russell@unturf.com
fdbb9a1aa9
All 12 O(N²) algorithmic complexity defects confirmed in Redot Engine 26.2-alpha (commit 360a8d3). Inherited verbatim from Godot Engine upstream. All patched. Defects span: scene group membership, 2D/3D physics area lookup, soft body bending constraints, A* decrease-key, skeleton child bones, GLTF extension tracking, font cyclic check, font RID traversal, graph layout ORDER/PRED macros, and spring bone collision dispatch. Most severe: redot-0001 fires every frame in dynamic scenes — 1,000× speedup at n=2,000 nodes. redot-0002/0003 fire 60Hz in physics-heavy games — 50×. Strategy: patch Redot first, Godot follows our lead.
58 lines
2.2 KiB
Diff
58 lines
2.2 KiB
Diff
# UNDF: UNDF-2026-000001231
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# CWE-407: Algorithmic Complexity — O(N²) → O(N) in SceneTree::add_to_group()
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#
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# Defect: E->value.nodes.has(p_node) is O(n) — Vector linear scan —
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# inside add_to_group(), which fires on every add_child() / enter_tree() event.
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# In large dynamic scenes with thousands of nodes in shared groups ("enemies",
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# "pickable", "save_data"), this fires every frame.
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# Total cost: O(N²) to add N nodes to a group. At n=2,000: ~2,000,000 comparisons.
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#
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# Fix: add HashSet<Node*> node_set shadow index to struct Group.
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# has()/insert()/erase() all O(1). Vector preserved for ordered iteration.
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# Total cost after: O(N). At n=2,000: ~2,000 comparisons.
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#
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# Complexity gate (unit/test-redot-0001-scene-tree-group.cpp):
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# k-scaling 5×: time ratio must be <17.5× (O(k) ≈5×, not O(k²) ≈25×)
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# Scale n=2,000 nodes: must complete in <2s
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# Speedup at n=2,000: 1,000×
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--- a/scene/main/scene_tree.h
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+++ b/scene/main/scene_tree.h
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@@ -123,6 +123,7 @@ class SceneTree : public MainLoop {
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struct Group {
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Vector<Node *> nodes;
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+ HashSet<Node *> node_set; // O(1) membership — shadow index for Vector
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bool changed = false;
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};
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--- a/scene/main/scene_tree.cpp
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+++ b/scene/main/scene_tree.cpp
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@@ -172,14 +172,16 @@ SceneTree::Group *SceneTree::add_to_group(const StringName &p_group, Node *p_node) {
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if (!E) {
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E = group_map.insert(p_group, Group());
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}
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- ERR_FAIL_COND_V_MSG(E->value.nodes.has(p_node), &E->value, "Already in group: " + p_group + ".");
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+ // FIX redot-0001: was nodes.has(p_node) — O(n) linear scan, CWE-407
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+ // nodes.has() uses Vector linear scan: O(n) per add_to_group call.
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+ // node_set provides O(1) lookup. Vector preserved for ordered iteration.
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+ ERR_FAIL_COND_V_MSG(E->value.node_set.has(p_node), &E->value, "Already in group: " + p_group + ".");
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E->value.nodes.push_back(p_node);
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+ E->value.node_set.insert(p_node);
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E->value.changed = true;
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return &E->value;
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}
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void SceneTree::remove_from_group(const StringName &p_group, Node *p_node) {
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_THREAD_SAFE_METHOD_
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HashMap<StringName, Group>::Iterator E = group_map.find(p_group);
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ERR_FAIL_COND(!E);
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E->value.nodes.erase(p_node);
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+ E->value.node_set.erase(p_node);
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if (E->value.nodes.is_empty()) {
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group_map.remove(E);
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}
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}
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