Create a new session on a file change.

This should restore throwing InconsistentAnalysisException.

Internal presubmit looks green.
https://fusion2.corp.google.com/presubmit/tap/424245133/OCL:424245133:BASE:424340361:1643210802936:6f26b405

Change-Id: I286d5db0fe51e8ea00d0fe83a70d4c9d59052715
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/230040
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

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

@@ -223,12 +223,7 @@ class AnalysisDriver implements AnalysisDriverGeneric {
   /// Whether resolved units should be indexed.
   final bool enableIndex;
 
-  /// The current analysis session.
-  late final AnalysisSessionImpl _currentSession = AnalysisSessionImpl(this);
-
-  /// The current library context, consistent with the [_currentSession].
-  ///
-  /// TODO(scheglov) We probably should tie it into the session.
+  /// The context in which libraries should be analyzed.
   LibraryContext? _libraryContext;
 
   /// Whether `dart:core` has been transitively discovered.
@@ -311,7 +306,9 @@ class AnalysisDriver implements AnalysisDriverGeneric {
   AnalysisOptions get analysisOptions => _analysisOptions;
 
   /// Return the current analysis session.
-  AnalysisSessionImpl get currentSession => _currentSession;
+  AnalysisSessionImpl get currentSession {
+    return libraryContext.elementFactory.analysisSession;
+  }
 
   /// Return the stream that produces [ExceptionResult]s.
   Stream<ExceptionResult> get exceptions => _exceptionController.stream;
@@ -337,7 +334,7 @@ class AnalysisDriver implements AnalysisDriverGeneric {
   LibraryContext get libraryContext {
     return _libraryContext ??= LibraryContext(
       testView: _testView.libraryContextTestView,
-      session: currentSession,
+      analysisSession: AnalysisSessionImpl(this),
       logger: _logger,
       byteStore: _byteStore,
       analysisOptions: _analysisOptions,
@@ -515,9 +512,7 @@ class AnalysisDriver implements AnalysisDriverGeneric {
   /// periodically.
   @visibleForTesting
   void clearLibraryContext() {
-    _libraryContext?.invalidAllLibraries();
     _libraryContext = null;
-    _currentSession.clearHierarchies();
   }
 
   /// Some state on which analysis depends has changed, so the driver needs to be
@@ -654,7 +649,7 @@ class AnalysisDriver implements AnalysisDriverGeneric {
 
     FileState file = _fileTracker.getFile(path);
     return FileResultImpl(
-        _currentSession, path, file.uri, file.lineInfo, file.isPart);
+        currentSession, path, file.uri, file.lineInfo, file.isPart);
   }
 
   /// Return the [FileResult] for the Dart file with the given [path].
@@ -1328,7 +1323,7 @@ class AnalysisDriver implements AnalysisDriverGeneric {
       declaredVariables,
       sourceFactory,
       libraryContext.elementFactory.libraryOfUri2(library.uriStr),
-      libraryContext.analysisSession.inheritanceManager,
+      libraryContext.elementFactory.analysisSession.inheritanceManager,
       library,
       testingData: testingData,
     ).analyzeForCompletion(
@@ -1441,7 +1436,7 @@ class AnalysisDriver implements AnalysisDriverGeneric {
           declaredVariables,
           sourceFactory,
           libraryContext.elementFactory.libraryOfUri2(library.uriStr),
-          libraryContext.analysisSession.inheritanceManager,
+          libraryContext.elementFactory.analysisSession.inheritanceManager,
           library,
           testingData: testingData,
         ).analyze();
@@ -1512,7 +1507,7 @@ class AnalysisDriver implements AnalysisDriverGeneric {
               declaredVariables,
               sourceFactory,
               libraryContext.elementFactory.libraryOfUri2(library.uriStr),
-              libraryContext.analysisSession.inheritanceManager,
+              libraryContext.elementFactory.analysisSession.inheritanceManager,
               library,
               testingData: testingData)
           .analyze();
@@ -1779,6 +1774,10 @@ class AnalysisDriver implements AnalysisDriverGeneric {
     _libraryContext?.elementFactory.removeLibraries(
       affected.map((e) => e.uriStr).toSet(),
     );
+
+    _libraryContext?.elementFactory.replaceAnalysisSession(
+      AnalysisSessionImpl(this),
+    );
   }
 
   void _reportException(String path, Object exception, StackTrace stackTrace) {

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

@@ -39,8 +39,6 @@ class LibraryContext {
   final LibraryContextTestView testView;
   final PerformanceLog logger;
   final ByteStore byteStore;
-  final AnalysisSessionImpl analysisSession;
-  final SummaryDataStore? externalSummaries;
   final SummaryDataStore store = SummaryDataStore([]);
 
   late final AnalysisContextImpl analysisContext;
@@ -48,21 +46,35 @@ class LibraryContext {
 
