/* 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/. */ "use strict"; this.EXPORTED_SYMBOLS = ["BrowserNewTabPreloader"]; const Cu = Components.utils; const Cc = Components.classes; const Ci = Components.interfaces; Cu.import("resource://gre/modules/Services.jsm"); Cu.import("resource://gre/modules/XPCOMUtils.jsm"); Cu.import("resource://gre/modules/Promise.jsm"); const HTML_NS = "http://www.w3.org/1999/xhtml"; const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"; const XUL_PAGE = "data:application/vnd.mozilla.xul+xml;charset=utf-8,<window%20id='win'/>"; const NEWTAB_URL = "about:newtab"; const PREF_BRANCH = "browser.newtab."; // The interval between swapping in a preload docShell and kicking off the // next preload in the background. const PRELOADER_INTERVAL_MS = 600; // The initial delay before we start preloading our first new tab page. The // timer is started after the first 'browser-delayed-startup' has been sent. const PRELOADER_INIT_DELAY_MS = 5000; // The number of miliseconds we'll wait after we received a notification that // causes us to update our list of browsers and tabbrowser sizes. This acts as // kind of a damper when too many events are occuring in quick succession. const PRELOADER_UPDATE_DELAY_MS = 3000; const TOPIC_TIMER_CALLBACK = "timer-callback"; const TOPIC_DELAYED_STARTUP = "browser-delayed-startup-finished"; const TOPIC_XUL_WINDOW_CLOSED = "xul-window-destroyed"; function createTimer(obj, delay) { let timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer); timer.init(obj, delay, Ci.nsITimer.TYPE_ONE_SHOT); return timer; } function clearTimer(timer) { if (timer) { timer.cancel(); } return null; } this.BrowserNewTabPreloader = { init: function Preloader_init() { Initializer.start(); }, uninit: function Preloader_uninit() { Initializer.stop(); HostFrame.destroy(); Preferences.uninit(); HiddenBrowsers.uninit(); }, newTab: function Preloader_newTab(aTab) { let win = aTab.ownerDocument.defaultView; if (win.gBrowser) { let utils = win.QueryInterface(Ci.nsIInterfaceRequestor) .getInterface(Ci.nsIDOMWindowUtils); let {width, height} = utils.getBoundsWithoutFlushing(win.gBrowser); let hiddenBrowser = HiddenBrowsers.get(width, height) if (hiddenBrowser) { return hiddenBrowser.swapWithNewTab(aTab); } } return false; } }; Object.freeze(BrowserNewTabPreloader); let Initializer = { _timer: null, _observing: false, start: function Initializer_start() { Services.obs.addObserver(this, TOPIC_DELAYED_STARTUP, false); this._observing = true; }, stop: function Initializer_stop() { this._timer = clearTimer(this._timer); if (this._observing) { Services.obs.removeObserver(this, TOPIC_DELAYED_STARTUP); this._observing = false; } }, observe: function Initializer_observe(aSubject, aTopic, aData) { if (aTopic == TOPIC_DELAYED_STARTUP) { Services.obs.removeObserver(this, TOPIC_DELAYED_STARTUP); this._observing = false; this._startTimer(); } else if (aTopic == TOPIC_TIMER_CALLBACK) { this._timer = null; this._startPreloader(); } }, _startTimer: function Initializer_startTimer() { this._timer = createTimer(this, PRELOADER_INIT_DELAY_MS); }, _startPreloader: function Initializer_startPreloader() { Preferences.init(); if (Preferences.enabled) { HiddenBrowsers.init(); } } }; let Preferences = { _enabled: null, _branch: null, get enabled() { if (this._enabled === null) { this._enabled = this._branch.getBoolPref("preload") && !this._branch.prefHasUserValue("url"); } return this._enabled; }, init: function Preferences_init() { this._branch = Services.prefs.getBranch(PREF_BRANCH); this._branch.addObserver("", this, false); }, uninit: function Preferences_uninit() { if (this._branch) { this._branch.removeObserver("", this); this._branch = null; } }, observe: function Preferences_observe() { let prevEnabled = this._enabled; this._enabled = null; if (prevEnabled && !this.enabled) { HiddenBrowsers.uninit(); } else if (!prevEnabled && this.enabled) { HiddenBrowsers.init(); } }, }; let HiddenBrowsers = { _browsers: null, _updateTimer: null, _topics: [ TOPIC_DELAYED_STARTUP, TOPIC_XUL_WINDOW_CLOSED ], init: function () { this._browsers = new Map(); this._updateBrowserSizes(); this._topics.forEach(t => Services.obs.addObserver(this, t, false)); }, uninit: function () { if (this._browsers) { this._topics.forEach(t => Services.obs.removeObserver(this, t, false)); this._updateTimer = clearTimer(this._updateTimer); for (let [key, browser] of this._browsers) { browser.destroy(); } this._browsers = null; } }, get: function (width, height) { // We haven't been initialized, yet. if (!this._browsers) { return null; } let key = width + "x" + height; if (!this._browsers.has(key)) { // Update all browsers' sizes if we can't find a matching one. this._updateBrowserSizes(); } // We should now have a matching browser. if (this._browsers.has(key)) { return this._browsers.get(key); } // We should never be here. Return the first browser we find. Cu.reportError("NewTabPreloader: no matching browser found after updating"); for (let [size, browser] of this._browsers) { return browser; } // We should really never be