perf: request block stylesheets and images on redirect pass (#2168)

lighthouse-core/config/default.js

@@ -28,6 +28,8 @@ module.exports = {
   {
     "passName": "redirectPass",
     "useThrottling": false,
+    // Speed up the redirect pass by blocking stylesheets, fonts, and images
+    "blockedUrlPatterns": ["*.css", "*.jpg", "*.jpeg", "*.png", "*.gif", "*.svg", "*.ttf", "*.woff", "*.woff2"],
     "gatherers": [
       "http-redirect",
       "html-without-javascript",

lighthouse-core/gather/driver.js

@@ -874,9 +874,18 @@ class Driver {
     return collectUsage;
   }
 
-  blockUrlPatterns(urlPatterns) {
-    const promiseArr = urlPatterns.map(url => this.sendCommand('Network.addBlockedURL', {url}));
-    return Promise.all(promiseArr);
+  /**
+   * @param {!Array<string>} urls URL patterns to block. Wildcards ('*') are allowed.
+   * @return {!Promise}
+   */
+  blockUrlPatterns(urls) {
+    return this.sendCommand('Network.setBlockedURLs', {urls})
+      .catch(err => {
+        // TODO: remove this handler once m59 hits stable
+        if (!/wasn't found/.test(err.message)) {
+          throw err;
+        }
+      });
   }
 
   /**

lighthouse-core/gather/gather-runner.js

@@ -40,12 +40,12 @@ let GathererResults; // eslint-disable-line no-unused-vars
  *     iv. evaluateScriptOnLoad rescue native Promise from potential polyfill
  *     v. cleanAndDisableBrowserCaches
  *     vi. clearDataForOrigin
- *     vii. blockUrlPatterns
  *
  * 2. For each pass in the config:
  *   A. GatherRunner.beforePass()
  *     i. navigate to about:blank
- *     ii. all gatherers' beforePass()
+ *     ii. Enable network request blocking for specified patterns
+ *     iii. all gatherers' beforePass()
  *   B. GatherRunner.pass()
  *     i. beginTrace (if requested) & beginDevtoolsLog
  *     ii. GatherRunner.loadPage()
@@ -112,7 +112,6 @@ class GatherRunner {
       .then(_ => driver.dismissJavaScriptDialogs())
       .then(_ => resetStorage && driver.cleanAndDisableBrowserCaches())
       .then(_ => resetStorage && driver.clearDataForOrigin(options.url))
-      .then(_ => driver.blockUrlPatterns(options.flags.blockedUrlPatterns || []))
       .then(_ => gathererResults.UserAgent = [driver.getUserAgent()]);
   }
 
@@ -171,9 +170,15 @@ class GatherRunner {
    * @return {!Promise}
    */
   static beforePass(options, gathererResults) {
+    const blockedUrls = (options.config.blockedUrlPatterns || [])
+      .concat(options.flags.blockedUrlPatterns || []);
     const blankPage = options.config.blankPage;
     const blankDuration = options.config.blankDuration;
-    const pass = GatherRunner.loadBlank(options.driver, blankPage, blankDuration);
+    const pass = GatherRunner.loadBlank(options.driver, blankPage, blankDuration)
+        // Set request blocking before any network activity
+        // No "clearing" is done at the end of the pass since blockUrlPatterns([]) will unset all if
+        // neccessary at the beginning of the next pass.
+        .then(() => options.driver.blockUrlPatterns(blockedUrls));
 
     return options.config.gatherers.reduce((chain, gatherer) => {
       return chain.then(_ => {

lighthouse-core/test/gather/gather-runner-test.js

@@ -77,7 +77,7 @@ function getMockedEmulationDriver(emulationFn, netThrottleFn, cpuThrottleFn, blo
         case 'Emulation.setDeviceMetricsOverride':
           fn = emulationFn;
           break;
-        case 'Network.addBlockedURL':
+        case 'Network.setBlockedURLs':
           fn = blockUrlFn;
           break;
         default:
@@ -303,25 +303,37 @@ describe('GatherRunner', function() {
   });
 
   it('tells the driver to block given URL patterns when blockedUrlPatterns is given', () => {
-    const receivedUrlPatterns = [];
-    const urlPatterns = ['http://*.evil.com', '.jpg', '.woff2'];
+    let receivedUrlPatterns = null;
     const driver = getMockedEmulationDriver(null, null, null, params => {
-      receivedUrlPatterns.push(params.url);
+      receivedUrlPatterns = params.urls;
     });
 
-    return GatherRunner.setupDriver(driver, {}, {flags: {blockedUrlPatterns: urlPatterns.slice()}})
-      .then(() => assert.deepStrictEqual(receivedUrlPatterns.sort(), urlPatterns.sort()));
+    return GatherRunner.beforePass({
+      driver,
+      flags: {
+        blockedUrlPatterns: ['http://*.evil.com', '.jpg', '.woff2'],
+      },
+      config: {
+        blockedUrlPatterns: ['*.jpeg'],
+        gatherers: [],
+      },
+    }).then(() => assert.deepStrictEqual(
+      receivedUrlPatterns.sort(),
+      ['*.jpeg', '.jpg', '.woff2', 'http://*.evil.com']
+    ));
   });
 
   it('does not throw when blockedUrlPatterns is not given', () => {
-    const receivedUrlPatterns = [];
+    let receivedUrlPatterns = null;
     const driver = getMockedEmulationDriver(null, null, null, params => {
-      receivedUrlPatterns.push(params.url);
+      receivedUrlPatterns = params.urls;
     });
 
-    return GatherRunner.setupDriver(driver, {}, {flags: {}})
-      .then(() => assert.equal(receivedUrlPatterns.length, 0))
-      .catch(() => assert.ok(false));
+    return GatherRunner.beforePass({
+      driver,
+      flags: {},
+      config: {gatherers: []},
+    }).then(() => assert.deepStrictEqual(receivedUrlPatterns, []));
   });
 
   it('tells the driver to begin tracing', () => {