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46 lines
1.2 KiB
JavaScript
46 lines
1.2 KiB
JavaScript
'use strict';
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const fs = require('fs');
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const path = require('path');
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const mkdirp = require('mkdirp');
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const winston = require('winston');
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const util = require('util');
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const mkdirpAsync = util.promisify(mkdirp);
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const writeFileAsync = util.promisify(fs.writeFile);
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const readFileAsync = util.promisify(fs.readFile);
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const filePath = path.join(__dirname, '../../build/cache-buster');
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let cached;
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// cache buster is an 11-character, lowercase, alphanumeric string
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function generate() {
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return (Math.random() * 1e18).toString(32).slice(0, 11);
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}
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exports.write = async function write() {
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await mkdirpAsync(path.dirname(filePath));
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await writeFileAsync(filePath, generate());
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};
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exports.read = async function read() {
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if (cached) {
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return cached;
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}
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try {
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const buster = await readFileAsync(filePath, 'utf8');
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if (!buster || buster.length !== 11) {
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winston.warn('[cache-buster] cache buster string invalid: expected /[a-z0-9]{11}/, got `' + buster + '`');
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return generate();
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}
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cached = buster;
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return cached;
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} catch (err) {
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winston.warn('[cache-buster] could not read cache buster', err);
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return generate();
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}
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};
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require('../promisify')(exports);
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