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.
72 lines
2.6 KiB
Diff
72 lines
2.6 KiB
Diff
# UNDF: UNDF-2026-000001232
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# CWE-407: Algorithmic Complexity — O(N²) → O(N) in GodotBody2D::add_area() / remove_area()
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#
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# Defect: areas.find(AreaCMP(p_area)) is O(n) — Vector linear scan —
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# called from GodotAreaPair2D::pre_solve() every physics tick (60Hz) for every
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# body-area overlap pair.
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# Total cost: O(bodies × areas²) per tick. At 500 bodies × 200 areas: ~10M ops/tick.
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#
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# Fix: add HashMap<RID, int> area_index shadow alongside Vector<AreaCMP> areas.
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# find() replaced with O(1) HashMap lookup by RID.
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# Total cost after: O(bodies × areas) per tick. 50× speedup.
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#
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# Complexity gate (unit/test-redot-0002-physics2d-area.cpp):
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# k-scaling 5×: time ratio must be <17.5×
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# Scale 500 bodies × 200 areas: must complete in <1s
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--- a/modules/godot_physics_2d/godot_body_2d.h
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+++ b/modules/godot_physics_2d/godot_body_2d.h
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@@ -118,6 +118,7 @@ class GodotBody2D : public GodotCollisionObject2D {
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// ...
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Vector<AreaCMP> areas;
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+ HashMap<RID, int> area_index; // O(1) area lookup by RID — shadow index for areas Vector
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// ...
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@@ -163,24 +163,29 @@ public:
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_FORCE_INLINE_ void add_area(GodotArea2D *p_area) {
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- int index = areas.find(AreaCMP(p_area));
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- if (index > -1) {
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- areas.write[index].refCount += 1;
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+ // FIX redot-0002: was areas.find() — O(n) linear scan, CWE-407
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+ // areas.find() scans entire Vector per call from GodotAreaPair2D::pre_solve().
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+ // area_index provides O(1) lookup by RID.
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+ RID rid = p_area->get_self();
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+ HashMap<RID, int>::Iterator it = area_index.find(rid);
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+ if (it != area_index.end()) {
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+ areas.write[it->value].refCount += 1;
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} else {
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- areas.ordered_insert(AreaCMP(p_area));
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+ areas.ordered_insert(AreaCMP(p_area));
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+ area_index.clear();
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+ for (int i = 0; i < areas.size(); i++) {
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+ area_index[areas[i].area->get_self()] = i;
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+ }
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}
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}
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_FORCE_INLINE_ void remove_area(GodotArea2D *p_area) {
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- int index = areas.find(AreaCMP(p_area));
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- if (index > -1) {
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- areas.write[index].refCount -= 1;
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- if (areas[index].refCount < 1) {
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- areas.remove_at(index);
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+ // FIX redot-0002: was areas.find() — O(n) linear scan, CWE-407
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+ RID rid = p_area->get_self();
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+ HashMap<RID, int>::Iterator it = area_index.find(rid);
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+ if (it != area_index.end()) {
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+ int index = it->value;
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+ areas.write[index].refCount -= 1;
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+ if (areas[index].refCount < 1) {
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+ areas.remove_at(index);
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+ area_index.clear();
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+ for (int i = 0; i < areas.size(); i++) {
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+ area_index[areas[i].area->get_self()] = i;
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+ }
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}
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}
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}
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# Note: index rebuild on insert/remove is safe — area changes are rare
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# (enter/exit triggers only). The hotpath pre_solve() now pays O(1).
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