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/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
* 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
const lazy = {};
ChromeUtils.defineESModuleGetters(lazy, {
});
XPCOMUtils.defineLazyPreferenceGetter(
lazy,
"gTabWarmingEnabled",
"browser.tabs.remote.warmup.enabled"
);
XPCOMUtils.defineLazyPreferenceGetter(
lazy,
"gTabWarmingMax",
"browser.tabs.remote.warmup.maxTabs"
);
XPCOMUtils.defineLazyPreferenceGetter(
lazy,
"gTabWarmingUnloadDelayMs",
"browser.tabs.remote.warmup.unloadDelayMs"
);
XPCOMUtils.defineLazyPreferenceGetter(
lazy,
"gTabCacheSize",
"browser.tabs.remote.tabCacheSize"
);
XPCOMUtils.defineLazyPreferenceGetter(
lazy,
"gTabUnloadDelay",
"browser.tabs.remote.unloadDelayMs",
300
);
/**
* The tab switcher is responsible for asynchronously switching
* tabs in e10s. It waits until the new tab is ready (i.e., the
* layer tree is available) before switching to it. Then it
* unloads the layer tree for the old tab.
*
* The tab switcher is a state machine. For each tab, it
* maintains state about whether the layer tree for the tab is
* available, being loaded, being unloaded, or unavailable. It
* also keeps track of the tab currently being displayed, the tab
* it's trying to load, and the tab the user has asked to switch
* to. The switcher object is created upon tab switch. It is
* released when there are no pending tabs to load or unload.
*
* The following general principles have guided the design:
*
* 1. We only request one layer tree at a time. If the user
* switches to a different tab while waiting, we don't request
* the new layer tree until the old tab has loaded or timed out.
*
* 2. If loading the layers for a tab times out, we show the
* spinner and possibly request the layer tree for another tab if
* the user has requested one.
*
* 3. We discard layer trees on a delay. This way, if the user is
* switching among the same tabs frequently, we don't continually
* load the same tabs.
*
* It's important that we always show either the spinner or a tab
* whose layers are available. Otherwise the compositor will draw
* an entirely black frame, which is very jarring. To ensure this
* never happens when switching away from a tab, we assume the
* old tab might still be drawn until a MozAfterPaint event
* occurs. Because layout and compositing happen asynchronously,
* we don't have any other way of knowing when the switch
* actually takes place. Therefore, we don't unload the old tab
* until the next MozAfterPaint event.
*/
export class AsyncTabSwitcher {
constructor(tabbrowser) {
this.log("START");
// How long to wait for a tab's layers to load. After this
// time elapses, we're free to put up the spinner and start
// trying to load a different tab.
this.TAB_SWITCH_TIMEOUT = 400; // ms
// When the user hasn't switched tabs for this long, we unload
// layers for all tabs that aren't in use.
this.UNLOAD_DELAY = lazy.gTabUnloadDelay; // ms
// The next three tabs form the principal state variables.
// See the assertions in postActions for their invariants.
// Tab the user requested most recently.
this.requestedTab = tabbrowser.selectedTab;
// Tab we're currently trying to load.
this.loadingTab = null;
// We show this tab in case the requestedTab hasn't loaded yet.
this.lastVisibleTab = tabbrowser.selectedTab;
// Auxilliary state variables:
this.visibleTab = tabbrowser.selectedTab; // Tab that's on screen.
this.spinnerTab = null; // Tab showing a spinner.
this.blankTab = null; // Tab showing blank.
this.lastPrimaryTab = tabbrowser.selectedTab; // Tab with primary="true"
this.tabbrowser = tabbrowser;
this.window = tabbrowser.ownerGlobal;
this.loadTimer = null; // TAB_SWITCH_TIMEOUT nsITimer instance.
this.unloadTimer = null; // UNLOAD_DELAY nsITimer instance.
// Map from tabs to STATE_* (below).
this.tabState = new Map();
// True if we're in the midst of switching tabs.
this.switchInProgress = false;
// Transaction id for the composite that will show the requested
// tab for the first tab after a tab switch.
// Set to -1 when we're not waiting for notification of a
// completed switch.
this.switchPaintId = -1;
// Set of tabs that might be visible right now. We maintain
// this set because we can't be sure when a tab is actually
// drawn. A tab is added to this set when we ask to make it
// visible. All tabs but the most recently shown tab are
// removed from the set upon MozAfterPaint.
this.maybeVisibleTabs = new Set([tabbrowser.selectedTab]);
// This holds onto the set of tabs that we've been asked to warm up,
// and tabs are evicted once they're done loading or are unloaded.
this.warmingTabs = new WeakSet();
this.STATE_UNLOADED = 0;
this.STATE_LOADING = 1;
this.STATE_LOADED = 2;
this.STATE_UNLOADING = 3;
// re-entrancy guard:
this._processing = false;
// For telemetry, keeps track of what most recently cleared
// the loadTimer, which can tell us something about the cause
// of tab switch spinners.
this._loadTimerClearedBy = "none";
this._useDumpForLogging = false;
this._logInit = false;
this._logFlags = [];
this.window.addEventListener("MozAfterPaint", this);
this.window.addEventListener("MozLayerTreeReady", this);
this.window.addEventListener("MozLayerTreeCleared", this);
this.window.addEventListener("TabRemotenessChange", this);
this.window.addEventListener("SwapDocShells", this, true);
this.window.addEventListener("EndSwapDocShells", this, true);
this.window.document.addEventListener("visibilitychange", this);
let initialTab = this.requestedTab;
let initialBrowser = initialTab.linkedBrowser;
let tabIsLoaded =
!initialBrowser.isRemoteBrowser ||
initialBrowser.frameLoader.remoteTab?.hasLayers;
// If we minimized the window before the switcher was activated,
// we might have set the preserveLayers flag for the current
// browser. Let's clear it.
