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<!DOCTYPE html>
<!--
Copyright 2017 The Chromium Authors. All rights reserved.
Use of this source code is governed by a BSD-style license that can be
found in the LICENSE file.
-->
<link rel="import" href="/tracing/metrics/metric_registry.html">
<link rel="import" href="/tracing/value/histogram.html">
<script>
'use strict';
// The |androidStartupMetric| produces metrics that start counting at the
// earliest moment the Chrome code on Android is executed.
// A few histograms are produced with the names as described below:
//
// 1. messageloop_start_time - time till the message loop of the browser main
// starts processing posted tasts (after having loaded the Profile)
// 2. experimental_content_start_time - time when the renderer enters the main
// entrypoint.
// 3. experimental_navigation_start_time - This roughly corresponds to the time
// the initial navigation network request is sent.
// 4. navigation_commit_time - This is when the renderer has received the first
// part of the response from the network and started loading the page.
// 5. first_contentful_paint_time - time to the first contentful paint of the
// page loaded at startup
//
// The metric also supports multiple browser restarts, in this case multiple
// samples would be added to the histograms above.
tr.exportTo('tr.metrics.sh', function() {
const MESSAGE_LOOP_EVENT_NAME = 'Startup.BrowserMessageLoopStartTime';
const CONTENT_START_EVENT_NAME = 'content::Start';
const NAVIGATION_EVENT_NAME = 'Navigation StartToCommit';
const FIRST_CONTENTFUL_PAINT_EVENT_NAME = 'firstContentfulPaint';
function androidStartupMetric(histograms, model) {
// Walk the browser slices, extract timestamps for the browser start,
// message loop start.
let messageLoopStartEvents = [];
let navigationEvents = [];
const chromeHelper =
model.getOrCreateHelper(tr.model.helpers.ChromeModelHelper);
if (!chromeHelper) return;
for (const helper of chromeHelper.browserHelpers) {
for (const ev of helper.mainThread.asyncSliceGroup.childEvents()) {
if (ev.title === MESSAGE_LOOP_EVENT_NAME) {
messageLoopStartEvents.push(ev);
} else if (ev.title === NAVIGATION_EVENT_NAME) {
navigationEvents.push(ev);
}
}
}
// Walk the renderer slices and extract the 'first contentful paint'
// histogram samples.
let contentStartEvents = [];
let firstContentfulPaintEvents = [];
const rendererHelpers = chromeHelper.rendererHelpers;
const pids = Object.keys(rendererHelpers);
for (const rendererHelper of Object.values(chromeHelper.rendererHelpers)) {
if (!rendererHelper.mainThread) continue;
for (const ev of rendererHelper.mainThread.sliceGroup.childEvents()) {
if (ev.title === FIRST_CONTENTFUL_PAINT_EVENT_NAME) {
firstContentfulPaintEvents.push(ev);
// There are usually several 'First Contentful Paint' events recorded
// for each page load. Take only the first one per renderer.
break;
} else if (ev.title === CONTENT_START_EVENT_NAME) {
contentStartEvents.push(ev);
}
}
}
// Fallback to scanning all processes if important events are not found.
let totalBrowserStarts = messageLoopStartEvents.length;
let totalContentStartEvents = contentStartEvents.length;
let totalFcpEvents = firstContentfulPaintEvents.length;
let totalNavigations = navigationEvents.length;
if (totalFcpEvents !== totalBrowserStarts ||
totalNavigations !== totalBrowserStarts ||
totalContentStartEvents !== totalBrowserStarts ||
totalBrowserStarts === 0) {
messageLoopStartEvents = [];
contentStartEvents = [];
navigationEvents = [];
firstContentfulPaintEvents = [];
// Sometimes either the browser process or the renderer process does not
// have the proper name attached. This often happens when both chrome
// trace and systrace are merged. Other multi-process trickery, like
// Perfetto, may also cause this.
