core(simulator): start nodes in observed order (#5362)

lighthouse-core/gather/computed/metrics/lantern-estimated-input-latency.js

@@ -94,7 +94,7 @@ class LanternEstimatedInputLatency extends LanternMetric {
       });
     }
 
-    return events;
+    return events.sort((a, b) => a.start - b.start);
   }
 }
 

lighthouse-core/gather/computed/metrics/lantern-first-cpu-idle.js

@@ -52,6 +52,7 @@ class LanternFirstCPUIdle extends LanternInteractive {
       longTasks.push({start: timing.startTime, end: timing.endTime});
     }
 
+    longTasks.sort((a, b) => a.start - b.start);
     // Require here to resolve circular dependency.
     const FirstCPUIdle = require('./first-cpu-idle');
     return FirstCPUIdle.findQuietWindow(fmpTimeInMs, Infinity, longTasks);

lighthouse-core/lib/dependency-graph/simulator/simulator.js

@@ -181,6 +181,17 @@ class Simulator {
     });
   }
 
+  /**
+   * @param {Set<Node>} nodes
+   * @return {Node[]}
+   */
+  _getNodesSortedByStartTime(nodes) {
+    return Array.from(nodes).sort((nodeA, nodeB) => {
+      // Sort nodes by startTime to match original execution order
+      return nodeA.startTime - nodeB.startTime;
+    });
+  }
+
   /**
    * @param {Node} node
    * @param {number} totalElapsedTime
@@ -354,18 +365,23 @@ class Simulator {
     }
   }
 
+  /**
+   * @return {Map<Node, LH.Gatherer.Simulation.NodeTiming>}
+   */
   _computeFinalNodeTimings() {
-    /** @type {Map<Node, LH.Gatherer.Simulation.NodeTiming>} */
-    const nodeTimings = new Map();
+    /** @type {Array<[Node, LH.Gatherer.Simulation.NodeTiming]>} */
+    const nodeTimingEntries = [];
     for (const [node, timing] of this._nodeTimings) {
-      nodeTimings.set(node, {
+      nodeTimingEntries.push([node, {
         startTime: timing.startTime,
         endTime: timing.endTime,
         duration: timing.endTime - timing.startTime,
-      });
+      }]);
     }
 
-    return nodeTimings;
+    // Most consumers will want the entries sorted by startTime, so insert them in that order
+    nodeTimingEntries.sort((a, b) => a[1].startTime - b[1].startTime);
+    return new Map(nodeTimingEntries);
   }
 
   /**
@@ -419,7 +435,7 @@ class Simulator {
     // loop as long as we have nodes in the queue or currently in progress
     while (nodesReadyToStart.size || nodesInProgress.size) {
       // move all possible queued nodes to in progress
-      for (const node of nodesReadyToStart) {
+      for (const node of this._getNodesSortedByStartTime(nodesReadyToStart)) {
         this._startNodeIfPossible(node, totalElapsedTime);
       }
 

lighthouse-core/test/audits/__snapshots__/metrics-test.js.snap

@@ -2,7 +2,7 @@
 
 exports[`Performance: metrics evaluates valid input correctly 1`] = `
 Object {
-  "estimatedInputLatency": 104,
+  "estimatedInputLatency": 100,
   "estimatedInputLatencyTs": undefined,
   "firstCPUIdle": 3351,
   "firstCPUIdleTs": undefined,
@@ -32,7 +32,7 @@ Object {
   "observedSpeedIndexTs": 225414776724,
   "observedTraceEnd": 12540,
   "observedTraceEndTs": 225426711887,
-  "speedIndex": 1656,
+  "speedIndex": 1657,
   "speedIndexTs": undefined,
 }
 `;

lighthouse-core/test/audits/__snapshots__/predictive-perf-test.js.snap

@@ -2,7 +2,7 @@
 
 exports[`Performance: predictive performance audit should compute the predicted values 1`] = `
 Object {
-  "optimisticEIL": 101,
+  "optimisticEIL": 93,
   "optimisticFCP": 911,
   "optimisticFMP": 1211,
   "optimisticSI": 605,
@@ -11,13 +11,13 @@ Object {
   "pessimisticEIL": 158,
   "pessimisticFCP": 911,
   "pessimisticFMP": 1498,
-  "pessimisticSI": 1630,
+  "pessimisticSI": 1631,
   "pessimisticTTFCPUI": 3502,
   "pessimisticTTI": 3502,
-  "roughEstimateOfEIL": 104,
+  "roughEstimateOfEIL": 100,
   "roughEstimateOfFCP": 911,
   "roughEstimateOfFMP": 1355,
-  "roughEstimateOfSI": 1656,
+  "roughEstimateOfSI": 1657,
   "roughEstimateOfTTFCPUI": 3351,
   "roughEstimateOfTTI": 3427,
 }

lighthouse-core/test/audits/byte-efficiency/__snapshots__/byte-efficiency-audit-test.js.snap

