_write()) {
-		/* Make sure copy on write of lamp data is always properly updated for
-		 * visible lamps.
-		 */
-		OperationKey ob_copy_on_write_key(&object->id,
-		                                  DEG_NODE_TYPE_COPY_ON_WRITE,
-		                                  DEG_OPCODE_COPY_ON_WRITE);
-		OperationKey lamp_copy_on_write_key(&lamp->id,
-		                                    DEG_NODE_TYPE_COPY_ON_WRITE,
-		                                    DEG_OPCODE_COPY_ON_WRITE);
-		add_relation(lamp_copy_on_write_key, ob_copy_on_write_key, "Eval Order");
-	}
+	/* Make sure copy on write of lamp data is always properly updated for
+	 * visible lamps.
+	 */
+	OperationKey ob_copy_on_write_key(&object->id,
+	                                  DEG_NODE_TYPE_COPY_ON_WRITE,
+	                                  DEG_OPCODE_COPY_ON_WRITE);
+	OperationKey lamp_copy_on_write_key(&lamp->id,
+	                                    DEG_NODE_TYPE_COPY_ON_WRITE,
+	                                    DEG_OPCODE_COPY_ON_WRITE);
+	add_relation(lamp_copy_on_write_key, ob_copy_on_write_key, "Eval Order");
 }
 
 void DepsgraphRelationBuilder::build_nodetree(bNodeTree *ntree)
@@ -2085,9 +2081,6 @@ void DepsgraphRelationBuilder::build_copy_on_write_relations()
  */
 void DepsgraphRelationBuilder::build_nested_datablock(ID *owner, ID *id)
 {
-	if (!DEG_depsgraph_use_copy_on_write()) {
-		return;
-	}
 	OperationKey owner_copy_on_write_key(owner,
 	                                     DEG_NODE_TYPE_COPY_ON_WRITE,
 	                                     DEG_OPCODE_COPY_ON_WRITE);
diff --git a/source/blender/depsgraph/intern/depsgraph.cc b/source/blender/depsgraph/intern/depsgraph.cc
index 32cbee7597c..a247b458cc7 100644
--- a/source/blender/depsgraph/intern/depsgraph.cc
+++ b/source/blender/depsgraph/intern/depsgraph.cc
@@ -70,18 +70,6 @@ extern "C" {
 #include "intern/depsgraph_intern.h"
 #include "util/deg_util_foreach.h"
 
-static bool use_copy_on_write = true;
-
-bool DEG_depsgraph_use_copy_on_write(void)
-{
-	return use_copy_on_write;
-}
-
-void DEG_depsgraph_disable_copy_on_write(void)
-{
-	use_copy_on_write = false;
-}
-
 namespace DEG {
 
 static DEG_EditorUpdateIDCb deg_editor_update_id_cb = NULL;
@@ -340,7 +328,7 @@ IDDepsNode *Depsgraph::add_id_node(ID *id, ID *id_cow_hint)
 void Depsgraph::clear_id_nodes()
 {
 	/* Free memory used by ID nodes. */
-	if (use_copy_on_write) {
+	{
 		/* Stupid workaround to ensure we free IDs in a proper order. */
 		foreach (IDDepsNode *id_node, id_nodes) {
 			if (id_node->id_cow == NULL) {
diff --git a/source/blender/depsgraph/intern/depsgraph_build.cc b/source/blender/depsgraph/intern/depsgraph_build.cc
index 84b9bad17c9..c39f6222a13 100644
--- a/source/blender/depsgraph/intern/depsgraph_build.cc
+++ b/source/blender/depsgraph/intern/depsgraph_build.cc
@@ -231,9 +231,7 @@ void DEG_graph_build_from_view_layer(Depsgraph *graph,
 	DEG::DepsgraphRelationBuilder relation_builder(bmain, deg_graph);
 	relation_builder.begin_build();
 	relation_builder.build_view_layer(scene, view_layer);
-	if (DEG_depsgraph_use_copy_on_write()) {
-		relation_builder.build_copy_on_write_relations();
-	}
+	relation_builder.build_copy_on_write_relations();
 
