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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
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
const EXPORTED_SYMBOLS = ["BackgroundPageThumbs"];
const DEFAULT_CAPTURE_TIMEOUT = 30000; // ms
// For testing, the above timeout is excessive, and makes our tests overlong.
const TESTING_CAPTURE_TIMEOUT = 5000; // ms
const DESTROY_BROWSER_TIMEOUT = 60000; // ms
// Let the page settle for this amount of milliseconds before capturing to allow
// for any in-page changes or redirects.
const SETTLE_WAIT_TIME = 2500;
// For testing, the above timeout is excessive, and makes our tests overlong.
const TESTING_SETTLE_WAIT_TIME = 0;
const TELEMETRY_HISTOGRAM_ID_PREFIX = "FX_THUMBNAILS_BG_";
const ABOUT_NEWTAB_SEGREGATION_PREF =
"privacy.usercontext.about_newtab_segregation.enabled";
const { PageThumbs, PageThumbsStorage } = ChromeUtils.import(
);
const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
// possible FX_THUMBNAILS_BG_CAPTURE_DONE_REASON_2 telemetry values
const TEL_CAPTURE_DONE_OK = 0;
const TEL_CAPTURE_DONE_TIMEOUT = 1;
// 2 and 3 were used when we had special handling for private-browsing.
const TEL_CAPTURE_DONE_CRASHED = 4;
const TEL_CAPTURE_DONE_BAD_URI = 5;
const TEL_CAPTURE_DONE_LOAD_FAILED = 6;
const TEL_CAPTURE_DONE_IMAGE_ZERO_DIMENSION = 7;
ChromeUtils.defineModuleGetter(
this,
"ContextualIdentityService",
);
const BackgroundPageThumbs = {
/**
* Asynchronously captures a thumbnail of the given URL.
*
* The page is loaded anonymously, and plug-ins are disabled.
*
* @param url The URL to capture.
* @param options An optional object that configures the capture. Its
* properties are the following, and all are optional:
* @opt onDone A function that will be asynchronously called when the
* capture is complete or times out. It's called as
* onDone(url),
* where `url` is the captured URL.
* @opt timeout The capture will time out after this many milliseconds have
* elapsed after the capture has progressed to the head of
* the queue and started. Defaults to 30000 (30 seconds).
* @opt isImage If true, backgroundPageThumbsContent will attempt to render
* the url directly to canvas. Note that images will mostly get
* detected and rendered as such anyway, but this will ensure it.
* @opt targetWidth The target width when capturing an image.
* @opt backgroundColor The background colour when capturing an image.
* @opt dontStore If set to true, the image blob won't be stored to disk, an
* object will instead be passed as third argument to onDone:
* {
* data: an ArrayBuffer containing the data
* contentType: the data content-type
* originalUrl: the originally requested url
* currentUrl: the final url after redirects
* }
* @opt contentType can be set to an image contentType for the capture,
* defaults to PageThumbs.contentType.
*/
capture(url, options = {}) {
if (!PageThumbs._prefEnabled()) {
if (options.onDone) {
schedule(() => options.onDone(url));
}
return;
}
this._captureQueue = this._captureQueue || [];
this._capturesByURL = this._capturesByURL || new Map();
tel("QUEUE_SIZE_ON_CAPTURE", this._captureQueue.length);
// We want to avoid duplicate captures for the same URL. If there is an
// existing one, we just add the callback to that one and we are done.
let existing = this._capturesByURL.get(url);
if (existing) {
if (options.onDone) {
existing.doneCallbacks.push(options.onDone);
}
// The queue is already being processed, so nothing else to do...
return;
}
let cap = new Capture(url, this._onCaptureOrTimeout.bind(this), options);
this._captureQueue.push(cap);
this._capturesByURL.set(url, cap);
this._processCaptureQueue();
},
/**
* Asynchronously captures a thumbnail of the given URL if one does not
* already exist. Otherwise does nothing.