initialBrowser.preserveLayers(false);
if (!this.windowHidden) {
this.log("Initial tab is loaded?: " + tabIsLoaded);
this.setTabState(
initialTab,
tabIsLoaded ? this.STATE_LOADED : this.STATE_LOADING
);
}
for (let ppBrowser of this.tabbrowser._printPreviewBrowsers) {
let ppTab = this.tabbrowser.getTabForBrowser(ppBrowser);
let state = ppBrowser.hasLayers ? this.STATE_LOADED : this.STATE_LOADING;
this.setTabState(ppTab, state);
}
}
destroy() {
if (this.unloadTimer) {
this.clearTimer(this.unloadTimer);
this.unloadTimer = null;
}
if (this.loadTimer) {
this.clearTimer(this.loadTimer);
this.loadTimer = null;
}
this.window.removeEventListener("MozAfterPaint", this);
this.window.removeEventListener("MozLayerTreeReady", this);
this.window.removeEventListener("MozLayerTreeCleared", this);
this.window.removeEventListener("TabRemotenessChange", this);
this.window.removeEventListener("SwapDocShells", this, true);
this.window.removeEventListener("EndSwapDocShells", this, true);
this.window.document.removeEventListener("visibilitychange", this);
this.tabbrowser._switcher = null;
}
// Wraps nsITimer. Must not use the vanilla setTimeout and
// clearTimeout, because they will be blocked by nsIPromptService
// dialogs.
setTimer(callback, timeout) {
let event = {
notify: callback,
};
var timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
timer.initWithCallback(event, timeout, Ci.nsITimer.TYPE_ONE_SHOT);
return timer;
}
clearTimer(timer) {
timer.cancel();
}
getTabState(tab) {
let state = this.tabState.get(tab);
// As an optimization, we lazily evaluate the state of tabs
// that we've never seen before. Once we've figured it out,
// we stash it in our state map.
if (state === undefined) {
state = this.STATE_UNLOADED;
if (tab && tab.linkedPanel) {
let b = tab.linkedBrowser;
if (b.renderLayers && b.hasLayers) {
state = this.STATE_LOADED;
} else if (b.renderLayers && !b.hasLayers) {
state = this.STATE_LOADING;
} else if (!b.renderLayers && b.hasLayers) {
state = this.STATE_UNLOADING;
}
}
this.setTabStateNoAction(tab, state);
}
return state;
}
setTabStateNoAction(tab, state) {
if (state == this.STATE_UNLOADED) {
this.tabState.delete(tab);
} else {
this.tabState.set(tab, state);
}
}
setTabState(tab, state) {
if (state == this.getTabState(tab)) {
return;
}
this.setTabStateNoAction(tab, state);
let browser = tab.linkedBrowser;
let { remoteTab } = browser.frameLoader;
if (state == this.STATE_LOADING) {
this.assert(!this.windowHidden);
// If we're not in the process of warming this tab, we
// don't need to delay activating its DocShell.
if (!this.warmingTabs.has(tab)) {
browser.docShellIsActive = true;
}
if (remoteTab) {
browser.renderLayers = true;
remoteTab.priorityHint = true;
}
if (browser.hasLayers) {
this.onLayersReady(browser);
}
} else if (state == this.STATE_UNLOADING) {
this.unwarmTab(tab);
// Setting the docShell to be inactive will also cause it
// to stop rendering layers.
browser.docShellIsActive = false;
if (remoteTab) {
remoteTab.priorityHint = false;
}
if (!browser.hasLayers) {
this.onLayersCleared(browser);
}
} else if (state == this.STATE_LOADED) {
this.maybeActivateDocShell(tab);
}
if (!tab.linkedBrowser.isRemoteBrowser) {
// setTabState is potentially re-entrant, so we must re-get the state for
// this assertion.
let nonRemoteState = this.getTabState(tab);
// Non-remote tabs can never stay in the STATE_LOADING
// or STATE_UNLOADING states. By the time this function
// exits, a non-remote tab must be in STATE_LOADED or
// STATE_UNLOADED, since the painting and the layer
// upload happen synchronously.
this.assert(
nonRemoteState == this.STATE_UNLOADED ||
nonRemoteState == this.STATE_LOADED
);
}
}
get windowHidden() {
return this.window.document.hidden;
}
get tabLayerCache() {
return this.tabbrowser._tabLayerCache;
}
finish() {
this.log("FINISH");
this.assert(this.tabbrowser._switcher);
this.assert(this.tabbrowser._switcher === this);
this.assert(!this.spinnerTab);
this.assert(!this.blankTab);
this.assert(!this.loadTimer);
this.assert(!this.loadingTab);
this.assert(this.lastVisibleTab === this.requestedTab);
this.assert(
this.windowHidden ||
this.getTabState(this.requestedTab) == this.STATE_LOADED
);
this.destroy();
this.window.document.commandDispatcher.unlock();
let event = new this.window.CustomEvent("TabSwitchDone", {
bubbles: true,
cancelable: true,
});
this.tabbrowser.dispatchEvent(event);
}
// This function is called after all the main state changes to
// make sure we display the right tab.
updateDisplay() {
let requestedTabState = this.getTabState(this.requestedTab);
let requestedBrowser = this.requestedTab.linkedBrowser;
// It is often more desirable to show a blank tab when appropriate than
// the tab switch spinner - especially since the spinner is usually
// preceded by a perceived lag of TAB_SWITCH_TIMEOUT ms in the
// tab switch. We can hide this lag, and hide the time being spent
// constructing BrowserChild's, layer trees, etc, by showing a blank
// tab instead and focusing it immediately.
let shouldBeBlank = false;
if (requestedBrowser.isRemoteBrowser) {
// If a tab is remote and the window is not minimized, we can show a
// blank tab instead of a spinner in the following cases:
//
// 1. The tab has just crashed, and we haven't started showing the
// tab crashed page yet (in this case, the RemoteTab is null)
// 2. The tab has never presented, and has not finished loading
// a non-local-about: page.
