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49 lines
1.1 KiB
JavaScript
49 lines
1.1 KiB
JavaScript
'use strict';
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var async = require('async');
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var fs = require('fs');
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var path = require('path');
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var mkdirp = require('mkdirp');
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var winston = require('winston');
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var filePath = path.join(__dirname, '../../build/cache-buster');
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var 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 = function write(callback) {
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async.waterfall([
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function (next) {
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mkdirp(path.dirname(filePath), next);
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},
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function (data, next) {
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fs.writeFile(filePath, generate(), next);
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},
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], callback);
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};
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exports.read = function read(callback) {
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if (cached) {
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return callback(null, cached);
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}
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fs.readFile(filePath, 'utf8', function (err, buster) {
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if (err) {
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winston.warn('[cache-buster] could not read cache buster', err);
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return callback(null, generate());
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}
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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 callback(null, generate());
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}
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cached = buster;
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callback(null, cached);
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});
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};
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