Elements. Restore lazy reading ClassElement members.

Bug: flutter/flutter#161306
Change-Id: I65b606b8aa012cebf62d866128bc35c5532e5638
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/403924
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

pkg/analyzer/lib/src/dart/analysis/driver.dart

@@ -99,7 +99,7 @@ import 'package:meta/meta.dart';
 // TODO(scheglov): Clean up the list of implicitly analyzed files.
 class AnalysisDriver {
   /// The version of data format, should be incremented on every format change.
-  static const int DATA_VERSION = 426;
+  static const int DATA_VERSION = 427;
 
   /// The number of exception contexts allowed to write. Once this field is
   /// zero, we stop writing any new exception contexts in this process.

pkg/analyzer/lib/src/dart/element/element.dart

@@ -451,7 +451,7 @@ class ClassElementImpl extends ClassOrMixinElementImpl
   }
 
   @override
-  ClassFragment? get nextFragment => super.nextFragment as ClassFragment?;
+  ClassElementImpl? get nextFragment => super.nextFragment as ClassElementImpl?;
 
   @override
   ClassFragment? get previousFragment =>
@@ -5433,6 +5433,11 @@ abstract class InstanceElementImpl extends _ExistingElementImpl
 
   @override
   List<PropertyAccessorElementImpl> get accessors {
+    if (!identical(_accessors, _Sentinel.propertyAccessorElement)) {
+      return _accessors;
+    }
+
+    linkedData?.readMembers(this);
     return _accessors;
   }
 
@@ -5462,6 +5467,11 @@ abstract class InstanceElementImpl extends _ExistingElementImpl
 
   @override
   List<FieldElementImpl> get fields {
+    if (!identical(_fields, _Sentinel.fieldElement)) {
+      return _fields;
+    }
+
+    linkedData?.readMembers(this);
     return _fields;
   }
 
@@ -5490,6 +5500,11 @@ abstract class InstanceElementImpl extends _ExistingElementImpl
 
   @override
   List<MethodElementImpl> get methods {
+    if (!identical(_methods, _Sentinel.methodElement)) {
+      return _methods;
+    }
+
+    linkedData?.readMembers(this);
     return _methods;
   }
 
@@ -5975,6 +5990,7 @@ abstract class InterfaceElementImpl extends InstanceElementImpl
     }
 
     _buildMixinAppConstructors();
+    linkedData?.readMembers(this);
     return _constructors;
   }
 

pkg/analyzer/lib/src/summary2/bundle_reader.dart

@@ -76,6 +76,7 @@ class BundleReader {
       return _LibraryHeader(
         uri: uriCache.parse(_reader.readStringReference()),
         offset: _reader.readUInt30(),
+        classMembersLengths: _reader.readUInt30List(),
         macroGeneratedCode: _reader.readOptionalObject((reader) {
           return _reader.readStringUtf8();
         }),
@@ -94,6 +95,7 @@ class BundleReader {
         referenceReader: referenceReader,
         reference: reference,
         offset: libraryHeader.offset,
+        classMembersLengths: libraryHeader.classMembersLengths,
         infoDeclarationStore: _infoDeclarationStore,
         macroGeneratedCode: libraryHeader.macroGeneratedCode,
       );
@@ -103,6 +105,8 @@ class BundleReader {
 
 class ClassElementLinkedData extends ElementLinkedData<ClassElementImpl> {
   ApplyConstantOffsets? applyConstantOffsets;
+  void Function()? _readMembers;
+  void Function()? applyInformativeDataToMembers;
 
   ClassElementLinkedData({
     required Reference reference,
@@ -112,17 +116,14 @@ class ClassElementLinkedData extends ElementLinkedData<ClassElementImpl> {
   }) : super(reference, libraryReader, unitElement, offset);
 
   @override
-  void readMembers(InstanceElementImpl element) {
-    if (element is! ClassElementImpl) {
-      return;
-    }
-
-    // We might read class members before other properties.
-    element.linkedData?.read(element);
-    element.linkedData = null;
-
-    if (element.isMixinApplication) {
-      element.constructors;
+  void readMembers(covariant ClassElementImpl fragment) {
+    // Read members of all fragments, in order.
+    // So we always read a method augmentation after its target.
+    for (var fragment in fragment.element.fragments) {
+      var linkedData = fragment.linkedData;
+      if (linkedData is ClassElementLinkedData) {
+        linkedData._readSingleFragmentMembers(fragment);
+      }
     }
   }
 
