Replace try/finally with PerformanceTag.makeCurrentWhile().

pkg/analyzer/lib/src/generated/engine.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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine;
 
 import "dart:math" as math;
@@ skipping 2270 matching lines @@
 
   @override
   ht.HtmlUnit parseHtmlUnit(Source source) =>
       _getHtmlParseData(source, HtmlEntry.PARSED_UNIT, null);
 
   @override
   AnalysisResult performAnalysisTask() {
     if (_TRACE_PERFORM_TASK) {
       print("----------------------------------------");
     }
-    PerformanceTag prevTag = PerformanceStatistics.performAnaysis.makeCurrent();
-    try {
+    return PerformanceStatistics.performAnaysis.makeCurrentWhile(() {
       int getStart = JavaSystem.currentTimeMillis();
       AnalysisTask task = nextAnalysisTask;
       int getEnd = JavaSystem.currentTimeMillis();
       if (task == null && _validateCacheConsistency()) {
         task = nextAnalysisTask;
       }
       if (task == null) {
         _validateLastIncrementalResolutionResult();
         if (_performAnalysisTaskStopwatch != null) {
           AnalysisEngine.instance.instrumentationService.logPerformance(
@@ skipping 45 matching lines @@
 //        } else if (notice.getHtmlUnit() != null) {
 //          notifyResolvedHtml(source, notice.getHtmlUnit());
 //        }
         _notifyErrors(source, notice.errors, notice.lineInfo);
       }
       return new AnalysisResult(
           notices,
           getEnd - getStart,
           task.runtimeType.toString(),
           performEnd - performStart);
-    } finally {
-      prevTag.makeCurrent();
-    }
+    });
   }
 
   @override
   void recordLibraryElements(Map<Source, LibraryElement> elementMap) {
     Source htmlSource = _sourceFactory.forUri(DartSdk.DART_HTML);
     elementMap.forEach((Source librarySource, LibraryElement library) {
       //
       // Cache the element in the library's info.
       //
       DartEntry dartEntry = _getReadableDartEntry(librarySource);
@@ skipping 1082 matching lines @@
    *
    * @param source the source whose content is to be resolved
    * @param dartEntry the entry for the source
    * @return task data representing the created task
    */
   AnalysisContextImpl_TaskData _createResolveDartLibraryTask(Source source,
       DartEntry dartEntry) {
     try {
       AnalysisContextImpl_CycleBuilder builder =
           new AnalysisContextImpl_CycleBuilder(this);
-      PerformanceTag prevTag = PerformanceStatistics.cycles.makeCurrent();
-      try {
+      PerformanceStatistics.cycles.makeCurrentWhile(() {
         builder.computeCycleContaining(source);
-      } finally {
-        prevTag.makeCurrent();
-      }
+      });
       AnalysisContextImpl_TaskData taskData = builder.taskData;
       if (taskData != null) {
         return taskData;
       }
       return new AnalysisContextImpl_TaskData(
           new ResolveDartLibraryCycleTask(this, source, source, builder.librariesInCycle),
           false);
     } on AnalysisException catch (exception, stackTrace) {
       dartEntry.recordResolutionError(
           new CaughtException(exception, stackTrace));
@@ skipping 5310 matching lines @@
   @override
   String get taskDescription =>
       "generate errors and warnings for ${source.fullName}";
 
   @override
   accept(AnalysisTaskVisitor visitor) =>
       visitor.visitGenerateDartErrorsTask(this);
 
   @override
   void internalPerform() {
-    PerformanceTag prevTag = PerformanceStatistics.errors.makeCurrent();
-    try {
+    PerformanceStatistics.errors.makeCurrentWhile(() {
       RecordingErrorListener errorListener = new RecordingErrorListener();
       ErrorReporter errorReporter = new ErrorReporter(errorListener, source);
       TypeProvider typeProvider = context.typeProvider;
       //
       // Validate the directives
       //
       validateDirectives(context, source, _unit, errorListener);
       //
       // Use the ConstantVerifier to verify the use of constants.
       // This needs to happen before using the ErrorVerifier because some error
       // codes need the computed constant values.
       //
       // TODO(paulberry): as a temporary workaround for issue 21572,
       // ConstantVerifier is being run right after ConstantValueComputer, so we
       // don't need to run it here.  Once issue 21572 is fixed, re-enable the
       // call to ConstantVerifier.
 //      ConstantVerifier constantVerifier = new ConstantVerifier(errorReporter, libraryElement, typeProvider);
 //      _unit.accept(constantVerifier);
       //
       // Use the ErrorVerifier to compute the rest of the errors.
       //
       ErrorVerifier errorVerifier = new ErrorVerifier(
           errorReporter,
           libraryElement,
           typeProvider,
           new InheritanceManager(libraryElement));
       _unit.accept(errorVerifier);
       _errors = errorListener.getErrorsForSource(source);
-    } finally {
-      prevTag.makeCurrent();
-    }
+    });
   }
 
   /**
    * Check each directive in the given compilation unit to see if the referenced source exists and
    * report an error if it does not.
    *
    * @param context the context in which the library exists
    * @param librarySource the source representing the library containing the directives
    * @param unit the compilation unit containing the directives to be validated
    * @param errorListener the error listener to which errors should be reported
@@ skipping 1216 matching lines @@
   }
 