*
* @param url The URL to capture.
* @param options An optional object that configures the capture. See
* capture() for description.
* unloadingPromise This option is resolved when the calling context is
* unloading, so things can be cleaned up to avoid leak.
* @return {Promise} A Promise that resolves when this task completes
*/
async captureIfMissing(url, options = {}) {
// Short circuit this function if pref is enabled, or else we leak observers.
// See Bug 1400562
if (!PageThumbs._prefEnabled()) {
if (options.onDone) {
options.onDone(url);
}
return url;
}
// The fileExistsForURL call is an optimization, potentially but unlikely
// incorrect, and no big deal when it is. After the capture is done, we
// atomically test whether the file exists before writing it.
let exists = await PageThumbsStorage.fileExistsForURL(url);
if (exists) {
if (options.onDone) {
options.onDone(url);
}
return url;
}
let thumbPromise = new Promise((resolve, reject) => {
let observe = (subject, topic, data) => {
if (data === url) {
switch (topic) {
case "page-thumbnail:create":
resolve();
break;
case "page-thumbnail:error":
reject(new Error("page-thumbnail:error"));
break;
}
cleanup();
}
};
Services.obs.addObserver(observe, "page-thumbnail:create");
Services.obs.addObserver(observe, "page-thumbnail:error");
// Make sure to clean up to avoid leaks by removing observers when
// observed or when our caller is unloading
function cleanup() {
if (observe) {
Services.obs.removeObserver(observe, "page-thumbnail:create");
Services.obs.removeObserver(observe, "page-thumbnail:error");
observe = null;
}
}
if (options.unloadingPromise) {
options.unloadingPromise.then(cleanup);
}
});
try {
this.capture(url, options);
await thumbPromise;
} catch (err) {
if (options.onDone) {
options.onDone(url);
}
throw err;
}
return url;
},
/**
* Tell the service that the thumbnail browser should be recreated at next
* call of _ensureBrowser().
*/
renewThumbnailBrowser() {
this._renewThumbBrowser = true;
},
get useFissionBrowser() {
return Services.appinfo.fissionAutostart;
},
/**
* Ensures that initialization of the thumbnail browser's parent window has
* begun.
*
* @return True if the parent window is completely initialized and can be
* used, and false if initialization has started but not completed.
*/
_ensureParentWindowReady() {
if (this._parentWin) {
// Already fully initialized.
return true;
}
if (this._startedParentWinInit) {
// Already started initializing.
return false;
}
this._startedParentWinInit = true;
// Create a windowless browser and load our hosting
// (privileged) document in it.
const flags = this.useFissionBrowser
? Ci.nsIWebBrowserChrome.CHROME_REMOTE_WINDOW |
Ci.nsIWebBrowserChrome.CHROME_FISSION_WINDOW
: 0;
let wlBrowser = Services.appShell.createWindowlessBrowser(true, flags);
wlBrowser.QueryInterface(Ci.nsIInterfaceRequestor);
let webProgress = wlBrowser.getInterface(Ci.nsIWebProgress);
this._listener = {
QueryInterface: ChromeUtils.generateQI([
"nsIWebProgressListener",
"nsIWebProgressListener2",
"nsISupportsWeakReference",
]),
};
this._listener.onStateChange = (wbp, request, stateFlags, status) => {
if (!request) {
return;
}
if (
stateFlags & Ci.nsIWebProgressListener.STATE_STOP &&
stateFlags & Ci.nsIWebProgressListener.STATE_IS_NETWORK
) {
webProgress.removeProgressListener(this._listener);
delete this._listener;
// Get the window reference via the document.
