abort completion request - fixes #24271

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

Index: pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart b/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
index 602503e789842eda3251958ee1ae8fc44ce2fbc3..5cfdacef0120bf9de9db13431207ad612a3c9b19 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
@@ -25,10 +25,12 @@ 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
@@ -44,17 +46,15 @@ class DartCompletionManager implements CompletionContributor {
   @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) {
@@ -78,6 +78,7 @@ class DartCompletionManager implements CompletionContributor {
       List<CompletionSuggestion> contributorSuggestions =
           await contributor.computeSuggestions(dartRequest);
       performance.logElapseTime(contributorTag);
+      request.checkAborted();
 
       for (CompletionSuggestion newSuggestion in contributorSuggestions) {
         var oldSuggestion = suggestionMap.putIfAbsent(
@@ -95,6 +96,7 @@ class DartCompletionManager implements CompletionContributor {
     performance.logStartTime(SORT_TAG);
     await contributionSorter.sort(dartRequest, suggestions);
     performance.logElapseTime(SORT_TAG);
+    request.checkAborted();
     return suggestions;
   }
 }
@@ -139,6 +141,8 @@ class DartCompletionRequestImpl implements DartCompletionRequest {
 
   OpType _opType;
 
+  final CompletionRequest _originalRequest;
+
   final CompletionPerformance performance;
 
   DartCompletionRequestImpl._(
@@ -149,6 +153,7 @@ class DartCompletionRequestImpl implements DartCompletionRequest {
       this.source,
       this.offset,
       CompilationUnit unit,
+      this._originalRequest,
       this.performance) {
     _updateTargets(unit);
   }
@@ -200,26 +205,35 @@ class DartCompletionRequestImpl implements DartCompletionRequest {
     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;
@@ -233,13 +247,12 @@ class DartCompletionRequestImpl implements DartCompletionRequest {
     // 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
@@ -285,9 +298,11 @@ class DartCompletionRequestImpl implements DartCompletionRequest {
 
   /**
    * 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';
@@ -313,12 +328,12 @@ class DartCompletionRequestImpl implements DartCompletionRequest {
 
     // 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._(
@@ -329,6 +344,7 @@ class DartCompletionRequestImpl implements DartCompletionRequest {
         request.source,
         request.offset,
         unit,
+        request,
         performance);
 
     // Resolve the expression in which the completion occurs
@@ -341,12 +357,33 @@ class DartCompletionRequestImpl implements DartCompletionRequest {
         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;
+  }
 }
 
 /**