abort completion request - fixes #24271

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

 // Copyright (c) 2015, 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.manager;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/provisional/completion/completion_core.dart'
     show CompletionContributor, CompletionRequest;
 import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
 import 'package:analysis_server/src/provisional/completion/dart/completion_plugin.dart';
 import 'package:analysis_server/src/provisional/completion/dart/completion_target.dart';
 import 'package:analysis_server/src/services/completion/completion_core.dart';
 import 'package:analysis_server/src/services/completion/completion_performance.dart';
 import 'package:analysis_server/src/services/completion/dart/common_usage_sorter.dart';
 import 'package:analysis_server/src/services/completion/dart/contribution_sorter.dart';
 import 'package:analysis_server/src/services/completion/dart/optype.dart';
 import 'package:analysis_server/src/services/search/search_engine.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/context/context.dart'
     show AnalysisFutureHelper, AnalysisContextImpl;
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/engine.dart' hide AnalysisContextImpl;
+import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/task/dart.dart';
 import 'package:analyzer/task/dart.dart';
+import 'package:analyzer/task/model.dart';
 
 /**
  * [DartCompletionManager] determines if a completion request is Dart specific
  * and forwards those requests to all [DartCompletionContributor]s.
  */
 class DartCompletionManager implements CompletionContributor {
   /**
    * The [contributionSorter] is a long-lived object that isn't allowed
    * to maintain state between calls to [DartContributionSorter#sort(...)].
    */
   static DartContributionSorter contributionSorter = new CommonUsageSorter();
 
   @override
   Future<List<CompletionSuggestion>> computeSuggestions(
       CompletionRequest request) async {
+    request.checkAborted();
     if (!AnalysisEngine.isDartFileName(request.source.shortName)) {
       return EMPTY_LIST;
     }
 
     CompletionPerformance performance =
         (request as CompletionRequestImpl).performance;
-    const BUILD_REQUEST_TAG = 'build DartCompletionRequestImpl';
-    performance.logStartTime(BUILD_REQUEST_TAG);
     DartCompletionRequestImpl dartRequest =
         await DartCompletionRequestImpl.from(request);
-    performance.logElapseTime(BUILD_REQUEST_TAG);
 
     // Don't suggest in comments.
     if (dartRequest.target.isCommentText) {
       return EMPTY_LIST;
     }
 
     ReplacementRange range =
         new ReplacementRange.compute(dartRequest.offset, dartRequest.target);
     (request as CompletionRequestImpl)
       ..replacementOffset = range.offset
       ..replacementLength = range.length;
 
     // Request Dart specific completions from each contributor
     Map<String, CompletionSuggestion> suggestionMap =
         <String, CompletionSuggestion>{};
     for (DartCompletionContributor contributor
         in dartCompletionPlugin.contributors) {
       String contributorTag =
           'DartCompletionManager - ${contributor.runtimeType}';
       performance.logStartTime(contributorTag);
       List<CompletionSuggestion> contributorSuggestions =
           await contributor.computeSuggestions(dartRequest);
       performance.logElapseTime(contributorTag);
+      request.checkAborted();
 
       for (CompletionSuggestion newSuggestion in contributorSuggestions) {
         var oldSuggestion = suggestionMap.putIfAbsent(
             newSuggestion.completion, () => newSuggestion);
         if (newSuggestion != oldSuggestion &&
             newSuggestion.relevance > oldSuggestion.relevance) {
           suggestionMap[newSuggestion.completion] = newSuggestion;
         }
       }
     }
 
     // Adjust suggestion relevance before returning
     List<CompletionSuggestion> suggestions = suggestionMap.values.toList();
     const SORT_TAG = 'DartCompletionManager - sort';
     performance.logStartTime(SORT_TAG);
     await contributionSorter.sort(dartRequest, suggestions);
     performance.logElapseTime(SORT_TAG);
+    request.checkAborted();
     return suggestions;
   }
 }
 
