fix duration event of timeline summary (#47742)

* fix duration event of timeline summary

* Revert "fix duration event of timeline summary"

This reverts commit 699aa45ed3d115f8bbea95cf6d37116b442db399.

* fix duration event of timeline summary

packages/flutter_driver/lib/src/driver/timeline_summary.dart

@@ -57,27 +57,27 @@ class TimelineSummary {
   ///
   /// Returns null if no frames were recorded.
   double computeAverageFrameRasterizerTimeMillis() {
-    return _averageInMillis(_extractDuration(_extractGpuRasterizerDrawEvents()));
+    return _averageInMillis(_extractGpuRasterizerDrawDurations());
   }
 
   /// The longest frame rasterization time in milliseconds.
   ///
   /// Returns null if no frames were recorded.
   double computeWorstFrameRasterizerTimeMillis() {
-    return _maxInMillis(_extractDuration(_extractGpuRasterizerDrawEvents()));
+    return _maxInMillis(_extractGpuRasterizerDrawDurations());
   }
 
   /// The [p]-th percentile frame rasterization time in milliseconds.
   ///
   /// Returns null if no frames were recorded.
   double computePercentileFrameRasterizerTimeMillis(double p) {
-    return _percentileInMillis(_extractDuration(_extractGpuRasterizerDrawEvents()), p);
+    return _percentileInMillis(_extractGpuRasterizerDrawDurations(), p);
   }
 
   /// The number of frames that missed the [kBuildBudget] on the GPU and
   /// therefore are in the danger of missing frames.
-  int computeMissedFrameRasterizerBudgetCount([ Duration frameBuildBudget = kBuildBudget ]) => _extractGpuRasterizerDrawEvents()
-      .where((TimedEvent event) => event.duration > kBuildBudget)
+  int computeMissedFrameRasterizerBudgetCount([ Duration frameBuildBudget = kBuildBudget ]) => _extractGpuRasterizerDrawDurations()
+      .where((Duration duration) => duration > kBuildBudget)
       .length;
 
   /// The total number of frames recorded in the timeline.
@@ -100,8 +100,8 @@ class TimelineSummary {
       'frame_build_times': _extractFrameDurations()
         .map<int>((Duration duration) => duration.inMicroseconds)
         .toList(),
-      'frame_rasterizer_times': _extractGpuRasterizerDrawEvents()
-        .map<int>((TimedEvent event) => event.duration.inMicroseconds)
+      'frame_rasterizer_times': _extractGpuRasterizerDrawDurations()
+        .map<int>((Duration duration) => duration.inMicroseconds)
         .toList(),
     };
   }
@@ -142,15 +142,11 @@ class TimelineSummary {
       .toList();
   }
 
-  List<Duration> _extractDurations(String name) {
-    return _extractNamedEvents(name).map<Duration>((TimelineEvent event) => event.duration).toList();
-  }
-
-  /// Extracts timed events that are reported as a pair of begin/end events.
+  /// Extracts Duration list that are reported as a pair of begin/end events.
   ///
   /// See: https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU
-  List<TimedEvent> _extractBeginEndEvents(String name) {
-    final List<TimedEvent> result = <TimedEvent>[];
+  List<Duration> _extractBeginEndEvents(String name) {
+    final List<Duration> result = <Duration>[];
 
     // Timeline does not guarantee that the first event is the "begin" event.
     final Iterator<TimelineEvent> events = _extractNamedEvents(name)
@@ -159,10 +155,7 @@ class TimelineSummary {
       final TimelineEvent beginEvent = events.current;
       if (events.moveNext()) {
         final TimelineEvent endEvent = events.current;
-        result.add(TimedEvent(
-          beginEvent.timestampMicros,
-          endEvent.timestampMicros,
-        ));
+        result.add(Duration(microseconds: endEvent.timestampMicros - beginEvent.timestampMicros));
       }
     }
 
@@ -194,21 +187,7 @@ class TimelineSummary {
         .reduce(math.max);
   }
 
-  List<TimedEvent> _extractGpuRasterizerDrawEvents() => _extractBeginEndEvents('GPURasterizer::Draw');
-
-  List<Duration> _extractFrameDurations() => _extractDurations('Frame');
-
-  Iterable<Duration> _extractDuration(Iterable<TimedEvent> events) {
-    return events.map<Duration>((TimedEvent e) => e.duration);
-  }
-}
-
-/// Timing information about an event that happened in the event loop.
-class TimedEvent {
-  /// Creates a timed event given begin and end timestamps in microseconds.
-  TimedEvent(int beginTimeMicros, int endTimeMicros)
-    : duration = Duration(microseconds: endTimeMicros - beginTimeMicros);
+  List<Duration> _extractGpuRasterizerDrawDurations() => _extractBeginEndEvents('GPURasterizer::Draw');
 