   LibraryContext({
     required this.testView,
-    required AnalysisSessionImpl session,
+    required AnalysisSessionImpl analysisSession,
     required PerformanceLog logger,
     required ByteStore byteStore,
     required AnalysisOptionsImpl analysisOptions,
     required DeclaredVariables declaredVariables,
     required SourceFactory sourceFactory,
-    required this.externalSummaries,
+    required SummaryDataStore? externalSummaries,
   })  : logger = logger,
-        byteStore = byteStore,
-        analysisSession = session {
+        byteStore = byteStore {
     var synchronousSession =
         SynchronousSession(analysisOptions, declaredVariables);
     analysisContext = AnalysisContextImpl(synchronousSession, sourceFactory);
 
-    _createElementFactory();
+    elementFactory = LinkedElementFactory(
+      analysisContext,
+      analysisSession,
+      Reference.root(),
+    );
+    if (externalSummaries != null) {
+      for (var bundle in externalSummaries.bundles) {
+        elementFactory.addBundle(
+          BundleReader(
+            elementFactory: elementFactory,
+            resolutionBytes: bundle.resolutionBytes,
+            unitsInformativeBytes: {},
+          ),
+        );
+      }
+    }
   }
 
   /// Computes a [CompilationUnitElement] for the given library/unit pair.
@@ -86,11 +98,6 @@ class LibraryContext {
     return elementFactory.libraryOfUriIfReady(uriStr);
   }
 
-  /// We are about to discard this context, mark all libraries invalid.
-  void invalidAllLibraries() {
-    elementFactory.invalidateAllLibraries();
-  }
-
   /// Load data required to access elements of the given [targetLibrary].
   void load2(FileState targetLibrary) {
     timerLoad2.start();
@@ -222,25 +229,6 @@ class LibraryContext {
     timerLoad2.stop();
   }
 
-  void _createElementFactory() {
-    elementFactory = LinkedElementFactory(
-      analysisContext,
-      analysisSession,
-      Reference.root(),
-    );
-    if (externalSummaries != null) {
-      for (var bundle in externalSummaries!.bundles) {
-        elementFactory.addBundle(
-          BundleReader(
-            elementFactory: elementFactory,
-            resolutionBytes: bundle.resolutionBytes,
-            unitsInformativeBytes: {},
-          ),
-        );
-      }
-    }
-  }
-
   /// Ensure that type provider is created.
   void _createElementFactoryTypeProvider() {
     if (!analysisContext.hasTypeProvider) {

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

@@ -3586,13 +3586,7 @@ class LibraryElementImpl extends _ExistingElementImpl
   final AnalysisContext context;
 
   @override
-  final AnalysisSession session;
-
-  /// If `true`, then this library is valid in the session.
-  ///
-  /// A library becomes invalid when one of its files, or one of its
-  /// dependencies, changes.
-  bool isValid = true;
+  AnalysisSession session;
 
   /// The language version for the library.
   LibraryLanguageVersion? _languageVersion;

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

@@ -13,7 +13,7 @@ import 'package:analyzer/src/summary2/reference.dart';
 
 class LinkedElementFactory {
   final AnalysisContextImpl analysisContext;
-  final AnalysisSessionImpl analysisSession;
+  AnalysisSessionImpl analysisSession;
   final Reference rootReference;
   final Map<String, LibraryReader> _libraryReaders = {};
   final Map<String, List<Reference>> _exportsOfLibrary = {};
@@ -165,13 +165,6 @@ class LinkedElementFactory {
     return _libraryReaders[uriStr] != null;
   }
 
-  /// We are about to discard this factory, mark all libraries invalid.
-  void invalidateAllLibraries() {
-    for (var libraryReference in rootReference.children) {
-      _invalidateLibrary(libraryReference);
-    }
-  }
-
   LibraryElementImpl? libraryOfUri(String uriStr) {
     var reference = rootReference.getChild(uriStr);
     return elementOfReference(reference) as LibraryElementImpl?;
@@ -204,8 +197,7 @@ class LinkedElementFactory {
     for (var uriStr in uriStrSet) {
       _exportsOfLibrary.remove(uriStr);
       _libraryReaders.remove(uriStr);
-      var libraryReference = rootReference.removeChild(uriStr);
-      _invalidateLibrary(libraryReference);
+      rootReference.removeChild(uriStr);
     }
 
     analysisSession.classHierarchy.removeOfLibraries(uriStrSet);
@@ -230,6 +222,16 @@ class LinkedElementFactory {
     }
   }
 