//
// For (2), "finished loading a non-local-about: page" is
// determined by the busy state on the tab element and checking
// if the loaded URI is local.
let isBusy = this.requestedTab.hasAttribute("busy");
let isLocalAbout = requestedBrowser.currentURI.schemeIs("about");
let hasSufficientlyLoaded = !isBusy && !isLocalAbout;
let fl = requestedBrowser.frameLoader;
shouldBeBlank =
!this.windowHidden &&
(!fl.remoteTab ||
(!hasSufficientlyLoaded && !fl.remoteTab.hasPresented));
if (this.logging()) {
let flag = shouldBeBlank ? "blank" : "nonblank";
this.addLogFlag(
flag,
this.windowHidden,
fl.remoteTab,
isBusy,
isLocalAbout,
fl.remoteTab ? fl.remoteTab.hasPresented : 0
);
}
}
if (requestedBrowser.isRemoteBrowser) {
this.addLogFlag("isRemote");
}
// Figure out which tab we actually want visible right now.
let showTab = null;
if (
requestedTabState != this.STATE_LOADED &&
this.lastVisibleTab &&
this.loadTimer &&
!shouldBeBlank
) {
// If we can't show the requestedTab, and lastVisibleTab is
// available, show it.
showTab = this.lastVisibleTab;
} else {
// Show the requested tab. If it's not available, we'll show the spinner or a blank tab.
showTab = this.requestedTab;
}
// First, let's deal with blank tabs, which we show instead
// of the spinner when the tab is not currently set up
// properly in the content process.
if (!shouldBeBlank && this.blankTab) {
this.blankTab.linkedBrowser.removeAttribute("blank");
this.blankTab = null;
} else if (shouldBeBlank && this.blankTab !== showTab) {
if (this.blankTab) {
this.blankTab.linkedBrowser.removeAttribute("blank");
}
this.blankTab = showTab;
this.blankTab.linkedBrowser.setAttribute("blank", "true");
}
// Show or hide the spinner as needed.
let needSpinner =
this.getTabState(showTab) != this.STATE_LOADED &&
!this.windowHidden &&
!shouldBeBlank &&
!this.loadTimer;
if (!needSpinner && this.spinnerTab) {
this.noteSpinnerHidden();
this.tabbrowser.tabpanels.removeAttribute("pendingpaint");
this.spinnerTab.linkedBrowser.removeAttribute("pendingpaint");
this.spinnerTab = null;
} else if (needSpinner && this.spinnerTab !== showTab) {
if (this.spinnerTab) {
this.spinnerTab.linkedBrowser.removeAttribute("pendingpaint");
} else {
this.noteSpinnerDisplayed();
}
this.spinnerTab = showTab;
this.tabbrowser.tabpanels.toggleAttribute("pendingpaint", true);
this.spinnerTab.linkedBrowser.toggleAttribute("pendingpaint", true);
}
// Switch to the tab we've decided to make visible.
if (this.visibleTab !== showTab) {
this.tabbrowser._adjustFocusBeforeTabSwitch(this.visibleTab, showTab);
this.visibleTab = showTab;
this.maybeVisibleTabs.add(showTab);
let tabpanels = this.tabbrowser.tabpanels;
let showPanel = this.tabbrowser.tabContainer.getRelatedElement(showTab);
let index = Array.prototype.indexOf.call(tabpanels.children, showPanel);
if (index != -1) {
this.log(`Switch to tab ${index} - ${this.tinfo(showTab)}`);
tabpanels.updateSelectedIndex(index);
if (showTab === this.requestedTab) {
if (requestedTabState == this.STATE_LOADED) {
// The new tab will be made visible in the next paint, record the expected
// transaction id for that, and we'll mark when we get notified of its
// completion.
this.switchPaintId = this.window.windowUtils.lastTransactionId + 1;
} else {
this.noteMakingTabVisibleWithoutLayers();
}
this.tabbrowser._adjustFocusAfterTabSwitch(showTab);
this.window.gURLBar.afterTabSwitchFocusChange();
this.maybeActivateDocShell(this.requestedTab);
}
}
// This doesn't necessarily exist if we're a new window and haven't switched tabs yet
if (this.lastVisibleTab) {
this.lastVisibleTab._visuallySelected = false;
}
this.visibleTab._visuallySelected = true;
}
this.lastVisibleTab = this.visibleTab;
}
assert(cond) {
if (!cond) {
dump("Assertion failure\n" + Error().stack);
// Don't break a user's browser if an assertion fails.
if (AppConstants.DEBUG) {
throw new Error("Assertion failure");
}
}
}
maybeClearLoadTimer(caller) {
if (this.loadingTab) {
this._loadTimerClearedBy = caller;
this.loadingTab = null;
if (this.loadTimer) {
this.clearTimer(this.loadTimer);
this.loadTimer = null;
}
}
}
// We've decided to try to load requestedTab.
loadRequestedTab() {
this.assert(!this.loadTimer);
this.assert(!this.windowHidden);
// loadingTab can be non-null here if we timed out loading the current tab.
