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/**
* 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
*/
/**
* The nsIAboutNewTabService is accessed by the AboutRedirector anytime
* about:home, about:newtab or about:welcome are requested. The primary
* job of an nsIAboutNewTabService is to tell the AboutRedirector what
* resources to actually load for those requests.
*
* The nsIAboutNewTabService is not involved when the user has overridden
* the default about:home or about:newtab pages.
*
* There are two implementations of this service - one for the parent
* process, and one for content processes. Each one has some secondary
* responsibilties that are process-specific.
*
* The need for two implementations is an unfortunate consequence of how
* document loading and process redirection for about: pages currently
* works in Gecko. The commonalities between the two implementations has
* been put into an abstract base class.
*/
import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
import { E10SUtils } from "resource://gre/modules/E10SUtils.sys.mjs";
import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
const lazy = {};
ChromeUtils.defineESModuleGetters(lazy, {
BasePromiseWorker: "resource://gre/modules/PromiseWorker.sys.mjs",
NimbusFeatures: "resource://nimbus/ExperimentAPI.sys.mjs",
});
/**
* BEWARE: Do not add variables for holding state in the global scope.
* Any state variables should be properties of the appropriate class
* below. This is to avoid confusion where the state is set in one process,
* but not in another.
*
* Constants are fine in the global scope.
*/
const PREF_ABOUT_HOME_CACHE_TESTING =
"browser.startup.homepage.abouthome_cache.testing";
const ABOUT_WELCOME_URL =
"chrome://browser/content/aboutwelcome/aboutwelcome.html";
const CACHE_WORKER_URL = "resource://activity-stream/lib/cache.worker.js";
const IS_PRIVILEGED_PROCESS =
Services.appinfo.remoteType === E10SUtils.PRIVILEGEDABOUT_REMOTE_TYPE;
const PREF_SEPARATE_PRIVILEGEDABOUT_CONTENT_PROCESS =
"browser.tabs.remote.separatePrivilegedContentProcess";
const PREF_ACTIVITY_STREAM_DEBUG = "browser.newtabpage.activity-stream.debug";
/**
* The AboutHomeStartupCacheChild is responsible for connecting the
* nsIAboutNewTabService with a cached document and script for about:home
* if one happens to exist. The AboutHomeStartupCacheChild is only ever
* handed the streams for those caches when the "privileged about content
* process" first launches, so subsequent loads of about:home do not read
* from this cache.
*
* for further details.
*/
export const AboutHomeStartupCacheChild = {
_initted: false,
CACHE_REQUEST_MESSAGE: "AboutHomeStartupCache:CacheRequest",
CACHE_RESPONSE_MESSAGE: "AboutHomeStartupCache:CacheResponse",
CACHE_USAGE_RESULT_MESSAGE: "AboutHomeStartupCache:UsageResult",
STATES: {
UNAVAILABLE: 0,
UNCONSUMED: 1,
PAGE_CONSUMED: 2,
PAGE_AND_SCRIPT_CONSUMED: 3,
FAILED: 4,
DISQUALIFIED: 5,
},
REQUEST_TYPE: {
PAGE: 0,
SCRIPT: 1,
},
_state: 0,
_consumerBCID: null,
/**
* Called via a process script very early on in the process lifetime. This
* prepares the AboutHomeStartupCacheChild to pass an nsIChannel back to
* the nsIAboutNewTabService when the initial about:home document is
* eventually requested.
*
* @param pageInputStream (nsIInputStream)
* The stream for the cached page markup.
* @param scriptInputStream (nsIInputStream)
* The stream for the cached script to run on the page.
*/
init(pageInputStream, scriptInputStream) {
if (
!IS_PRIVILEGED_PROCESS &&
!Services.prefs.getBoolPref(PREF_ABOUT_HOME_CACHE_TESTING, false)
) {
throw new Error(
"Can only instantiate in the privileged about content processes."