this._parentWin = wlBrowser.document.defaultView;
this._processCaptureQueue();
}
};
webProgress.addProgressListener(
this._listener,
Ci.nsIWebProgress.NOTIFY_STATE_ALL
);
let loadURIOptions = {
triggeringPrincipal: Services.scriptSecurityManager.getSystemPrincipal(),
};
wlBrowser.loadURI(
loadURIOptions
);
this._windowlessContainer = wlBrowser;
return false;
},
_init() {
Services.prefs.addObserver(ABOUT_NEWTAB_SEGREGATION_PREF, this);
Services.obs.addObserver(this, "profile-before-change");
},
observe(subject, topic, data) {
if (topic == "profile-before-change") {
this._destroy();
} else if (
topic == "nsPref:changed" &&
data == ABOUT_NEWTAB_SEGREGATION_PREF
) {
BackgroundPageThumbs.renewThumbnailBrowser();
}
},
/**
* Destroys the service. Queued and pending captures will never complete, and
* their consumer callbacks will never be called.
*/
_destroy() {
if (this._captureQueue) {
this._captureQueue.forEach(cap => cap.destroy());
}
this._destroyBrowser();
if (this._windowlessContainer) {
this._windowlessContainer.close();
}
delete this._captureQueue;
delete this._windowlessContainer;
delete this._startedParentWinInit;
delete this._parentWin;
delete this._listener;
},
QueryInterface: ChromeUtils.generateQI([
Ci.nsIWebProgressListener,
Ci.nsIWebProgressListener2,
Ci.nsISupportsWeakReference,
]),
onStateChange(wbp, request, stateFlags, status) {
if (!request || !wbp.isTopLevel) {
return;
}
if (
stateFlags & Ci.nsIWebProgressListener.STATE_STOP &&
stateFlags & Ci.nsIWebProgressListener.STATE_IS_NETWORK
) {
// If about:blank is being loaded after a capture, move on
// to the next capture, otherwise ignore about:blank loads.
if (
request instanceof Ci.nsIChannel &&
request.URI.spec == "about:blank"
) {
if (this._expectingAboutBlank) {
this._expectingAboutBlank = false;
if (this._captureQueue.length) {
this._processCaptureQueue();
}
}
return;
}
if (!this._captureQueue.length) {
return;
}
let currentCapture = this._captureQueue[0];
if (
Components.isSuccessCode(status) ||
status === Cr.NS_BINDING_ABORTED
) {
this._thumbBrowser.ownerGlobal.requestIdleCallback(() => {
currentCapture.pageLoaded(this._thumbBrowser);
});
} else {
currentCapture._done(
this._thumbBrowser,
null,
currentCapture.timedOut
? TEL_CAPTURE_DONE_TIMEOUT
: TEL_CAPTURE_DONE_LOAD_FAILED
);
}
}
},
/**
* Creates the thumbnail browser if it doesn't already exist.
*/
_ensureBrowser() {
if (this._thumbBrowser && !this._renewThumbBrowser) {
return;
}
this._destroyBrowser();
this._renewThumbBrowser = false;
let browser = this._parentWin.document.createXULElement("browser");
browser.setAttribute("type", "content");
browser.setAttribute("remote", "true");
if (this.useFissionBrowser) {
browser.setAttribute("maychangeremoteness", "true");
}
browser.setAttribute("disableglobalhistory", "true");
browser.setAttribute("messagemanagergroup", "thumbnails");
if (Services.prefs.getBoolPref(ABOUT_NEWTAB_SEGREGATION_PREF)) {
// Use the private container for thumbnails.
let privateIdentity = ContextualIdentityService.getPrivateIdentity(
"userContextIdInternal.thumbnail"
);
browser.setAttribute("usercontextid", privateIdentity.userContextId);
}
// Size the browser. Make its aspect ratio the same as the canvases' that
// the thumbnails are drawn into; the canvases' aspect ratio is the same as
// the screen's, so use that. Aim for a size in the ballpark of 1024x768.
let [swidth, sheight] = [{}, {}];
Cc["@mozilla.org/gfx/screenmanager;1"]
.getService(Ci.nsIScreenManager)
.primaryScreen.GetRectDisplayPix({}, {}, swidth, sheight);
let bwidth = Math.min(1024, swidth.value);
// Setting the width and height attributes doesn't work -- the resulting
// thumbnails are blank and transparent -- but setting the style does.
