core: initial refactor of computedArtifact import/caching

lighthouse-core/audits/manifest-short-name-length.js

@@ -6,6 +6,7 @@
 'use strict';
 
 const Audit = require('./audit');
+const ManifestValues = require('../gather/computed/manifest-values');
 
 class ManifestShortNameLength extends Audit {
   /**
@@ -25,10 +26,11 @@ class ManifestShortNameLength extends Audit {
 
   /**
    * @param {LH.Artifacts} artifacts
+   * @param {LH.Audit.Context} context
    * @return {Promise<LH.Audit.Product>}
    */
-  static async audit(artifacts) {
-    const manifestValues = await artifacts.requestManifestValues(artifacts.Manifest);
+  static async audit(artifacts, context) {
+    const manifestValues = await ManifestValues.request(context, artifacts.Manifest);
     // If there's no valid manifest, this audit is not applicable
     if (manifestValues.isParseFailure) {
       return {

lighthouse-core/audits/multi-check-audit.js

@@ -14,10 +14,12 @@ const Audit = require('./audit');
 class MultiCheckAudit extends Audit {
   /**
    * @param {LH.Artifacts} artifacts
+   * @param {LH.Audit.Context} context
    * @return {Promise<LH.Audit.Product>}
    */
-  static audit(artifacts) {
-    return Promise.resolve(this.audit_(artifacts)).then(result => this.createAuditProduct(result));
+  static async audit(artifacts, context) {
+    const multiProduct = await this.audit_(artifacts, context);
+    return this.createAuditProduct(multiProduct);
   }
 
   /**
@@ -63,9 +65,10 @@ class MultiCheckAudit extends Audit {
 
   /**
    * @param {LH.Artifacts} artifacts
+   * @param {LH.Audit.Context} context
    * @return {Promise<{failures: Array<string>, warnings?: Array<string>, manifestValues?: LH.Artifacts.ManifestValues}>}
    */
-  static audit_(artifacts) {
+  static audit_(artifacts, context) {
     throw new Error('audit_ unimplemented');
   }
 

lighthouse-core/audits/splash-screen.js

@@ -6,6 +6,7 @@
 'use strict';
 
 const MultiCheckAudit = require('./multi-check-audit');
+const ManifestValues = require('../gather/computed/manifest-values');
 
 /**
  * @fileoverview
@@ -64,20 +65,20 @@ class SplashScreen extends MultiCheckAudit {
 
   /**
    * @param {LH.Artifacts} artifacts
+   * @param {LH.Audit.Context} context
    * @return {Promise<{failures: Array<string>, manifestValues: LH.Artifacts.ManifestValues}>}
    */
-  static audit_(artifacts) {
+  static async audit_(artifacts, context) {
     /** @type {Array<string>} */
     const failures = [];
 
-    return artifacts.requestManifestValues(artifacts.Manifest).then(manifestValues => {
-      SplashScreen.assessManifest(manifestValues, failures);
+    const manifestValues = await ManifestValues.request(context, artifacts.Manifest);
+    SplashScreen.assessManifest(manifestValues, failures);
 
-      return {
-        failures,
-        manifestValues,
-      };
-    });
+    return {
+      failures,
+      manifestValues,
+    };
   }
 }
 

lighthouse-core/audits/themed-omnibox.js

@@ -7,6 +7,7 @@
 
 const MultiCheckAudit = require('./multi-check-audit');
 const validColor = require('../lib/web-inspector').Color.parse;
+const ManifestValues = require('../gather/computed/manifest-values');
 
 /**
  * @fileoverview
@@ -63,22 +64,22 @@ class ThemedOmnibox extends MultiCheckAudit {
 
   /**
    * @param {LH.Artifacts} artifacts
+   * @param {LH.Audit.Context} context
    * @return {Promise<{failures: Array<string>, manifestValues: LH.Artifacts.ManifestValues, themeColor: ?string}>}
    */
-  static audit_(artifacts) {
+  static async audit_(artifacts, context) {
     /** @type {Array<string>} */
     const failures = [];
 
-    return artifacts.requestManifestValues(artifacts.Manifest).then(manifestValues => {
-      ThemedOmnibox.assessManifest(manifestValues, failures);
-      ThemedOmnibox.assessMetaThemecolor(artifacts.ThemeColor, failures);
+    const manifestValues = await ManifestValues.request(context, artifacts.Manifest);
+    ThemedOmnibox.assessManifest(manifestValues, failures);
+    ThemedOmnibox.assessMetaThemecolor(artifacts.ThemeColor, failures);
 
