Elide tree walks (#48413)

packages/flutter/lib/src/foundation/assertions.dart

@@ -20,6 +20,130 @@ typedef DiagnosticPropertiesTransformer = Iterable<DiagnosticsNode> Function(Ite
 /// and other callbacks that collect information describing an error.
 typedef InformationCollector = Iterable<DiagnosticsNode> Function();
 
+/// Partial information from a stack frame for stack filtering purposes.
+///
+/// See also:
+///
+///  * [SubStackFilter], which uses this class to compare against [StackFrame]s.
+@immutable
+class PartialStackFrame {
+  /// Creates a new [PartialStackFrame] instance. All arguments are required and
+  /// must not be null.
+  const PartialStackFrame({
+    @required this.package,
+    @required this.className,
+    @required this.method,
+  }) : assert(className != null),
+       assert(method != null),
+       assert(package != null);
+
+  /// An `<asynchronous suspension>` line in a stack trace.
+  static const PartialStackFrame asynchronousSuspension = PartialStackFrame(
+    package: '',
+    className: '',
+    method: 'asynchronous suspension',
+  );
+
+  /// The package to match, e.g. `package:flutter/src/foundation/assertions.dart`,
+  /// or `dart:ui/window.dart`.
+  final Pattern package;
+
+  /// The class name for the method.
+  ///
+  /// On web, this is ignored, since class names are not available.
+  ///
+  /// On all platforms, top level methods should use the empty string.
+  final String className;
+
+  /// The method name for this frame line.
+  ///
+  /// On web, private methods are wrapped with `[]`.
+  final String method;
+
+  /// Tests whether the [StackFrame] matches the information in this
+  /// [PartialStackFrame].
+  bool matches(StackFrame stackFrame) {
+    final String stackFramePackage = '${stackFrame.packageScheme}:${stackFrame.package}/${stackFrame.packagePath}';
+    // Ideally this wouldn't be necessary.
+    // TODO(dnfield): https://github.com/dart-lang/sdk/issues/40117
+    if (kIsWeb) {
+      return package.allMatches(stackFramePackage).isNotEmpty
+          && stackFrame.method == (method.startsWith('_') ? '[$method]' : method);
+    }
+    return package.allMatches(stackFramePackage).isNotEmpty
+        && stackFrame.method == method
+        && stackFrame.className == className;
+  }
+}
+
+/// A class that filters stack frames for additional filtering on
+/// [FlutterError.defaultStackFilter].
+abstract class StackFilter {
+  /// A const constructor to allow subclasses to be const.
+  const StackFilter();
+
+  /// Filters the list of [StackFrame]s by updating corrresponding indices in
+  /// `reasons`.
+  ///
+  /// To elide a frame or number of frames, set the string
+  void filter(List<StackFrame> stackFrames, List<String> reasons);
+}
+
+
+/// A [StackFilter] that filters based on repeating lists of
+/// [PartialStackFrame]s.
+///
+/// See also:
+///
+///   * [FlutterError.addDefaultStackFilter], a method to register additional
+///     stack filters for [FlutterError.defaultStackFilter].
+///   * [StackFrame], a class that can help with parsing stack frames.
+///   * [PartialStackFrame], a class that helps match partial method information
+///     to a stack frame.
+class RepetitiveStackFrameFilter extends StackFilter {
+  /// Creates a new SubStackFilter. All parameters are required and must not be
+  /// null.
+  const RepetitiveStackFrameFilter({
+    @required this.frames,
+    @required this.replacement,
+  }) : assert(frames != null),
+       assert(replacement != null);
+
+  /// The shape of this repetative stack pattern.
+  final List<PartialStackFrame> frames;
+
+  /// The number of frames in this pattern.
+  int get numFrames => frames.length;
+
+  /// The string to replace the frames with.
+  ///
+  /// If the same replacement string is used multiple times in a row, the
+  /// [FlutterError.defaultStackFilter] will simply update a counter after this
+  /// line rather than repeating it.
+  final String replacement;
+
+  List<String> get _replacements => List<String>.filled(numFrames, replacement);
+
+  @override
+  void filter(List<StackFrame> stackFrames, List<String> reasons) {
+    for (int index = 0; index < stackFrames.length; index += 1) {
+      if (_matchesFrames(stackFrames.skip(index).take(numFrames).toList())) {
+        reasons.setRange(index, index + numFrames, _replacements);
+        index += numFrames;
+      }
+    }
+  }
+
+  bool _matchesFrames(List<StackFrame> stackFrames) {
+    for (int index = 0; index < stackFrames.length; index++) {
+      if (!frames[index].matches(stackFrames[index])) {
+        return false;
+      }
+    }
+    return true;
+  }
+}
+
 abstract class _ErrorDiagnostic extends DiagnosticsProperty<List<Object>> {
   /// This constructor provides a reliable hook for a kernel transformer to find
   /// error messages that need to be rewritten to include object references for
@@ -653,6 +777,19 @@ class FlutterError extends Error with DiagnosticableTreeMixin implements Asserti
     _errorCount += 1;
   }
 
