Listen for context add/remove and unit invalidation to update the index.

pkg/analysis_server/lib/src/services/index2/index2.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/generated/engine.dart' show AnalysisContext;
 import 'package:analyzer/src/generated/source.dart';
@@ skipping 77 matching lines @@
   }
 
   /**
    * Remove all index information for the given [context].
    */
   void removeContext(AnalysisContext context) {
     _contextIndexMap.remove(context);
   }
 
   /**
+   * Remove index information about the unit in the given [context].
+   */
+  void removeUnit(
+      AnalysisContext context, Source librarySource, Source unitSource) {
+    _contextIndexMap[context]?.removeUnit(librarySource, unitSource);
+  }
+
+  /**
    * Return the [_ContextIndex] instance for the given [context].
    */
   _ContextIndex _getContextIndex(AnalysisContext context) {
     return _contextIndexMap.putIfAbsent(context, () {
       return new _ContextIndex(context);
     });
   }
 
   /**
    * Complete with a list of all results returned by the [callback] for every
@@ skipping 92 matching lines @@
   final Map<String, PackageIndex> indexMap = <String, PackageIndex>{};
 
   _ContextIndex(this.context);
 
   /**
    * Complete with a list of locations where elements of the given [kind] with
    * names satisfying the given [regExp] are defined.
    */
   Future<List<Location>> getDefinedNames(
       RegExp regExp, IndexNameKind kind) async {
-    return _mergeLocations((PackageIndex index) {
-      _PackageIndexRequester requester = new _PackageIndexRequester(index);
+    return _mergeLocations((_PackageIndexRequester requester) {
       return requester.getDefinedNames(context, regExp, kind);
     });
   }
 
   /**
    * Complete with a list of locations where the given [element] has relation
    * of the given [kind].
    */
   Future<List<Location>> getRelations(Element element, IndexRelationKind kind) {
-    return _mergeLocations((PackageIndex index) {
-      _PackageIndexRequester requester = new _PackageIndexRequester(index);
+    return _mergeLocations((_PackageIndexRequester requester) {
       return requester.getRelations(context, element, kind);
     });
   }
 
   /**
    * Complete with a list of locations where a class members with the given
    * [name] is referenced with a qualifier, but is not resolved.
    */
   Future<List<Location>> getUnresolvedMemberReferences(String name) async {
-    return _mergeLocations((PackageIndex index) {
-      _PackageIndexRequester requester = new _PackageIndexRequester(index);
+    return _mergeLocations((_PackageIndexRequester requester) {
       return requester.getUnresolvedMemberReferences(context, name);
     });
   }
 
   /**
    * Index the given fully resolved [unit].
    */
   void indexUnit(CompilationUnit unit) {
     // Index the unit.
     PackageIndexAssembler assembler = new PackageIndexAssembler();
     assembler.index(unit);
     PackageIndexBuilder indexBuilder = assembler.assemble();
     // Put the index into the map.
     List<int> indexBytes = indexBuilder.toBuffer();
     PackageIndex index = new PackageIndex.fromBuffer(indexBytes);
     String key = _getUnitKeyForElement(unit.element);
     indexMap[key] = index;
   }
 
+  /**
+   * Remove index information about the unit.
+   */
+  void removeUnit(Source librarySource, Source unitSource) {
+    String key = _getUnitKeyForSource(librarySource, unitSource);
+    indexMap.remove(key);
+  }
+
   String _getUnitKeyForElement(CompilationUnitElement unitElement) {
     Source librarySource = unitElement.library.source;
     Source unitSource = unitElement.source;
     return _getUnitKeyForSource(librarySource, unitSource);
   }
 
   String _getUnitKeyForSource(Source librarySource, Source unitSource) {
     String unitLibraryUri = librarySource.uri.toString();
     String unitUnitUri = unitSource.uri.toString();
     return '$unitLibraryUri;$unitUnitUri';
   }
 
   Future<List<Location>> _mergeLocations(
-      List<Location> callback(PackageIndex index)) async {
+      List<Location> callback(_PackageIndexRequester requester)) async {
     List<Location> locations = <Location>[];
     for (PackageIndex index in indexMap.values) {
-      List<Location> indexLocations = callback(index);
+      _PackageIndexRequester requester = new _PackageIndexRequester(index);
+      List<Location> indexLocations = callback(requester);
       locations.addAll(indexLocations);
     }
     return locations;
   }
 }
 
 /**
  * Helper for requesting information from a single [PackageIndex].
  */
 class _PackageIndexRequester {
@@ skipping 237 matching lines @@
         i < unitIndex.usedNames.length && unitIndex.usedNames[i] == nameId;
         i++) {
       unitLibraryUri ??= packageRequester.getUnitLibraryUri(unitIndex.unit);
       unitUnitUri ??= packageRequester.getUnitUnitUri(unitIndex.unit);
       locations.add(new Location(context, unitLibraryUri, unitUnitUri,
           unitIndex.usedNameOffsets[i], name.length, true));
     }
     return locations;
   }
 }