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Introduce TraceOfTab computed artifact (#1549)
* Introduce TraceOfTab computed artifact, and migrate FMP audit to it. * Migrate user-timing to TraceOfTab artifact and off devtools-timeline-model.
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| /** | ||
| * @license | ||
| * Copyright 2017 Google Inc. All rights reserved. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
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| 'use strict'; | ||
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| /** | ||
| * @fileoverview Singluar helper to parse a raw trace and extract the most useful data for | ||
| * various tools. This artifact will take a trace and then: | ||
| * | ||
| * 1. Find the TracingStartedInPage and navigationStart events of our intended tab & frame. | ||
| * 2. Find the firstContentfulPaint and marked firstMeaningfulPaint events | ||
| * 3. Isolate only the trace events from the tab's process (including all threads like compositor) | ||
| * * Sort those trace events in chronological order (as order isn't guaranteed) | ||
| * 4. Return all those items in one handy bundle. | ||
| */ | ||
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| const ComputedArtifact = require('./computed-artifact'); | ||
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| class TraceOfTab extends ComputedArtifact { | ||
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| get name() { | ||
| return 'TraceOfTab'; | ||
| } | ||
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| // We want an fMP at or after our fCP, however we see traces with the sole fMP | ||
| // being up to 1ms BEFORE the fCP. We're okay if this happens, however if we see | ||
| // a gap of more than 2 frames (32,000 microseconds), then it's a bug that should | ||
| // be addressed in FirstMeaningfulPaintDetector.cpp | ||
| static get fmpToleranceMs() { | ||
| return 32 * 1000; | ||
| } | ||
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| /** | ||
| * @param {{traceEvents: !Array}} trace | ||
| * @return {!{processEvents: !Array<TraceEvent>, startedInPageEvt: TraceEvent, navigationStartEvt: TraceEvent, firstContentfulPaintEvt: TraceEvent, firstMeaningfulPaintEvt: TraceEvent}} | ||
| */ | ||
| compute_(trace) { | ||
| // Parse the trace for our key events and sort them by timestamp. | ||
| const keyEvents = trace.traceEvents.filter(e => { | ||
| return e.cat.includes('blink.user_timing') || e.name === 'TracingStartedInPage'; | ||
| }).sort((event0, event1) => event0.ts - event1.ts); | ||
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| // The first TracingStartedInPage in the trace is definitely our renderer thread of interest | ||
| // Beware: the tracingStartedInPage event can appear slightly after a navigationStart | ||
| const startedInPageEvt = keyEvents.find(e => e.name === 'TracingStartedInPage'); | ||
| // Filter to just events matching the frame ID for sanity | ||
| const frameEvents = keyEvents.filter(e => e.args.frame === startedInPageEvt.args.data.page); | ||
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| // Find our first FCP | ||
| const firstFCP = frameEvents.find(e => e.name === 'firstContentfulPaint'); | ||
| // Our navStart will be the latest one before fCP. | ||
| const navigationStart = frameEvents.filter(e => | ||
| e.name === 'navigationStart' && e.ts < firstFCP.ts).pop(); | ||
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| // fMP will follow at/after the FCP, though we allow some timestamp tolerance | ||
| const firstMeaningfulPaint = frameEvents.find(e => | ||
| e.name === 'firstMeaningfulPaint' && e.ts >= (firstFCP.ts - TraceOfTab.fmpToleranceMs)); | ||
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| // subset all trace events to just our tab's process (incl threads other than main) | ||
| const processEvents = trace.traceEvents.filter(e => { | ||
| return e.pid === startedInPageEvt.pid; | ||
| }).sort((event0, event1) => event0.ts - event1.ts); | ||
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| return { | ||
| processEvents, | ||
| startedInPageEvt: startedInPageEvt, | ||
| navigationStartEvt: navigationStart, | ||
| firstContentfulPaintEvt: firstFCP, | ||
| firstMeaningfulPaintEvt: firstMeaningfulPaint | ||
| }; | ||
| } | ||
| } | ||
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| module.exports = TraceOfTab; |
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