`library::local_original_count` feeds the "On this device" chip and runs
beside the rating counts on every star keystroke. On the reference library
it cost 1.3-1.4 ms best-of-50 (3 ms on a busy machine) to find 254
originals among 19,000 visible images.
It was a correlated EXISTS per visible image:
SCAN i USING INDEX images_grid_order
SEARCH ic EXISTS USING INTEGER PRIMARY KEY (rowid=?)
`image_cache` holds a row only for what has been fetched, so the question
is driven from it: `i.id IN (SELECT image_id FROM image_cache WHERE
tier_actual >= Original)`, which SQLite plans as the list first and a probe
of `images` by id for each entry:
SEARCH i USING INTEGER PRIMARY KEY (rowid=?)
LIST SUBQUERY 1
SCAN image_cache
`image_id` is the cache's primary key, so each image is in the list at most
once and the count is the one the EXISTS gave (254). After: 0.05 ms. On a
library whose every original is cached this is as much work as before,
which is the proportion the rule asks for.
The count stays on the keystroke path: dropping it there would leave the
chip stale after a background download until something else refreshed it,
and at this cost there is nothing left to save. catalog_bench spells the
query as dr-ui does, so its copy changes with it.
library.rs was 7,729 lines wiring together everything "open a remote
library" touches: scanning, pulling other devices' judgements out of
sidecars found along the way, writing local edits back out to the
sidecar outbox, pushing/reloading XMP by hand, fetching and prefetching
thumbnails and originals, generating thumbnails locally, the metadata
and thumbnail background sweeps, on-disk paths for the catalog and
model files, and reading the grid's cells, spans and rating filter.
Same motivation as the develop.rs split (docs/dev/code-health.md CH-1):
a pure, no-behaviour-change move into one file per area, each under
about 1,500 lines.
Tracing actual call sites rather than trusting the file's physical
layout mattered here: `persist`, `load_folder_etags`, `pull_sidecars`,
`load_sidecar_etags`, `record_sidecar_read` and `apply_judgement` sit
textually beside the XMP push/reload functions but are called only
from `run_scan` (pulling a device's own past judgements out of the
sidecars a scan just walked), so they went to scan.rs and not xmp.rs.
`cells` came out at over 1,800 lines once its tests moved with it and
split further into cells.rs (windowed reads, trash, ordinals) and
spans.rs (collection scope, manual reordering, the capture-time
histogram) -- ten submodules rather than the nine first planned.
Previously-private items reached from a sibling module became
`pub(super)`, narrower than the whole-crate reachability one file gave
them. Tests moved with the code they test; the two test fixtures used
across more than one file (`scanned`, and develop.rs's
`session_with_a_left_half_subject` in the matching commit) joined the
shared `test_support` module alongside the existing `entry`/
`with_images`/`image_ids` helpers. `mod.rs` re-exports every module's
public items under `library::`, including the `pub(crate)`
`test_support` module `repairs.rs` reads its fixtures from, so no file
outside `library` needed a change.
The previous commit split develop.rs the same way; taken alone it left
dr-ui without library.rs, so that intermediate commit does not build on
its own. This one restores it.
dtourolle