@@ -3,10 +3,10 @@
 exports[`Byte efficiency base audit should allow overriding of computeWasteWithTTIGraph 1`] = `
 Object {
   "default": 1330,
-  "justTTI": 950,
+  "justTTI": 800,
 }
 `;
 
 exports[`Byte efficiency base audit should create load simulator with the specified settings 1`] = `1330`;
 
-exports[`Byte efficiency base audit should create load simulator with the specified settings 2`] = `22950`;
+exports[`Byte efficiency base audit should create load simulator with the specified settings 2`] = `22730`;

lighthouse-core/test/gather/computed/metrics/__snapshots__/estimated-input-latency-test.js.snap

@@ -2,8 +2,8 @@
 
 exports[`Metrics: EIL should compute a simulated value 1`] = `
 Object {
-  "optimistic": 101,
+  "optimistic": 93,
   "pessimistic": 158,
-  "timing": 104,
+  "timing": 100,
 }
 `;

lighthouse-core/test/gather/computed/metrics/__snapshots__/lantern-estimated-input-latency-test.js.snap

@@ -2,8 +2,8 @@
 
 exports[`Metrics: Lantern EIL should compute a simulated value 1`] = `
 Object {
-  "optimistic": 101,
+  "optimistic": 93,
   "pessimistic": 158,
-  "timing": 104,
+  "timing": 100,
 }
 `;

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

@@ -3,7 +3,7 @@
 exports[`Metrics: Lantern Speed Index should compute predicted value 1`] = `
 Object {
   "optimistic": 605,
-  "pessimistic": 1630,
-  "timing": 1656,
+  "pessimistic": 1631,
+  "timing": 1657,
 }
 `;

lighthouse-core/test/gather/computed/metrics/__snapshots__/speed-index-test.js.snap

@@ -3,7 +3,7 @@
 exports[`Metrics: Speed Index should compute a simulated value 1`] = `
 Object {
   "optimistic": 605,
-  "pessimistic": 1630,
-  "timing": 1656,
+  "pessimistic": 1631,
+  "timing": 1657,
 }
 `;

lighthouse-core/test/gather/computed/metrics/lantern-first-cpu-idle-test.js

@@ -28,4 +28,20 @@ describe('Metrics: Lantern TTFCPUI', () => {
     assert.ok(result.optimisticGraph, 'should have created optimistic graph');
     assert.ok(result.pessimisticGraph, 'should have created pessimistic graph');
   });
+
+  describe('#getFirstCPUIdleWindowStart', () => {
+    it('should sort tasks', () => {
+      const tasks = new Map([
+        [{type: 'cpu'}, {startTime: 600, endTime: 700, duration: 100}],
+        [{type: 'cpu'}, {startTime: 300, endTime: 400, duration: 100}],
+        [{type: 'cpu'}, {startTime: 0, endTime: 100, duration: 100}],
+        [{type: 'cpu'}, {startTime: 100, endTime: 200, duration: 100}],
+        [{type: 'cpu'}, {startTime: 500, endTime: 600, duration: 100}],
+        [{type: 'cpu'}, {startTime: 200, endTime: 300, duration: 100}],
+        [{type: 'cpu'}, {startTime: 400, endTime: 500, duration: 100}],
+      ]);
+
+      assert.equal(LanternFirstCPUIdle.getFirstCPUIdleWindowStart(tasks, 0), 700);
+    });
+  });
 });

lighthouse-core/test/lib/dependency-graph/simulator/simulator-test.js

@@ -9,6 +9,7 @@ const NetworkNode = require('../../../../lib/dependency-graph/network-node');
 const CpuNode = require('../../../../lib/dependency-graph/cpu-node');
 const Simulator = require('../../../../lib/dependency-graph/simulator/simulator');
 const DNSCache = require('../../../../lib/dependency-graph/simulator/dns-cache');
+const PageDependencyGraph = require('../../../../gather/computed/page-dependency-graph');
 
 const assert = require('assert');
 let nextRequestId = 1;
@@ -30,7 +31,7 @@ function request(opts) {
 function cpuTask({tid, ts, duration}) {
   tid = tid || nextTid++;
   ts = ts || 0;
-  const dur = (duration || 0) * 1000 / 5;
+  const dur = ((duration || 0) * 1000) / 5;
   return {tid, ts, dur};
 }
 