 /**
  * The information about a requested list of completions within a Dart file.
  */
 class DartCompletionRequestImpl implements DartCompletionRequest {
   @override
   final AnalysisContext context;
@@ skipping 24 matching lines @@
    */
   LibraryElement _coreLib;
 
   /**
    * The [DartType] for Object in dart:core
    */
   InterfaceType _objectType;
 
   OpType _opType;
 
+  final CompletionRequest _originalRequest;
+
   final CompletionPerformance performance;
 
   DartCompletionRequestImpl._(
       this.context,
       this.resourceProvider,
       this.searchEngine,
       this.librarySource,
       this.source,
       this.offset,
       CompilationUnit unit,
+      this._originalRequest,
       this.performance) {
     _updateTargets(unit);
   }
 
   @override
   LibraryElement get coreLib {
     if (_coreLib == null) {
       Source coreUri = context.sourceFactory.forUri('dart:core');
       _coreLib = context.computeLibraryElement(coreUri);
     }
@@ skipping 31 matching lines @@
     return _objectType;
   }
 
   OpType get opType {
     if (_opType == null) {
       _opType = new OpType.forCompletion(target, offset);
     }
     return _opType;
   }
 
+  /**
+   * Throw [AbortCompletion] if the completion request has been aborted.
+   */
+  void checkAborted() {
+    _originalRequest.checkAborted();
+  }
+
   // For internal use only
   @override
   Future<List<Directive>> resolveDirectives() async {
+    checkAborted();
+
     CompilationUnit libUnit;
     if (librarySource != null) {
       // TODO(danrubel) only resolve the directives
-      const RESOLVE_DIRECTIVES_TAG = 'resolve directives';
-      performance.logStartTime(RESOLVE_DIRECTIVES_TAG);
-      libUnit = await new AnalysisFutureHelper<CompilationUnit>(
-              context,
-              new LibrarySpecificUnit(librarySource, librarySource),
-              RESOLVED_UNIT3)
-          .computeAsync();
-      performance.logElapseTime(RESOLVE_DIRECTIVES_TAG);
+      libUnit = await _computeAsync(
+          this,
+          new LibrarySpecificUnit(librarySource, librarySource),
+          RESOLVED_UNIT3,
+          performance,
+          'resolve directives');
     }
     return libUnit?.directives;
   }
 
   @override
   Future resolveExpression(Expression expression) async {
+    checkAborted();
+
     // Return immediately if the expression has already been resolved
     if (expression.propagatedType != null) {
       return;
     }
 
     // Gracefully degrade if librarySource cannot be determined
     if (librarySource == null) {
       return;
     }
 
     // Resolve declarations in the target unit
     // TODO(danrubel) resolve the expression or containing method
     // rather than the entire complilation unit
-    const RESOLVE_EXPRESSION_TAG = 'resolve expression';
-    performance.logStartTime(RESOLVE_EXPRESSION_TAG);
-    CompilationUnit resolvedUnit =
-        await new AnalysisFutureHelper<CompilationUnit>(context,
-                new LibrarySpecificUnit(librarySource, source), RESOLVED_UNIT)
-            .computeAsync();
-    performance.logElapseTime(RESOLVE_EXPRESSION_TAG);
+    CompilationUnit resolvedUnit = await _computeAsync(
+        this,
+        new LibrarySpecificUnit(librarySource, source),
+        RESOLVED_UNIT,
+        performance,
+        'resolve expression');
 
     // TODO(danrubel) determine if the underlying source has been modified
     // in a way that invalidates the completion request
     // and return null
 
     // Gracefully degrade if unit cannot be resolved
     if (resolvedUnit == null) {
       return;
     }
 
@@ skipping 25 matching lines @@
     }
     if (node is PrefixedIdentifier) {
       if (identical(node.identifier, target.entity)) {
         dotTarget = node.prefix;
       }
     }
   }
 