// In that case we just overwrite it with a different tab; it's had its chance.
this.loadingTab = this.requestedTab;
this.log("Loading tab " + this.tinfo(this.loadingTab));
this.loadTimer = this.setTimer(
() => this.handleEvent({ type: "loadTimeout" }),
this.TAB_SWITCH_TIMEOUT
);
this.setTabState(this.requestedTab, this.STATE_LOADING);
}
maybeActivateDocShell(tab) {
// If we've reached the point where the requested tab has entered
// the loaded state, but the DocShell is still not yet active, we
// should activate it.
let browser = tab.linkedBrowser;
let state = this.getTabState(tab);
let canCheckDocShellState =
!browser.mDestroyed &&
(browser.docShell || browser.frameLoader.remoteTab);
if (
tab == this.requestedTab &&
canCheckDocShellState &&
state == this.STATE_LOADED &&
!browser.docShellIsActive &&
!this.windowHidden
) {
browser.docShellIsActive = true;
this.logState(
"Set requested tab docshell to active and preserveLayers to false"
);
// If we minimized the window before the switcher was activated,
// we might have set the preserveLayers flag for the current
// browser. Let's clear it.
browser.preserveLayers(false);
}
}
// This function runs before every event. It fixes up the state
// to account for closed tabs.
preActions() {
this.assert(this.tabbrowser._switcher);
this.assert(this.tabbrowser._switcher === this);
for (let i = 0; i < this.tabLayerCache.length; i++) {
let tab = this.tabLayerCache[i];
if (!tab.linkedBrowser) {
this.tabState.delete(tab);
this.tabLayerCache.splice(i, 1);
i--;
}
}
for (let [tab] of this.tabState) {
if (!tab.linkedBrowser) {
this.tabState.delete(tab);
this.unwarmTab(tab);
}
}
if (this.lastVisibleTab && !this.lastVisibleTab.linkedBrowser) {
this.lastVisibleTab = null;
}
if (this.lastPrimaryTab && !this.lastPrimaryTab.linkedBrowser) {
this.lastPrimaryTab = null;
}
if (this.blankTab && !this.blankTab.linkedBrowser) {
this.blankTab = null;
}
if (this.spinnerTab && !this.spinnerTab.linkedBrowser) {
this.noteSpinnerHidden();
this.spinnerTab = null;
}
if (this.loadingTab && !this.loadingTab.linkedBrowser) {
this.maybeClearLoadTimer("preActions");
}
}
// This code runs after we've responded to an event or requested a new
// tab. It's expected that we've already updated all the principal
// state variables. This function takes care of updating any auxilliary
// state.
postActions(eventString) {
// Once we finish loading loadingTab, we null it out. So the state should
// always be LOADING.
this.assert(
!this.loadingTab ||
this.getTabState(this.loadingTab) == this.STATE_LOADING
);
// We guarantee that loadingTab is non-null iff loadTimer is non-null. So
// the timer is set only when we're loading something.
this.assert(!this.loadTimer || this.loadingTab);
this.assert(!this.loadingTab || this.loadTimer);
// If we're switching to a non-remote tab, there's no need to wait
// for it to send layers to the compositor, as this will happen
// synchronously. Clearing this here means that in the next step,
// we can load the non-remote browser immediately.
if (!this.requestedTab.linkedBrowser.isRemoteBrowser) {
this.maybeClearLoadTimer("postActions");
}
// If we're not loading anything, try loading the requested tab.
let stateOfRequestedTab = this.getTabState(this.requestedTab);
if (
!this.loadTimer &&
!this.windowHidden &&
(stateOfRequestedTab == this.STATE_UNLOADED ||
stateOfRequestedTab == this.STATE_UNLOADING ||
this.warmingTabs.has(this.requestedTab))
) {
this.assert(stateOfRequestedTab != this.STATE_LOADED);
this.loadRequestedTab();
}
let numBackgroundCached = 0;
for (let tab of this.tabLayerCache) {
if (tab !== this.requestedTab) {
numBackgroundCached++;
}
}
// See how many tabs still have work to do.
let numPending = 0;
let numWarming = 0;
for (let [tab, state] of this.tabState) {
if (!this.shouldDeactivateDocShell(tab.linkedBrowser)) {
continue;
}
if (
state == this.STATE_LOADED &&
tab !== this.requestedTab &&
!this.tabLayerCache.includes(tab)
) {
numPending++;
if (tab !== this.visibleTab) {
numWarming++;
}
}
if (state == this.STATE_LOADING || state == this.STATE_UNLOADING) {
numPending++;
}
}
this.updateDisplay();
// It's possible for updateDisplay to trigger one of our own event
// handlers, which might cause finish() to already have been called.
// Check for that before calling finish() again.
if (!this.tabbrowser._switcher) {
return;
}
this.maybeFinishTabSwitch();
if (numBackgroundCached > 0) {
this.deactivateCachedBackgroundTabs();
}
if (numWarming > lazy.gTabWarmingMax) {
this.logState("Hit tabWarmingMax");
if (this.unloadTimer) {
this.clearTimer(this.unloadTimer);
}
this.unloadNonRequiredTabs();
}
if (numPending == 0) {
this.finish();
}
this.logState("/" + eventString);
}
// Fires when we're ready to unload unused tabs.
onUnloadTimeout() {
this.unloadTimer = null;
this.unloadNonRequiredTabs();
}
deactivateCachedBackgroundTabs() {
for (let tab of this.tabLayerCache) {
if (tab !== this.requestedTab) {
let browser = tab.linkedBrowser;
browser.preserveLayers(true);
browser.docShellIsActive = false;
}
}
}
// If there are any non-visible and non-requested tabs in
// STATE_LOADED, sets them to STATE_UNLOADING. Also queues
// up the unloadTimer to run onUnloadTimeout if there are still
// tabs in the process of unloading.