+  static final List<StackFilter> _stackFilters = <StackFilter>[];
+
+  /// Adds a stack filtering function to [defaultStackFilter].
+  ///
+  /// For example, the framework adds common patterns of element building to
+  /// elide tree-walking patterns in the stacktrace.
+  ///
+  /// Added filters are checked in order of addition. The first matching filter
+  /// wins, and subsequent filters will not be checked.
+  static void addDefaultStackFilter(StackFilter filter) {
+    _stackFilters.add(filter);
+  }
+
   /// Converts a stack to a string that is more readable by omitting stack
   /// frames that correspond to Dart internals.
   ///
@@ -665,38 +802,76 @@ class FlutterError extends Error with DiagnosticableTreeMixin implements Asserti
   /// format but the frame numbers will not be consecutive (frames are elided)
   /// and the final line may be prose rather than a stack frame.
   static Iterable<String> defaultStackFilter(Iterable<String> frames) {
-    const Set<String> filteredPackages = <String>{
-      'dart:async-patch',
-      'dart:async',
-      'package:stack_trace',
-    };
-    const Set<String> filteredClasses = <String>{
-      '_AssertionError',
-      '_FakeAsync',
-      '_FrameCallbackEntry',
+    final Map<String, int> removedPackagesAndClasses = <String, int>{
+      'dart:async-patch': 0,
+      'dart:async': 0,
+      'package:stack_trace': 0,
+      'class _AssertionError': 0,
+      'class _FakeAsync': 0,
+      'class _FrameCallbackEntry': 0,
+      'class _Timer': 0,
+      'class _RawReceivePortImpl': 0,
     };
+    int skipped = 0;
+
+    final List<StackFrame> parsedFrames = StackFrame.fromStackString(frames.join('\n'));
+
+    for (int index = 0; index < parsedFrames.length; index += 1) {
+      final StackFrame frame = parsedFrames[index];
+      final String className = 'class ${frame.className}';
+      final String package = '${frame.packageScheme}:${frame.package}';
+      if (removedPackagesAndClasses.containsKey(className)) {
+        skipped += 1;
+        removedPackagesAndClasses[className] += 1;
+        parsedFrames.removeAt(index);
+        index -= 1;
+      } else if (removedPackagesAndClasses.containsKey(package)) {
+        skipped += 1;
+        removedPackagesAndClasses[package] += 1;
+        parsedFrames.removeAt(index);
+        index -= 1;
+      }
+    }
+    final List<String> reasons = List<String>(parsedFrames.length);
+    for (final StackFilter filter in _stackFilters) {
+      filter.filter(parsedFrames, reasons);
+    }
+
     final List<String> result = <String>[];
-    final List<String> skipped = <String>[];
-    for (final String line in frames) {
-      final StackFrame frameLine = StackFrame.fromStackTraceLine(line);
-      if (filteredClasses.contains(frameLine.className)) {
-        skipped.add('class ${frameLine.className}');
-      } else if (filteredPackages.contains(frameLine.packageScheme + ':' + frameLine.package)) {
-        skipped.add('package ${frameLine.packageScheme == 'dart' ? 'dart:' : ''}${frameLine.package}');
-      } else {
-        result.add(line);
+
+    // Collapse duplicated reasons.
+    for (int index = 0; index < parsedFrames.length; index += 1) {
+      final int start = index;
+      while (index < reasons.length - 1 && reasons[index] != null && reasons[index + 1] == reasons[index]) {
+        index++;
       }
+      String suffix = '';
+      if (reasons[index] != null) {
+        if (index != start) {
+          suffix = ' (${index - start + 2} frames)';
+        } else {
+          suffix = ' (1 frame)';
+        }
+      }
+      final String resultLine = '${reasons[index] ?? parsedFrames[index].source}$suffix';
+      result.add(resultLine);
     }
-    if (skipped.length == 1) {
-      result.add('(elided one frame from ${skipped.single})');
-    } else if (skipped.length > 1) {
-      final List<String> where = Set<String>.from(skipped).toList()..sort();
+
+    // Only include packages we actually elided from.
+    final List<String> where = <String>[
+      for (MapEntry<String, int> entry in removedPackagesAndClasses.entries)
+        if (entry.value > 0)
+          entry.key
+    ]..sort();
+    if (skipped == 1) {
+      result.add('(elided one frame from ${where.single})');
+    } else if (skipped > 1) {
       if (where.length > 1)
         where[where.length - 1] = 'and ${where.last}';
       if (where.length > 2) {
-        result.add('(elided ${skipped.length} frames from ${where.join(", ")})');
+        result.add('(elided $skipped frames from ${where.join(", ")})');
       } else {
-        result.add('(elided ${skipped.length} frames from ${where.join(" ")})');
+        result.add('(elided $skipped frames from ${where.join(" ")})');
       }
     }
     return result;

