/* 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 { cacheWrapper } from 'workbox-core/_private/cacheWrapper.js'; import { fetchWrapper } from 'workbox-core/_private/fetchWrapper.js'; import { getFriendlyURL } from 'workbox-core/_private/getFriendlyURL.js'; import { logger } from 'workbox-core/_private/logger.js'; import { WorkboxError } from 'workbox-core/_private/WorkboxError.js'; import { messages } from './utils/messages.js'; import { cacheOkAndOpaquePlugin } from './plugins/cacheOkAndOpaquePlugin.js'; import './_version.js'; /** * An implementation of a * [network first]{@link https://developers.google.com/web/fundamentals/instant-and-offline/offline-cookbook/#network-falling-back-to-cache} * request strategy. * * By default, this strategy will cache responses with a 200 status code as * well as [opaque responses]{@link https://developers.google.com/web/tools/workbox/guides/handle-third-party-requests}. * Opaque responses are are cross-origin requests where the response doesn't * support [CORS]{@link https://enable-cors.org/}. * * If the network request fails, and there is no cache match, this will throw * a `WorkboxError` exception. * * @memberof module:workbox-strategies */ class NetworkFirst { /** * @param {Object} options * @param {string} options.cacheName Cache name to store and retrieve * requests. Defaults to cache names provided by * [workbox-core]{@link module:workbox-core.cacheNames}. * @param {Array} options.plugins [Plugins]{@link https://developers.google.com/web/tools/workbox/guides/using-plugins} * to use in conjunction with this caching strategy. * @param {Object} options.fetchOptions Values passed along to the * [`init`](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch#Parameters) * of all fetch() requests made by this strategy. * @param {Object} options.matchOptions [`CacheQueryOptions`](https://w3c.github.io/ServiceWorker/#dictdef-cachequeryoptions) * @param {number} options.networkTimeoutSeconds If set, any network requests * that fail to respond within the timeout will fallback to the cache. * * This option can be used to combat * "[lie-fi]{@link https://developers.google.com/web/fundamentals/performance/poor-connectivity/#lie-fi}" * scenarios. */ constructor(options = {}) { this._cacheName = cacheNames.getRuntimeName(options.cacheName); if (options.plugins) { const isUsingCacheWillUpdate = options.plugins.some((plugin) => !!plugin.cacheWillUpdate); this._plugins = isUsingCacheWillUpdate ? options.plugins : [cacheOkAndOpaquePlugin, ...options.plugins]; } else { // No plugins passed in, use the default plugin. this._plugins = [cacheOkAndOpaquePlugin]; } this._networkTimeoutSeconds = options.networkTimeoutSeconds || 0; if (process.env.NODE_ENV !== 'production') { if (this._networkTimeoutSeconds) { assert.isType(this._networkTimeoutSeconds, 'number', { moduleName: 'workbox-strategies', className: 'NetworkFirst', funcName: 'constructor', paramName: 'networkTimeoutSeconds', }); } } this._fetchOptions = options.fetchOptions; this._matchOptions = options.matchOptions; } /** * This method will perform a request strategy and follows an API that * will work with the * [Workbox Router]{@link module:workbox-routing.Router}. * * @param {Object} options * @param {Request|string} options.request A request to run this strategy for. * @param {Event} [options.event] The event that triggered the request. * @return {Promise} */ async handle({ event, request }) { const logs = []; if (typeof request === 'string') { request = new Request(request); } if (process.env.NODE_ENV !== 'production') { assert.isInstance(request, Request, { moduleName: 'workbox-strategies', className: 'NetworkFirst', funcName: 'handle', paramName: 'makeRequest', }); } const promises = []; let timeoutId; if (this._networkTimeoutSeconds) { const { id, promise } = this._getTimeoutPromise({ request, event, logs }); timeoutId = id; promises.push(promise); } const networkPromise = this._getNetworkPromise({ timeoutId, request, event, logs }); promises.push(networkPromise); // Promise.race() will resolve as soon as the first promise resolves. let response = await Promise.race(promises); // If Promise.race() resolved with null, it might be due to a network // timeout + a cache miss. If that were to happen, we'd rather wait until // the networkPromise resolves instead of returning null. // Note that it's fine to await an already-resolved promise, so we don't // have to check to see if it's still "in flight". if (!response) { response = await networkPromise; } if (process.env.NODE_ENV !== 'production') { logger.groupCollapsed(messages.strategyStart('NetworkFirst', request)); for (const log of logs) { logger.log(log); } messages.printFinalResponse(response); logger.groupEnd(); } if (!response) { throw new WorkboxError('no-response', { url: request.url }); } return response; } /** * @param {Object} options * @param {Request} options.request * @param {Array} options.logs A reference to the logs array * @param {Event} [options.event] * @return {Promise} * * @private */ _getTimeoutPromise({ request, logs, event }) { let timeoutId; const timeoutPromise = new Promise((resolve) => { const onNetworkTimeout = async () => { if (process.env.NODE_ENV !== 'production') { logs.push(`Timing out the network response at ` + `${this._networkTimeoutSeconds} seconds.`); } resolve(await this._respondFromCache({ request, event })); }; timeoutId = setTimeout(onNetworkTimeout, this._networkTimeoutSeconds * 1000); }); return { promise: timeoutPromise, id: timeoutId, }; } /** * @param {Object} options * @param {number|undefined} options.timeoutId * @param {Request} options.request * @param {Array} options.logs A reference to the logs Array. * @param {Event} [options.event] * @return {Promise} * * @private */ async _getNetworkPromise({ timeoutId, request, logs, event }) { let error; let response; try { response = await fetchWrapper.fetch({ request, event, fetchOptions: this._fetchOptions, plugins: this._plugins, }); } catch (err) { error = err; } if (timeoutId) { clearTimeout(timeoutId); } if (process.env.NODE_ENV !== 'production') { if (response) { logs.push(`Got response from network.`); } else { logs.push(`Unable to get a response from the network. Will respond ` + `with a cached response.`); } } if (error || !response) { response = await this._respondFromCache({ request, event }); if (process.env.NODE_ENV !== 'production') { if (response) { logs.push(`Found a cached response in the '${this._cacheName}'` + ` cache.`); } else { logs.push(`No response found in the '${this._cacheName}' cache.`); } } } else { // Keep the service worker alive while we put the request in the cache const responseClone = response.clone(); const cachePut = cacheWrapper.put({ cacheName: this._cacheName, request, response: responseClone, event, plugins: this._plugins, }); if (event) { try { // The event has been responded to so we can keep the SW alive to // respond to the request event.waitUntil(cachePut); } catch (err) { if (process.env.NODE_ENV !== 'production') { logger.warn(`Unable to ensure service worker stays alive when ` + `updating cache for '${getFriendlyURL(request.url)}'.`); } } } } return response; } /** * Used if the network timeouts or fails to make the request. * * @param {Object} options * @param {Request} request The request to match in the cache * @param {Event} [options.event] * @return {Promise} * * @private */ _respondFromCache({ event, request }) { return cacheWrapper.match({ cacheName: this._cacheName, request, event, matchOptions: this._matchOptions, plugins: this._plugins, }); } } export { NetworkFirst };