86 lines
2.7 KiB
JavaScript
86 lines
2.7 KiB
JavaScript
'use strict';
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const ONE_MINUTE_IN_SECONDS = 60;
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const THREE_MINUTE_IN_SECONDS = 60 * 3;
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const FIVE_MINUTES_IN_SECONDS = ONE_MINUTE_IN_SECONDS * 5;
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const TEN_MINUTES_IN_SECONDS = ONE_MINUTE_IN_SECONDS * 10;
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const FIFTEEN_MINUTES_IN_SECONDS = ONE_MINUTE_IN_SECONDS * 15;
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const THIRTY_MINUTES_IN_SECONDS = ONE_MINUTE_IN_SECONDS * 30;
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const ONE_HOUR_IN_SECONDS = ONE_MINUTE_IN_SECONDS * 60;
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const ONE_YEAR_IN_SECONDS = ONE_HOUR_IN_SECONDS * 24 * 365;
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const FALLBACK_TTL = global.environment.varnish.fallbackTtl || FIVE_MINUTES_IN_SECONDS;
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const validFallbackTTL = [
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ONE_MINUTE_IN_SECONDS,
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THREE_MINUTE_IN_SECONDS,
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FIVE_MINUTES_IN_SECONDS,
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TEN_MINUTES_IN_SECONDS,
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FIFTEEN_MINUTES_IN_SECONDS,
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THIRTY_MINUTES_IN_SECONDS,
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ONE_HOUR_IN_SECONDS
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];
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module.exports = function setCacheControlHeader ({
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ttl = ONE_YEAR_IN_SECONDS,
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fallbackTtl = FALLBACK_TTL,
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revalidate = false
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} = {}) {
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if (!validFallbackTTL.includes(fallbackTtl)) {
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const message = [
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'Invalid fallback TTL value for Cache-Control header.',
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`Got ${fallbackTtl}, expected ${validFallbackTTL.join(', ')}`
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].join(' ');
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throw new Error(message);
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}
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return function setCacheControlHeaderMiddleware (req, res, next) {
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if (req.method !== 'GET') {
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return next();
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}
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const { mapConfigProvider = { getAffectedTables: callback => callback() }, logger } = res.locals;
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mapConfigProvider.getAffectedTables((err, affectedTables) => {
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if (err) {
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logger.warn({ error: err }, 'Error generating Cache Control Header');
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return next();
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}
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const directives = ['public'];
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if (everyAffectedTableCanBeInvalidated(affectedTables)) {
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directives.push(`max-age=${ttl}`);
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} else {
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directives.push(`max-age=${computeNextTTL({ ttlInSeconds: fallbackTtl })}`);
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}
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if (revalidate) {
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directives.push('must-revalidate');
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}
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res.set('Cache-Control', directives.join(','));
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next();
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});
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};
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};
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function everyAffectedTableCanBeInvalidated (affectedTables) {
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const skipNotUpdatedAtTables = false;
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const skipAnalysisCachedTables = true;
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return affectedTables &&
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affectedTables.getTables(skipNotUpdatedAtTables, skipAnalysisCachedTables)
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.every(table => table.updated_at !== null);
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}
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function computeNextTTL ({ ttlInSeconds } = {}) {
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const nowInSeconds = Math.ceil(Date.now() / 1000);
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const secondsAfterPreviousTTLStep = nowInSeconds % ttlInSeconds;
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const secondsToReachTheNextTTLStep = ttlInSeconds - secondsAfterPreviousTTLStep;
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return secondsToReachTheNextTTLStep;
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}
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