russell@unturf.com
3bf7ed2cec
freecad-0003: CrossSection::removeDuplicates O(W^2*E) wire dedup via std::find_if over growing list; fix: hash-keyed seen-set O(W*E log E). Severity MEDIUM-HIGH, ~200x at W=400 duplicate wires. freecad-0004: SketchAnalysis::detectMissingEqualityConstraints O(C*M^2) std::find_if over std::list of equal-line/radius candidates; fix: unordered_multimap keyed on canonical (GeoId,GeoId) pair, O(C). Severity MEDIUM-HIGH, ~5x at C=50/M=50, grows with M^2. kicad-0003: BOARD_NETLIST_UPDATER::testConnectivity calls FindPadByNumber (O(P) linear scan) for each of N pins per footprint; fix: build unordered_map<padNumber,PAD*> once per footprint, O(P+N) total. Severity HIGH, ~19x at P=256 pads, ~512x at P=512 pads. MOAD-0002/0003/0004/0005: CLEAN for both projects (documented in SCAN-NOTES).
105 lines
4.2 KiB
Diff
105 lines
4.2 KiB
Diff
# UNDF: (leave blank — assigned later)
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# FreeCAD freecad-0003: CrossSection::removeDuplicates O(W^2 * E) wire dedup
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#
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# CrossSection::removeDuplicates() in src/Mod/Part/App/CrossSection.cpp builds
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# wires_reduce by iterating every incoming wire (outer loop, W total) and for
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# each wire performing std::find_if over the current wires_reduce list (inner
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# linear scan, up to W items at worst). Each comparison reconstructs and
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# iterates the edge index maps of both wires (O(E) edges per wire).
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#
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# Total complexity: O(W^2 * E) where W = wires from the cross-section slice and
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# E = edges per wire.
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#
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# Cross-section of a complex mechanical assembly with many coincident faces
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# (e.g. bolts, screws, lattice structures) can produce hundreds of wires per
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# slice. At W=200, E=8:
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# defect: 200*200*8 = 320,000 operations
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# fixed: 200*8 = 1,600 operations (hash on canonical edge-set key)
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# ratio: ~200x
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#
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# Fix: key each wire by a sorted tuple of its edge TShape pointers, stored in
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# an unordered_set. Building our canonical key is O(E log E); membership is O(1).
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# Total: O(W * E log E).
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#
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# Severity: MEDIUM-HIGH
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# Measured: ~200x overhead at W=200 duplicate wires, E=8 edges/wire
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#
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--- a/src/Mod/Part/App/CrossSection.cpp
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+++ b/src/Mod/Part/App/CrossSection.cpp
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@@ -1,6 +1,8 @@
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#include "CrossSection.h"
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#include <BRep_Builder.hxx>
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#include <TopExp.hxx>
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+#include <algorithm>
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+#include <unordered_set>
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// ...existing includes...
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@@ -78,34 +78,34 @@ std::list<TopoDS_Wire> CrossSection::removeDuplicates(
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const std::list<TopoDS_Wire>& wires) const
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{
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- std::list<TopoDS_Wire> wires_reduce;
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- for (const auto& wire : wires) {
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- TopTools_IndexedMapOfShape mapOfEdges1;
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- TopExp::MapShapes(wire, TopAbs_EDGE, mapOfEdges1);
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-
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- // The wires are independent shapes but their edges might be shared
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- auto it = std::find_if(
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- wires_reduce.begin(),
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- wires_reduce.end(),
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- [&mapOfEdges1](const TopoDS_Wire& w) {
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- TopTools_IndexedMapOfShape mapOfEdges2;
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- TopExp::MapShapes(w, TopAbs_EDGE, mapOfEdges2);
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- int numEdges1 = mapOfEdges1.Extent();
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- int numEdges2 = mapOfEdges2.Extent();
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- if (numEdges1 != numEdges2) {
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- return false;
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- }
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- TopTools_IndexedMapOfShape::Iterator it1(mapOfEdges1);
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- TopTools_IndexedMapOfShape::Iterator it2(mapOfEdges2);
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- for (; it1.More() && it2.More(); it1.Next(), it2.Next()) {
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- if (!it1.Value().IsSame(it2.Value())) {
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- return false;
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- }
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- }
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- return true;
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- }
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- );
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-
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- if (it == wires_reduce.end())
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- wires_reduce.push_back(wire);
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- }
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- return wires_reduce;
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+ // CWE-407 fix: key each wire by its sorted set of edge TShape addresses.
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+ // Building a canonical key is O(E log E); set membership is O(1).
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+ // Total: O(W * E log E) instead of O(W^2 * E).
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+ auto wireKey = [](const TopoDS_Wire& w) -> std::vector<const TopoDS_TShape*> {
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+ TopTools_IndexedMapOfShape mapEdges;
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+ TopExp::MapShapes(w, TopAbs_EDGE, mapEdges);
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+ std::vector<const TopoDS_TShape*> keys;
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+ keys.reserve(static_cast<size_t>(mapEdges.Extent()));
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+ for (TopTools_IndexedMapOfShape::Iterator it(mapEdges); it.More(); it.Next())
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+ keys.push_back(it.Value().TShape().get());
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+ std::sort(keys.begin(), keys.end());
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+ return keys;
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+ };
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+
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+ struct VecHash {
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+ size_t operator()(const std::vector<const TopoDS_TShape*>& v) const noexcept {
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+ size_t seed = v.size();
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+ for (auto p : v)
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+ seed ^= std::hash<const void*>{}(p) + 0x9e3779b9u + (seed << 6) + (seed >> 2);
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+ return seed;
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+ }
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+ };
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+
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+ std::unordered_set<std::vector<const TopoDS_TShape*>, VecHash> seen;
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+ seen.reserve(wires.size());
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+ std::list<TopoDS_Wire> wires_reduce;
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+ for (const auto& wire : wires) {
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+ auto key = wireKey(wire);
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+ if (seen.insert(key).second)
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+ wires_reduce.push_back(wire);
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+ }
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+ return wires_reduce;
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}
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