/* Copyright 2018 Google LLC Use of this source code is governed by an MIT-style license that can be found in the LICENSE file or at https://opensource.org/licenses/MIT. */ import { assert } from 'workbox-core/_private/assert.js'; import { cacheNames } from 'workbox-core/_private/cacheNames.js'; import { dontWaitFor } from 'workbox-core/_private/dontWaitFor.js'; import { getFriendlyURL } from 'workbox-core/_private/getFriendlyURL.js'; import { logger } from 'workbox-core/_private/logger.js'; import { registerQuotaErrorCallback } from 'workbox-core/registerQuotaErrorCallback.js'; import { WorkboxError } from 'workbox-core/_private/WorkboxError.js'; import { CacheExpiration } from './CacheExpiration.js'; import './_version.js'; /** * This plugin can be used in the Workbox APIs to regularly enforce a * limit on the age and / or the number of cached requests. * * Whenever a cached request is used or updated, this plugin will look * at the used Cache and remove any old or extra requests. * * When using `maxAgeSeconds`, requests may be used *once* after expiring * because the expiration clean up will not have occurred until *after* the * cached request has been used. If the request has a "Date" header, then * a light weight expiration check is performed and the request will not be * used immediately. * * When using `maxEntries`, the entry least-recently requested will be removed * from the cache first. * * @memberof module:workbox-expiration */ class ExpirationPlugin { /** * @param {Object} config * @param {number} [config.maxEntries] The maximum number of entries to cache. * Entries used the least will be removed as the maximum is reached. * @param {number} [config.maxAgeSeconds] The maximum age of an entry before * it's treated as stale and removed. * @param {boolean} [config.purgeOnQuotaError] Whether to opt this cache in to * automatic deletion if the available storage quota has been exceeded. */ constructor(config = {}) { /** * A "lifecycle" callback that will be triggered automatically by the * `workbox-strategies` handlers when a `Response` is about to be returned * from a [Cache](https://developer.mozilla.org/en-US/docs/Web/API/Cache) to * the handler. It allows the `Response` to be inspected for freshness and * prevents it from being used if the `Response`'s `Date` header value is * older than the configured `maxAgeSeconds`. * * @param {Object} options * @param {string} options.cacheName Name of the cache the response is in. * @param {Response} options.cachedResponse The `Response` object that's been * read from a cache and whose freshness should be checked. * @return {Response} Either the `cachedResponse`, if it's * fresh, or `null` if the `Response` is older than `maxAgeSeconds`. * * @private */ this.cachedResponseWillBeUsed = async ({ event, request, cacheName, cachedResponse }) => { if (!cachedResponse) { return null; } const isFresh = this._isResponseDateFresh(cachedResponse); // Expire entries to ensure that even if the expiration date has // expired, it'll only be used once. const cacheExpiration = this._getCacheExpiration(cacheName); dontWaitFor(cacheExpiration.expireEntries()); // Update the metadata for the request URL to the current timestamp, // but don't `await` it as we don't want to block the response. const updateTimestampDone = cacheExpiration.updateTimestamp(request.url); if (event) { try { event.waitUntil(updateTimestampDone); } catch (error) { if (process.env.NODE_ENV !== 'production') { // The event may not be a fetch event; only log the URL if it is. if ('request' in event) { logger.warn(`Unable to ensure service worker stays alive when ` + `updating cache entry for ` + `'${getFriendlyURL(event.request.url)}'.`); } } } } return isFresh ? cachedResponse : null; }; /** * A "lifecycle" callback that will be triggered automatically by the * `workbox-strategies` handlers when an entry is added to a cache. * * @param {Object} options * @param {string} options.cacheName Name of the cache that was updated. * @param {string} options.request The Request for the cached entry. * * @private */ this.cacheDidUpdate = async ({ cacheName, request }) => { if (process.env.NODE_ENV !