unloadNonRequiredTabs() {
this.warmingTabs = new WeakSet();
let numPending = 0;
// Unload any tabs that can be unloaded.
for (let [tab, state] of this.tabState) {
if (!this.shouldDeactivateDocShell(tab.linkedBrowser)) {
continue;
}
let isInLayerCache = this.tabLayerCache.includes(tab);
if (
state == this.STATE_LOADED &&
!this.maybeVisibleTabs.has(tab) &&
tab !== this.lastVisibleTab &&
tab !== this.loadingTab &&
tab !== this.requestedTab &&
!isInLayerCache
) {
this.setTabState(tab, this.STATE_UNLOADING);
}
if (
state != this.STATE_UNLOADED &&
tab !== this.requestedTab &&
!isInLayerCache
) {
numPending++;
}
}
if (numPending) {
// Keep the timer going since there may be more tabs to unload.
this.unloadTimer = this.setTimer(
() => this.handleEvent({ type: "unloadTimeout" }),
this.UNLOAD_DELAY
);
}
}
// Fires when an ongoing load has taken too long.
onLoadTimeout() {
this.maybeClearLoadTimer("onLoadTimeout");
}
// Fires when the layers become available for a tab.
onLayersReady(browser) {
let tab = this.tabbrowser.getTabForBrowser(browser);
if (!tab) {
// We probably got a layer update from a tab that got before
// the switcher was created, or for browser that's not being
// tracked by the async tab switcher (like the preloaded about:newtab).
return;
}
this.logState(`onLayersReady(${tab._tPos}, ${browser.isRemoteBrowser})`);
this.assert(
this.getTabState(tab) == this.STATE_LOADING ||
this.getTabState(tab) == this.STATE_LOADED
);
this.setTabState(tab, this.STATE_LOADED);
this.unwarmTab(tab);
if (this.loadingTab === tab) {
this.maybeClearLoadTimer("onLayersReady");
}
}
// Fires when we paint the screen. Any tab switches we initiated
// previously are done, so there's no need to keep the old layers
// around.
onPaint(event) {
this.addLogFlag(
"onPaint",
this.switchPaintId != -1,
event.transactionId >= this.switchPaintId
);
this.notePaint(event);
this.maybeVisibleTabs.clear();
}
// Called when we're done clearing the layers for a tab.
onLayersCleared(browser) {
let tab = this.tabbrowser.getTabForBrowser(browser);
if (!tab) {
return;
}
this.logState(`onLayersCleared(${tab._tPos})`);
this.assert(
this.getTabState(tab) == this.STATE_UNLOADING ||
this.getTabState(tab) == this.STATE_UNLOADED
);
this.setTabState(tab, this.STATE_UNLOADED);
}
// Called when a tab switches from remote to non-remote. In this case
// a MozLayerTreeReady notification that we requested may never fire,
// so we need to simulate it.
onRemotenessChange(tab) {
this.logState(
`onRemotenessChange(${tab._tPos}, ${tab.linkedBrowser.isRemoteBrowser})`
);
if (!tab.linkedBrowser.isRemoteBrowser) {
if (this.getTabState(tab) == this.STATE_LOADING) {
this.onLayersReady(tab.linkedBrowser);
} else if (this.getTabState(tab) == this.STATE_UNLOADING) {
this.onLayersCleared(tab.linkedBrowser);
}
} else if (this.getTabState(tab) == this.STATE_LOADED) {
// A tab just changed from non-remote to remote, which means
// that it's gone back into the STATE_LOADING state until
// it sends up a layer tree.
this.setTabState(tab, this.STATE_LOADING);
}
}
onTabRemoved(tab) {
if (this.lastVisibleTab == tab) {
this.handleEvent({ type: "tabRemoved", tab });
}
}
// Called when a tab has been removed, and the browser node is
// about to be removed from the DOM.
onTabRemovedImpl() {
this.lastVisibleTab = null;
}
onVisibilityChange() {
if (this.windowHidden) {
for (let [tab, state] of this.tabState) {
if (!this.shouldDeactivateDocShell(tab.linkedBrowser)) {
continue;
}
if (state == this.STATE_LOADING || state == this.STATE_LOADED) {
this.setTabState(tab, this.STATE_UNLOADING);
}
}
this.maybeClearLoadTimer("onSizeModeOrOcc");
} else {
// We're no longer minimized or occluded. This means we might want
// to activate the current tab's docShell.
this.maybeActivateDocShell(this.tabbrowser.selectedTab);
}
}
onSwapDocShells(ourBrowser, otherBrowser) {
// This event fires before the swap. ourBrowser is from
// our window. We save the state of otherBrowser since ourBrowser
// needs to take on that state at the end of the swap.
let otherTabbrowser = otherBrowser.ownerGlobal.gBrowser;
let otherState;
if (otherTabbrowser && otherTabbrowser._switcher) {
let otherTab = otherTabbrowser.getTabForBrowser(otherBrowser);
let otherSwitcher = otherTabbrowser._switcher;
otherState = otherSwitcher.getTabState(otherTab);
} else {
otherState = otherBrowser.docShellIsActive
? this.STATE_LOADED
: this.STATE_UNLOADED;
}
if (!this.swapMap) {
this.swapMap = new WeakMap();
}
this.swapMap.set(otherBrowser, {
state: otherState,
});
}
onEndSwapDocShells(ourBrowser, otherBrowser) {
// The swap has happened. We reset the loadingTab in
// case it has been swapped. We also set ourBrowser's state
// to whatever otherBrowser's state was before the swap.
