perf: reduce snapshot read memory retention#985
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* fix: recover two per-op editing slowdowns regressed since 1.11 Both are constant-factor regressions on the per-op (auto-commit) editing path introduced by the lazy-snapshot work in #985, found while bisecting current HEAD against the 1.11.1 release. 1. map/list/movable-list insert: ensure_no_regular_container_value heap-allocated a Vec on every insert, even for scalar values (the common case). Add a scalar fast-path that skips the allocation and traversal. `map create 10^4 key`: ~19.4ms -> ~10.7ms. 2. text insert/delete: the per-op bounds-check len()/len_unicode()/ len_utf16() took two DocState locks (decoded-check, then query). Consolidate into one DocState::get_text_len taking a single lock + container-store lookup, preserving the lazy-snapshot memory behavior (a still-lazy container reads cached length metadata without materializing the richtext state). `bench_text B4 apply`: ~389ms -> ~352ms. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * chore: sync Cargo.lock with loro-wasm 1.13.4 version bump Lockfile update to match the crates/loro-wasm Cargo.toml version bump that landed via the main merge (chore: version packages). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * fix: read cached byte length for PosType::Bytes text len Addresses a review finding on the per-op text length consolidation: the PosType::Bytes branch of DocState::get_text_len built the full plain string via get_value_by_idx().as_string().len(), so insert_utf8/delete_utf8 bounds checks on an already-decoded text became O(text length) per op (the old code read cached byte-length metadata in the decoded case). Add a text_utf8_len store helper mirroring text_unicode_len/text_utf16_len: - decoded state reads the O(1) cached byte length (RichtextState::len_utf8 = root_cache().bytes) - a still-lazy container reads the byte length from the already-materialized text value string (O(1) str::len), preserving the no-force-decode behavior Also route the public TextHandler::len_utf8 through the same single-lock helper; it had the same has_decoded_state double-lock + string-construction pattern. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This was referenced Jun 17, 2026
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Summary
toJSONandloro-mirrorstyle reads.Measurements
Using the 32 MB fixture probe after exporting/importing a snapshot:
toJSON()then dropping JSON: 41.81 MB -> 25.58 MBTradeoff: repeated full read-only traversals decode again instead of reusing retained decoded values. Current release probe timings were roughly
toJSON72 ms, mirror shallow 79/59 ms, and mirror schema root 143/131 ms.Validation
cargo check -p loro-internalcargo test -p loro-internal handler --libcargo test -p loro-internal map --libcargo test -p loro-internal list --libcargo test -p loro-internal snapshot --libcargo test -p loro-internal richtext --libgit diff --check