russell@unturf.com
5575f6cd9c
jitsi-meet-0003: av-moderation pendingAudio/Video/Desktop Array.find() dedup O(P^2) in large moderated meetings — 249.5x op-count at P=500, 138.5x measured at P=2000. Fix: Map<id, participant> for O(1) dedup. jitsi-meet-0004: visitors middleware delta Array.findIndex() per update O(U*V) in large broadcast events — 15x at V=5000 U=1000. Fix: Map-based apply-delta O(1) per join/leave. solvespace-0002: VRML export colours_present std::vector + find_if O(T*C) per triangle — 250x op-count at T=50k C=500. Fix: unordered_map keyed by ToPackedInt() RGBA uint32. MOAD-0002/0003/0004/0005: CLEAN for both targets. All 13 unit tests PASS.
62 lines
2.5 KiB
Markdown
62 lines
2.5 KiB
Markdown
# solvespace-0002 — MOAD-0001 CWE-407
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## Location
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`src/export.cpp`, `ExportWrlMeshes()` (VRML/WRL export), lines 1225-1240
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## Pattern
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O(T × C): During VRML mesh export, Solvespace builds a per-shape colour palette
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by iterating every triangle and scanning a `std::vector<RgbaColor>` to check
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whether our triangle's colour is already present:
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```cpp
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std::vector<int> triangle_colour_ids;
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std::vector<RgbaColor> colours_present;
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for(const auto & sp : op.second) { // outer: spans
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for(const auto & tr : sp) { // inner: triangles O(T)
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const auto colour_itr = std::find_if(
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colours_present.begin(), colours_present.end(),
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[&](const RgbaColor & c) {
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return c.Equals(tr.meta.color); // O(C) per triangle
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});
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if(colour_itr == colours_present.end()) {
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colours_present.insert(colours_present.end(), tr.meta.color);
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triangle_colour_ids.push_back(colours_present.size() - 1);
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} else {
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triangle_colour_ids.push_back(colour_itr - colours_present.begin());
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}
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}
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}
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```
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Each triangle triggers a full O(C) walk of `colours_present`. Total cost: O(T × C).
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## Severity
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MEDIUM-HIGH. A mechanical assembly export with:
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- T = 100,000 triangles (typical for a detailed 3D model)
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- C = 64 distinct colours (per-part colour coding is common)
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Results in 6,400,000 comparisons vs 100,000 with an `unordered_map`.
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`RgbaColor` is a packed `uint32_t` (four `uint8_t` fields: red, green, blue, alpha).
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Our hash map key is `color.ToPackedIntBGRA()` (already defined in our codebase).
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Fix is a single-line `unordered_map<uint32_t, int>` substitution. 64x overhead at
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typical export size.
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## Fix
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Replace `std::vector<RgbaColor> colours_present` with
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`std::unordered_map<uint32_t, int> colour_to_index`. Key: `tr.meta.color.ToPackedIntBGRA()`.
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Value: index into our VRML color array. Membership test becomes `colour_to_index.count(key)`
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(O(1)). The array output for VRML is built in insertion order from our map values.
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`ToPackedIntBGRA()` is already defined in `dsc.h` line 649 — no new infrastructure needed.
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## All 5 MOADs
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- MOAD-0001: CONFIRMED (this defect)
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- MOAD-0002: CLEAN (SS/SK globals are intentional single-user desktop CAD singletons; no coupling to new subsystems)
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- MOAD-0003: CLEAN (single-threaded tool; no request-scoped context leakage)
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- MOAD-0004: CLEAN (no network features; no credentials handled anywhere)
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- MOAD-0005: CLEAN (single-process, single-threaded; no concurrent cache access possible)
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