gecko-dev/devtools/server/performance/timeline.js

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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/. */
"use strict";
/**
* Many Gecko operations (painting, reflows, restyle, ...) can be tracked
* in real time. A marker is a representation of one operation. A marker
* has a name, start and end timestamps. Markers are stored in docShells.
*
* This module exposes this tracking mechanism. To use with devtools' RDP,
* use devtools/server/actors/timeline.js directly.
*
* To start/stop recording markers:
* timeline.start()
* timeline.stop()
* timeline.isRecording()
*
* When markers are available, an event is emitted:
* timeline.on("markers", function(markers) {...})
*/
const { Ci, Cu } = require("chrome");
const { Class } = require("sdk/core/heritage");
// Be aggressive about lazy loading, as this will run on every
// toolbox startup
loader.lazyRequireGetter(this, "events", "sdk/event/core");
loader.lazyRequireGetter(this, "Task", "resource://gre/modules/Task.jsm", true);
loader.lazyRequireGetter(this, "Memory", "devtools/server/performance/memory", true);
loader.lazyRequireGetter(this, "Framerate", "devtools/server/performance/framerate", true);
loader.lazyRequireGetter(this, "StackFrameCache", "devtools/server/actors/utils/stack", true);
loader.lazyRequireGetter(this, "EventTarget", "sdk/event/target", true);
// How often do we pull markers from the docShells, and therefore, how often do
// we send events to the front (knowing that when there are no markers in the
// docShell, no event is sent).
const DEFAULT_TIMELINE_DATA_PULL_TIMEOUT = 200; // ms
/**
* The timeline actor pops and forwards timeline markers registered in docshells.
*/
var Timeline = exports.Timeline = Class({
extends: EventTarget,
/**
* Initializes this actor with the provided connection and tab actor.
*/
initialize: function (tabActor) {
this.tabActor = tabActor;
this._isRecording = false;
this._stackFrames = null;
this._memory = null;
this._framerate = null;
// Make sure to get markers from new windows as they become available
this._onWindowReady = this._onWindowReady.bind(this);
this._onGarbageCollection = this._onGarbageCollection.bind(this);
events.on(this.tabActor, "window-ready", this._onWindowReady);
},
/**
* Destroys this actor, stopping recording first.
*/
destroy: function() {
this.stop();
events.off(this.tabActor, "window-ready", this._onWindowReady);
this.tabActor = null;
},
/**
* Get the list of docShells in the currently attached tabActor. Note that we
* always list the docShells included in the real root docShell, even if the
* tabActor was switched to a child frame. This is because for now, paint
* markers are only recorded at parent frame level so switching the timeline
* to a child frame would hide all paint markers.
* See https://bugzilla.mozilla.org/show_bug.cgi?id=1050773#c14
* @return {Array}
*/
get docShells() {
let originalDocShell;
let docShells = [];
if (this.tabActor.isRootActor) {
originalDocShell = this.tabActor.docShell;
} else {
originalDocShell = this.tabActor.originalDocShell;
}
if (!originalDocShell) {
return docShells;
}
let docShellsEnum = originalDocShell.getDocShellEnumerator(
Ci.nsIDocShellTreeItem.typeAll,
Ci.nsIDocShell.ENUMERATE_FORWARDS
);
while (docShellsEnum.hasMoreElements()) {
let docShell = docShellsEnum.getNext();
docShells.push(docShell.QueryInterface(Ci.nsIDocShell));
}
return docShells;
},
/**
* At regular intervals, pop the markers from the docshell, and forward
* markers, memory, tick and frames events, if any.
*/
_pullTimelineData: function() {
let docShells = this.docShells;
if (!this._isRecording || !docShells.length) {
return;
}
let endTime = docShells[0].now();
let markers = [];
// Gather markers if requested.
if (this._withMarkers || this._withDocLoadingEvents) {
for (let docShell of docShells) {
for (let marker of docShell.popProfileTimelineMarkers()) {
markers.push(marker);
// The docshell may return markers with stack traces attached.
// Here we transform the stack traces via the stack frame cache,
// which lets us preserve tail sharing when transferring the
// frames to the client. We must waive xrays here because Firefox
// doesn't understand that the Debugger.Frame object is safe to
// use from chrome. See Tutorial-Alloc-Log-Tree.md.
if (this._withFrames) {
if (marker.stack) {
marker.stack = this._stackFrames.addFrame(Cu.waiveXrays(marker.stack));
}
if (marker.endStack) {
marker.endStack = this._stackFrames.addFrame(Cu.waiveXrays(marker.endStack));
}
}
// Emit some helper events for "DOMContentLoaded" and "Load" markers.
if (this._withDocLoadingEvents) {
if (marker.name == "document::DOMContentLoaded" ||
marker.name == "document::Load") {
events.emit(this, "doc-loading", marker, endTime);
}
}
}
}
}
// Emit markers if requested.
if (this._withMarkers && markers.length > 0) {
events.emit(this, "markers", markers, endTime);
}
// Emit framerate data if requested.
if (this._withTicks) {
events.emit(this, "ticks", endTime, this._framerate.getPendingTicks());
}
// Emit memory data if requested.
if (this._withMemory) {
events.emit(this, "memory", endTime, this._memory.measure());
}
// Emit stack frames data if requested.
if (this._withFrames && this._withMarkers) {
let frames = this._stackFrames.makeEvent();
if (frames) {
events.emit(this, "frames", endTime, frames);
}
}
this._dataPullTimeout = setTimeout(() => {
this._pullTimelineData();
}, DEFAULT_TIMELINE_DATA_PULL_TIMEOUT);
},
/**
* Are we recording profile markers currently?