packages/flutter/lib/src/widgets/binding.dart

@@ -254,6 +254,12 @@ mixin WidgetsBinding on BindingBase, ServicesBinding, SchedulerBinding, GestureB
   void initInstances() {
     super.initInstances();
     _instance = this;
+
+    assert(() {
+      _debugAddStackFilters();
+      return true;
+    }());
+
     // Initialization of [_buildOwner] has to be done after
     // [super.initInstances] is called, as it requires [ServicesBinding] to
     // properly setup the [defaultBinaryMessenger] instance.
@@ -265,6 +271,84 @@ mixin WidgetsBinding on BindingBase, ServicesBinding, SchedulerBinding, GestureB
     FlutterErrorDetails.propertiesTransformers.add(transformDebugCreator);
   }
 
+  void _debugAddStackFilters() {
+    const PartialStackFrame elementInflateWidget = PartialStackFrame(package: 'package:flutter/src/widgets/framework.dart', className: 'Element', method: 'inflateWidget');
+    const PartialStackFrame elementUpdateChild = PartialStackFrame(package: 'package:flutter/src/widgets/framework.dart', className: 'Element', method: 'updateChild');
+    const PartialStackFrame elementRebuild = PartialStackFrame(package: 'package:flutter/src/widgets/framework.dart', className: 'Element', method: 'rebuild');
+    const PartialStackFrame componentElementPerformRebuild = PartialStackFrame(package: 'package:flutter/src/widgets/framework.dart', className: 'ComponentElement', method: 'performRebuild');
+    const PartialStackFrame componentElementFristBuild = PartialStackFrame(package: 'package:flutter/src/widgets/framework.dart', className: 'ComponentElement', method: '_firstBuild');
+    const PartialStackFrame componentElementMount = PartialStackFrame(package: 'package:flutter/src/widgets/framework.dart', className: 'ComponentElement', method: 'mount');
+    const PartialStackFrame statefulElementFristBuild = PartialStackFrame(package: 'package:flutter/src/widgets/framework.dart', className: 'StatefulElement', method: '_firstBuild');
+    const PartialStackFrame singleChildMount = PartialStackFrame(package: 'package:flutter/src/widgets/framework.dart', className: 'SingleChildRenderObjectElement', method: 'mount');
+
+    const String replacementString = '...     Normal element mounting';
+
+    // ComponentElement variations
+    FlutterError.addDefaultStackFilter(const RepetitiveStackFrameFilter(
+      frames: <PartialStackFrame>[
+        elementInflateWidget,
+        elementUpdateChild,
+        componentElementPerformRebuild,
+        elementRebuild,
+        componentElementFristBuild,
+        componentElementMount,
+      ],
+      replacement: replacementString,
+    ));
+    FlutterError.addDefaultStackFilter(const RepetitiveStackFrameFilter(
+      frames: <PartialStackFrame>[
+        elementUpdateChild,
+        componentElementPerformRebuild,
+        elementRebuild,
+        componentElementFristBuild,
+        componentElementMount,
+      ],
+      replacement: replacementString,
+    ));
+
+    // StatefulElement variations
+    FlutterError.addDefaultStackFilter(const RepetitiveStackFrameFilter(
+      frames: <PartialStackFrame>[
+        elementInflateWidget,
+        elementUpdateChild,
+        componentElementPerformRebuild,
+        elementRebuild,
+        componentElementFristBuild,
+        statefulElementFristBuild,
+        componentElementMount,
+      ],
+      replacement: replacementString,
+    ));
+    FlutterError.addDefaultStackFilter(const RepetitiveStackFrameFilter(
+      frames: <PartialStackFrame>[
+        elementUpdateChild,
+        componentElementPerformRebuild,
+        elementRebuild,
+        componentElementFristBuild,
+        statefulElementFristBuild,
+        componentElementMount,
+      ],
+      replacement: replacementString,
+    ));
+
+    // SingleChildRenderObjectElement variations
+    FlutterError.addDefaultStackFilter(const RepetitiveStackFrameFilter(
+      frames: <PartialStackFrame>[
+        elementInflateWidget,
+        elementUpdateChild,
+        singleChildMount,
+      ],
+      replacement: replacementString,
+    ));
+    FlutterError.addDefaultStackFilter(const RepetitiveStackFrameFilter(
+      frames: <PartialStackFrame>[
+        elementUpdateChild,
+        singleChildMount,
+      ],
+      replacement: replacementString,
+    ));
+  }
+
   /// The current [WidgetsBinding], if one has been created.
   ///
   /// If you need the binding to be constructed before calling [runApp],