);
}
if (
!Services.prefs.getBoolPref(
"browser.startup.homepage.abouthome_cache.enabled"
)
) {
return;
}
if (this._initted) {
throw new Error("AboutHomeStartupCacheChild already initted.");
}
Services.obs.addObserver(this, "memory-pressure");
Services.cpmm.addMessageListener(this.CACHE_REQUEST_MESSAGE, this);
this._pageInputStream = pageInputStream;
this._scriptInputStream = scriptInputStream;
this._initted = true;
this.setState(this.STATES.UNCONSUMED);
},
/**
* A function that lets us put the AboutHomeStartupCacheChild back into
* its initial state. This is used by tests to let us simulate the startup
* behaviour of the module without having to manually launch a new privileged
* about content process every time.
*/
uninit() {
if (!Services.prefs.getBoolPref(PREF_ABOUT_HOME_CACHE_TESTING, false)) {
throw new Error(
"Cannot uninit AboutHomeStartupCacheChild unless testing."
);
}
if (!this._initted) {
return;
}
Services.obs.removeObserver(this, "memory-pressure");
Services.cpmm.removeMessageListener(this.CACHE_REQUEST_MESSAGE, this);
if (this._cacheWorker) {
this._cacheWorker.terminate();
this._cacheWorker = null;
}
this._pageInputStream = null;
this._scriptInputStream = null;
this._initted = false;
this._state = this.STATES.UNAVAILABLE;
this._consumerBCID = null;
},
/**
* A public method called from nsIAboutNewTabService that attempts
* return an nsIChannel for a cached about:home document that we
* were initialized with. If we failed to be initted with the
* cache, or the input streams that we were sent have no data
* yet available, this function returns null. The caller should
* fall back to generating the page dynamically.
*
* This function will be called when loading about:home, or
* about:home?jscache - the latter returns the cached script.
*
* It is expected that the same BrowsingContext that loads the cached
* page will also load the cached script.
*
* @param uri (nsIURI)
* The URI for the requested page, as passed by nsIAboutNewTabService.
* @param loadInfo (nsILoadInfo)
* The nsILoadInfo for the requested load, as passed by
* nsIAboutNewWTabService.
* @return nsIChannel or null.
*/
maybeGetCachedPageChannel(uri, loadInfo) {
if (!this._initted) {
return null;
}
if (this._state >= this.STATES.PAGE_AND_SCRIPT_CONSUMED) {
return null;
}
let requestType =
uri.query === "jscache"
? this.REQUEST_TYPE.SCRIPT
: this.REQUEST_TYPE.PAGE;
// If this is a page request, then we need to be in the UNCONSUMED state,
// since we expect the page request to come first. If this is a script
// request, we expect to be in PAGE_CONSUMED state, since the page cache
// stream should he been consumed already.
if (
(requestType === this.REQUEST_TYPE.PAGE &&
this._state !== this.STATES.UNCONSUMED) ||
(requestType === this.REQUEST_TYPE_SCRIPT &&
this._state !== this.STATES.PAGE_CONSUMED)
) {
return null;
}
// If by this point, we don't have anything in the streams,
// then either the cache was too slow to give us data, or the cache
// doesn't exist. The caller should fall back to generating the
// page dynamically.
//
// We only do this on the page request, because by the time
// we get to the script request, we should have already drained
// the page input stream.
if (requestType === this.REQUEST_TYPE.PAGE) {
try {
if (
!this._scriptInputStream.available() ||
!this._pageInputStream.available()
) {
this.setState(this.STATES.FAILED);
this.reportUsageResult(false /* success */);
return null;
}
} catch (e) {
this.setState(this.STATES.FAILED);
if (e.result === Cr.NS_BASE_STREAM_CLOSED) {
this.reportUsageResult(false /* success */);
return null;
}
throw e;
}
}
if (
requestType === this.REQUEST_TYPE.SCRIPT &&
this._consumerBCID !== loadInfo.browsingContextID
) {
// Some other document is somehow requesting the script - one
// that didn't originally request the page. This is not allowed.
