[flutter_driver] show refresh rate status in timeline summary (#95699)

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

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'timeline.dart';
+
+/// Event name for refresh rate related timeline events.
+const String kUIThreadVsyncProcessEvent = 'VsyncProcessCallback';
+
+/// A summary of [TimelineEvents]s corresponding to `kUIThreadVsyncProcessEvent` events.
+///
+/// `RefreshRate` is the time between the start of a vsync pulse and the target time of that vsync.
+class RefreshRateSummary {
+
+  /// Creates a [RefreshRateSummary] given the timeline events.
+  factory RefreshRateSummary({required List<TimelineEvent> vsyncEvents}) {
+    return RefreshRateSummary._(refreshRates: _computeRefreshRates(vsyncEvents));
+  }
+
+  RefreshRateSummary._({required List<double> refreshRates}) {
+    _numberOfTotalFrames = refreshRates.length;
+    for (final double refreshRate in refreshRates) {
+      if ((refreshRate - 30).abs() < _kErrorMargin) {
+        _numberOf30HzFrames++;
+        continue;
+      }
+      if ((refreshRate - 60).abs() < _kErrorMargin) {
+        _numberOf60HzFrames++;
+        continue;
+      }
+      if ((refreshRate - 90).abs() < _kErrorMargin) {
+        _numberOf90HzFrames++;
+        continue;
+      }
+      if ((refreshRate - 120).abs() < _kErrorMargin) {
+        _numberOf120HzFrames++;
+        continue;
+      }
+      _framesWithIllegalRefreshRate.add(refreshRate);
+    }
+    assert(_numberOfTotalFrames ==
+        _numberOf30HzFrames +
+            _numberOf60HzFrames +
+            _numberOf90HzFrames +
+            _numberOf120HzFrames +
+            _framesWithIllegalRefreshRate.length);
+  }
+
+  static const double _kErrorMargin = 6.0;
+
+  /// Number of frames with 30hz refresh rate
+  int get numberOf30HzFrames => _numberOf30HzFrames;
+
+  /// Number of frames with 60hz refresh rate
+  int get numberOf60HzFrames => _numberOf60HzFrames;
+
+  /// Number of frames with 90hz refresh rate
+  int get numberOf90HzFrames => _numberOf90HzFrames;
+
+  /// Number of frames with 120hz refresh rate
+  int get numberOf120HzFrames => _numberOf120HzFrames;
+
+  /// The percentage of 30hz frames.
+  ///
+  /// For example, if this value is 20, it means there are 20 percent of total
+  /// frames are 30hz. 0 means no frames are 30hz, 100 means all frames are 30hz.
+  double get percentageOf30HzFrames => _numberOfTotalFrames > 0
+      ? _numberOf30HzFrames / _numberOfTotalFrames * 100
+      : 0;
+
+  /// The percentage of 60hz frames.
+  ///
+  /// For example, if this value is 20, it means there are 20 percent of total
+  /// frames are 60hz. 0 means no frames are 60hz, 100 means all frames are 60hz.
+  double get percentageOf60HzFrames => _numberOfTotalFrames > 0
+      ? _numberOf60HzFrames / _numberOfTotalFrames * 100
+      : 0;
+
+  /// The percentage of 90hz frames.
+  ///
+  /// For example, if this value is 20, it means there are 20 percent of total
+  /// frames are 90hz. 0 means no frames are 90hz, 100 means all frames are 90hz.
+  double get percentageOf90HzFrames => _numberOfTotalFrames > 0
+      ? _numberOf90HzFrames / _numberOfTotalFrames * 100
+      : 0;
+
+  /// The percentage of 90hz frames.
+  ///
+  /// For example, if this value is 20, it means there are 20 percent of total
+  /// frames are 120hz. 0 means no frames are 120hz, 100 means all frames are 120hz.
+  double get percentageOf120HzFrames => _numberOfTotalFrames > 0
+      ? _numberOf120HzFrames / _numberOfTotalFrames * 100
+      : 0;
+
+  /// A list of all the frames with Illegal refresh rate.
+  ///
+  /// A refresh rate is consider illegal if it does not belong to anyone below:
+  /// 30hz, 60hz, 90hz or 120hz.
+  List<double> get framesWithIllegalRefreshRate =>
+      _framesWithIllegalRefreshRate;
+
+  int _numberOf30HzFrames = 0;
+  int _numberOf60HzFrames = 0;
+  int _numberOf90HzFrames = 0;
+  int _numberOf120HzFrames = 0;
+  int _numberOfTotalFrames = 0;
+
+  final List<double> _framesWithIllegalRefreshRate = <double>[];
+
+  static List<double> _computeRefreshRates(List<TimelineEvent> vsyncEvents) {
+    final List<double> result = <double>[];
+    for (int i = 0; i < vsyncEvents.length; i++) {
+      final TimelineEvent event = vsyncEvents[i];
+      if (event.phase != 'B') {
+        continue;
+      }
+      assert(event.name == kUIThreadVsyncProcessEvent);
+      assert(event.arguments != null);
+      final Map<String, dynamic> arguments = event.arguments!;
+      const double nanosecondsPerSecond = 1e+9;
+      final int startTimeInNanoseconds = int.parse(arguments['StartTime'] as String);
+      final int targetTimeInNanoseconds = int.parse(arguments['TargetTime'] as String);
+      final int frameDurationInNanoseconds = targetTimeInNanoseconds - startTimeInNanoseconds;
+      final double refreshRate = nanosecondsPerSecond /
+          frameDurationInNanoseconds;
+      result.add(refreshRate);
+    }
+    return result;
+  }
+}

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

@@ -13,6 +13,7 @@ import 'gc_summarizer.dart';
 import 'percentile_utils.dart';
 import 'profiling_summarizer.dart';
 import 'raster_cache_summarizer.dart';
+import 'refresh_rate_summarizer.dart';
 import 'scene_display_lag_summarizer.dart';
 import 'timeline.dart';
 import 'vsync_frame_lag_summarizer.dart';
@@ -220,6 +221,7 @@ class TimelineSummary {
     final Map<String, dynamic> profilingSummary = _profilingSummarizer().summarize();
     final RasterCacheSummarizer rasterCacheSummarizer = _rasterCacheSummarizer();
     final GCSummarizer gcSummarizer = _gcSummarizer();
+    final RefreshRateSummary refreshRateSummary = RefreshRateSummary(vsyncEvents: _extractNamedEvents(kUIThreadVsyncProcessEvent));
 
     final Map<String, dynamic> timelineSummary = <String, dynamic>{
       'average_frame_build_time_millis': computeAverageFrameBuildTimeMillis(),
@@ -271,6 +273,11 @@ class TimelineSummary {
       '99th_percentile_picture_cache_memory': rasterCacheSummarizer.computePercentilePictureMemory(99.0),
       'worst_picture_cache_memory': rasterCacheSummarizer.computeWorstPictureMemory(),
       'total_ui_gc_time': gcSummarizer.totalGCTimeMillis,
+      '30hz_frame_percentage': refreshRateSummary.percentageOf30HzFrames,
+      '60hz_frame_percentage': refreshRateSummary.percentageOf60HzFrames,
+      '90hz_frame_percentage': refreshRateSummary.percentageOf90HzFrames,
+      '120hz_frame_percentage': refreshRateSummary.percentageOf120HzFrames,
+      'illegal_refresh_rate_frame_count': refreshRateSummary.framesWithIllegalRefreshRate.length,
     };
 
     timelineSummary.addAll(profilingSummary);