   /**
    * Return a [Future] that completes with a newly created completion request
-   * based on the given [request].
+   * based on the given [request]. This method will throw [AbortCompletion]
+   * if the completion request has been aborted.
    */
   static Future<DartCompletionRequest> from(CompletionRequest request) async {
+    request.checkAborted();
     CompletionPerformance performance =
         (request as CompletionRequestImpl).performance;
     const BUILD_REQUEST_TAG = 'build DartCompletionRequest';
     performance.logStartTime(BUILD_REQUEST_TAG);
 
     Source source = request.source;
     AnalysisContext context = request.context;
 
     const PARSE_TAG = 'parse unit';
     performance.logStartTime(PARSE_TAG);
     CompilationUnit unit = request.context.computeResult(source, PARSED_UNIT);
     performance.logElapseTime(PARSE_TAG);
 
     Source libSource;
     if (unit.directives.any((d) => d is PartOfDirective)) {
       List<Source> libraries = context.getLibrariesContaining(source);
       if (libraries.isNotEmpty) {
         libSource = libraries[0];
       }
     } else {
       libSource = source;
     }
 
     // Most (all?) contributors need declarations in scope to be resolved
     if (libSource != null) {
-      const RESOLVE_DECLARATIONS_TAG = 'resolve declarations';
-      performance.logStartTime(RESOLVE_DECLARATIONS_TAG);
-      unit = await new AnalysisFutureHelper<CompilationUnit>(context,
-              new LibrarySpecificUnit(libSource, source), RESOLVED_UNIT3)
-          .computeAsync();
-      performance.logElapseTime(RESOLVE_DECLARATIONS_TAG);
+      unit = await _computeAsync(
+          request,
+          new LibrarySpecificUnit(libSource, source),
+          RESOLVED_UNIT3,
+          performance,
+          'resolve declarations');
     }
 
     DartCompletionRequestImpl dartRequest = new DartCompletionRequestImpl._(
         request.context,
         request.resourceProvider,
         request.searchEngine,
         libSource,
         request.source,
         request.offset,
         unit,
+        request,
         performance);
 
     // Resolve the expression in which the completion occurs
     // to properly determine if identifiers should be suggested
     // rather than invocations.
     if (dartRequest.target.maybeFunctionalArgument()) {
       AstNode node = dartRequest.target.containingNode.parent;
       if (node is Expression) {
         const FUNCTIONAL_ARG_TAG = 'resolve expression for isFunctionalArg';
         performance.logStartTime(FUNCTIONAL_ARG_TAG);
         await dartRequest.resolveExpression(node);
         performance.logElapseTime(FUNCTIONAL_ARG_TAG);
+        dartRequest.checkAborted();
       }
     }
 
     performance.logElapseTime(BUILD_REQUEST_TAG);
     return dartRequest;
   }
+
+  static Future _computeAsync(CompletionRequest request, AnalysisTarget target,
+      ResultDescriptor descriptor, CompletionPerformance performance, String perfTag) async {
+    request.checkAborted();
+    performance.logStartTime(perfTag);
+    var result;
+    try {
+      result =
+          await new AnalysisFutureHelper(request.context, target, descriptor)
+              .computeAsync();
+    } catch (e, s) {
+      if (e is AnalysisNotScheduledError) {
+        request.checkAborted();
+      }
+      throw new AnalysisException(
+          'failed to $perfTag', new CaughtException(e, s));
+    }
+    request.checkAborted();
+    return result;
+  }
 }
 
 /**
  * Utility class for computing the code completion replacement range
  */
 class ReplacementRange {
   int offset;
   int length;
 
   ReplacementRange(this.offset, this.length);
@@ skipping 38 matching lines @@
               // Replacement range for import URI
               return new ReplacementRange(start, end - start);
             }
           }
         }
       }
     }
     return new ReplacementRange(requestOffset, 0);
   }
 }