@@ -154,6 +155,22 @@ class ClassElementLinkedData extends ElementLinkedData<ClassElementImpl> {
 
     applyConstantOffsets?.perform();
   }
+
+  void _readSingleFragmentMembers(ClassElementImpl element) {
+    // We might read class members before other properties.
+    element.linkedData?.read(element);
+    element.linkedData = null;
+
+    if (element.isMixinApplication) {
+      element.constructors;
+    } else {
+      _readMembers?.call();
+      _readMembers = null;
+
+      applyInformativeDataToMembers?.call();
+      applyInformativeDataToMembers = null;
+    }
+  }
 }
 
 class CompilationUnitElementLinkedData
@@ -615,6 +632,9 @@ class LibraryReader {
   final InfoDeclarationStore _deserializedDataStore;
   final String? macroGeneratedCode;
 
+  final Uint32List _classMembersLengths;
+  int _classMembersLengthsIndex = 0;
+
   late final LibraryElementImpl _libraryElement;
   late InstanceElementImpl2 _currentInstanceElement;
 
@@ -627,6 +647,7 @@ class LibraryReader {
     required _ReferenceReader referenceReader,
     required Reference reference,
     required int offset,
+    required Uint32List classMembersLengths,
     required InfoDeclarationStore infoDeclarationStore,
     required this.macroGeneratedCode,
   })  : _elementFactory = elementFactory,
@@ -636,6 +657,7 @@ class LibraryReader {
         _referenceReader = referenceReader,
         _reference = reference,
         _offset = offset,
+        _classMembersLengths = classMembersLengths,
         _deserializedDataStore = infoDeclarationStore;
 
   LibraryElementImpl readElement({required Source librarySource}) {
@@ -644,6 +666,11 @@ class LibraryReader {
 
     _reader.offset = _offset;
 
+    // TODO(scheglov): https://github.com/dart-lang/sdk/issues/51855
+    // This should not be needed.
+    // But I have a suspicion that we attempt to read the library twice.
+    _classMembersLengthsIndex = 0;
+
     // Read enough data to create the library.
     var name = _reader.readStringReference();
     var featureSet = _readFeatureSet();
@@ -754,22 +781,37 @@ class LibraryReader {
     fragment.typeParameters = _readTypeParameters();
 
     if (!fragment.isMixinApplication) {
-      var accessors = <PropertyAccessorElementImpl>[];
-      var fields = <FieldElementImpl>[];
-      _readFields(unitElement, fragment, reference, accessors, fields);
-      _readPropertyAccessors(
-          unitElement, fragment, reference, accessors, fields, '@field');
-      fragment.fields = fields.toFixedList();
-      fragment.accessors = accessors.toFixedList();
-
-      fragment.constructors =
-          _readConstructors(unitElement, fragment, reference);
-      fragment.methods = _readMethods(unitElement, fragment, reference);
+      var membersOffset = _reader.offset;
+      linkedData._readMembers = () {
+        _reader.offset = membersOffset;
+        _readClassElementMembers(fragment, reference);
+      };
+      _reader.offset += _classMembersLengths[_classMembersLengthsIndex++];
     }
 
     return fragment;
   }
 
+  void _readClassElementMembers(
+    ClassElementImpl fragment,
+    Reference reference,
+  ) {
+    // print('[_readClassElementMembers][reference: $reference]');
+    var unitElement = fragment.enclosingElement3;
+    _currentInstanceElement = fragment.element;
+
+    var accessors = <PropertyAccessorElementImpl>[];
+    var fields = <FieldElementImpl>[];
+    _readFields(unitElement, fragment, reference, accessors, fields);
+    _readPropertyAccessors(
+        unitElement, fragment, reference, accessors, fields, '@field');
+    fragment.fields = fields.toFixedList();
+    fragment.accessors = accessors.toFixedList();
+
+    fragment.constructors = _readConstructors(unitElement, fragment, reference);
+    fragment.methods = _readMethods(unitElement, fragment, reference);
+  }
+
   void _readClasses(
     CompilationUnitElementImpl unitElement,
     Reference unitReference,
@@ -2665,12 +2707,18 @@ class _LibraryHeader {
   final Uri uri;
   final int offset;
 
+  /// We don't read class members when reading libraries, by performance
+  /// reasons - in many cases only some classes of a library are used. But
+  /// we need to know how much data to skip for each class.
+  final Uint32List classMembersLengths;
+
   /// The only (if any) macro generated augmentation code.
   final String? macroGeneratedCode;
 