   @override
   accept(AnalysisTaskVisitor visitor) => visitor.visitParseDartTask(this);
 
   @override
   void internalPerform() {
     //
     // Then parse the token stream.
     //
-    PerformanceTag prevTag = PerformanceStatistics.parse.makeCurrent();
-    try {
+    PerformanceStatistics.parse.makeCurrentWhile(() {
       RecordingErrorListener errorListener = new RecordingErrorListener();
       Parser parser = new Parser(source, errorListener);
       AnalysisOptions options = context.analysisOptions;
       parser.parseFunctionBodies = options.analyzeFunctionBodies;
       _unit = parser.parseCompilationUnit(_tokenStream);
       _unit.lineInfo = lineInfo;
       AnalysisContext analysisContext = context;
       for (Directive directive in _unit.directives) {
         if (directive is PartOfDirective) {
           _containsPartOfDirective = true;
@@ skipping 13 matching lines @@
                 }
               } else {
                 throw new AnalysisException(
                     "$runtimeType failed to handle a ${directive.runtimeType}");
               }
             }
           }
         }
       }
       _errors = errorListener.getErrorsForSource(source);
-    } finally {
-      prevTag.makeCurrent();
-    }
+    });
   }
 
   /**
    * Efficiently convert the given set of sources to an array.
    *
    * @param sources the set to be converted
    * @return an array containing all of the sources in the given set
    */
   List<Source> _toArray(HashSet<Source> sources) {
     int size = sources.length;
@@ skipping 1178 matching lines @@
     ResolverVisitor resolverVisitor = new ResolverVisitor.con2(
         _libraryElement,
         source,
         typeProvider,
         inheritanceManager,
         errorListener);
     unit.accept(resolverVisitor);
     //
     // Perform additional error checking.
     //
-    PerformanceTag prevTag = PerformanceStatistics.errors.makeCurrent();
-    try {
+    PerformanceStatistics.errors.makeCurrentWhile(() {
       ErrorReporter errorReporter = new ErrorReporter(errorListener, source);
       ErrorVerifier errorVerifier = new ErrorVerifier(
           errorReporter,
           _libraryElement,
           typeProvider,
           inheritanceManager);
       unit.accept(errorVerifier);
       // TODO(paulberry): as a temporary workaround for issue 21572,
       // ConstantVerifier is being run right after ConstantValueComputer, so we
       // don't need to run it here.  Once issue 21572 is fixed, re-enable the
       // call to ConstantVerifier.
 //       ConstantVerifier constantVerifier = new ConstantVerifier(errorReporter, _libraryElement, typeProvider);
 //       unit.accept(constantVerifier);
-    } finally {
-      prevTag.makeCurrent();
-    }
+    });
     //
     // Capture the results.
     //
     _resolvedUnit = unit;
   }
 
   /**
    * Search the compilation units that are part of the given library and return the element
    * representing the compilation unit with the given source. Return `null` if there is no
    * such compilation unit.
@@ skipping 207 matching lines @@
    *
    * @return the token stream that was produced by scanning the source
    */
   Token get tokenStream => _tokenStream;
 
   @override
   accept(AnalysisTaskVisitor visitor) => visitor.visitScanDartTask(this);
 
   @override
   void internalPerform() {
-    RecordingErrorListener errorListener = new RecordingErrorListener();
-    PerformanceTag prevTag = PerformanceStatistics.scan.makeCurrent();
-    try {
-      Scanner scanner =
-          new Scanner(source, new CharSequenceReader(_content), errorListener);
-      scanner.preserveComments = context.analysisOptions.preserveComments;
-      _tokenStream = scanner.tokenize();
-      _lineInfo = new LineInfo(scanner.lineStarts);
-      _errors = errorListener.getErrorsForSource(source);
-    } catch (exception, stackTrace) {
-      throw new AnalysisException(
-          "Exception",
-          new CaughtException(exception, stackTrace));
-    } finally {
-      prevTag.makeCurrent();
-    }
+    PerformanceStatistics.scan.makeCurrentWhile(() {
+      RecordingErrorListener errorListener = new RecordingErrorListener();
+      try {
+        Scanner scanner =
+            new Scanner(source, new CharSequenceReader(_content), errorListener);
+        scanner.preserveComments = context.analysisOptions.preserveComments;
+        _tokenStream = scanner.tokenize();
+        _lineInfo = new LineInfo(scanner.lineStarts);
+        _errors = errorListener.getErrorsForSource(source);
+      } catch (exception, stackTrace) {
+        throw new AnalysisException(
+            "Exception",
+            new CaughtException(exception, stackTrace));
+      }
+    });
   }
 }
 
 /**
  * Instances of the class `SdkAnalysisContext` implement an [AnalysisContext] that only
  * contains sources for a Dart SDK.
  */
 class SdkAnalysisContext extends AnalysisContextImpl {
   @override
   AnalysisCache createCacheFromSourceFactory(SourceFactory factory) {
@@ skipping 863 matching lines @@
     if (element.id == _id) {
       result = element;
       throw new _ElementByIdFinderException();
     }
     super.visitElement(element);
   }
 }
 
 class _ElementByIdFinderException {
 }