// Clearing the load timer means that we will
// immediately display a spinner if ourBrowser isn't
// ready yet. Typically it will already be ready
// though. If it's not, we're probably in a new window,
// in which case we have no other tabs to display anyway.
this.maybeClearLoadTimer("onEndSwapDocShells");
let { state: otherState } = this.swapMap.get(otherBrowser);
this.swapMap.delete(otherBrowser);
let ourTab = this.tabbrowser.getTabForBrowser(ourBrowser);
if (ourTab) {
this.setTabStateNoAction(ourTab, otherState);
}
}
/**
* Check if the browser should be deactivated. If the browser is a print preivew or
* PiP browser then we won't deactive it.
* @param browser The browser to check if it should be deactivated
* @returns false if a print preview or PiP browser else true
*/
shouldDeactivateDocShell(browser) {
return !(
this.tabbrowser._printPreviewBrowsers.has(browser) ||
lazy.PictureInPicture.isOriginatingBrowser(browser)
);
}
shouldActivateDocShell(browser) {
let tab = this.tabbrowser.getTabForBrowser(browser);
let state = this.getTabState(tab);
return state == this.STATE_LOADING || state == this.STATE_LOADED;
}
activateBrowserForPrintPreview(browser) {
let tab = this.tabbrowser.getTabForBrowser(browser);
let state = this.getTabState(tab);
if (state != this.STATE_LOADING && state != this.STATE_LOADED) {
this.setTabState(tab, this.STATE_LOADING);
this.logState(
"Activated browser " + this.tinfo(tab) + " for print preview"
);
}
}
canWarmTab(tab) {
if (!lazy.gTabWarmingEnabled) {
return false;
}
if (!tab) {
return false;
}
// If the tab is not yet inserted, closing, not remote,
// crashed, already visible, or already requested, warming
// up the tab makes no sense.
if (
this.windowHidden ||
!tab.linkedPanel ||
tab.closing ||
!tab.linkedBrowser.isRemoteBrowser ||
!tab.linkedBrowser.frameLoader.remoteTab
) {
return false;
}
return true;
}
shouldWarmTab(tab) {
if (this.canWarmTab(tab)) {
// Tabs that are already in STATE_LOADING or STATE_LOADED
// have no need to be warmed up.
let state = this.getTabState(tab);
if (state === this.STATE_UNLOADING || state === this.STATE_UNLOADED) {
return true;
}
}
return false;
}
unwarmTab(tab) {
this.warmingTabs.delete(tab);
}
warmupTab(tab) {
if (!this.shouldWarmTab(tab)) {
return;
}
this.logState("warmupTab " + this.tinfo(tab));
this.warmingTabs.add(tab);
this.setTabState(tab, this.STATE_LOADING);
this.queueUnload(lazy.gTabWarmingUnloadDelayMs);
}
cleanUpTabAfterEviction(tab) {
this.assert(tab !== this.requestedTab);
let browser = tab.linkedBrowser;
if (browser) {
browser.preserveLayers(false);
}
this.setTabState(tab, this.STATE_UNLOADING);
}
evictOldestTabFromCache() {
let tab = this.tabLayerCache.shift();
this.cleanUpTabAfterEviction(tab);
}
maybePromoteTabInLayerCache(tab) {
if (
lazy.gTabCacheSize > 1 &&
tab.linkedBrowser.isRemoteBrowser &&
tab.linkedBrowser.currentURI.spec != "about:blank"
) {
let tabIndex = this.tabLayerCache.indexOf(tab);
if (tabIndex != -1) {
this.tabLayerCache.splice(tabIndex, 1);
}
this.tabLayerCache.push(tab);
if (this.tabLayerCache.length > lazy.gTabCacheSize) {
this.evictOldestTabFromCache();
}
}
}
// Called when the user asks to switch to a given tab.
requestTab(tab) {
if (tab === this.requestedTab) {
return;
}
let tabState = this.getTabState(tab);
this.noteTabRequested(tab, tabState);
this.logState("requestTab " + this.tinfo(tab));
this.startTabSwitch();
let oldBrowser = this.requestedTab.linkedBrowser;
oldBrowser.deprioritize();
this.requestedTab = tab;
if (tabState == this.STATE_LOADED) {
this.maybeVisibleTabs.clear();
}
tab.linkedBrowser.setAttribute("primary", "true");
if (this.lastPrimaryTab && this.lastPrimaryTab != tab) {
this.lastPrimaryTab.linkedBrowser.removeAttribute("primary");
}
this.lastPrimaryTab = tab;
this.queueUnload(this.UNLOAD_DELAY);
}
queueUnload(unloadTimeout) {
this.handleEvent({ type: "queueUnload", unloadTimeout });
}
onQueueUnload(unloadTimeout) {
if (this.unloadTimer) {
this.clearTimer(this.unloadTimer);
}
this.unloadTimer = this.setTimer(
() => this.handleEvent({ type: "unloadTimeout" }),
unloadTimeout
);
}
handleEvent(event, delayed = false) {
if (this._processing) {
this.setTimer(() => this.handleEvent(event, true), 0);
return;
}
if (delayed && this.tabbrowser._switcher != this) {
// if we delayed processing this event, we might be out of date, in which
// case we drop the delayed events
return;
}
this._processing = true;
try {
this.preActions();
switch (event.type) {
case "queueUnload":
this.onQueueUnload(event.unloadTimeout);
break;
case "unloadTimeout":
this.onUnloadTimeout();
break;
case "loadTimeout":
this.onLoadTimeout();
break;
case "tabRemoved":
this.onTabRemovedImpl(event.tab);
break;
case "MozLayerTreeReady": {
let browser = event.originalTarget;
if (!browser.renderLayers) {
// By the time we handle this event, it's possible that something
// else has already set renderLayers to false, in which case this
// event is stale and we can safely ignore it.