here. Cu.reportError("NewTabPreloader: not even a single browser was found?"); return null; }, observe: function (subject, topic, data) { if (topic === TOPIC_TIMER_CALLBACK) { this._updateTimer = null; this._updateBrowserSizes(); } else { this._updateTimer = clearTimer(this._updateTimer); this._updateTimer = createTimer(this, PRELOADER_UPDATE_DELAY_MS); } }, _updateBrowserSizes: function () { let sizes = this._collectTabBrowserSizes(); let toRemove = []; // Iterate all browsers and check that they // each can be assigned to one of the sizes. for (let [key, browser] of this._browsers) { if (sizes.has(key)) { // We already have a browser for that size, great! sizes.delete(key); } else { // This browser is superfluous or needs to be resized. toRemove.push(browser); this._browsers.delete(key); } } // Iterate all sizes that we couldn't find a browser for. for (let [key, {width, height}] of sizes) { let browser; if (toRemove.length) { // Let's just resize one of the superfluous // browsers and put it back into the map. browser = toRemove.shift(); browser.resize(width, height); } else { // No more browsers to reuse, create a new one. browser = new HiddenBrowser(width, height); } this._browsers.set(key, browser); } // Finally, remove all browsers we don't need anymore. toRemove.forEach(b => b.destroy()); }, _collectTabBrowserSizes: function () { let sizes = new Map(); function tabBrowserBounds() { let wins = Services.ww.getWindowEnumerator("navigator:browser"); while (wins.hasMoreElements()) { let win = wins.getNext(); if (win.gBrowser) { let utils = win.QueryInterface(Ci.nsIInterfaceRequestor) .getInterface(Ci.nsIDOMWindowUtils); yield utils.getBoundsWithoutFlushing(win.gBrowser); } } } // Collect the sizes of all <tabbrowser>s out there. for (let {width, height} of tabBrowserBounds()) { if (width > 0 && height > 0) { let key = width + "x" + height; if (!sizes.has(key)) { sizes.set(key, {width: width, height: height}); } } } return sizes; } }; function HiddenBrowser(width, height) { this.resize(width, height); HostFrame.get().then(aFrame => { let doc = aFrame.document; this._browser = doc.createElementNS(XUL_NS, "browser"); this._browser.setAttribute("type", "content"); this._browser.setAttribute("src", NEWTAB_URL); this._applySize(); doc.getElementById("win").appendChild(this._browser); }); } HiddenBrowser.prototype = { _width: null, _height: null, _timer: null, _needsFrameScripts: true, get isPreloaded() { return this._browser && this._browser.contentDocument && this._browser.contentDocument.readyState === "complete" && this._browser.currentURI.spec === NEWTAB_URL; }, swapWithNewTab: function (aTab) { if (!this.isPreloaded || this._timer) { return false; } let win = aTab.ownerDocument.defaultView; let tabbrowser = win.gBrowser; if (!tabbrowser) { return false; } // Swap docShells. tabbrowser.swapNewTabWithBrowser(aTab, this._browser); // Load all default frame scripts. if (this._needsFrameScripts) { this._needsFrameScripts = false; let mm = aTab.linkedBrowser.messageManager; mm.loadFrameScript("chrome://browser/content/content.js", true); mm.loadFrameScript("chrome://browser/content/content-sessionStore.js", true); if ("TabView" in win) { mm.loadFrameScript("chrome://browser/content/tabview-content.js", true); } } // Start a timer that will kick off preloading the next newtab page. this._timer = createTimer(this, PRELOADER_INTERVAL_MS); // Signal that we swapped docShells. return true; }, observe: function () { this._timer = null; // Start pre-loading the new tab page. this._browser.loadURI(NEWTAB_URL); }, resize: function (width, height) { this._width = width; this._height = height; this._applySize(); }, _applySize: function () { if (this._browser) { this._browser.style.width = this._width + "px"; this._browser.style.height = this._height + "px"; } }, destroy: function () { if (this._browser) { this._browser.remove(); this._browser = null; } this._timer = clearTimer(this._timer); } }; let HostFrame = { _frame: null, _deferred: null, get hiddenDOMDocument() { return Services.appShell.hiddenDOMWindow.document; }, get isReady() { return this.hiddenDOMDocument.readyState === "complete"; }, get: function () { if (!this._deferred) { this._deferred = Promise.defer(); this._create(); } return this._deferred.promise; }, destroy: function () { if (this._frame) { if (!Cu.isDeadWrapper(this._frame)) { this._frame.removeEventListener("load", this, true); this._frame.remove(); } this._frame = null; this._deferred = null; } }, handleEvent: function () { let contentWindow = this._frame.contentWindow; if (contentWindow.location.href === XUL_PAGE) { this._frame.removeEventListener("load", this, true); this._deferred.resolve(contentWindow); } else { contentWindow.location = XUL_PAGE; } }, _create: function () { if (this.isReady) { let doc = this.hiddenDOMDocument; this._frame = doc.createElementNS(HTML_NS, "iframe"); this._frame.addEventListener("load", this, true); doc.documentElement.appendChild(this._frame); } else { let flags = Ci.nsIThread.DISPATCH_NORMAL; Services.tm.currentThread.dispatch(() => this._create(), flags); } } };