== 'production') { assert.isType(cacheName, 'string', { moduleName: 'workbox-expiration', className: 'Plugin', funcName: 'cacheDidUpdate', paramName: 'cacheName', }); assert.isInstance(request, Request, { moduleName: 'workbox-expiration', className: 'Plugin', funcName: 'cacheDidUpdate', paramName: 'request', }); } const cacheExpiration = this._getCacheExpiration(cacheName); await cacheExpiration.updateTimestamp(request.url); await cacheExpiration.expireEntries(); }; if (process.env.NODE_ENV !== 'production') { if (!(config.maxEntries || config.maxAgeSeconds)) { throw new WorkboxError('max-entries-or-age-required', { moduleName: 'workbox-expiration', className: 'Plugin', funcName: 'constructor', }); } if (config.maxEntries) { assert.isType(config.maxEntries, 'number', { moduleName: 'workbox-expiration', className: 'Plugin', funcName: 'constructor', paramName: 'config.maxEntries', }); } if (config.maxAgeSeconds) { assert.isType(config.maxAgeSeconds, 'number', { moduleName: 'workbox-expiration', className: 'Plugin', funcName: 'constructor', paramName: 'config.maxAgeSeconds', }); } } this._config = config; this._maxAgeSeconds = config.maxAgeSeconds; this._cacheExpirations = new Map(); if (config.purgeOnQuotaError) { registerQuotaErrorCallback(() => this.deleteCacheAndMetadata()); } } /** * A simple helper method to return a CacheExpiration instance for a given * cache name. * * @param {string} cacheName * @return {CacheExpiration} * * @private */ _getCacheExpiration(cacheName) { if (cacheName === cacheNames.getRuntimeName()) { throw new WorkboxError('expire-custom-caches-only'); } let cacheExpiration = this._cacheExpirations.get(cacheName); if (!cacheExpiration) { cacheExpiration = new CacheExpiration(cacheName, this._config); this._cacheExpirations.set(cacheName, cacheExpiration); } return cacheExpiration; } /** * @param {Response} cachedResponse * @return {boolean} * * @private */ _isResponseDateFresh(cachedResponse) { if (!this._maxAgeSeconds) { // We aren't expiring by age, so return true, it's fresh return true; } // Check if the 'date' header will suffice a quick expiration check. // See https://github.com/GoogleChromeLabs/sw-toolbox/issues/164 for // discussion. const dateHeaderTimestamp = this._getDateHeaderTimestamp(cachedResponse); if (dateHeaderTimestamp === null) { // Unable to parse date, so assume it's fresh. return true; } // If we have a valid headerTime, then our response is fresh iff the // headerTime plus maxAgeSeconds is greater than the current time. const now = Date.now(); return dateHeaderTimestamp >= now - (this._maxAgeSeconds * 1000); } /** * This method will extract the data header and parse it into a useful * value. * * @param {Response} cachedResponse * @return {number|null} * * @private */ _getDateHeaderTimestamp(cachedResponse) { if (!cachedResponse.headers.has('date')) { return null; } const dateHeader = cachedResponse.headers.get('date'); const parsedDate = new Date(dateHeader); const headerTime = parsedDate.getTime(); // If the Date header was invalid for some reason, parsedDate.getTime() // will return NaN. if (isNaN(headerTime)) { return null; } return headerTime; } /** * This is a helper method that performs two operations: * * - Deletes *all* the underlying Cache instances associated with this plugin * instance, by calling caches.delete() on your behalf. * - Deletes the metadata from IndexedDB used to keep track of expiration * details for each Cache instance. * * When using cache expiration, calling this method is preferable to calling * `caches.delete()` directly, since this will ensure that the IndexedDB * metadata is also cleanly removed and open IndexedDB instances are deleted. * * Note that if you're *not* using cache expiration for a given cache, calling * `caches.delete()` and passing in the cache's name should be sufficient. * There is no Workbox-specific method needed for cleanup in that case. */ async deleteCacheAndMetadata() { // Do this one at a time instead of all at once via `Promise.all()` to // reduce the chance of inconsistency if a promise rejects. for (const [cacheName, cacheExpiration] of this._cacheExpirations) { await self.caches.delete(cacheName); await cacheExpiration.delete(); } // Reset this._cacheExpirations to its initial state. this._cacheExpirations = new Map(); } } export { ExpirationPlugin };