-      return {
-        failures,
-        manifestValues,
-        themeColor: artifacts.ThemeColor,
-      };
-    });
+    return {
+      failures,
+      manifestValues,
+      themeColor: artifacts.ThemeColor,
+    };
   }
 }
 

lighthouse-core/audits/webapp-install-banner.js

@@ -7,6 +7,7 @@
 
 const MultiCheckAudit = require('./multi-check-audit');
 const SWAudit = require('./service-worker');
+const ManifestValues = require('../gather/computed/manifest-values');
 
 /**
  * @fileoverview
@@ -118,33 +119,33 @@ class WebappInstallBanner extends MultiCheckAudit {
 
   /**
    * @param {LH.Artifacts} artifacts
+   * @param {LH.Audit.Context} context
    * @return {Promise<{failures: Array<string>, warnings: Array<string>, manifestValues: LH.Artifacts.ManifestValues}>}
    */
-  static audit_(artifacts) {
+  static async audit_(artifacts, context) {
     /** @type {Array<string>} */
     let offlineFailures = [];
     /** @type {Array<string>} */
     let offlineWarnings = [];
 
-    return artifacts.requestManifestValues(artifacts.Manifest).then(manifestValues => {
-      const manifestFailures = WebappInstallBanner.assessManifest(manifestValues);
-      const swFailures = WebappInstallBanner.assessServiceWorker(artifacts);
-      if (!swFailures.length) {
-        const {failures, warnings} = WebappInstallBanner.assessOfflineStartUrl(artifacts);
-        offlineFailures = failures;
-        offlineWarnings = warnings;
-      }
+    const manifestValues = await ManifestValues.request(context, artifacts.Manifest);
+    const manifestFailures = WebappInstallBanner.assessManifest(manifestValues);
+    const swFailures = WebappInstallBanner.assessServiceWorker(artifacts);
+    if (!swFailures.length) {
+      const {failures, warnings} = WebappInstallBanner.assessOfflineStartUrl(artifacts);
+      offlineFailures = failures;
+      offlineWarnings = warnings;
+    }
 
-      return {
-        warnings: offlineWarnings,
-        failures: [
-          ...manifestFailures,
-          ...swFailures,
-          ...offlineFailures,
-        ],
-        manifestValues,
-      };
-    });
+    return {
+      warnings: offlineWarnings,
+      failures: [
+        ...manifestFailures,
+        ...swFailures,
+        ...offlineFailures,
+      ],
+      manifestValues,
+    };
   }
 }
 

lighthouse-core/gather/computed/manifest-values.js

@@ -5,7 +5,7 @@
  */
 'use strict';
 
-const ComputedArtifact = require('./computed-artifact');
+const makeComputedArtifact = require('./new-computed-artifact');
 const icons = require('../../lib/icons');
 
 const PWA_DISPLAY_VALUES = ['minimal-ui', 'fullscreen', 'standalone'];
@@ -14,11 +14,7 @@ const PWA_DISPLAY_VALUES = ['minimal-ui', 'fullscreen', 'standalone'];
 // For more discussion, see https://github.com/GoogleChrome/lighthouse/issues/69 and https://developer.chrome.com/apps/manifest/name#short_name
 const SUGGESTED_SHORTNAME_LENGTH = 12;
 
-class ManifestValues extends ComputedArtifact {
-  get name() {
-    return 'ManifestValues';
-  }
-
+class ManifestValues {
   static get validityIds() {
     return ['hasManifest', 'hasParseableManifest'];
   }
@@ -88,7 +84,7 @@ class ManifestValues extends ComputedArtifact {
    * @param {LH.Artifacts['Manifest']} manifest
    * @return {Promise<LH.Artifacts.ManifestValues>}
    */
-  async compute_(manifest) {
+  static async compute_(manifest) {
     // if the manifest isn't there or is invalid json, we report that and bail
     let parseFailureReason;
 
@@ -125,4 +121,4 @@ class ManifestValues extends ComputedArtifact {
   }
 }
 
-module.exports = ManifestValues;
+module.exports = makeComputedArtifact(ManifestValues);