for (const proc of Object.values(model.processes)) {
for (const ev of proc.getDescendantEvents()) {
if (ev.title === MESSAGE_LOOP_EVENT_NAME) {
messageLoopStartEvents.push(ev);
} else if (ev.title === NAVIGATION_EVENT_NAME) {
navigationEvents.push(ev);
} else if (ev.title === CONTENT_START_EVENT_NAME) {
contentStartEvents.push(ev);
}
}
for (const ev of proc.getDescendantEvents()) {
if (ev.title === FIRST_CONTENTFUL_PAINT_EVENT_NAME) {
firstContentfulPaintEvents.push(ev);
break;
}
}
}
totalBrowserStarts = messageLoopStartEvents.length;
totalContentStartEvents = contentStartEvents.length;
totalNavigations = navigationEvents.length;
totalFcpEvents = firstContentfulPaintEvents.length;
}
// Sometimes a number of early trace events are not recorded because tracing
// takes time to start. This leads to having more FCP events than
// messageloop_start events. As a workaround ignore the FCP events for which
// there are no browser starts. Navigation and content start events are
// recorded on a best effort basis if they are found in the trace; their
// absence doesn't cause FCP events to be dropped.
function orderEvents(event1, event2) {
return event1.start - event2.start;
}
messageLoopStartEvents.sort(orderEvents);
contentStartEvents.sort(orderEvents);
navigationEvents.sort(orderEvents);
firstContentfulPaintEvents.sort(orderEvents);
if (totalFcpEvents < totalBrowserStarts) {
throw new Error('Found fewer FCP events (' + totalFcpEvents +
') than browser starts (' + totalBrowserStarts + ')');
}
// Group the relevant events with the corresponding browser starts and emit
// the metrics.
const messageLoopStartHistogram = histograms.createHistogram(
'messageloop_start_time',
tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, []);
const contentStartHistogram = histograms.createHistogram(
'experimental_content_start_time',
tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, []);
const navigationStartHistogram = histograms.createHistogram(
'experimental_navigation_start_time',
tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, []);
const navigationCommitHistogram = histograms.createHistogram(
'navigation_commit_time',
tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, []);
const firstContentfulPaintHistogram = histograms.createHistogram(
'first_contentful_paint_time',
tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, []);
// The earliest browser start is skipped because it is affected by the state
// of the system coming from the time before the benchmark started. Removing
// these influencing factors allows reducing measurement noise.
// Note: Two early starts are ignored below, the reasons for spurious
// slowdowns of the 2nd run are not known yet, see http://crbug.com/891797.
let contentIndex = 0;
let navIndex = 0;
let fcpIndex = 0;
for (let loopStartIndex = 0; loopStartIndex < totalBrowserStarts;) {
const startEvent = messageLoopStartEvents[loopStartIndex];
if (fcpIndex === totalFcpEvents) {
break;
}
// Skip all events that appear before the next browser start.
const contentStartEvent = contentIndex < contentStartEvents.length ?
contentStartEvents[contentIndex] : null;
if (contentStartEvent && contentStartEvent.start < startEvent.start) {
contentIndex++;
continue;
}
const navEvent = navIndex < navigationEvents.length ?
navigationEvents[navIndex] : null;
if (navEvent && navEvent.start < startEvent.start) {
navIndex++;
continue;
}
const fcpEvent = firstContentfulPaintEvents[fcpIndex];
if (fcpEvent.start < startEvent.start) {
fcpIndex++;
continue;
}
// The pair of matching events is found.
loopStartIndex++;
// Skip the two initial FCP events and (potentially missing) browser
// starts.
if (fcpIndex < 2) {
continue;
}
// Record the histograms.
messageLoopStartHistogram.addSample(startEvent.duration,
{events: new tr.v.d.RelatedEventSet([startEvent])});
if (contentStartEvent) {
contentStartHistogram.addSample(
contentStartEvent.start - startEvent.start,
{events: new tr.v.d.RelatedEventSet([startEvent,
contentStartEvent])});
}
if (navEvent) {
navigationStartHistogram.addSample(
navEvent.start - startEvent.start,
{events: new tr.v.d.RelatedEventSet([startEvent, navEvent])});
navigationCommitHistogram.addSample(
navEvent.end - startEvent.start,
{events: new tr.v.d.RelatedEventSet([startEvent, navEvent])});
}
firstContentfulPaintHistogram.addSample(
fcpEvent.end - startEvent.start,
{events: new tr.v.d.RelatedEventSet([startEvent, fcpEvent])});
}
}
tr.metrics.MetricRegistry.register(androidStartupMetric);
return {
androidStartupMetric,
};
});
</script>
|
