gecko-dev/services/settings/Utils.jsm

178 строки
5.7 KiB
JavaScript

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
var EXPORTED_SYMBOLS = ["Utils"];
const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
const { XPCOMUtils } = ChromeUtils.import(
"resource://gre/modules/XPCOMUtils.jsm"
);
XPCOMUtils.defineLazyGlobalGetters(this, ["fetch"]);
// Create a new instance of the ConsoleAPI so we can control the maxLogLevel with a pref.
// See LOG_LEVELS in Console.jsm. Common examples: "all", "debug", "info", "warn", "error".
XPCOMUtils.defineLazyGetter(this, "log", () => {
const { ConsoleAPI } = ChromeUtils.import(
"resource://gre/modules/Console.jsm",
{}
);
return new ConsoleAPI({
maxLogLevel: "warn",
maxLogLevelPref: "services.settings.loglevel",
prefix: "services.settings",
});
});
var Utils = {
CHANGES_PATH: "/buckets/monitor/collections/changes/records",
/**
* Logger instance.
*/
log,
/**
* Check if local data exist for the specified client.
*
* @param {RemoteSettingsClient} client
* @return {bool} Whether it exists or not.
*/
async hasLocalData(client) {
const kintoCol = await client.openCollection();
const timestamp = await kintoCol.db.getLastModified();
return timestamp !== null;
},
/**
* Check if we ship a JSON dump for the specified bucket and collection.
*
* @param {String} bucket
* @param {String} collection
* @return {bool} Whether it is present or not.
*/
async hasLocalDump(bucket, collection) {
try {
await fetch(
`resource://app/defaults/settings/${bucket}/${collection}.json`
);
return true;
} catch (e) {
return false;
}
},
/**
* Fetch the list of remote collections and their timestamp.
* @param {String} serverUrl The server URL (eg. `https://server.org/v1`)
* @param {int} expectedTimestamp The timestamp that the server is supposed to return.
* We obtained it from the Megaphone notification payload,
* and we use it only for cache busting (Bug 1497159).
* @param {String} lastEtag (optional) The Etag of the latest poll to be matched
* by the server (eg. `"123456789"`).
* @param {Object} filters
*/
async fetchLatestChanges(serverUrl, options = {}) {
const { expectedTimestamp, lastEtag = "", filters = {} } = options;
//
// Fetch the list of changes objects from the server that looks like:
// {"data":[
// {
// "host":"kinto-ota.dev.mozaws.net",
// "last_modified":1450717104423,
// "bucket":"blocklists",
// "collection":"certificates"
// }]}
let url = serverUrl + Utils.CHANGES_PATH;
// Use ETag to obtain a `304 Not modified` when no change occurred,
// and `?_since` parameter to only keep entries that weren't processed yet.
const headers = {};
const params = { ...filters };
if (lastEtag != "") {
headers["If-None-Match"] = lastEtag;
params._since = lastEtag;
}
if (expectedTimestamp) {
params._expected = expectedTimestamp;
}
if (params) {
url +=
"?" +
Object.entries(params)
.map(([k, v]) => `${k}=${encodeURIComponent(v)}`)
.join("&");
}
const response = await fetch(url, { headers });
let changes = [];
// If no changes since last time, go on with empty list of changes.
if (response.status != 304) {
const is404FromCustomServer =
response.status == 404 &&
Services.prefs.prefHasUserValue("services.settings.server");
const ct = response.headers.get("Content-Type");
if (!is404FromCustomServer && (!ct || !ct.includes("application/json"))) {
throw new Error(`Unexpected content-type "${ct}"`);
}
let payload;
try {
payload = await response.json();
} catch (e) {
payload = e.message;
}
if (!payload.hasOwnProperty("data")) {
// If the server is failing, the JSON response might not contain the
// expected data. For example, real server errors (Bug 1259145)
// or dummy local server for tests (Bug 1481348)
if (!is404FromCustomServer) {
throw new Error(
`Server error ${response.status} ${
response.statusText
}: ${JSON.stringify(payload)}`
);
}
} else {
changes = payload.data;
}
}
// The server should always return ETag. But we've had situations where the CDN
// was interfering.
const currentEtag = response.headers.has("ETag")
? response.headers.get("ETag")
: undefined;
let serverTimeMillis = Date.parse(response.headers.get("Date"));
// Since the response is served via a CDN, the Date header value could have been cached.
const cacheAgeSeconds = response.headers.has("Age")
? parseInt(response.headers.get("Age"), 10)
: 0;
serverTimeMillis += cacheAgeSeconds * 1000;
// Age of data (time between publication and now).
let lastModifiedMillis = Date.parse(response.headers.get("Last-Modified"));
const ageSeconds = (serverTimeMillis - lastModifiedMillis) / 1000;
// Check if the server asked the clients to back off.
let backoffSeconds;
if (response.headers.has("Backoff")) {
const value = parseInt(response.headers.get("Backoff"), 10);
if (!isNaN(value)) {
backoffSeconds = value;
}
}
return {
changes,
currentEtag,
serverTimeMillis,
backoffSeconds,
ageSeconds,
};
},
};