lighthouse-core/gather/computed/new-computed-artifact.js

@@ -0,0 +1,40 @@
+/**
+ * @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 ArbitraryEqualityMap = require('../../lib/arbitrary-equality-map.js');
+
+/**
+ * @template {string} N
+ * @template A
+ * @template R
+ * @param {{name: N, compute_: (artifact: A) => Promise<R>}} computableArtifact
+ * @return {{name: N, request: (context: LH.Audit.Context, artifact: A) => Promise<R>}}
+ */
+function makeComputedArtifact(computableArtifact) {
+  /**
+   * @param {LH.Audit.Context} context
+   * @param {A} artifact
+   */
+  const request = ({computedCache}, artifact) => {
+    const cache = computedCache.get(computableArtifact.name) || new ArbitraryEqualityMap();
+    computedCache.set(computableArtifact.name, cache);
+
+    const computed = /** @type {Promise<R>|undefined} */ (cache.get(artifact));
+    if (computed) {
+      return computed;
+    }
+
+    const artifactPromise = computableArtifact.compute_(artifact);
+    cache.set(artifact, artifactPromise);
+
+    return artifactPromise;
+  };
+
+  return Object.assign(computableArtifact, {request});
+}
+
+module.exports = makeComputedArtifact;

lighthouse-core/lib/arbitrary-equality-map.js

@@ -12,10 +12,10 @@ const isEqual = require('lodash.isequal');
  * It is not meant to be performant and is well-suited to use cases where the number of entries is
  * likely to be small (like computed artifacts).
  */
-module.exports = class ArbitraryEqualityMap {
+class ArbitraryEqualityMap {
   constructor() {
-    this._equalsFn = /** @type {function(any,any):boolean} */ ((a, b) => a === b);
-    /** @type {Array<{key: string, value: *}>} */
+    this._equalsFn = /** @type {function(*,*):boolean} */ ((a, b) => a === b);
+    /** @type {Array<{key: *, value: *}>} */
     this._entries = [];
   }
 
@@ -27,15 +27,15 @@ module.exports = class ArbitraryEqualityMap {
   }
 
   /**
-   * @param {string} key
+   * @param {*} key
    * @return {boolean}
    */
   has(key) {
     return this._findIndexOf(key) !== -1;
   }
 
   /**
-   * @param {string} key
+   * @param {*} key
    * @return {*}
    */
   get(key) {
@@ -44,7 +44,7 @@ module.exports = class ArbitraryEqualityMap {
   }
 
   /**
-   * @param {string} key
+   * @param {*} key
    * @param {*} value
    */
   set(key, value) {
@@ -54,7 +54,7 @@ module.exports = class ArbitraryEqualityMap {
   }
 
   /**
-   * @param {string} key
+   * @param {*} key
    * @return {number}
    */
   _findIndexOf(key) {
@@ -76,4 +76,6 @@ module.exports = class ArbitraryEqualityMap {
   static deepEquals(objA, objB) {
     return isEqual(objA, objB);
   }
-};
+}
+
+module.exports = ArbitraryEqualityMap;

lighthouse-core/runner.js

@@ -205,10 +205,17 @@ class Runner {
       }
     }
 
+    // Members of LH.Audit.Context that are shared across all audits.
+    const sharedAuditContext = {
+      settings,
+      LighthouseRunWarnings: runWarnings,
+      computedCache: new Map(),
+    };
+
     // Run each audit sequentially
     const auditResults = [];
     for (const auditDefn of audits) {
-      const auditResult = await Runner._runAudit(auditDefn, artifacts, settings, runWarnings);
+      const auditResult = await Runner._runAudit(auditDefn, artifacts, sharedAuditContext);
       auditResults.push(auditResult);
     }
 
@@ -220,12 +227,11 @@ class Runner {
    * Otherwise returns error audit result.
    * @param {LH.Config.AuditDefn} auditDefn
    * @param {LH.Artifacts} artifacts
-   * @param {LH.Config.Settings} settings
-   * @param {Array<string>} runWarnings
+   * @param {Pick<LH.Audit.Context, 'settings'|'LighthouseRunWarnings'|'computedCache'>} sharedAuditContext
    * @return {Promise<LH.Audit.Result>}
    * @private
    */
-  static async _runAudit(auditDefn, artifacts, settings, runWarnings) {
+  static async _runAudit(auditDefn, artifacts, sharedAuditContext) {
     const audit = auditDefn.implementation;
     const status = `Evaluating: ${i18n.getFormatted(audit.meta.title, 'en-US')}`;
 
@@ -274,8 +280,7 @@ class Runner {
       const auditOptions = Object.assign({}, audit.defaultOptions, auditDefn.options);
       const auditContext = {
         options: auditOptions,
-        settings,
-        LighthouseRunWarnings: runWarnings,
+        ...sharedAuditContext,
       };
 
       const product = await audit.audit(artifacts, auditContext);
@@ -380,6 +385,10 @@ class Runner {
       'metrics', // the sub folder that contains metric names
       'metrics/lantern-metric.js', // lantern metric base class
       'metrics/metric.js', // computed metric base class
+
+      // Computed artifacts switching to the new system.
+      'new-computed-artifact.js',
+      'manifest-values.js',
     ];
 
     const fileList = [