packages/flutter/test/foundation/error_reporting_test.dart

@@ -81,7 +81,7 @@ Future<void> main() async {
       '#2      getSampleStack \\([^)]+flutter/test/foundation/error_reporting_test\\.dart:[0-9]+:[0-9]+\\)\n'
       '#3      main \\([^)]+flutter/test/foundation/error_reporting_test\\.dart:[0-9]+:[0-9]+\\)\n'
       '(.+\n)+' // TODO(ianh): when fixing #4021, also filter out frames from the test infrastructure below the first call to our main()
-      '\\(elided [0-9]+ frames from package dart:async\\)\n'
+      '\\(elided [0-9]+ frames from class _RawReceivePortImpl and dart:async\\)\n'
       '\n'
       'line 1 of extra information\n'
       'line 2 of extra information\n'
@@ -153,7 +153,7 @@ Future<void> main() async {
       '#2      getSampleStack \\([^)]+flutter/test/foundation/error_reporting_test\\.dart:[0-9]+:[0-9]+\\)\n'
       '#3      main \\([^)]+flutter/test/foundation/error_reporting_test\\.dart:[0-9]+:[0-9]+\\)\n'
       '(.+\n)+' // TODO(ianh): when fixing #4021, also filter out frames from the test infrastructure below the first call to our main()
-      '\\(elided [0-9]+ frames from package dart:async\\)\n'
+      '\\(elided [0-9]+ frames from class _RawReceivePortImpl and dart:async\\)\n'
       '\n'
       'line 1 of extra information\n'
       'line 2 of extra information\n'

packages/flutter/test/foundation/stack_frame_test.dart

@@ -71,7 +71,8 @@ void main() {
   }, skip: isBrowser);
 }
 
-const String stackString = '''#0      _AssertionError._doThrowNew (dart:core-patch/errors_patch.dart:42:39)
+const String stackString = '''
+#0      _AssertionError._doThrowNew (dart:core-patch/errors_patch.dart:42:39)
 #1      _AssertionError._throwNew (dart:core-patch/errors_patch.dart:38:5)
 #2      new Text (package:flutter/src/widgets/text.dart:287:10)
 #3      _MyHomePageState.build (package:hello_flutter/main.dart:72:16)
@@ -104,7 +105,8 @@ const List<StackFrame> stackFrames = <StackFrame>[
 ];
 
 
-const String asyncStackString = '''#0      getSampleStack.<anonymous closure> (file:///path/to/flutter/packages/flutter/test/foundation/error_reporting_test.dart:40:57)
+const String asyncStackString = '''
+#0      getSampleStack.<anonymous closure> (file:///path/to/flutter/packages/flutter/test/foundation/error_reporting_test.dart:40:57)
 #1      new Future.sync (dart:async/future.dart:224:31)
 #2      getSampleStack (file:///path/to/flutter/packages/flutter/test/foundation/error_reporting_test.dart:40:10)
 #3      main (file:///path/to/flutter/packages/flutter/test/foundation/error_reporting_test.dart:46:40)
@@ -190,7 +192,8 @@ const List<StackFrame> asyncStackFrames = <StackFrame>[
   StackFrame(number: 38, className: '_RawReceivePortImpl', method: '_handleMessage', packageScheme: 'dart',    package: 'isolate-patch',  packagePath: 'isolate_patch.dart',                                                          line: 174,  column: 12, source: '#38     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:174:12)'),
 ];
 