return;
}
this.onLayersReady(browser);
break;
}
case "MozAfterPaint":
this.onPaint(event);
break;
case "MozLayerTreeCleared": {
let browser = event.originalTarget;
if (browser.renderLayers) {
// By the time we handle this event, it's possible that something
// else has already set renderLayers to true, in which case this
// event is stale and we can safely ignore it.
return;
}
this.onLayersCleared(browser);
break;
}
case "TabRemotenessChange":
this.onRemotenessChange(event.target);
break;
case "visibilitychange":
this.onVisibilityChange();
break;
case "SwapDocShells":
this.onSwapDocShells(event.originalTarget, event.detail);
break;
case "EndSwapDocShells":
this.onEndSwapDocShells(event.originalTarget, event.detail);
break;
}
this.postActions(event.type);
} finally {
this._processing = false;
}
}
/*
* Telemetry and Profiler related helpers for recording tab switch
* timing.
*/
startTabSwitch() {
this.noteStartTabSwitch();
this.switchInProgress = true;
}
/**
* Something has occurred that might mean that we've completed
* the tab switch (layers are ready, paints are done, spinners
* are hidden). This checks to make sure all conditions are
* satisfied, and then records the tab switch as finished.
*/
maybeFinishTabSwitch() {
if (
this.switchInProgress &&
this.requestedTab &&
(this.getTabState(this.requestedTab) == this.STATE_LOADED ||
this.requestedTab === this.blankTab)
) {
if (this.requestedTab !== this.blankTab) {
this.maybePromoteTabInLayerCache(this.requestedTab);
}
this.noteFinishTabSwitch();
this.switchInProgress = false;
let event = new this.window.CustomEvent("TabSwitched", {
bubbles: true,
detail: {
tab: this.requestedTab,
},
});
this.tabbrowser.dispatchEvent(event);
}
}
/*
* Debug related logging for switcher.
*/
logging() {
if (this._useDumpForLogging) {
return true;
}
if (this._logInit) {
return this._shouldLog;
}
let result = Services.prefs.getBoolPref(
"browser.tabs.remote.logSwitchTiming",
false
);
this._shouldLog = result;
this._logInit = true;
return this._shouldLog;
}
tinfo(tab) {
if (tab) {
return tab._tPos + "(" + tab.linkedBrowser.currentURI.spec + ")";
}
return "null";
}
log(s) {
if (!this.logging()) {
return;
}
if (this._useDumpForLogging) {
dump(s + "\n");
} else {
Services.console.logStringMessage(s);
}
}
addLogFlag(flag, ...subFlags) {
if (this.logging()) {
if (subFlags.length) {
flag += `(${subFlags.map(f => (f ? 1 : 0)).join("")})`;
}
this._logFlags.push(flag);
}
}
logState(suffix) {
if (!this.logging()) {
return;
}
let getTabString = tab => {
let tabString = "";
let state = this.getTabState(tab);
let isWarming = this.warmingTabs.has(tab);
let isCached = this.tabLayerCache.includes(tab);
let isClosing = tab.closing;
let linkedBrowser = tab.linkedBrowser;
let isActive = linkedBrowser && linkedBrowser.docShellIsActive;
let isRendered = linkedBrowser && linkedBrowser.renderLayers;
let isPiP =
linkedBrowser &&
lazy.PictureInPicture.isOriginatingBrowser(linkedBrowser);
if (tab === this.lastVisibleTab) {
tabString += "V";
}
if (tab === this.loadingTab) {
tabString += "L";
}
if (tab === this.requestedTab) {
tabString += "R";
}
if (tab === this.blankTab) {
tabString += "B";
}
if (this.maybeVisibleTabs.has(tab)) {
tabString += "M";
}
let extraStates = "";
if (isWarming) {
extraStates += "W";
}
if (isCached) {
extraStates += "C";
}
if (isClosing) {
extraStates += "X";
}
if (isActive) {
extraStates += "A";
}
if (isRendered) {
extraStates += "R";
}
if (isPiP) {
extraStates += "P";
}
if (extraStates != "") {
tabString += `(${extraStates})`;
}
switch (state) {
case this.STATE_LOADED: {
tabString += "(loaded)";
break;
}
case this.STATE_LOADING: {
tabString += "(loading)";
break;
}
case this.STATE_UNLOADING: {
tabString += "(unloading)";
break;
}
case this.STATE_UNLOADED: {
tabString += "(unloaded)";
break;
}
}
return tabString;
};
let accum = "";
// This is a bit tricky to read, but what we're doing here is collapsing
// identical tab states down to make the overal string shorter and easier
// to read, and we move all simply unloaded tabs to the back of the list.
// I.e., we turn
// "0:(unloaded) 1:(unloaded) 2:(unloaded) 3:(loaded)""
// into
// "3:(loaded) 0...2:(unloaded)"
let tabStrings = this.tabbrowser.tabs.map(t => getTabString(t));
let lastMatch = -1;
let unloadedTabsStrings = [];
for (let i = 0; i <= tabStrings.length; i++) {
if (i > 0) {
if (i < tabStrings.length && tabStrings[i] == tabStrings[lastMatch]) {
continue;
}
if (tabStrings[lastMatch] == "(unloaded)") {
if (lastMatch == i - 1) {
unloadedTabsStrings.push(lastMatch.toString());
} else {
unloadedTabsStrings.push(`${lastMatch}...${i - 1}`);
}
} else if (lastMatch == i - 1) {
accum += `${lastMatch}:${tabStrings[lastMatch]} `;
} else {
accum += `${lastMatch}...${i - 1}:${tabStrings[lastMatch]} `;
}
}
lastMatch = i;
}
if (unloadedTabsStrings.length) {
accum += `${unloadedTabsStrings.join(",")}:(unloaded) `;
}
accum += "cached: " + this.tabLayerCache.length + " ";
if (this._logFlags.length) {
accum += `[${this._logFlags.join(",")}] `;
this._logFlags = [];
}
// It can be annoying to read through the entirety of a log string just
// to check if something changed or not. So if we can tell that nothing
// changed, just write "unchanged" to save the reader's time.
let logString;
if (this._lastLogString == accum) {
accum = "unchanged";
} else {
this._lastLogString = accum;
}
logString = `ATS: ${accum}{${suffix}}`;
if (this._useDumpForLogging) {
dump(logString + "\n");
} else {
Services.console.logStringMessage(logString);
}
}
noteMakingTabVisibleWithoutLayers() {
// We're making the tab visible even though we haven't yet got layers for it.
