/*
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.mjs';
import {getFriendlyURL} from 'workbox-core/_private/getFriendlyURL.mjs';
import {logger} from 'workbox-core/_private/logger.mjs';
import {Deferred} from 'workbox-core/_private/Deferred.mjs';
import {responsesAreSame} from './responsesAreSame.mjs';
import {broadcastUpdate} from './broadcastUpdate.mjs';
import {DEFAULT_HEADERS_TO_CHECK, DEFAULT_BROADCAST_CHANNEL_NAME,
DEFAULT_DEFER_NOTIFICATION_TIMEOUT} from './utils/constants.mjs';
import './_version.mjs';
/**
* Uses the [Broadcast Channel API]{@link https://developers.google.com/web/updates/2016/09/broadcastchannel}
* to notify interested parties when a cached response has been updated.
* In browsers that do not support the Broadcast Channel API, the instance
* falls back to sending the update via `postMessage()` to all window clients.
*
* For efficiency's sake, the underlying response bodies are not compared;
* only specific response headers are checked.
*
* @memberof workbox.broadcastUpdate
*/
class BroadcastCacheUpdate {
/**
* Construct a BroadcastCacheUpdate instance with a specific `channelName` to
* broadcast messages on
*
* @param {Object} options
* @param {Array<string>}
* [options.headersToCheck=['content-length', 'etag', 'last-modified']]
* A list of headers that will be used to determine whether the responses
* differ.
* @param {string} [options.channelName='workbox'] The name that will be used
*. when creating the `BroadcastChannel`, which defaults to 'workbox' (the
* channel name used by the `workbox-window` package).
* @param {string} [options.deferNoticationTimeout=10000] The amount of time
* to wait for a ready message from the window on navigation requests
* before sending the update.
*/
constructor({headersToCheck, channelName, deferNoticationTimeout} = {}) {
this._headersToCheck = headersToCheck || DEFAULT_HEADERS_TO_CHECK;
this._channelName = channelName || DEFAULT_BROADCAST_CHANNEL_NAME;
this._deferNoticationTimeout =
deferNoticationTimeout || DEFAULT_DEFER_NOTIFICATION_TIMEOUT;
if (process.env.NODE_ENV !== 'production') {
assert.isType(this._channelName, 'string', {
moduleName: 'workbox-broadcast-update',
className: 'BroadcastCacheUpdate',
funcName: 'constructor',
paramName: 'channelName',
});
assert.isArray(this._headersToCheck, {
moduleName: 'workbox-broadcast-update',
className: 'BroadcastCacheUpdate',
funcName: 'constructor',
paramName: 'headersToCheck',
});
}
this._initWindowReadyDeferreds();
}
/**
* Compare two [Responses](https://developer.mozilla.org/en-US/docs/Web/API/Response)
* and send a message via the
* {@link https://developers.google.com/web/updates/2016/09/broadcastchannel|Broadcast Channel API}
* if they differ.
*
* Neither of the Responses can be {@link http://stackoverflow.com/questions/39109789|opaque}.
*
* @param {Object} options
* @param {Response} options.oldResponse Cached response to compare.
* @param {Response} options.newResponse Possibly updated response to compare.
* @param {string} options.url The URL of the request.
* @param {string} options.cacheName Name of the cache the responses belong
* to. This is included in the broadcast message.
* @param {Event} [options.event] event An optional event that triggered
* this possible cache update.
* @return {Promise} Resolves once the update is sent.
*/
notifyIfUpdated({oldResponse, newResponse, url, cacheName, event}) {
if (!responsesAreSame(oldResponse, newResponse, this._headersToCheck)) {
if (process.env.NODE_ENV !== 'production') {
logger.log(`Newer response found (and cached) for:`, url);
}
const sendUpdate = async () => {
// In the case of a navigation request, the requesting page will likely
// not have loaded its JavaScript in time to recevied the update
// notification, so we defer it until ready (or we timeout waiting).
if (event && event.request && event.request.mode === 'navigate') {
if (process.env.NODE_ENV !== 'production') {
logger.debug(`Original request was a navigation request, ` +
`waiting for a ready message from the window`, event.request);
}
await this._windowReadyOrTimeout(event);
}
await this._broadcastUpdate({
channel: this._getChannel(),
cacheName,
url,
});
};
// Send the update and ensure the SW stays alive until it's sent.
const done = sendUpdate();
if (event) {
try {
event.waitUntil(done);
} catch (error) {
if (process.env.NODE_ENV !== 'production') {
logger.warn(`Unable to ensure service worker stays alive ` +
`when broadcasting cache update for ` +
`${getFriendlyURL(event.request.url)}'.`);
}
}
}
return done;
}
}
/**
* NOTE: this is exposed on the instance primarily so it can be spied on
* in tests.
*
* @param {Object} opts
* @private
*/
async _broadcastUpdate(opts) {
await broadcastUpdate(opts);
}
/**
* @return {BroadcastChannel|undefined} The BroadcastChannel instance used for
* broadcasting updates, or undefined if the browser doesn't support the
* Broadcast Channel API.
*
* @private
*/
_getChannel() {
if (('BroadcastChannel' in self) && !this._channel) {
this._channel = new BroadcastChannel(this._channelName);
}
return this._channel;
}
/**
* Waits for a message from the window indicating that it's capable of
* receiving broadcasts. By default, this will only wait for the amount of
* time specified via the `deferNoticationTimeout` option.
*
* @param {Event} event The navigation fetch event.
* @return {Promise}
* @private
*/
_windowReadyOrTimeout(event) {
if (!this._navigationEventsDeferreds.has(event)) {
const deferred = new Deferred();
// Set the deferred on the `_navigationEventsDeferreds` map so it will
// be resolved when the next ready message event comes.
this._navigationEventsDeferreds.set(event, deferred);
// But don't wait too long for the message since it may never come.
const timeout = setTimeout(() => {
if (process.env.NODE_ENV !== 'production') {
logger.debug(`Timed out after ${this._deferNoticationTimeout}` +
`ms waiting for message from window`);
}
deferred.resolve();
}, this._deferNoticationTimeout);
// Ensure the timeout is cleared if the deferred promise is resolved.
deferred.promise.then(() => clearTimeout(timeout));
}
return this._navigationEventsDeferreds.get(event).promise;
}
/**
* Creates a mapping between navigation fetch events and deferreds, and adds
* a listener for message events from the window. When message events arrive,
* all deferreds in the mapping are resolved.
*
* Note: it would be easier if we could only resolve the deferred of
* navigation fetch event whose client ID matched the source ID of the
* message event, but currently client IDs are not exposed on navigation
* fetch events: https://www.chromestatus.com/feature/4846038800138240
*
* @private
*/
_initWindowReadyDeferreds() {
// A mapping between navigation events and their deferreds.
this._navigationEventsDeferreds = new Map();
// The message listener needs to be added in the initial run of the
// service worker, but since we don't actually need to be listening for
// messages until the cache updates, we only invoke the callback if set.
self.addEventListener('message', (event) => {
if (event.data.type === 'WINDOW_READY' &&
event.data.meta === 'workbox-window' &&
this._navigationEventsDeferreds.size > 0) {
if (process.env.NODE_ENV !== 'production') {
logger.debug(`Received WINDOW_READY event: `, event);
}
// Resolve any pending deferreds.
for (const deferred of this._navigationEventsDeferreds.values()) {
deferred.resolve();
}
this._navigationEventsDeferreds.clear();
}
});
}
}
export {BroadcastCacheUpdate};