perf: round 18 — calendar-event in-place iCal edit, ResourceList incremental id-index
Two items from the ROUND17 deferred list, each benchmark-gated with a
BEFORE/AFTER equivalence gate and a rollback-on-regression check (ROUND2–17
discipline). See benches/ROUND18.md.
[C1] backend — CalendarEvent::update_ical_property / remove_ical_property
rewrote the ENTIRE ical_data body with format!("{}{}{}") on every call and
allocated two search needles per call. calendar_storage_adapter::update_event
fans a multi-field edit out into one call per changed field, so a full REST
edit paid one full-body (up to ~11 KB) allocation per property. The body is
now mutated in place (replace_range for an existing property, four insert/
insert_str for a new one, byte-identical spans) and the single "\nNAME:"
needle is built on the stack (the "\r\nNAME:" needle was redundant — the LF
form is its suffix). bench_round18_micro [C1]: 70 -> 2 allocs/op (68 fewer),
2.46x wall, emitted body byte-identical.
[F1] frontend — ResourceList itemIndexById rebuilt a fresh Map over the whole
accumulated list every infinite-scroll page (O(N)/page, O(N^2) drain) and,
being a new instance each page, re-fired the reap-stale effect (another O(N)
id Set/page). New ItemIndexBuilder extends a persistent Map with the fresh
page only and reuses the reference across appends; the reap-stale effect now
tests membership against it. round18.bench.test.ts [F1]: 40x50 drain 74.1 ->
6.4 ms (11.5x), deep-equal to the reference at every page, reference-contract
gate (same-ref append / new-ref rebuild).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FoxFtikahM1N4PE5s3ZVH3
This commit is contained in:
Claude
@@ -79,6 +79,7 @@
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import { formatDate, iconNameFromClass, fileIconKindClass } from '$lib/utils/display';
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import { gridColumns } from '$lib/utils/grid';
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import { ResourceSectionsBuilder } from '$lib/utils/resourceSections';
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import { ItemIndexBuilder } from '$lib/utils/itemIndex';
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import { fileThumbnailUrl, thumbSizeForView } from '$lib/api/endpoints/files';
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import {
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canThumbnailClientSide,
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@@ -468,13 +469,18 @@
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// stale-selection cleanup only fires when items truly leave the
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// dataset (reload, delete, etc.), not when the filter hides them.
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//
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// Index rebuilt only when `items` changes; the projection is then
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// O(k · log k) in the selection size k instead of a full O(N) re-scan
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// of the list on every toggle (O(N²)-ish across a shift-range gesture
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// once the batch toolbar is mounted — benches/ROUND11.md §S1). The
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// index sort preserves item order, so the toolbar sees the same array
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// the old filter produced.
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const itemIndexById = $derived(new Map(items.map((i, idx) => [i.id, idx])));
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// Index extended over the freshly-appended page only (never re-scanned in
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// full) via `ItemIndexBuilder`: an infinite-scroll drain with a selection
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// active collapses from Σ O(N²) Map rebuilds to O(N) total, and the Map
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// reference is reused across appends so the reap-stale effect below no
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// longer re-fires (nor re-allocates an O(N) id Set) on a page that removed
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// nothing — its reference only changes on a rebuild (reload / deletion),
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// exactly when a reap is warranted. The projection is then O(k · log k) in
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// the selection size k, not a full O(N) re-scan on every toggle
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// (benches/ROUND11.md §S1, benches/ROUND18.md §F1). The index sort preserves
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// item order, so the toolbar sees the same array the old filter produced.
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const itemIndex = new ItemIndexBuilder<FileItem | FolderItem>();
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const itemIndexById = $derived(itemIndex.sync(items));
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const selectedItems = $derived.by(() => {
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const picked: { idx: number; item: FileItem | FolderItem }[] = [];
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for (const id of selected) {
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@@ -487,15 +493,20 @@
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// Drop selection ids that are no longer present after a reload.
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$effect(() => {
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// With nothing selected (the common case) every infinite-scroll page
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// re-fired this effect and built a throwaway O(N) id Set for a loop
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// that never runs — skip straight out. `selected.size` is reactive,
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// so the effect re-fires when a selection appears.
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// With nothing selected (the common case) the loop never runs — skip
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// straight out. `selected.size` is reactive, so the effect re-fires
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// when a selection appears.
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if (selected.size === 0) return;
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const ids = new Set(items.map((i) => i.id));
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// Test membership against the incremental `itemIndexById` rather than a
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// throwaway O(N) id Set rebuilt per page. Its reference is stable across
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// infinite-scroll appends (which never remove an id — nothing to reap)
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// so this effect no longer re-fires on every page; the reference changes
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// only on a rebuild (reload / deletion), which is exactly when a stale
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// selection must be dropped (benches/ROUND18.md §F1).
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const index = itemIndexById;
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let changed = false;
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for (const id of selected) {
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if (!ids.has(id)) {
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if (!index.has(id)) {
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selected.delete(id);
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changed = true;
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}
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@@ -0,0 +1,134 @@
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// Round-18 frontend micro-pack (benches/ROUND18.md §F1).
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//
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// Each section is BEFORE (verbatim replica of the shipped-before shape) vs
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// AFTER (the shipped incremental builder), with an equivalence gate, a
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// reference-contract gate, and a wall-time perf gate — the same discipline as
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// the Rust micro-packs: an AFTER that doesn't beat its BEFORE fails the gate.