browser.style.width = bwidth + "px";
browser.style.height = (bwidth * sheight.value) / swidth.value + "px";
browser.style.colorScheme = "env(-moz-content-preferred-color-scheme)";
this._parentWin.document.documentElement.appendChild(browser);
browser.addProgressListener(this, Ci.nsIWebProgress.NOTIFY_STATE_WINDOW);
browser.mute();
// an event that is sent if the remote process crashes - no need to remove
// it as we want it to be there as long as the browser itself lives.
browser.addEventListener("oop-browser-crashed", event => {
if (!event.isTopFrame) {
// It was a subframe that crashed. We'll ignore this.
return;
}
Cu.reportError(
"BackgroundThumbnails remote process crashed - recovering"
);
this._destroyBrowser();
let curCapture = this._captureQueue.length ? this._captureQueue[0] : null;
// we could retry the pending capture, but it's possible the crash
// was due directly to it, so trying again might just crash again.
// We could keep a flag to indicate if it previously crashed, but
// "resetting" the capture requires more work - so for now, we just
// discard it.
if (curCapture) {
// Continue queue processing by calling curCapture._done(). Do it after
// this crashed listener returns, though. A new browser will be created
// immediately (on the same stack as the _done call stack) if there are
// any more queued-up captures, and that seems to mess up the new
// browser's message manager if it happens on the same stack as the
// listener. Trying to send a message to the manager in that case
// throws NS_ERROR_NOT_INITIALIZED.
Services.tm.dispatchToMainThread(() => {
curCapture._done(browser, null, TEL_CAPTURE_DONE_CRASHED);
});
}
// else: we must have been idle and not currently doing a capture (eg,
// maybe a GC or similar crashed) - so there's no need to attempt a
// queue restart - the next capture request will set everything up.
});
this._thumbBrowser = browser;
browser.docShellIsActive = false;
},
_destroyBrowser() {
if (!this._thumbBrowser) {
return;
}
this._expectingAboutBlank = false;
this._thumbBrowser.remove();
delete this._thumbBrowser;
},
async _loadAboutBlank() {
if (this._expectingAboutBlank) {
return;
}
this._expectingAboutBlank = true;
let loadURIOptions = {
triggeringPrincipal: Services.scriptSecurityManager.getSystemPrincipal(),
loadFlags: Ci.nsIWebNavigation.LOAD_FLAGS_STOP_CONTENT,
};
this._thumbBrowser.loadURI("about:blank", loadURIOptions);
},
/**
* Starts the next capture if the queue is not empty and the service is fully
* initialized.
*/
_processCaptureQueue() {
if (!this._captureQueue.length) {
if (this._thumbBrowser) {
BackgroundPageThumbs._loadAboutBlank();
}
return;
}
if (
this._captureQueue[0].pending ||
!this._ensureParentWindowReady() ||
this._expectingAboutBlank
) {
return;
}
// Ready to start the first capture in the queue.
this._ensureBrowser();
this._captureQueue[0].start(this._thumbBrowser);
if (this._destroyBrowserTimer) {
this._destroyBrowserTimer.cancel();
delete this._destroyBrowserTimer;
}
},
/**
* Called when the current capture completes or fails (eg, times out, remote
* process crashes.)
