NetterSilverandClaude Opus 5.5 393a524aa3 Speed up XLSX worksheet writing ...

Saving a large workbook spent about half its time building worksheet XML,
mostly in small per-cell allocations. The writer now appends to the part
directly:

- Cell references, row numbers, style ids, shared string indexes and
  numbers are appended without temporary strings (push_a1, push_u64,
  push_num), and text is escaped in place (push_esc, with a fast path for
  plain ASCII).
- sheetData walks the cell store in its own row-major order instead of
  copying every address into a BTreeSet and a per-row BTreeMap and looking
  each cell up again. Cells outside the store (pictures, spill values,
  table headers) still go through the sorted set.
- Formulas with nothing the file spells differently (no LET/LAMBDA, no
  _xlfn function, no spill, @, trim operator or structured reference) are
  printed from the shared expression instead of being cloned and rebuilt
  twice by the file rewrite.
- The A1 printer in gridcraft-formula appends references to the output
  instead of formatting each anchor into its own string.

The output is byte-for-byte unchanged.

write_perf, 200,000 rows (2.0M cells, 14.2 MB package), release, Ryzen
16 threads / Linux, 36 interleaved runs each:
  before: median 2083.9 ms, min 1615.7 ms
  after:  median 1501.3 ms, min 1192.3 ms  (-28.0 % median, -26.2 % min)

What remains is mostly deflate (zlib-rs, level 6), about 70 % of the save.

Tests pin the exact sheetData of a workbook covering row settings between
cell rows, spill values, every value kind, number spellings, escaping and
formulas with and without a file spelling (generated with the previous
writer), and check each appending helper and the formula fast path against
the code they replace.

The formula fast path is guarded by a test that runs both paths over every
function in the gridcraft-functions registry (a new dev-dependency, allowed
by the layer rules), in 15 surrounding shapes covering every operator and
rewrite, so a function or rewrite added later without updating the trigger
list fails it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2026-10-27 16:46:25 +01:00

..

src

Speed up XLSX worksheet writing

2026-10-27 16:46:25 +01:00

tests/it

CI: one test binary per crate, nextest, line tables only (#2372)

2026-10-23 12:59:46 -04:00

Cargo.toml

Rename SheetCraft to GridCraft everywhere (crates, apps, bundle ids, packaging, docs)

2026-10-06 01:39:08 -04:00