   _LibraryHeader({
     required this.uri,
     required this.offset,
+    required this.classMembersLengths,
     required this.macroGeneratedCode,
   });
 }

pkg/analyzer/lib/src/summary2/bundle_writer.dart

@@ -57,6 +57,11 @@ class BundleWriter {
     references: _references,
   );
 
+  /// [_writeClassElement] remembers the length of data written into [_sink]
+  /// while writing members. So, when we read, we can skip members initially,
+  /// and read them later on demand.
+  List<int> _classMembersLengths = [];
+
   final StringIndexer _stringIndexer = StringIndexer();
 
   final List<_Library> _libraries = [];
@@ -73,6 +78,7 @@ class BundleWriter {
     _sink.writeList<_Library>(_libraries, (library) {
       _sink._writeStringReference(library.uriStr);
       _sink.writeUInt30(library.offset);
+      _sink.writeUint30List(library.classMembersOffsets);
       _sink.writeOptionalObject(library.macroGenerated, (it) {
         _sink.writeStringUtf8(it.code);
       });
@@ -99,6 +105,7 @@ class BundleWriter {
 
   void writeLibraryElement(LibraryElementImpl libraryElement) {
     var libraryOffset = _sink.offset;
+    _classMembersLengths = [];
 
     // Write non-resolution data for the library.
     _sink._writeStringReference(libraryElement.name);
@@ -128,6 +135,7 @@ class BundleWriter {
       _Library(
         uriStr: '${libraryElement.source.uri}',
         offset: libraryOffset,
+        classMembersOffsets: _classMembersLengths,
         macroGenerated: macroGenerated,
       ),
     );
@@ -171,6 +179,7 @@ class BundleWriter {
       }
 
       if (!element.isMixinApplication) {
+        var membersOffset = _sink.offset;
         _writeList(
           element.fields.where((e) => !e.isSynthetic).toList(),
           _writeFieldElement,
@@ -181,6 +190,7 @@ class BundleWriter {
         );
         _writeList(element.constructors, _writeConstructorElement);
         _writeList(element.methods, _writeMethodElement);
+        _classMembersLengths.add(_sink.offset - membersOffset);
       }
     });
   }
@@ -1296,13 +1306,15 @@ class _BundleWriterReferences {
 class _Library {
   final String uriStr;
   final int offset;
+  final List<int> classMembersOffsets;
 
   /// The only (if any) macro generated fragment.
   final MacroGeneratedLibraryFragment? macroGenerated;
 
   _Library({
     required this.uriStr,
     required this.offset,
+    required this.classMembersOffsets,
     required this.macroGenerated,
   });
 }

pkg/analyzer/lib/src/summary2/informative_data.dart

@@ -227,10 +227,6 @@ class InformativeDataApplier {
       element.typeParameters_unresolved,
       info.typeParameters,
     );
-    _applyToConstructors(element.constructors, info.constructors);
-    _applyToFields(element.fields, info.fields);
-    _applyToAccessors(element.accessors, info.accessors);
-    _applyToMethods(element.methods, info.methods);
 
     var applyOffsets = ApplyConstantOffsets(
       info.constantOffsets,
@@ -240,11 +236,20 @@ class InformativeDataApplier {
       },
     );
 
+    void applyToMembers() {
+      _applyToConstructors(element.constructors, info.constructors);
+      _applyToFields(element.fields, info.fields);
+      _applyToAccessors(element.accessors, info.accessors);
+      _applyToMethods(element.methods, info.methods);
+    }
+
     var linkedData = element.linkedData;
     if (linkedData is ClassElementLinkedData) {
       linkedData.applyConstantOffsets = applyOffsets;
+      linkedData.applyInformativeDataToMembers = applyToMembers;
     } else {
       applyOffsets.perform();
+      applyToMembers();
     }
   }
 

pkg/analyzer/lib/src/utilities/extensions/element.dart

@@ -25,6 +25,17 @@ extension ClassElementExtension on ClassElement {
   }
 }
 
+extension ClassElementImpl2Extension on ClassElementImpl2 {
+  List<ClassElementImpl> get fragments {
+    return [
+      for (ClassElementImpl? fragment = firstFragment;
+          fragment != null;
+          fragment = fragment.nextFragment)
+        fragment,
+    ];
+  }
+}
+
 extension CompilationUnitElementExtension on CompilationUnitElement {
   LibraryFragment get asElement2 {
     return this as LibraryFragment;