*/
_onCaptureOrTimeout(capture, reason) {
// Since timeouts start as an item is being processed, only the first
// item in the queue can be passed to this method.
if (capture !== this._captureQueue[0]) {
throw new Error("The capture should be at the head of the queue.");
}
this._captureQueue.shift();
this._capturesByURL.delete(capture.url);
if (reason != TEL_CAPTURE_DONE_OK) {
Services.obs.notifyObservers(null, "page-thumbnail:error", capture.url);
}
// Start the destroy-browser timer *before* processing the capture queue.
let timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
timer.initWithCallback(
this._destroyBrowser.bind(this),
this._destroyBrowserTimeout,
Ci.nsITimer.TYPE_ONE_SHOT
);
this._destroyBrowserTimer = timer;
this._processCaptureQueue();
},
_destroyBrowserTimeout: DESTROY_BROWSER_TIMEOUT,
};
BackgroundPageThumbs._init();
Object.defineProperty(this, "BackgroundPageThumbs", {
value: BackgroundPageThumbs,
enumerable: true,
writable: false,
});
/**
* Represents a single capture request in the capture queue.
*
* @param url The URL to capture.
* @param captureCallback A function you want called when the capture
* completes.
* @param options The capture options.
*/
function Capture(url, captureCallback, options) {
this.url = url;
this.captureCallback = captureCallback;
this.redirectTimer = null;
this.timedOut = false;
this.options = options;
this.id = Capture.nextID++;
this.creationDate = new Date();
this.doneCallbacks = [];
if (options.onDone) {
this.doneCallbacks.push(options.onDone);
}
}
Capture.prototype = {
get pending() {
return !!this._timeoutTimer;
},
/**
* Sends a message to the content script to start the capture.
*
* @param browser The thumbnail browser.
*/
start(browser) {
this.startDate = new Date();
tel("CAPTURE_QUEUE_TIME_MS", this.startDate - this.creationDate);
let fallbackTimeout = Cu.isInAutomation
? TESTING_CAPTURE_TIMEOUT
: DEFAULT_CAPTURE_TIMEOUT;
// timeout timer
let timeout =
typeof this.options.timeout == "number"
? this.options.timeout
: fallbackTimeout;
this._timeoutTimer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
this._timeoutTimer.initWithCallback(
this,
timeout,
Ci.nsITimer.TYPE_ONE_SHOT
);
this._browser = browser;
if (!browser.browsingContext) {
return;
}
this._pageLoadStartTime = new Date();
BackgroundPageThumbs._expectingAboutBlank = false;
let thumbnailsActor = browser.browsingContext.currentWindowGlobal.getActor(
"BackgroundThumbnails"
);
thumbnailsActor
.sendQuery("Browser:Thumbnail:LoadURL", {
url: this.url,
})
.then(
success => {
// If it failed, then this was likely a bad url. If successful,
// BackgroundPageThumbs.onStateChange will call _done() after the
// load has completed.
if (!success) {
this._done(browser, null, TEL_CAPTURE_DONE_BAD_URI);
}
},
failure => {
// The query can fail when a crash occurs while loading. The error causes
// thumbnail crash tests to fail with an uninteresting error message.
}
);
},
readBlob: function readBlob(blob) {
return new Promise((resolve, reject) => {
let reader = new FileReader();
reader.onloadend = function onloadend() {
if (reader.readyState != FileReader.DONE) {
reject(reader.error);
} else {
resolve(reader.result);
}
};
reader.readAsArrayBuffer(blob);
});
},
async pageLoaded(aBrowser) {
if (this.timedOut) {
this._done(aBrowser, null, TEL_CAPTURE_DONE_TIMEOUT);
return;
}
let waitTime = Cu.isInAutomation
? TESTING_SETTLE_WAIT_TIME
: SETTLE_WAIT_TIME;
// There was additional activity, so restart the wait timer
if (this.redirectTimer) {
this.redirectTimer.delay = waitTime;
return;
}
// The requested page has loaded or stopped/aborted, so capture the page
// soon but first let it settle in case of in-page redirects