-  /// The duration of the event.
-  final Duration duration;
+  List<Duration> _extractFrameDurations() => _extractBeginEndEvents('Frame');
 }

packages/flutter_driver/test/src/timeline_summary_test.dart

@@ -20,11 +20,16 @@ void main() {
       }));
     }
 
-    Map<String, dynamic> build(int timeStamp, int duration) => <String, dynamic>{
+    Map<String, dynamic> frameBegin(int timeStamp) => <String, dynamic>{
       'name': 'Frame',
-      'ph': 'X',
+      'ph': 'B',
+      'ts': timeStamp,
+    };
+
+    Map<String, dynamic> frameEnd(int timeStamp) => <String, dynamic>{
+      'name': 'Frame',
+      'ph': 'E',
       'ts': timeStamp,
-      'dur': duration,
     };
 
     Map<String, dynamic> begin(int timeStamp) => <String, dynamic>{
@@ -54,8 +59,8 @@ void main() {
       test('counts frames', () {
         expect(
           summarize(<Map<String, dynamic>>[
-            build(1000, 1000),
-            build(3000, 2000),
+            frameBegin(1000), frameEnd(2000),
+            frameBegin(3000), frameEnd(5000),
           ]).countFrames(),
           2,
         );
@@ -73,12 +78,32 @@ void main() {
       test('computes average frame build time in milliseconds', () {
         expect(
           summarize(<Map<String, dynamic>>[
-            build(1000, 1000),
-            build(3000, 2000),
+            frameBegin(1000), frameEnd(2000),
+            frameBegin(3000), frameEnd(5000),
           ]).computeAverageFrameBuildTimeMillis(),
           1.5,
         );
       });
+
+      test('skips leading "end" events', () {
+        expect(
+          summarize(<Map<String, dynamic>>[
+            frameEnd(1000),
+            frameBegin(2000), frameEnd(4000),
+          ]).computeAverageFrameBuildTimeMillis(),
+          2.0,
+        );
+      });
+
+      test('skips trailing "begin" events', () {
+        expect(
+          summarize(<Map<String, dynamic>>[
+            frameBegin(2000), frameEnd(4000),
+            frameBegin(5000),
+          ]).computeAverageFrameBuildTimeMillis(),
+          2.0,
+        );
+      });
     });
 
     group('worst_frame_build_time_millis', () {
@@ -92,15 +117,35 @@ void main() {
       test('computes worst frame build time in milliseconds', () {
         expect(
           summarize(<Map<String, dynamic>>[
-            build(1000, 1000),
-            build(3000, 2000),
+            frameBegin(1000), frameEnd(2000),
+            frameBegin(3000), frameEnd(5000),
+          ]).computeWorstFrameBuildTimeMillis(),
+          2.0,
+        );
+        expect(
+          summarize(<Map<String, dynamic>>[
+            frameBegin(3000), frameEnd(5000),
+            frameBegin(1000), frameEnd(2000),
           ]).computeWorstFrameBuildTimeMillis(),
           2.0,
         );
+      });
+
+      test('skips leading "end" events', () {
+        expect(
+          summarize(<Map<String, dynamic>>[
+            frameEnd(1000),
+            frameBegin(2000), frameEnd(4000),
+          ]).computeWorstFrameBuildTimeMillis(),
+          2.0,
+        );
+      });
+
+      test('skips trailing "begin" events', () {
         expect(
           summarize(<Map<String, dynamic>>[
-            build(3000, 2000),
-            build(1000, 1000),
+            frameBegin(2000), frameEnd(4000),
+            frameBegin(5000),
           ]).computeWorstFrameBuildTimeMillis(),
           2.0,
         );
@@ -110,9 +155,9 @@ void main() {
     group('computeMissedFrameBuildBudgetCount', () {
       test('computes the number of missed build budgets', () {
         final TimelineSummary summary = summarize(<Map<String, dynamic>>[
-          build(1000, 17000),
-          build(19000, 9000),
-          build(29000, 18000),
+          frameBegin(1000), frameEnd(18000),
+          frameBegin(19000), frameEnd(28000),
+          frameBegin(29000), frameEnd(47000),
         ]);
 
         expect(summary.countFrames(), 3);
@@ -267,9 +312,9 @@ void main() {
             begin(1000), end(19000),
             begin(19000), end(29000),
             begin(29000), end(49000),
-            build(1000, 17000),
-            build(19000, 9000),
-            build(29000, 19000),
+            frameBegin(1000), frameEnd(18000),
+            frameBegin(19000), frameEnd(28000),
+            frameBegin(29000), frameEnd(48000),
           ]).summaryJson,
           <String, dynamic>{
             'average_frame_build_time_millis': 15.0,
@@ -317,9 +362,9 @@ void main() {
           begin(1000), end(19000),
           begin(19000), end(29000),
           begin(29000), end(49000),
-          build(1000, 17000),
-          build(19000, 9000),
-          build(29000, 19000),
+          frameBegin(1000), frameEnd(18000),
+          frameBegin(19000), frameEnd(28000),
+          frameBegin(29000), frameEnd(48000),
         ]).writeSummaryToFile('test', destinationDirectory: tempDir.path);
         final String written =
             await fs.file(path.join(tempDir.path, 'test.timeline_summary.json')).readAsString();