@@ -255,5 +256,32 @@ describe('DependencyGraph/Simulator', () => {
       const simulator = new Simulator({serverResponseTimeByOrigin});
       assert.throws(() => simulator.simulate(rootNode), /cycle/);
     });
+
+    describe('on a real trace', () => {
+      const trace = require('../../../fixtures/traces/progressive-app-m60.json');
+      const devtoolsLog = require('../../../fixtures/traces/progressive-app-m60.devtools.log.json');
+      let result;
+
+      beforeAll(async () => {
+        const computedCache = new Map();
+        const graph = await PageDependencyGraph.request({trace, devtoolsLog}, {computedCache});
+        const simulator = new Simulator({serverResponseTimeByOrigin});
+        result = simulator.simulate(graph);
+      });
+
+      it('should compute a timeInMs', () => {
+        expect(result.timeInMs).toBeGreaterThan(100);
+      });
+
+      it('should sort the task event times', () => {
+        const nodeTimings = Array.from(result.nodeTimings.entries());
+
+        for (let i = 1; i < nodeTimings.length; i++) {
+          const startTime = nodeTimings[i][1].startTime;
+          const previousStartTime = nodeTimings[i - 1][1].startTime;
+          expect(startTime).toBeGreaterThanOrEqual(previousStartTime);
+        }
+      });
+    });
   });
 });

lighthouse-core/test/results/sample_v2.json

@@ -1951,9 +1951,9 @@
       "id": "unminified-javascript",
       "title": "Minify JavaScript",
       "description": "Minifying JavaScript files can reduce payload sizes and script parse time. [Learn more](https://developers.google.com/speed/docs/insights/MinifyResources).",
-      "score": 1,
+      "score": 0.88,
       "scoreDisplayMode": "numeric",
-      "rawValue": 0,
+      "rawValue": 150,
       "displayValue": "Potential savings of 30 KB",
       "warnings": [],
       "details": {
@@ -1983,7 +1983,7 @@
             "wastedPercent": 42.52388078488413
           }
         ],
-        "overallSavingsMs": 0,
+        "overallSavingsMs": 150,
         "overallSavingsBytes": 30470
       }
     },
@@ -2070,9 +2070,9 @@
       "id": "uses-text-compression",
       "title": "Enable text compression",
       "description": "Text-based resources should be served with compression (gzip, deflate or brotli) to minimize total network bytes. [Learn more](https://developers.google.com/web/tools/lighthouse/audits/text-compression).",
-      "score": 0.88,
+      "score": 0.75,
       "scoreDisplayMode": "numeric",
-      "rawValue": 150,
+      "rawValue": 300,
       "displayValue": "Potential savings of 63 KB",
       "details": {
         "type": "opportunity",
@@ -2105,7 +2105,7 @@
             "wastedBytes": 8442
           }
         ],
-        "overallSavingsMs": 150,
+        "overallSavingsMs": 300,
         "overallSavingsBytes": 64646
       }
     },

proto/sample_v2_round_trip.json

@@ -2075,12 +2075,12 @@
                     }
                 ], 
                 "overallSavingsBytes": 30470.0, 
-                "overallSavingsMs": 0.0, 
+                "overallSavingsMs": 150.0, 
                 "type": "opportunity"
             }, 
             "displayValue": "Potential savings of 30\u00a0KB", 
             "id": "unminified-javascript", 
-            "score": 1.0, 
+            "score": 0.88, 
             "scoreDisplayMode": "numeric", 
             "title": "Minify JavaScript", 
             "warnings": []
@@ -2452,12 +2452,12 @@
                     }
                 ], 
                 "overallSavingsBytes": 64646.0, 
-                "overallSavingsMs": 150.0, 
+                "overallSavingsMs": 300.0, 
                 "type": "opportunity"
             }, 
             "displayValue": "Potential savings of 63\u00a0KB", 
             "id": "uses-text-compression", 
-            "score": 0.88, 
+            "score": 0.75, 
             "scoreDisplayMode": "numeric", 
             "title": "Enable text compression"
         },