+  void replaceAnalysisSession(AnalysisSessionImpl newSession) {
+    analysisSession = newSession;
+    for (var libraryReference in rootReference.children) {
+      var libraryElement = libraryReference.element;
+      if (libraryElement is LibraryElementImpl) {
+        libraryElement.session = newSession;
+      }
+    }
+  }
+
   /// Set exports of the library with [uriStr], after building exports during
   /// linking, or after reading a linked bundle.
   void setExportsOfLibrary(String uriStr, List<Reference> exports) {
@@ -255,11 +257,4 @@ class LinkedElementFactory {
 
     libraryElement.createLoadLibraryFunction();
   }
-
-  void _invalidateLibrary(Reference? libraryReference) {
-    var libraryElement = libraryReference?.element;
-    if (libraryElement is LibraryElementImpl) {
-      libraryElement.isValid = false;
-    }
-  }
 }

pkg/analyzer/test/src/dart/analysis/driver_test.dart

@@ -819,12 +819,13 @@ import 'c.dart';
       ],
     );
 
-    // All libraries are valid.
-    expect(a_element.isValid, true);
-    expect(b_element.isValid, true);
-    expect(c_element.isValid, true);
-    expect(d_element.isValid, true);
-    expect(e_element.isValid, true);
+    // All libraries have the current session.
+    var session1 = driver.currentSession;
+    expect(a_element.session, session1);
+    expect(b_element.session, session1);
+    expect(c_element.session, session1);
+    expect(d_element.session, session1);
+    expect(e_element.session, session1);
 
     // Change `b.dart`, also removes `c.dart` and `d.dart` that import it.
     // But `a.dart` and `d.dart` is not affected.
@@ -841,12 +842,17 @@ import 'c.dart';
       ],
     );
 
-    // Only `a.dart` and `e.dart` are still valid.
-    expect(a_element.isValid, true);
-    expect(b_element.isValid, false);
-    expect(c_element.isValid, false);
-    expect(d_element.isValid, false);
-    expect(e_element.isValid, true);
+    // We have a new session.
+    var session2 = driver.currentSession;
+    expect(session2, isNot(session1));
+
+    // `a.dart` and `e.dart` moved to the new session.
+    // Invalidated libraries stuck with the old session.
+    expect(a_element.session, session2);
+    expect(b_element.session, session1);
+    expect(c_element.session, session1);
+    expect(d_element.session, session1);
+    expect(e_element.session, session2);
   }
 
   test_changeFile_potentiallyAffected_part() async {
@@ -880,10 +886,11 @@ import 'b.dart';
       ],
     );
 
-    // All libraries are valid.
-    expect(b_element.isValid, true);
-    expect(c_element.isValid, true);
-    expect(d_element.isValid, true);
+    // All libraries have the current session.
+    var session1 = driver.currentSession;
+    expect(b_element.session, session1);
+    expect(c_element.session, session1);
+    expect(d_element.session, session1);
 
     // Change `a.dart`, remove `b.dart` that part it.
     // Removes `c.dart` that imports `b.dart`.
@@ -899,10 +906,15 @@ import 'b.dart';
       ],
     );
 
-    // Only `d.dart` is still valid.
-    expect(b_element.isValid, false);
-    expect(c_element.isValid, false);
-    expect(d_element.isValid, true);
+    // We have a new session.
+    var session2 = driver.currentSession;
+    expect(session2, isNot(session1));
+
+    // `d.dart` moved to the new session.
+    // Invalidated libraries stuck with the old session.
+    expect(b_element.session, session1);
+    expect(c_element.session, session1);
+    expect(d_element.session, session2);
   }
 
   test_changeFile_selfConsistent() async {
@@ -1180,9 +1192,8 @@ const x = 1;
     var session2 = driver.currentSession;
     expect(session2, isNotNull);
 
-    // We don't discard the session anymore.
-    // So, the session is always the same.
-    expect(session2, same(session1));
+    // We get a new session.
+    expect(session2, isNot(session1));
   }
 
   test_discoverAvailableFiles_packages() async {

pkg/analyzer/test/src/dart/analysis/session_test.dart

@@ -134,6 +134,16 @@ class AnalysisSessionImplTest extends PubPackageResolutionTest {
     expect(errorsResult.errors, isNotEmpty);
   }
 