// It's hard to know which composite the layers will first be available in (and
// the parent process might not even get MozAfterPaint delivered for it), so just
// give up measuring this for now. :(
Glean.performanceInteraction.tabSwitchComposite.cancel(
this._tabswitchTimerId
);
this._tabswitchTimerId = null;
}
notePaint(event) {
if (this.switchPaintId != -1 && event.transactionId >= this.switchPaintId) {
if (this._tabswitchTimerId) {
Glean.performanceInteraction.tabSwitchComposite.stopAndAccumulate(
this._tabswitchTimerId
);
this._tabswitchTimerId = null;
}
let { innerWindowId } = this.window.windowGlobalChild;
ChromeUtils.addProfilerMarker("AsyncTabSwitch:Composited", {
innerWindowId,
});
this.switchPaintId = -1;
}
}
noteTabRequested(tab, tabState) {
if (lazy.gTabWarmingEnabled) {
let warmingState = "disqualified";
if (this.canWarmTab(tab)) {
if (tabState == this.STATE_LOADING) {
warmingState = "stillLoading";
} else if (tabState == this.STATE_LOADED) {
warmingState = "loaded";
} else if (
tabState == this.STATE_UNLOADING ||
tabState == this.STATE_UNLOADED
) {
// At this point, if the tab's browser was being inserted
// lazily, we never had a chance to warm it up, and unfortunately
// there's no great way to detect that case. Those cases will
// end up in the "notWarmed" bucket, along with legitimate cases
// where tabs could have been warmed but weren't.
warmingState = "notWarmed";
}
}
Services.telemetry
.getHistogramById("FX_TAB_SWITCH_REQUEST_TAB_WARMING_STATE")
.add(warmingState);
}
}
noteStartTabSwitch() {
TelemetryStopwatch.cancel("FX_TAB_SWITCH_TOTAL_E10S_MS", this.window);
TelemetryStopwatch.start("FX_TAB_SWITCH_TOTAL_E10S_MS", this.window);
if (this._tabswitchTimerId) {
Glean.performanceInteraction.tabSwitchComposite.cancel(
this._tabswitchTimerId
);
}
this._tabswitchTimerId =
Glean.performanceInteraction.tabSwitchComposite.start();
let { innerWindowId } = this.window.windowGlobalChild;
ChromeUtils.addProfilerMarker("AsyncTabSwitch:Start", { innerWindowId });
}
noteFinishTabSwitch() {
// After this point the tab has switched from the content thread's point of view.
// The changes will be visible after the next refresh driver tick + composite.
let time = TelemetryStopwatch.timeElapsed(
"FX_TAB_SWITCH_TOTAL_E10S_MS",
this.window
);
if (time != -1) {
TelemetryStopwatch.finish("FX_TAB_SWITCH_TOTAL_E10S_MS", this.window);
this.log("DEBUG: tab switch time = " + time);
let { innerWindowId } = this.window.windowGlobalChild;
ChromeUtils.addProfilerMarker("AsyncTabSwitch:Finish", { innerWindowId });
}
}
noteSpinnerDisplayed() {
this.assert(!this.spinnerTab);
let browser = this.requestedTab.linkedBrowser;
this.assert(browser.isRemoteBrowser);
TelemetryStopwatch.start("FX_TAB_SWITCH_SPINNER_VISIBLE_MS", this.window);
// We have a second, similar probe for capturing recordings of
// when the spinner is displayed for very long periods.
TelemetryStopwatch.start(
"FX_TAB_SWITCH_SPINNER_VISIBLE_LONG_MS",
this.window
);
let { innerWindowId } = this.window.windowGlobalChild;
ChromeUtils.addProfilerMarker("AsyncTabSwitch:SpinnerShown", {
innerWindowId,
});
Services.telemetry
.getHistogramById("FX_TAB_SWITCH_SPINNER_VISIBLE_TRIGGER")
.add(this._loadTimerClearedBy);
if (AppConstants.NIGHTLY_BUILD) {
Services.obs.notifyObservers(null, "tabswitch-spinner");
}
}
noteSpinnerHidden() {
this.assert(this.spinnerTab);
this.log(
"DEBUG: spinner time = " +
TelemetryStopwatch.timeElapsed(
"FX_TAB_SWITCH_SPINNER_VISIBLE_MS",
this.window
)
);
TelemetryStopwatch.finish("FX_TAB_SWITCH_SPINNER_VISIBLE_MS", this.window);
TelemetryStopwatch.finish(
"FX_TAB_SWITCH_SPINNER_VISIBLE_LONG_MS",
this.window
);
let { innerWindowId } = this.window.windowGlobalChild;
ChromeUtils.addProfilerMarker("AsyncTabSwitch:SpinnerHidden", {
innerWindowId,
});
// we do not get a onPaint after displaying the spinner
this._loadTimerClearedBy = "none";
}
}