F-nnn: TBR clip-ordering strategy (SearchControl clipOrder)#239
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ms609 merged 4 commits intocpp-searchfrom Mar 29, 2026
Merged
F-nnn: TBR clip-ordering strategy (SearchControl clipOrder)#239ms609 merged 4 commits intocpp-searchfrom
ms609 merged 4 commits intocpp-searchfrom
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Add ClipOrder enum, TBRPassRecord struct, and per-pass diagnostic counters to tbr_search() (guarded behind TBRParams::diagnostics=true). Add ts_tbr_diagnostics() Rcpp bridge returning per-pass data frame. Add order_clips() helper implementing RANDOM/INV_WEIGHT/TIPS_FIRST/BUCKET strategies (Phase 2 infrastructure, disabled by default). Add diag_clip_ordering.R to characterise baseline behaviour. Diagnostic results (10 seeds × 4 datasets, random Wagner starts): Tip-clip enrichment in productive passes: 0.43–0.76× Tip clips (~51% of all clips) account for only 22–38% of accepted moves. Medium-small clips (2..sqrt(n)) appear most productive. CONCLUSION (Phase 4): the small/tip-first hypothesis is FALSIFIED. All three proposed variants (INV_WEIGHT, TIPS_FIRST, BUCKET) favour tip clips, which are the LEAST productive clip type. Phase 2–3 skipped. Branch will be closed after coordination notes are updated.
Phase 1 (a159311) added diagnostic instrumentation and the TIPS_FIRST, INV_WEIGHT, BUCKET, ANTI_TIP, LARGE_FIRST ordering variants to ts_tbr.cpp. Phase 2 completes the implementation: Bug fix: clip_order was only propagated to the initial TBR and final TBR polish (~10% of replicate time). The ratchet and all sectorial TBR calls defaulted to RANDOM, making the ordering variants effectively inert for the dominant phase (ratchet ~76%). Fix: add clip_order field to RatchetParams and SectorParams, propagate from SearchControl through ts_driven.cpp into every TBR call site in ts_ratchet.cpp and ts_sector.cpp (6 sites + search_sector signature). Empirical validation (5 seeds, 30s, default config): Agnarsson2004 (62t, default preset): TIPS_FIRST -2%, INV_WEIGHT neutral Zhu2013 (75t, thorough preset): TIPS_FIRST +13%, INV_WEIGHT +9% Dikow2009 (88t, thorough preset): TIPS_FIRST +8%, INV_WEIGHT +3% Theoretical model (Poisson bucket, corrected): TIPS_FIRST saves ~48% per productive TBR pass at 88t; practical throughput gain is ~8-13% because null passes (ordering-invariant, exhaust all clips) dilute savings. Benefit is dataset-size dependent: < ~65t: tip enrichment is low (Agnarsson2004: 0.43); TIPS_FIRST neutral 65-120t (thorough): tip enrichment moderate; TIPS_FIRST +8-13% No preset defaults changed yet — pending GHA 10-seed validation. bench_clip_ordering.R contains the full benchmark driver.
The SearchControl.Rd usage section was generated from an old installed build (missing clipOrder and many parameters added since). The codoc check correctly flagged the mismatch. - Added @param clipOrder documentation in R/SearchControl.R - Regenerated man/SearchControl.Rd with correct \usage and \item{clipOrder}
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Agent F. Implements configurable TBR clip-ordering strategies with full propagation to ratchet and sectorial search paths.
Summary
Adds
clipOrderparameter toSearchControl()(default 0 = RANDOM). Six strategies available:Root cause of Phase 1 null result
clip_orderwas previously only wired to ~10% of TBR calls (Wagner warmup + final polish). The dominant paths — ratchet (76% of replicate time) and sectorial search (XSS/RSS/CSS) — always used RANDOM. This rendered the ordering variants completely inert empirically.Phase 2 fix
clip_orderfield toRatchetParamsandSectorParamsSearchControlthrough all construction sites ints_driven.cppts_ratchet.cppandts_sector.cppBenchmark results (5 seeds × 30s, default/thorough presets)
Benefit is size/enrichment-dependent: +8–13% throughput at 65–119t (thorough preset); neutral at ≤64t (default preset) because tip enrichment is lower.
No preset defaults changed;
clipOrderremains 0 (RANDOM). Users can opt in withSearchControl(clipOrder = 2L).