v0.4.1 — performance recovery

Recovers the Get (hit) and Delete (bulk) regressions flagged in v0.4.0. Single-file refactor of put.go / delete.go / helpers.go; public API unchanged; Len remains O(1).

Performance

median of 5 reps, -benchtime=3s -count=5, VirtualApple @ 2.50 GHz, Go 1.24.2

Operation	v0.4.0	v0.4.1	Δ
Get (hit)	57.57 ns/op	44.81 ns/op	fully recovered to pre-generics baseline (43.22 ns/op)
Delete (bulk)	124.5 ns/key	115.3 ns/key	−9 ns/key (~7 %); residual ~45 ns/key gap vs pre-generics (70.0 ns/key) tracked for follow-up

ART is now ~21× faster than google/btree on Get (hit), up from 15× at v0.4.0.

What changed

• Tree.size is now tracked at the insertLeaf / clearTerminalIfMatches chokepoints instead of being propagated through recursive return tuples. Parent frames detect no-op by pointer equality on the returned subtree. putInto / putIntoNodeN / deleteFrom revert to single-return-value signatures.
• The Get recovery is a code-layout / register-pressure side effect of the put/delete refactor — no change to get.go.

Documented

• benchmarks.md re-baselined at commit d14c9c6. Regression annotations removed / adjusted.
• CHANGELOG.md backfilled with entries for v0.3.0, v0.4.0, v0.4.1.

Install

go get github.com/KentBeck/AdaptiveRadixTree2@v0.4.1

Compare: v0.4.0...v0.4.1