Depsgraph: Avoid having per-node lock when scheduling children

Use atomic operations instead, should in theory improve timing of
scheduling. However, probably not so visible yet because actual
task scheduling still have some locks and memory allocations.

Baby steps, what would i say.

1 files changed, 2 insertions, 6 deletions

diff --git a/source/blender/depsgraph/intern/depsgraph_eval.cc b/source/blender/depsgraph/intern/depsgraph_eval.cc
index fb6722cc893..15c8b1a9dd3 100644
--- a/source/blender/depsgraph/intern/depsgraph_eval.cc
+++ b/source/blender/depsgraph/intern/depsgraph_eval.cc
@@ -248,12 +248,8 @@ static void schedule_node(TaskPool *pool, Depsgraph *graph, int layers,
 		}
 
 		if (node->num_links_pending == 0) {
-			BLI_spin_lock(&graph->lock);
-			bool need_schedule = !node->scheduled;
-			node->scheduled = true;
-			BLI_spin_unlock(&graph->lock);
-
-			if (need_schedule) {
+			bool is_scheduled = atomic_fetch_and_or_uint8((uint8_t*)&node->scheduled, (uint8_t)true);
+			if (!is_scheduled) {
 				if (node->is_noop()) {
 					/* skip NOOP node, schedule children right away */
 					schedule_children(pool, graph, node, layers);