core(metrics): switch to speedIndex from perceptualSpeedIndex (#4980)

lighthouse-cli/test/smokehouse/perf/expectations.js

@@ -13,15 +13,8 @@ module.exports = [
     initialUrl: 'http://localhost:10200/preload.html',
     url: 'http://localhost:10200/preload.html',
     audits: {
-      'speed-index-metric': {
+      'speed-index': {
         score: '>=0.80',
-        extendedInfo: {
-          value: {
-            timings: {},
-            timestamps: {},
-            frames: [],
-          },
-        },
       },
       'first-meaningful-paint': {
         score: '>=0.90',

lighthouse-core/audits/metrics.js

@@ -31,10 +31,12 @@ class Metrics extends Audit {
     const metricComputationData = {trace, devtoolsLog, settings: context.settings};
 
     const traceOfTab = await artifacts.requestTraceOfTab(trace);
+    const speedline = await artifacts.requestSpeedline(trace);
     const firstContentfulPaint = await artifacts.requestFirstContentfulPaint(metricComputationData);
     const firstMeaningfulPaint = await artifacts.requestFirstMeaningfulPaint(metricComputationData);
     const firstCPUIdle = await artifacts.requestFirstCPUIdle(metricComputationData);
     const timeToInteractive = await artifacts.requestConsistentlyInteractive(metricComputationData);
+    const speedIndex = await artifacts.requestSpeedIndex(metricComputationData);
     const metrics = [];
 
     // Include the simulated/observed performance metrics
@@ -43,19 +45,42 @@ class Metrics extends Audit {
       firstMeaningfulPaint,
       firstCPUIdle,
       timeToInteractive,
+      speedIndex,
     };
+
     for (const [metricName, values] of Object.entries(metricsMap)) {
-      metrics.push(Object.assign({metricName}, values));
+      metrics.push({
+        metricName,
+        timing: Math.round(values.timing),
+        timestamp: values.timestamp,
+      });
     }
 
     // Include all timestamps of interest from trace of tab
     for (const [traceEventName, timing] of Object.entries(traceOfTab.timings)) {
       const uppercased = traceEventName.slice(0, 1).toUpperCase() + traceEventName.slice(1);
-      const metricName = `trace${uppercased}`;
+      const metricName = `observed${uppercased}`;
       const timestamp = traceOfTab.timestamps[traceEventName];
       metrics.push({metricName, timing, timestamp});
     }
 
+    // Include some visual metrics from speedline
+    metrics.push({
+      metricName: 'observedFirstVisualChange',
+      timing: speedline.first,
+      timestamp: (speedline.first + speedline.beginning) * 1000,
+    });
+    metrics.push({
+      metricName: 'observedLastVisualChange',
+      timing: speedline.complete,
+      timestamp: (speedline.complete + speedline.beginning) * 1000,
+    });
+    metrics.push({
+      metricName: 'observedSpeedIndex',
+      timing: speedline.speedIndex,
+      timestamp: (speedline.speedIndex + speedline.beginning) * 1000,
+    });
+
     const headings = [
       {key: 'metricName', itemType: 'text', text: 'Name'},
       {key: 'timing', itemType: 'ms', granularity: 10, text: 'Value (ms)'},

lighthouse-core/audits/speed-index.js

@@ -0,0 +1,62 @@
+/**
+ * @license Copyright 2016 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.
+ */
+'use strict';
+
+const Audit = require('./audit');
+const Util = require('../report/v2/renderer/util');
+
+class SpeedIndex extends Audit {
+  /**
+   * @return {!AuditMeta}
+   */
+  static get meta() {
+    return {
+      name: 'speed-index',
+      description: 'Speed Index',
+      helpText: 'Speed Index shows how quickly the contents of a page are visibly populated. ' +
+          '[Learn more](https://developers.google.com/web/tools/lighthouse/audits/speed-index).',
+      scoreDisplayMode: Audit.SCORING_MODES.NUMERIC,
+      requiredArtifacts: ['traces', 'devtoolsLogs'],
+    };
+  }
+
+  /**
+   * @return {LH.Audit.ScoreOptions}
+   */
+  static get defaultOptions() {
+    return {
+      // see https://www.desmos.com/calculator/mdgjzchijg
+      scorePODR: 1250,
+      scoreMedian: 5500,
+    };
+  }
+
+  /**
+   * Audits the page to give a score for the Speed Index.
+   * @see https://github.com/GoogleChrome/lighthouse/issues/197
+   * @param {Artifacts} artifacts The artifacts from the gather phase.
+   * @param {LH.Audit.Context} context
+   * @return {Promise<AuditResult>}
+   */
+  static async audit(artifacts, context) {
+    const trace = artifacts.traces[Audit.DEFAULT_PASS];
+    const devtoolsLog = artifacts.devtoolsLogs[Audit.DEFAULT_PASS];
+    const metricComputationData = {trace, devtoolsLog, settings: context.settings};
+    const metricResult = await artifacts.requestSpeedIndex(metricComputationData);
+
+    return {
+      score: Audit.computeLogNormalScore(
+        metricResult.timing,
+        context.options.scorePODR,
+        context.options.scoreMedian
+      ),
+      rawValue: metricResult.timing,
+      displayValue: Util.formatMilliseconds(metricResult.timing),
+    };
+  }
+}
+
+module.exports = SpeedIndex;