this.setState(this.STATES.FAILED);
return null;
}
let channel = Cc[
"@mozilla.org/network/input-stream-channel;1"
].createInstance(Ci.nsIInputStreamChannel);
channel.QueryInterface(Ci.nsIChannel);
channel.setURI(uri);
channel.loadInfo = loadInfo;
channel.contentStream =
requestType === this.REQUEST_TYPE.PAGE
? this._pageInputStream
: this._scriptInputStream;
if (requestType === this.REQUEST_TYPE.SCRIPT) {
this.setState(this.STATES.PAGE_AND_SCRIPT_CONSUMED);
this.reportUsageResult(true /* success */);
} else {
this.setState(this.STATES.PAGE_CONSUMED);
// Stash the BrowsingContext ID so that when the script stream
// attempts to be consumed, we ensure that it's from the same
// BrowsingContext that loaded the page.
this._consumerBCID = loadInfo.browsingContextID;
}
return channel;
},
/**
* This function takes the state information required to generate
* the about:home cache markup and script, and then generates that
* markup in script asynchronously. Once that's done, a message
* is sent to the parent process with the nsIInputStream's for the
* markup and script contents.
*
* @param state (Object)
* The Redux state of the about:home document to render.
* @return Promise
* @resolves undefined
* After the message with the nsIInputStream's have been sent to
* the parent.
*/
async constructAndSendCache(state) {
if (!IS_PRIVILEGED_PROCESS) {
throw new Error("Wrong process type.");
}
let worker = this.getOrCreateWorker();
TelemetryStopwatch.start("FX_ABOUTHOME_CACHE_CONSTRUCTION");
let { page, script } = await worker
.post("construct", [state])
.finally(() => {
TelemetryStopwatch.finish("FX_ABOUTHOME_CACHE_CONSTRUCTION");
});
let pageInputStream = Cc[
"@mozilla.org/io/string-input-stream;1"
].createInstance(Ci.nsIStringInputStream);
pageInputStream.setUTF8Data(page);
let scriptInputStream = Cc[
"@mozilla.org/io/string-input-stream;1"
].createInstance(Ci.nsIStringInputStream);
scriptInputStream.setUTF8Data(script);
Services.cpmm.sendAsyncMessage(this.CACHE_RESPONSE_MESSAGE, {
pageInputStream,
scriptInputStream,
});
},
_cacheWorker: null,
getOrCreateWorker() {
if (this._cacheWorker) {
return this._cacheWorker;
}
this._cacheWorker = new lazy.BasePromiseWorker(CACHE_WORKER_URL);
return this._cacheWorker;
},
receiveMessage(message) {
if (message.name === this.CACHE_REQUEST_MESSAGE) {
let { state } = message.data;
this.constructAndSendCache(state);
}
},
reportUsageResult(success) {
Services.cpmm.sendAsyncMessage(this.CACHE_USAGE_RESULT_MESSAGE, {
success,
});
},
observe(subject, topic) {
if (topic === "memory-pressure" && this._cacheWorker) {
this._cacheWorker.terminate();
this._cacheWorker = null;
}
},
/**
* Transitions the AboutHomeStartupCacheChild from one state
* to the next, where each state is defined in this.STATES.
*
* States can only be transitioned in increasing order, otherwise
* an error is logged.
*/
setState(state) {
if (state > this._state) {
this._state = state;
} else {
console.error(
"AboutHomeStartupCacheChild could not transition from state " +
`${this._state} to ${state}`,
new Error().stack
);
}
},
/**
* If the cache hasn't been used, transitions it into the DISQUALIFIED
* state so that it cannot be used. This should be called if it's been
* determined that about:newtab is going to be loaded, which doesn't
* use the cache.
