thumb_request_bench measures UI-thread time and allocations for grid
thumbnail requests (with and without pending work), using the same counting
allocator as the other bench examples. REAL_PHOTOS=1 samples up to four
photos from PHOTO_ROOT, which must now be set explicitly; the original
defaulted to a local photo library path.
Split from a327b98 (T0 thumbnail work).
Co-authored-by: Codex <noreply@openai.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
An unchanged grid frame used to copy every visible id, hash them twice
(date-run and layout cache keys), clone the date runs, build a full
Vec<Cell>, rebuild the stack index, loop over every cell for the
viewport test and, in Local folder views, look up every photo to count
the browsed ones for "Add N to My Photos".
- engine: Session keeps the visible list as Arc<[PhotoId]> with a
process-unique generation that changes whenever the list is
recomputed; `visible_shared()` hands both out without copying.
- grid: date runs, layout, stack index and the Local count are cached
by that generation (GridCache; replaces the id-hashing date_runs and
grid_layout caches). The layout gains a row index (GridRow), so the
visible + prefetch rows and the date headers are found by binary
search; the sticky header too.
- GridStats counters (frames, cells visited, view/layout/stack-index
builds, last frame time) for the bench and tests.
Measured with the new `cargo run --release -p lightcraft-ui-egui
--example grid_bench` (synthetic library, 1400x900, thumbs 160, missing
files so no decoding is timed, scrolled to the middle, 120 unchanged
frames; machine at load ~200-250, so medians of the whole app frame,
before/after interleaved in the same session):
photos layout source median frame ms allocs/frame cells visited
before -> after before -> after before -> after
200 photo all 1.29 -> 1.28 4747 -> 4729 200 -> 93
200 square all 1.09 -> 1.09 4771 -> 4753 200 -> 74
10 000 photo all 1.52 -> 1.41 5425 -> 4911 10000 -> 100
10 000 photo local 1.90 -> 1.42 5475 -> 4948 10000 -> 100
10 000 square local 1.62 -> 1.07 5365 -> 4838 10000 -> 76
85 000 photo all 2.41 -> 1.29 8996 -> 4729 85000 -> 93
85 000 square all 2.29 -> 1.08 9020 -> 4753 85000 -> 74
85 000 photo local 17.6-34.0 -> 1.32 9049 -> 4766 85000 -> 93
85 000 square local 16.2-25.0 -> 1.10 9073 -> 4790 85000 -> 74
Frame cost no longer depends on the number of results; what is left
(~1 ms, ~4.7k allocs) is drawing the ~75-100 cells near the screen.
Headless snapshots of the demo grid (justified with a sticky header,
after keyboard navigation, square) are byte-identical before/after.
Tests: layout rows cover every cell in order and the binary search
matches a linear scan (square + justified, groups); a 3000-photo
headless library checks that unchanged frames build nothing and visit
< 300 cells, plus date headers, scroll-to-selection, stack badges,
keyboard navigation and a rotation re-laying the grid.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
radialmonster
Brandon Thomas