lighthouse-core/config/default-config.js

@@ -78,7 +78,7 @@ module.exports = {
     'first-contentful-paint',
     'first-meaningful-paint',
     'load-fast-enough-for-pwa',
-    'speed-index-metric',
+    'speed-index',
     'screenshot-thumbnails',
     'estimated-input-latency',
     'errors-in-console',
@@ -268,7 +268,7 @@ module.exports = {
         {id: 'first-meaningful-paint', weight: 3, group: 'perf-metric'},
         {id: 'first-cpu-idle', weight: 5, group: 'perf-metric'},
         {id: 'consistently-interactive', weight: 5, group: 'perf-metric'},
-        {id: 'speed-index-metric', weight: 1, group: 'perf-metric'},
+        {id: 'speed-index', weight: 1, group: 'perf-metric'},
         {id: 'estimated-input-latency', weight: 1, group: 'perf-metric'},
         {id: 'link-blocking-first-paint', weight: 0, group: 'perf-hint'},
         {id: 'script-blocking-first-paint', weight: 0, group: 'perf-hint'},

lighthouse-core/config/fast-config.js

@@ -18,7 +18,7 @@ module.exports = {
       'first-cpu-idle',
       'consistently-interactive',
       'estimated-input-latency',
-      'speed-index-metric',
+      'speed-index',
       'offscreen-images',
       'load-fast-enough-for-pwa',
     ],

lighthouse-core/config/plots-config.js

@@ -9,7 +9,7 @@ module.exports = {
   settings: {
     onlyAudits: [
       'first-meaningful-paint',
-      'speed-index-metric',
+      'speed-index',
       'estimated-input-latency',
       'first-cpu-idle',
       'consistently-interactive',

lighthouse-core/gather/computed/metrics/lantern-speed-index.js

@@ -49,7 +49,7 @@ class SpeedIndex extends MetricArtifact {
   getEstimateFromSimulation(simulationResult, extras) {
     const fcpTimeInMs = extras.fcpResult.timing;
     const estimate = extras.optimistic
-      ? extras.speedline.perceptualSpeedIndex
+      ? extras.speedline.speedIndex
       : SpeedIndex.computeLayoutBasedSpeedIndex(simulationResult.nodeTiming, fcpTimeInMs);
     return {
       timeInMs: estimate,

lighthouse-core/gather/computed/metrics/speed-index.js

@@ -0,0 +1,28 @@
+/**
+ * @license Copyright 2018 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.
+ */
+'use strict';
+
+const MetricArtifact = require('./metric');
+
+class SpeedIndex extends MetricArtifact {
+  get name() {
+    return 'SpeedIndex';
+  }
+
+  /**
+   * @param {LH.Artifacts.MetricComputationData} data
+   * @param {Object} artifacts
+   * @return {Promise<LH.Artifacts.Metric>}
+   */
+  async computeObservedMetric(data, artifacts) {
+    const speedline = await artifacts.requestSpeedline(data.trace);
+    const timing = Math.round(speedline.speedIndex);
+    const timestamp = (timing + speedline.beginning) * 1000;
+    return Promise.resolve({timing, timestamp});
+  }
+}
+
+module.exports = SpeedIndex;

lighthouse-core/gather/computed/speedline.js

@@ -30,14 +30,24 @@ class Speedline extends ComputedArtifact {
       return speedline(traceEvents, {
         timeOrigin: navStart,
         fastMode: true,
-        include: 'perceptualSpeedIndex',
+        include: 'speedIndex',
       });
     }).catch(err => {
       if (/No screenshots found in trace/.test(err.message)) {
         throw new LHError(LHError.errors.NO_SCREENSHOTS);
       }
 
       throw err;
+    }).then(speedline => {
+      if (speedline.frames.length === 0) {
+        throw new LHError(LHError.errors.NO_SPEEDLINE_FRAMES);
+      }
+
+      if (speedline.speedIndex === 0) {
+        throw new LHError(LHError.errors.SPEEDINDEX_OF_ZERO);
+      }
+
+      return speedline;
     });
   }
 }