+  test_getErrors_inconsistent() async {
+    var test = newFile(testFilePath, content: '');
+    var session = contextFor(test.path).currentSession;
+    driverFor(test.path).changeFile(test.path);
+    expect(
+      () => session.getErrors(test.path),
+      throwsA(isA<InconsistentAnalysisException>()),
+    );
+  }
+
   test_getErrors_invalidPath_notAbsolute() async {
     var session = contextFor(testFilePath).currentSession;
     var errorsResult = await session.getErrors('not_absolute.dart');
@@ -146,6 +156,16 @@ class AnalysisSessionImplTest extends PubPackageResolutionTest {
     expect(errorsResult, isA<InvalidPathResult>());
   }
 
+  test_getFileSync_inconsistent() async {
+    var test = newFile(testFilePath, content: '');
+    var session = contextFor(test.path).currentSession;
+    driverFor(test.path).changeFile(test.path);
+    expect(
+      () => session.getFile(test.path),
+      throwsA(isA<InconsistentAnalysisException>()),
+    );
+  }
+
   test_getFileSync_library() async {
     var a = newFile('$testPackageLibPath/a.dart', content: '');
 
@@ -180,6 +200,16 @@ class B {}
     expect(library.getType('C'), isNull);
   }
 
+  test_getLibraryByUri_inconsistent() async {
+    var test = newFile(testFilePath, content: '');
+    var session = contextFor(test.path).currentSession;
+    driverFor(test.path).changeFile(test.path);
+    expect(
+      () => session.getLibraryByUriValid('package:test/test.dart'),
+      throwsA(isA<InconsistentAnalysisException>()),
+    );
+  }
+
   test_getLibraryByUri_unresolvedUri() async {
     var session = contextFor(testFilePath).currentSession;
     var result = await session.getLibraryByUri('package:foo/foo.dart');
@@ -267,6 +297,16 @@ int foo = 0;
     expect(parsedLibrary.getElementDeclaration(fooElement.setter!), isNull);
   }
 
+  test_getParsedLibrary_inconsistent() async {
+    var test = newFile(testFilePath, content: '');
+    var session = contextFor(test.path).currentSession;
+    driverFor(test.path).changeFile(test.path);
+    expect(
+      () => session.getParsedLibrary(test.path),
+      throwsA(isA<InconsistentAnalysisException>()),
+    );
+  }
+
   test_getParsedLibrary_invalidPartUri() async {
     var test = newFile(testFilePath, content: r'''
 part 'a.dart';
@@ -407,6 +447,16 @@ class B {}
     expect(unitResult.unit.declarations, hasLength(2));
   }
 
+  test_getParsedUnit_inconsistent() async {
+    var test = newFile(testFilePath, content: '');
+    var session = contextFor(test.path).currentSession;
+    driverFor(test.path).changeFile(test.path);
+    expect(
+      () => session.getParsedUnit(test.path),
+      throwsA(isA<InconsistentAnalysisException>()),
+    );
+  }
+
   test_getParsedUnit_invalidPath_notAbsolute() async {
     var session = contextFor(testFilePath).currentSession;
     var result = session.getParsedUnit('not_absolute.dart');
@@ -512,6 +562,16 @@ int foo = 0;
     expect(resolvedLibrary.getElementDeclaration(fooElement.setter!), isNull);
   }
 
+  test_getResolvedLibrary_inconsistent() async {
+    var test = newFile(testFilePath, content: '');
+    var session = contextFor(test.path).currentSession;
+    driverFor(test.path).changeFile(test.path);
+    expect(
+      () => session.getResolvedLibrary(test.path),
+      throwsA(isA<InconsistentAnalysisException>()),
+    );
+  }
+
   test_getResolvedLibrary_invalidPartUri() async {
     var test = newFile(testFilePath, content: r'''
 part 'a.dart';
@@ -600,6 +660,16 @@ class B {}
     expect(unitResult.libraryElement, isNotNull);
   }
 
+  test_getResolvedUnit_inconsistent() async {
+    var test = newFile(testFilePath, content: '');
+    var session = contextFor(test.path).currentSession;
+    driverFor(test.path).changeFile(test.path);
+    expect(
+      () => session.getResolvedUnit(test.path),
+      throwsA(isA<InconsistentAnalysisException>()),
+    );
+  }
+
   test_getUnitElement() async {
     var test = newFile(testFilePath, content: r'''
 class A {}
@@ -614,6 +684,16 @@ class B {}
     expect(unitResult.element.classes, hasLength(2));
   }
 
+  test_getUnitElement_inconsistent() async {
+    var test = newFile(testFilePath, content: '');
+    var session = contextFor(test.path).currentSession;
+    driverFor(test.path).changeFile(test.path);
+    expect(
+      () => session.getUnitElement(test.path),
+      throwsA(isA<InconsistentAnalysisException>()),
+    );
+  }
+
   test_resourceProvider() async {
     var session = contextFor(testFilePath).currentSession;
     expect(session.resourceProvider, resourceProvider);