82 lines
2.8 KiB
JavaScript
82 lines
2.8 KiB
JavaScript
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// Centralised hot-reload watcher.
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//
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// After the cron rewrites the in-memory data files (search chunks, IMDb
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// mappings, IMDb ratings TSV), the existing per-call mtime checks already
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// reload them lazily — but the FIRST request post-cron pays a 1-2 s penalty.
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//
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// This module watches all four data sources and proactively triggers a reload
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// in the background as soon as the files change, so users never hit the cold
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// path. Debounced because the cron writes ~10 files within seconds.
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import { unwatchFile, watch, watchFile } from 'node:fs';
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import { IMDB_RATINGS, TMDBINTEGRAL_DIR } from '../config.js';
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import { preloadMappings } from './imdbMapping.js';
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import { getRatings } from './imdbRatings.js';
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import { imdbRatingsCount } from './metrics.js';
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import { reloadAllPools } from './searchEngine.js';
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const DEBOUNCE_MS = 5000;
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const timers = { chunks: null, mappings: null, ratings: null };
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const watchers = [];
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function debounce(key, fn) {
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clearTimeout(timers[key]);
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timers[key] = setTimeout(() => {
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Promise.resolve(fn()).catch((err) => console.error(`Hot reload (${key}) failed:`, err.message));
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}, DEBOUNCE_MS);
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}
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async function reloadRatings() {
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// getRatings() checks the file mtime and rebuilds the Map if it changed.
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// Calling it here pre-populates the cache so the next request is hot.
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const map = await getRatings();
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imdbRatingsCount.set(map.size);
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console.log(`Hot reload: imdbratings.tsv (${map.size} entries)`);
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}
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async function reloadMappings() {
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const out = await preloadMappings();
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console.log(`Hot reload: IMDb mappings (movie=${out.movie}, tv=${out.tv})`);
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}
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async function reloadChunks() {
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await reloadAllPools();
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}
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export function startWatchers() {
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// tmdbintegral/ — covers search chunks AND imdb2{movie,tv}.json
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try {
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const w = watch(TMDBINTEGRAL_DIR, (_event, filename) => {
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if (!filename) return;
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if (/^search(movie|tv)\d+\.json$/.test(filename)) {
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debounce('chunks', reloadChunks);
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} else if (filename === 'imdb2movie.json' || filename === 'imdb2tv.json') {
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debounce('mappings', reloadMappings);
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}
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});
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w.unref();
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watchers.push(w);
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} catch (err) {
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console.warn(`Cannot watch ${TMDBINTEGRAL_DIR}:`, err.message);
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}
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// imdbratings.tsv — fs.watch on a single file across a rename(tmp -> file)
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// is unreliable on Linux because the inode changes. fs.watchFile (poll
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// every 10 s) follows the path, not the inode. Cost: one stat() every 10 s.
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watchFile(IMDB_RATINGS, { interval: 10_000 }, (curr, prev) => {
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if (curr.mtimeMs !== prev.mtimeMs) debounce('ratings', reloadRatings);
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});
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watchers.push({ close: () => unwatchFile(IMDB_RATINGS) });
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}
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export function stopWatchers() {
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for (const w of watchers) {
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try {
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w.close();
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} catch {
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/* ignore */
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}
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}
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watchers.length = 0;
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}
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