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import { describe, expect, it } from 'vitest';
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import { buildItemIndex, ItemIndexBuilder } from '$lib/utils/itemIndex';
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// ────────────────────────────────────────────────────────────────────────────
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// [F1] ResourceList `itemIndexById` — rebuild-a-fresh-Map-per-page vs incremental
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// ────────────────────────────────────────────────────────────────────────────
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//
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// Audit finding (ROUND17 deferred list): ResourceList derived
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// `itemIndexById = new Map(items.map((i, idx) => [i.id, idx]))`. Every
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// infinite-scroll page (`items = [...items, ...page]`) rebuilt a brand-new Map
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// over the WHOLE accumulated list — O(N) per page, Σ O(N²) across a P-page
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// drain — and, being a fresh instance each page, re-fired the reap-stale
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// `$effect` that reference-diffs it (allocating another O(N) id Set for a reap
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// an append can never trigger). `ItemIndexBuilder` extends the persistent Map
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// with the fresh page only and returns the same reference on an append.
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interface Item {
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id: string;
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}
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/** A page of `{ id }` items (50/page, the default page size). */
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function pageOf(start: number, n: number): Item[] {
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return Array.from({ length: n }, (_, i) => ({ id: `it-${start + i}` }));
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}
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/** BEFORE: rebuild a fresh Map over the whole accumulated list each page. */
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function rebuildPerPage(pages: Item[][]): Map<string, number> {
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let acc: Item[] = [];
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let index = new Map<string, number>();
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for (const page of pages) {
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acc = [...acc, ...page]; // the component's `items = [...items, ...page]`
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index = new Map(acc.map((i, idx) => [i.id, idx])); // new instance + O(N) rebuild
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}
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return index;
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}
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/** AFTER: one persistent builder, extend with only the fresh page's ids. */
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function incrementalPerPage(pages: Item[][]): Map<string, number> {
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const builder = new ItemIndexBuilder<Item>();
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let acc: Item[] = [];
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let index = new Map<string, number>();
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for (const page of pages) {
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acc = [...acc, ...page];
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index = builder.sync(acc);
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}
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return index;
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}
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describe('round18 §F1 — ResourceList itemIndexById incremental Map', () => {
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it('final index is identical to the full rebuild (equivalence gate)', () => {
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const pages = Array.from({ length: 20 }, (_, p) => pageOf(p * 50, 50));
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const acc = pages.flat();
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const before = rebuildPerPage(pages);
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const after = incrementalPerPage(pages);
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const reference = buildItemIndex(acc);
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expect(after.size).toBe(before.size);
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for (const [id, idx] of reference) expect(after.get(id)).toBe(idx);
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for (const [id, idx] of after) expect(before.get(id)).toBe(idx);
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});
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it('the index stays deep-equal to the reference at EVERY page (equivalence gate)', () => {
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const builder = new ItemIndexBuilder<Item>();
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let acc: Item[] = [];
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for (let p = 0; p < 12; p++) {
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acc = [...acc, ...pageOf(p * 50, 50)];
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const got = builder.sync(acc);
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const want = buildItemIndex(acc);
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expect(got.size).toBe(want.size);
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for (const [id, idx] of want) expect(got.get(id)).toBe(idx);
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}
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});
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it('a later duplicate id resolves to its highest index, matching Map (equivalence gate)', () => {
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// The old `new Map(items.map(...))` keeps the last (highest-index)
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// occurrence of a duplicate id; the incremental extend must too.
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const builder = new ItemIndexBuilder<Item>();
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const dup: Item = { id: 'dup' };
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const p1 = [dup, { id: 'a' }];
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const p2 = [{ id: 'b' }, dup]; // 'dup' re-appears at index 3
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builder.sync(p1);
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const got = builder.sync([...p1, ...p2]);
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const want = buildItemIndex([...p1, ...p2]);
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expect(got.get('dup')).toBe(want.get('dup'));
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expect(got.get('dup')).toBe(3);
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});
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it('reuses the Map reference on append, mints a new one on rebuild (reference-contract gate)', () => {
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const builder = new ItemIndexBuilder<Item>();
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const p1 = pageOf(0, 50);
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const first = builder.sync(p1);
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// Append: same reference (so the reap-stale effect does NOT re-fire —
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// an append removes nothing).
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const appended = builder.sync([...p1, ...pageOf(50, 50)]);
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expect(appended).toBe(first);
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// Deletion (shorter, non-append prefix): fresh reference (so the
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// reap-stale effect DOES re-fire and drops the removed id).
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const afterDelete = builder.sync(p1.slice(0, 40));
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expect(afterDelete).not.toBe(first);
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expect(afterDelete.has('it-49')).toBe(false);
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// Reload with a different first element (non-append): fresh reference.
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const reloaded = builder.sync(pageOf(1000, 50));
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expect(reloaded).not.toBe(afterDelete);
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});
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it('a P-page drain builds the index ≥5x faster incrementally (perf gate)', () => {
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const PAGES = 40;
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const PER = 50; // 2 000 items total
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const pages = Array.from({ length: PAGES }, (_, p) => pageOf(p * PER, PER));
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const run = (f: (p: Item[][]) => Map<string, number>): number => {
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const t0 = performance.now();
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for (let r = 0; r < 20; r++) f(pages);
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return performance.now() - t0;
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};
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// Warm-up (JIT) then measure.
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run(rebuildPerPage);
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run(incrementalPerPage);
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const beforeMs = run(rebuildPerPage);
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const afterMs = run(incrementalPerPage);
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console.info(
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`§F1 ${PAGES} pages × ${PER}: rebuild-per-page ${beforeMs.toFixed(1)} ms vs incremental ${afterMs.toFixed(1)} ms (${(beforeMs / afterMs).toFixed(1)}x)`
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);
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expect(afterMs).toBeLessThan(beforeMs / 5);
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});
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});
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