/* 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 { logger } from 'workbox-core/_private/logger.js'; import { WorkboxError } from 'workbox-core/_private/WorkboxError.js'; import { cacheOkAndOpaquePlugin } from './plugins/cacheOkAndOpaquePlugin.js'; import { Strategy } from './Strategy.js'; import { messages } from './utils/messages.js'; import './_version.js'; /** * An implementation of a * [network first](https://developer.chrome.com/docs/workbox/caching-strategies-overview/#network-first-falling-back-to-cache) * request strategy. * * By default, this strategy will cache responses with a 200 status code as * well as [opaque responses](https://developer.chrome.com/docs/workbox/caching-resources-during-runtime/#opaque-responses). * Opaque responses are are cross-origin requests where the response doesn't * support [CORS](https://enable-cors.org/). * * If the network request fails, and there is no cache match, this will throw * a `WorkboxError` exception. * * @extends workbox-strategies.Strategy * @memberof workbox-strategies */ class NetworkFirst extends Strategy { /** * @param {Object} [options] * @param {string} [options.cacheName] Cache name to store and retrieve * requests. Defaults to cache names provided by * {@link 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 [non-navigation](https://github.com/GoogleChrome/workbox/issues/1796) * `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 = {}) { super(options); // If this instance contains no plugins with a 'cacheWillUpdate' callback, // prepend the `cacheOkAndOpaquePlugin` plugin to the plugins list. if (!this.plugins.some((p) => 'cacheWillUpdate' in p)) { this.plugins.unshift(cacheOkAndOpaquePlugin); } this._networkTimeoutSeconds = options.networkTimeoutSeconds || 0; if (process.env.NODE_ENV !== 'production') { if (this._networkTimeoutSeconds) { assert.isType(this._networkTimeoutSeconds, 'number', { moduleName: 'workbox-strategies', className: this.constructor.name, funcName: 'constructor', paramName: 'networkTimeoutSeconds', }); } } } /** * @private * @param {Request|string} request A request to run this strategy for. * @param {workbox-strategies.StrategyHandler} handler The event that * triggered the request. * @return {Promise} */ async _handle(request, handler) { const logs = []; if (process.env.NODE_ENV !== 'production') { assert.isInstance(request, Request, { moduleName: 'workbox-strategies', className: this.constructor.name, funcName: 'handle', paramName: 'makeRequest', }); } const promises = []; let timeoutId; if (this._networkTimeoutSeconds) { const { id, promise } = this._getTimeoutPromise({ request, logs, handler }); timeoutId = id; promises.push(promise); } const networkPromise = this._getNetworkPromise({ timeoutId, request, logs, handler, }); promises.push(networkPromise); const response = await handler.waitUntil((async () => { // Promise.race() will resolve as soon as the first promise resolves. return ((await handler.waitUntil(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". (await networkPromise)); })()); if (process.env.NODE_ENV !== 'production') { logger.groupCollapsed(messages.strategyStart(this.constructor.name, 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, handler, }) { let timeoutId; const timeoutPromise = new Promise((resolve) => { const onNetworkTimeout = async () => { if (process.env.NODE_ENV !== 'production') { logs.push(`Timing out the network response at ` + `${this._networkTimeoutSeconds} seconds.`); } resolve(await handler.cacheMatch(request)); }; timeoutId = setTimeout(onNetworkTimeout, this._networkTimeoutSeconds * 1000); }); return { promise: timeoutPromise, id: timeoutId, }; } /** * @param {Object} options * @param {number|undefined} options.timeoutId * @param {Request} options.request * @param {Array} options.logs A reference to the logs Array. * @param {Event} options.event * @return {Promise} * * @private */ async _getNetworkPromise({ timeoutId, request, logs, handler, }) { let error; let response; try { response = await handler.fetchAndCachePut(request); } catch (fetchError) { if (fetchError instanceof Error) { error = fetchError; } } if (timeoutId) { clearTimeout(timeoutId); } if (process.env.NODE_ENV !== 'production') { if (response) { logs.push(`Got response from network.`); } else { logs.push(`Unable to get a response from the network. Will respond ` + `with a cached response.`); } } if (error || !response) { response = await handler.cacheMatch(request); if (process.env.NODE_ENV !== 'production') { if (response) { logs.push(`Found a cached response in the '${this.cacheName}'` + ` cache.`); } else { logs.push(`No response found in the '${this.cacheName}' cache.`); } } } return response; } } export { NetworkFirst };