await new Promise(resolve => {
this.redirectTimer = Cc["@mozilla.org/timer;1"].createInstance(
Ci.nsITimer
);
this.redirectTimer.init(resolve, waitTime, Ci.nsITimer.TYPE_ONE_SHOT);
});
this.redirectTimer = null;
let pageLoadTime = new Date() - this._pageLoadStartTime;
let canvasDrawStartTime = new Date();
let canvas = PageThumbs.createCanvas(aBrowser.ownerGlobal, 1, 1);
try {
await PageThumbs.captureToCanvas(
aBrowser,
canvas,
{
isBackgroundThumb: true,
isImage: this.options.isImage,
backgroundColor: this.options.backgroundColor,
},
true
);
} catch (ex) {
this._done(
aBrowser,
null,
ex == "IMAGE_ZERO_DIMENSION"
? TEL_CAPTURE_DONE_IMAGE_ZERO_DIMENSION
: TEL_CAPTURE_DONE_LOAD_FAILED
);
return;
}
let canvasDrawTime = new Date() - canvasDrawStartTime;
let contentType =
(this.options.dontStore && this.options.contentType) ||
PageThumbs.contentType;
let imageData = await new Promise(resolve => {
canvas.toBlob(blob => {
resolve(blob, contentType);
}, contentType);
});
this._done(aBrowser, imageData, TEL_CAPTURE_DONE_OK, {
CAPTURE_PAGE_LOAD_TIME_MS: pageLoadTime,
CAPTURE_CANVAS_DRAW_TIME_MS: canvasDrawTime,
});
},
/**
* The only intended external use of this method is by the service when it's
* uninitializing and doing things like destroying the thumbnail browser. In
* that case the consumer's completion callback will never be called.
*/
destroy() {
// This method may be called for captures that haven't started yet, so
// guard against not yet having _timeoutTimer, _msgMan etc properties...
if (this._timeoutTimer) {
this._timeoutTimer.cancel();
delete this._timeoutTimer;
}
delete this.captureCallback;
delete this.doneCallbacks;
delete this.options;
},
// Called when the timeout timer fires.
notify() {
this.timedOut = true;
this._browser.stop();
},
_done(browser, imageData, reason, telemetry) {
// Note that _done will be called only once, by either receiveMessage or
// notify, since it calls destroy here, which cancels the timeout timer and
// removes the didCapture message listener.
let { captureCallback, doneCallbacks, options } = this;
this.destroy();
if (typeof reason != "number") {
throw new Error("A done reason must be given.");
}
tel("CAPTURE_DONE_REASON_2", reason);
if (telemetry) {
// Telemetry is currently disabled in the content process (bug 680508).
for (let id in telemetry) {
tel(id, telemetry[id]);
}
}
let done = (info = null) => {
captureCallback(this, reason);
for (let callback of doneCallbacks) {
try {
callback.call(options, this.url, reason, info);
} catch (err) {
Cu.reportError(err);
}
}
if (Services.prefs.getBoolPref(ABOUT_NEWTAB_SEGREGATION_PREF)) {
// Clear the data in the private container for thumbnails.
let privateIdentity = ContextualIdentityService.getPrivateIdentity(
"userContextIdInternal.thumbnail"
);
if (privateIdentity) {
Services.clearData.deleteDataFromOriginAttributesPattern({
userContextId: privateIdentity.userContextId,
});
}
}
};
if (!imageData) {
done();
return;
}
this.readBlob(imageData).then(buffer => {
if (options.dontStore) {
done({
data: buffer,
originalUrl: this.url,
finalUrl: browser.currentURI.spec,
contentType: options.contentType || PageThumbs.contentType,
});
} else {
PageThumbs._store(this.url, browser.currentURI.spec, buffer, true).then(
done,
done
);
}
});
},
};
Capture.nextID = 0;
/**
* Adds a value to one of this module's telemetry histograms.
*
* @param histogramID This is prefixed with this module's ID.
* @param value The value to add.
*/
function tel(histogramID, value) {
let id = TELEMETRY_HISTOGRAM_ID_PREFIX + histogramID;
Services.telemetry.getHistogramById(id).add(value);
}
function schedule(callback) {
Services.tm.dispatchToMainThread(callback);
}