*/
isRecording: function () {
return this._isRecording;
},
/**
* Start recording profile markers.
*
* @option {boolean} withMarkers
* Boolean indicating whether or not timeline markers are emitted
* once they're accumulated every `DEFAULT_TIMELINE_DATA_PULL_TIMEOUT`
* milliseconds.
* @option {boolean} withTicks
* Boolean indicating whether a `ticks` event is fired and a
* FramerateActor is created.
* @option {boolean} withMemory
* Boolean indiciating whether we want memory measurements sampled.
* @option {boolean} withFrames
* Boolean indicating whether or not stack frames should be handled
* from timeline markers.
* @option {boolean} withGCEvents
* Boolean indicating whether or not GC markers should be emitted.
* TODO: Remove these fake GC markers altogether in bug 1198127.
* @option {boolean} withDocLoadingEvents
* Boolean indicating whether or not DOMContentLoaded and Load
* marker events are emitted.
*/
start: Task.async(function *({
withMarkers,
withTicks,
withMemory,
withFrames,
withGCEvents,
withDocLoadingEvents,
}) {
let docShells = this.docShells;
if (!docShells.length) {
return -1;
}
let startTime = this._startTime = docShells[0].now();
if (this._isRecording) {
return startTime;
}
this._isRecording = true;
this._withMarkers = !!withMarkers;
this._withTicks = !!withTicks;
this._withMemory = !!withMemory;
this._withFrames = !!withFrames;
this._withGCEvents = !!withGCEvents;
this._withDocLoadingEvents = !!withDocLoadingEvents;
if (this._withMarkers || this._withDocLoadingEvents) {
for (let docShell of docShells) {
docShell.recordProfileTimelineMarkers = true;
}
}
if (this._withTicks) {
this._framerate = new Framerate(this.tabActor);
this._framerate.startRecording();
}
if (this._withMemory || this._withGCEvents) {
this._memory = new Memory(this.tabActor, this._stackFrames);
this._memory.attach();
}
if (this._withGCEvents) {
events.on(this._memory, "garbage-collection", this._onGarbageCollection);
}
if (this._withFrames && this._withMarkers) {
this._stackFrames = new StackFrameCache();
this._stackFrames.initFrames();
}
this._pullTimelineData();
return startTime;
}),
/**
* Stop recording profile markers.
*/
stop: Task.async(function *() {
let docShells = this.docShells;
if (!docShells.length) {
return -1;
}
let endTime = this._startTime = docShells[0].now();
if (!this._isRecording) {
return endTime;
}
if (this._withMarkers || this._withDocLoadingEvents) {
for (let docShell of docShells) {
docShell.recordProfileTimelineMarkers = false;
}
}
if (this._withTicks) {
this._framerate.stopRecording();
this._framerate.destroy();
this._framerate = null;
}
if (this._withMemory || this._withGCEvents) {
this._memory.detach();
this._memory.destroy();
}
if (this._withGCEvents) {
events.off(this._memory, "garbage-collection", this._onGarbageCollection);
}
if (this._withFrames && this._withMarkers) {
this._stackFrames = null;
}
this._isRecording = false;
this._withMarkers = false;
this._withTicks = false;
this._withMemory = false;
this._withFrames = false;
this._withDocLoadingEvents = false;
this._withGCEvents = false;
clearTimeout(this._dataPullTimeout);
return endTime;
}),
/**
* When a new window becomes available in the tabActor, start recording its
* markers if we were recording.
*/
_onWindowReady: function({ window }) {
if (this._isRecording) {
let docShell = window.QueryInterface(Ci.nsIInterfaceRequestor)
.getInterface(Ci.nsIWebNavigation)
.QueryInterface(Ci.nsIDocShell);
docShell.recordProfileTimelineMarkers = true;
}
},
/**
* Fired when the Memory component emits a `garbage-collection` event. Used to
* take the data and make it look like the rest of our markers.
*
* A GC "marker" here represents a full GC cycle, which may contain several incremental
* events within its `collection` array. The marker contains a `reason` field, indicating
* why there was a GC, and may contain a `nonincrementalReason` when SpiderMonkey could
* not incrementally collect garbage.
*/
_onGarbageCollection: function ({ collections, gcCycleNumber, reason, nonincrementalReason }) {
let docShells = this.docShells;
if (!this._isRecording || !docShells.length) {
return;
}
let endTime = docShells[0].now();
events.emit(this, "markers", collections.map(({ startTimestamp: start, endTimestamp: end }) => {
return {
name: "GarbageCollection",
causeName: reason,
nonincrementalReason: nonincrementalReason,
cycle: gcCycleNumber,
start,
end,
};
}), endTime);
},
});