[victor-ab]

Releases the load-memory stack (#65, #66, #67, #68, #74, #75 and #69) as 3.3.0. It is a minor release: the stack adds native LightGBM text loading and the opt-in layout-file feature, and removes or changes nothing public. LoadError and ModelFormat are #[non_exhaustive], so their new variants are additive; a .txt path, which 3.2.2 rejected, now loads as LightGBM text; the MSRV stays 1.97.

• Version 3.3.0 in Cargo.toml, Cargo.lock and experiments/layout-file/Cargo.lock, which CI checks with --locked. The README's release commands name 3.3.0.

• The changelog's Unreleased section becomes 3.3.0. Its opening paragraph now compares with 3.2.2 rather than 3.2.1 and gives the whole stack's figures, from the PRs' published measurements:

  • the loaded model's heap 66% lower: 34% of 3.2.2's ([memory] layout: hold fixed leaf values in their leaf nodes #74);
  • the loading peak under half of 3.2.2's: about 45%, from [memory] layout file: save a built forest and load it validated, owned or mapped #69's peak against its loaded heap, with 3.2.2's peak at 2.4 times its loaded model ([memory] load, parse: a categorical model loads in under half the heap, and the loaded model keeps no category lists or spare capacity #65).

  It no longer says the layout is unchanged, since [memory] layout: exceptions take 6 bytes, with 16-bit feature-relative slots and a 32-bit fallback #67, [memory] layout: fixed-point leaf values take 8 bytes #68 and [memory] layout: hold fixed leaf values in their leaf nodes #74 changed how it is stored, and it drops "loads 30% faster": [memory] load, parse: a categorical model loads in under half the heap, and the loaded model keeps no category lists or spare capacity #65 measured 72% of 3.2.2's load time, and the whole stack's load time hasn't been measured against 3.2.2.

• The prediction entry gives [memory] layout: fill a categorical feature only when its code changes, in one copy when dense #66's measured ranges rather than 15 to 20%: about 8 to 12% less time per request on AVX-512 (the skip and the copy were measured separately there) and 14 to 19% on an Apple M4.

• cargo package --locked builds the packaged crate, and the packaged crate also builds with layout-file. The package ships every file under src/, so build.rs's build ID is the same as a checkout of the tag's.

After merging: a signed v3.3.0 tag, whose release workflow runs the release tests and creates the GitHub release; then a crates.io owner publishes from the tag, as the README describes.