yonlu
620151aa41
All four collections were fetched at DOMContentLoaded and refetched on every invalidation, whichever view was showing. On a 26 138-track library the track list was 20.5 MB of that, and encoding it cost the backend ~170 MB of transient allocation — paid by someone looking at Home, which draws none of it. - The store warms only albums, artists and genres, on idle after first paint: 1.6 MB together, and what made those views instant. - A nav item prefetches on hover and on keyboard focus, which is the ~100 ms before the click that a cold open would otherwise wait. - An invalidation refetches what something had loaded, and nothing else — a scan no longer loads the track list of a library whose Tracks view nobody has opened. - `index.html`'s first-paint `<track-list>` is `view-hidden`, and `index.ts` no longer activates it: it is markup, not a decision about which view the launch lands on, and activating it was what fetched the whole list for a landing on Home. The track list itself loads on view activation, which the shell drives. Measured on 50 000 tracks: backend RSS at rest 543 → 296 MB, peak 571 → 296 MB, Go heap held 361 → 125 MB, JS heap 31.8 → 18 MB, binding bytes at rest 35.9 → 12.1 MB, heap after a browse 36.5 → 22.7 MB. Tracks first open 26 ms; slowest view open 57 ms. Closes #280
100 lines
3.0 KiB
TypeScript
100 lines
3.0 KiB
TypeScript
/**
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* #280: the app loads the library when a view needs it, not at startup.
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*
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* Every collection used to be fetched together at `DOMContentLoaded`
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* and refetched on every invalidation, whether or not anything was
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* showing it. On a 26 138-track library the track list was 20.5 MB of
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* that and cost the backend ~170 MB of transient allocation — for
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* someone looking at Home, which draws none of it.
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*
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* **This file must not load the track list before the first test.** It
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* asserts the state the app is actually left in by its own startup, so
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* a test added above that asks for tracks would invalidate the
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* precondition rather than silently pass.
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*/
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import { describe, expect, it, beforeEach } from 'vitest';
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import { libraryStore } from '@store/library-store';
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import { Events } from '../../src/events';
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import {
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calls,
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emit,
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flush,
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resetHarness,
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stub,
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} from '@test/support/harness';
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const TRACKS = 'library.Library.GetTrackTable';
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const SMALL = [
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'library.Library.GetAlbums',
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'library.Library.GetArtists',
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'library.Library.GetGenres',
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];
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/**
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* Wait for the store's own idle warm-up to land.
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*
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* It asks for the three small collections on `requestIdleCallback`, so
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* when it has happened is the browser's decision — waiting for the
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* effect rather than for a duration is the only way this is not a race.
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*/
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function stubReads(): void {
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stub(TRACKS, { strings: [''] });
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for (const path of SMALL) stub(path, []);
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}
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async function waitForWarm(): Promise<void> {
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for (let i = 0; i < 200 && libraryStore.getCachedAlbums() === null; i++) {
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await flush();
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}
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expect(libraryStore.getCachedAlbums(), 'the warm-up ran').not.toBeNull();
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}
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describe('what the app loads on its own (#280)', () => {
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beforeEach(async () => {
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stubReads();
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await waitForWarm();
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// resetHarness clears the stubs as well as the recorded calls.
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resetHarness();
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stubReads();
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});
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it('leaves the track list alone', () => {
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expect(libraryStore.getCachedTracks()).toBeNull();
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expect(calls(TRACKS)).toEqual([]);
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});
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it('does not load it to answer a scan', async () => {
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emit(Events.LibraryScanComplete);
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await flush();
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// The small collections are in use, so they are refreshed; the
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// track list nobody has opened is not.
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expect(calls().map((c) => c.path).sort()).toEqual([...SMALL].sort());
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});
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it('loads it for the view that draws it, and refreshes it from then on', async () => {
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libraryStore.prefetch('tracks');
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await flush();
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expect(calls(TRACKS)).toHaveLength(1);
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expect(libraryStore.getCachedTracks()).not.toBeNull();
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resetHarness();
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emit(Events.LibraryScanComplete);
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await flush();
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expect(calls(TRACKS), 'in use now, so a scan refreshes it').toHaveLength(1);
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});
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it('is asked for nothing by a prefetch for a view it has no data for', async () => {
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libraryStore.prefetch('home');
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libraryStore.prefetch('settings');
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libraryStore.prefetch('explore');
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await flush();
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expect(calls()).toEqual([]);
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});
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});
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