*/
disqualifyCache() {
if (this._state === this.STATES.UNCONSUMED) {
this.setState(this.STATES.DISQUALIFIED);
this.reportUsageResult(false /* success */);
}
},
};
/**
* This is an abstract base class for the nsIAboutNewTabService
* implementations that has some common methods and properties.
*/
class BaseAboutNewTabService {
constructor() {
if (!AppConstants.RELEASE_OR_BETA) {
XPCOMUtils.defineLazyPreferenceGetter(
this,
"activityStreamDebug",
PREF_ACTIVITY_STREAM_DEBUG,
false
);
} else {
this.activityStreamDebug = false;
}
XPCOMUtils.defineLazyPreferenceGetter(
this,
"privilegedAboutProcessEnabled",
PREF_SEPARATE_PRIVILEGEDABOUT_CONTENT_PROCESS,
false
);
this.classID = Components.ID("{cb36c925-3adc-49b3-b720-a5cc49d8a40e}");
this.QueryInterface = ChromeUtils.generateQI([
"nsIAboutNewTabService",
"nsIObserver",
]);
}
/**
* Returns the default URL.
*
* This URL depends on various activity stream prefs. Overriding
* the newtab page has no effect on the result of this function.
*/
get defaultURL() {
// Generate the desired activity stream resource depending on state, e.g.,
// "resource://activity-stream/prerendered/activity-stream.html"
// "resource://activity-stream/prerendered/activity-stream-debug.html"
// "resource://activity-stream/prerendered/activity-stream-noscripts.html"
return [
"activity-stream",
// Debug version loads dev scripts but noscripts separately loads scripts
this.activityStreamDebug && !this.privilegedAboutProcessEnabled
? "-debug"
: "",
this.privilegedAboutProcessEnabled ? "-noscripts" : "",
".html",
].join("");
}
get welcomeURL() {
/*
* Returns the about:welcome URL
*
* This is calculated in the same way the default URL is.
*/
lazy.NimbusFeatures.aboutwelcome.recordExposureEvent({ once: true });
if (lazy.NimbusFeatures.aboutwelcome.getVariable("enabled") ?? true) {
return ABOUT_WELCOME_URL;
}
return this.defaultURL;
}
aboutHomeChannel() {
throw Components.Exception(
"AboutHomeChannel not implemented for this process.",
Cr.NS_ERROR_NOT_IMPLEMENTED
);
}
}
/**
* The child-process implementation of nsIAboutNewTabService,
* which also does the work of redirecting about:home loads to
* the about:home startup cache if its available.
*/
class AboutNewTabChildService extends BaseAboutNewTabService {
aboutHomeChannel(uri, loadInfo) {
if (IS_PRIVILEGED_PROCESS) {
let cacheChannel = AboutHomeStartupCacheChild.maybeGetCachedPageChannel(
uri,
loadInfo
);
if (cacheChannel) {
return cacheChannel;
}
}
let pageURI = Services.io.newURI(this.defaultURL);
let fileChannel = Services.io.newChannelFromURIWithLoadInfo(
pageURI,
loadInfo
);
fileChannel.originalURI = uri;
return fileChannel;
}
get defaultURL() {
if (IS_PRIVILEGED_PROCESS) {
// This is a bit of a hack, but attempting to load about:newtab will
// enter this code path in order to get at the expected URL, and we
// can use that to disqualify the about:home cache, since we don't
// use it for about:newtab loads, and we don't want the about:home
// cache to be wildly out of date when about:home is eventually
// loaded (for example, in the first new window).
AboutHomeStartupCacheChild.disqualifyCache();
}
return super.defaultURL;
}
}
/**
* The AboutNewTabStubService is a function called in both the main and
* content processes when trying to get at the nsIAboutNewTabService. This
* function does the job of choosing the appropriate implementation of
* nsIAboutNewTabService for the process type.
*/
export function AboutNewTabStubService() {
if (Services.appinfo.processType === Services.appinfo.PROCESS_TYPE_DEFAULT) {
return new BaseAboutNewTabService();
}
return new AboutNewTabChildService();
}