include lower relevance suggestions only if they are already cached

pkg/analysis_server/lib/src/services/completion/dart_completion_cache.dart

 // Copyright (c) 2014, 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.
 
 library services.completion.dart.cache;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analysis_server/src/protocol_server.dart' hide Element,
@@ skipping 59 matching lines @@
       : super(context, source);
 
   /**
    * Return a hash of the import directives for the cached import info
    * or `null` if nothing has been cached.
    */
   String get importKey => _importKey;
 
   /**
    * Compute suggestions based upon the imports in the given compilation unit.
-   * Return a future that completes when the information has been cached.
+   * On return, the cache will be populated except for lower priority
+   * suggestions added as a result of a global search. Callers may wait
+   * on the returned future if they want to ensure those lower priority
+   * suggestions are part of the cached suggestions.
    */
   Future<bool> computeImportInfo(CompilationUnit unit,
       SearchEngine searchEngine) {
     importedTypeSuggestions = <CompletionSuggestion>[];
     libraryPrefixSuggestions = <CompletionSuggestion>[];
     otherImportedSuggestions = <CompletionSuggestion>[];
     importedVoidReturnSuggestions = <CompletionSuggestion>[];
     importedClassMap = new Map<String, ClassElement>();
     _importedCompletions = new HashSet<String>();
 
@@ skipping 32 matching lines @@
     LibraryElement coreLib = context.getLibraryElement(coreUri);
     Namespace coreNamespace =
         new NamespaceBuilder().createPublicNamespaceForLibrary(coreLib);
     coreNamespace.definedNames.forEach((String name, Element elem) {
       if (elem is ClassElement) {
         importedClassMap[name] = elem;
       }
       addSuggestion(elem, CompletionRelevance.DEFAULT);
     });
 
+    /*
+     * Don't wait for search of lower relevance results to complete.
+     * Set key indicating results are ready, and lower relevance results
+     * will be added to the cache when the search completes.
+     */
+    _importKey = _computeImportKey(unit);
+
     // Add non-imported elements as low relevance
-    var future = searchEngine.searchTopLevelDeclarations('');
+    Future<List<SearchMatch>> future =
+        searchEngine.searchTopLevelDeclarations('');
     return future.then((List<SearchMatch> matches) {
       matches.forEach((SearchMatch match) {
         if (match.kind == MatchKind.DECLARATION) {
           Element element = match.element;
           if (element.isPublic &&
               !excludedLibs.contains(element.library) &&
               !_importedCompletions.contains(element.displayName)) {
             addSuggestion(element, CompletionRelevance.LOW);
           }
         }
       });
-      _importKey = _computeImportKey(unit);
       return true;
     });
   }
 
   /**
    * Return `true` if the import information is cached for the given
    * compilation unit.
    */
   bool isImportInfoCached(CompilationUnit unit) =>
       _importKey != null && _importKey == _computeImportKey(unit);
@@ skipping 51 matching lines @@
   String _computeImportKey(CompilationUnit unit) {
     StringBuffer sb = new StringBuffer();
     unit.directives.forEach((Directive directive) {
       if (directive is ImportDirective) {
         sb.write(directive.toSource());
       }
     });
     return sb.toString();
   }
 }