 	/* Detect and solve cycles. */
 	DEG::deg_graph_detect_cycles(deg_graph);
diff --git a/source/blender/depsgraph/intern/depsgraph_tag.cc b/source/blender/depsgraph/intern/depsgraph_tag.cc
index 8e63bc85499..e22dc331605 100644
--- a/source/blender/depsgraph/intern/depsgraph_tag.cc
+++ b/source/blender/depsgraph/intern/depsgraph_tag.cc
@@ -284,7 +284,7 @@ void depsgraph_tag_component(Depsgraph *graph,
 		}
 	}
 	/* If component depends on copy-on-write, tag it as well. */
-	if (DEG_depsgraph_use_copy_on_write() && component_node->depends_on_cow()) {
+	if (component_node->depends_on_cow()) {
 		ComponentDepsNode *cow_comp =
 		        id_node->find_component(DEG_NODE_TYPE_COPY_ON_WRITE);
 		cow_comp->tag_update(graph);
diff --git a/source/blender/depsgraph/intern/eval/deg_eval.cc b/source/blender/depsgraph/intern/eval/deg_eval.cc
index 95084717dad..f911383b273 100644
--- a/source/blender/depsgraph/intern/eval/deg_eval.cc
+++ b/source/blender/depsgraph/intern/eval/deg_eval.cc
@@ -228,9 +228,6 @@ static void depsgraph_ensure_view_layer(Depsgraph *graph)
 	 * - It was tagged for update of CoW component.
 	 * This allows us to have proper view layer pointer.
 	 */
-	if (!DEG_depsgraph_use_copy_on_write()) {
-		return;
-	}
 	Scene *scene_cow = graph->scene_cow;
 	if (!deg_copy_on_write_is_expanded(&scene_cow->id) ||
 	     scene_cow->id.recalc & ID_RECALC_COPY_ON_WRITE)
diff --git a/source/blender/depsgraph/intern/nodes/deg_node_id.cc b/source/blender/depsgraph/intern/nodes/deg_node_id.cc
index 9f161db73ad..956c23978ab 100644
--- a/source/blender/depsgraph/intern/nodes/deg_node_id.cc
+++ b/source/blender/depsgraph/intern/nodes/deg_node_id.cc
@@ -112,14 +112,6 @@ void IDDepsNode::init(const ID *id, const char *UNUSED(subdata))
 
 void IDDepsNode::init_copy_on_write(ID *id_cow_hint)
 {
-	/* Early output for non-copy-on-write case: we keep CoW pointer same as
-	 * an original one.
-	 */
-	if (!DEG_depsgraph_use_copy_on_write()) {
-		UNUSED_VARS(id_cow_hint);
-		id_cow = id_orig;
-		return;
-	}
 	/* Create pointer as early as possible, so we can use it for function
 	 * bindings. Rest of data we'll be copying to the new datablock when
 	 * it is actually needed.
diff --git a/source/creator/creator_args.c b/source/creator/creator_args.c
index 95565b034e9..6973f500f84 100644
--- a/source/creator/creator_args.c
+++ b/source/creator/creator_args.c
@@ -586,9 +586,8 @@ static int arg_handle_print_help(int UNUSED(argc), const char **UNUSED(argv), vo
 
 	BLI_argsPrintArgDoc(ba, "--");
 
-	printf("\n");
-	printf("Experimental Features:\n");
-	BLI_argsPrintArgDoc(ba, "--disable-copy-on-write");
+	//printf("\n");
+	//printf("Experimental Features:\n");
 
 	/* Other options _must_ be last (anything not handled will show here) */
 	printf("\n");
@@ -1289,16 +1288,6 @@ static int arg_handle_threads_set(int argc, const char **argv, void *UNUSED(data
 	}
 }
 
-static const char arg_handle_use_copy_on_write_doc[] =
-"\n\tUse new dependency graph"
-;
-static int arg_handle_use_copy_on_write(int UNUSED(argc), const char **UNUSED(argv), void *UNUSED(data))
-{
-	printf("Disabling copy on write. Only use for testing whether something else is at fault\n");
-	DEG_depsgraph_disable_copy_on_write();
-	return 0;
-}
-
 static const char arg_handle_verbosity_set_doc[] =
 "<verbose>\n"
 "\tSet logging verbosity level."
@@ -1896,8 +1885,6 @@ void main_args_setup(bContext *C, bArgs *ba)
 	BLI_argsAdd(ba, 1, NULL, "--debug-gpu-shaders",
 	            CB_EX(arg_handle_debug_mode_generic_set, gpumem), (void *)G_DEBUG_GPU_SHADERS);
 
-	BLI_argsAdd(ba, 1, NULL, "--disable-copy-on-write", CB(arg_handle_use_copy_on_write), NULL);
-
 	BLI_argsAdd(ba, 1, NULL, "--verbose", CB(arg_handle_verbosity_set), NULL);
 
 	BLI_argsAdd(ba, 1, NULL, "--factory-startup", CB(arg_handle_factory_startup_set), NULL);