Dejan PortandClaude Sonnet 5 43a118c543 perf: fill-handle double-click scans a dense neighbour column ~2.4x faster ...

Follow-up to #210, which the reviewer correctly rejected: the stated
cause (a sparse column with a stray distant value) doesn't hold, since
the scan already stops at the first empty cell. This is a different,
narrower fix that doesn't change behaviour for any input — it never
truncates a long fill, unlike #210's cap — only how fast a genuinely
long, densely-populated run is scanned.

grid.rs's fill-handle double-click called Sheet::value_ref once per
row to find where the neighbouring column's data ends. Each call does
a band lookup + row lookup + column lookup (three BTreeMap probes) via
CellStore::get. For a real dense run (e.g. a filled column near the
1,048,576-row sheet limit) that's a lot of point lookups on the UI
thread in one frame: ~59ms for a 1,000,000-row run in a release build
(measured with the new fill_handle_perf example), likely worse under
wasm where GridCraft actually runs in the browser.

- crates/model/src/store.rs: CellStore::contiguous_value_run walks
  each band's row BTreeMap with `range` (one in-order pass per band)
  instead of one `get` per row, so a dense run costs roughly one
  tree-traversal step per row instead of one binary search per row.
  Deliberately narrower than `has`/`get`: a stored cell always decides
  the row on its own (even with an empty value), matching what
  `value_ref`'s callers actually test for, not `has`'s "formula counts
  regardless of its cached value" (used for Ctrl+arrow navigation).
- crates/model/src/sheet.rs: Sheet::last_contiguous_nonempty layers
  `spill` back in wherever contiguous_value_run finds no stored cell,
  exactly where plain `value_ref` would fall through to it.
- crates/ui-egui/src/grid.rs: the fill-handle double-click now calls
  this once instead of looping over value_ref.

Result: 999,999-row dense run, 59.2ms -> 24.7ms (2.40x), same answer
(asserted in the example). Four new tests in sheet.rs, including a
300-trial property test against a naive value_ref-loop reference
(spills, formula-with-empty-value, gaps, blanks) — all pass, plus the
full existing suite (`cargo test -p gridcraft-model -p gridcraft-ui-egui
-p gridcraft-engine`; the only failures are #210-era gridcraft-engine
CSV tests already failing on main, unrelated to this change).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

2026-10-12 02:01:49 +02:00

..

fill_handle_perf.rs

perf: fill-handle double-click scans a dense neighbour column ~2.4x faster

2026-10-12 02:01:49 +02:00

perf.rs

Web app: committing a cell no longer traps on the clock

2026-10-10 09:03:33 +02:00