-const String stackFrameNoCols = '''#0      blah (package:assertions/main.dart:4)
+const String stackFrameNoCols = '''
+#0      blah (package:assertions/main.dart:4)
 #1      main (package:assertions/main.dart:8)
 #2      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:239)
 #3      _rootRun (dart:async/zone.dart:1126)
@@ -214,7 +217,8 @@ const List<StackFrame> stackFrameNoColsFrames = <StackFrame>[
   StackFrame(number: 9,  className: '_RawReceivePortImpl', method: '_handleMessage', packageScheme: 'dart',    package: 'isolate-patch', packagePath: 'isolate-patch.dart', line: 174,  column: -1, source: '#9      _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:174)'),
 ];
 
-const String webStackTrace = r'''package:dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 196:49  throw_
+const String webStackTrace = r'''
+package:dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 196:49  throw_
 package:assertions/main.dart 4:3                                                      blah
 package:assertions/main.dart 8:5                                                      main$
 package:assertions/main_web_entrypoint.dart 9:3                                       main$

packages/flutter/test/foundation/stack_trace_test.dart

@@ -16,13 +16,13 @@ void main() {
     expect(filtered[0], matches(r'^#0 +main\.<anonymous closure> \(.*stack_trace_test\.dart:[0-9]+:[0-9]+\)$'));
     expect(filtered[1], matches(r'^#1 +Declarer\.test\.<anonymous closure>.<anonymous closure>.<anonymous closure> \(package:test_api/.+:[0-9]+:[0-9]+\)$'));
     expect(filtered[2], equals('<asynchronous suspension>'));
-    expect(filtered.last, matches(r'^\(elided [1-9][0-9]+ frames from package dart:async(, package dart:async-patch,)? and package stack_trace\)$'));
+    expect(filtered.last, matches(r'^\(elided [1-9][0-9]+ frames from class _RawReceivePortImpl, class _Timer, dart:async(, dart:async-patch,)? and package:stack_trace\)$'));
   });
 
   test('FlutterError.defaultStackFilter (async test body)', () async {
     final List<String> filtered = FlutterError.defaultStackFilter(StackTrace.current.toString().trimRight().split('\n')).toList();
     expect(filtered.length, greaterThanOrEqualTo(3));
     expect(filtered[0], matches(r'^#0 +main\.<anonymous closure> \(.*stack_trace_test\.dart:[0-9]+:[0-9]+\)$'));
-    expect(filtered.last, matches(r'^\(elided [1-9][0-9]+ frames from package dart:async(, package dart:async-patch,)? and package stack_trace\)$'));
+    expect(filtered.last, matches(r'^\(elided [1-9][0-9]+ frames from class _RawReceivePortImpl, class _Timer, dart:async(, dart:async-patch,)? and package:stack_trace\)$'));
   });
 }

packages/flutter/test/widgets/binding_test.dart

@@ -2,8 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
 import 'dart:typed_data';
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
@@ -137,6 +139,12 @@ void main() {
     tester.binding.scheduleWarmUpFrame(); // this actually tests flutter_test's implementation
     expect(tester.binding.hasScheduledFrame, isFalse);
     expect(frameCount, 1);
+
+    // Get the tester back to a resumed state for subsequent tests.
+    message = const StringCodec().encodeMessage('AppLifecycleState.resumed');
+    await defaultBinaryMessenger.handlePlatformMessage('flutter/lifecycle', message, (_) { });
+    expect(tester.binding.hasScheduledFrame, isTrue);
+    await tester.pump();
   });
 
   testWidgets('scheduleFrameCallback error control test', (WidgetTester tester) async {
@@ -170,4 +178,34 @@ void main() {
       '   argument.\n'
     );
   });
+
+  testWidgets('defaultStackFilter elides framework Element mounting stacks', (WidgetTester tester) async {
+    final FlutterExceptionHandler oldHandler = FlutterError.onError;
+    String filteredStack;
+    FlutterError.onError = (FlutterErrorDetails details) {
+      expect(details.exception, isAssertionError);
+      expect(filteredStack, isNull);
+      filteredStack = details.toString();
+    };
+    await tester.pumpWidget(Directionality(
+      textDirection: TextDirection.ltr,
+      child: FocusableActionDetector(
+        child: Builder(
+          builder: (BuildContext context) {
+            return Opacity(
+              opacity: .5,
+              child: Builder(
+                builder: (BuildContext context) => Text(null),
+              ),
+            );
+          },
+        ),
+      ),
+    ));
+    // We don't elide the root or the last element.
+    FlutterError.onError = oldHandler;
+    expect(tester.allElements.length, 10);
+    print(filteredStack);
+    expect(filteredStack, contains('...     Normal element mounting (42 frames)'));
+  });
 }