61 lines
2.0 KiB
JavaScript
61 lines
2.0 KiB
JavaScript
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// Precompress built SPA assets so the Rust web layer can serve them with
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// `ServeDir::precompressed_br()/precompressed_gzip()` instead of re-running
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// Brotli over the same immutable bundle on every request (the tower-http
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// CompressionLayer stays as the on-the-fly fallback for anything without a
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// sibling). Runs as the `build` script's final step; uses only node:zlib —
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// no dependencies. See benches/STATIC-PRECOMPRESSED.md for the measured win.
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import { promises as fs } from 'node:fs';
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import path from 'node:path';
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import zlib from 'node:zlib';
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const OUT_DIR = process.argv[2] ?? '../static-dist';
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// Compressible text assets; media formats are already compressed.
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const EXTENSIONS = new Set([
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'.js',
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'.mjs',
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'.css',
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'.html',
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'.svg',
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'.json',
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'.txt',
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'.xml',
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'.map',
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'.webmanifest'
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]);
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// Below this size the encoding overhead outweighs the transfer win
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// (mirrors the server's SizeAbove(256) predicate).
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const MIN_BYTES = 256;
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async function* walk(dir) {
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for (const entry of await fs.readdir(dir, { withFileTypes: true })) {
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const p = path.join(dir, entry.name);
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if (entry.isDirectory()) yield* walk(p);
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else yield p;
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}
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}
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let files = 0;
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let inBytes = 0;
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let brBytes = 0;
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for await (const file of walk(OUT_DIR)) {
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if (!EXTENSIONS.has(path.extname(file))) continue;
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const data = await fs.readFile(file);
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if (data.length < MIN_BYTES) continue;
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const br = zlib.brotliCompressSync(data, {
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params: {
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[zlib.constants.BROTLI_PARAM_QUALITY]: 11,
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[zlib.constants.BROTLI_PARAM_SIZE_HINT]: data.length
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}
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});
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const gz = zlib.gzipSync(data, { level: 9 });
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// Only keep siblings that actually shrink the asset.
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if (br.length < data.length) await fs.writeFile(`${file}.br`, br);
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if (gz.length < data.length) await fs.writeFile(`${file}.gz`, gz);
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files += 1;
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inBytes += data.length;
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brBytes += Math.min(br.length, data.length);
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}
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console.log(
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`precompress: ${files} assets, ${(inBytes / 1024).toFixed(0)} KiB → ${(brBytes / 1024).toFixed(0)} KiB brotli (${inBytes ? ((1 - brBytes / inBytes) * 100).toFixed(0) : 0}% smaller)`
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);
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