Only send "analysis.analyzedFiles" notification when the set of files changes.

pkg/analysis_server/lib/src/operation/operation_analysis.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 operation.analysis;
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/computer/computer_highlights.dart';
 import 'package:analysis_server/src/computer/computer_navigation.dart';
 import 'package:analysis_server/src/computer/computer_occurrences.dart';
@@ skipping 83 matching lines @@
   }
   // errors
   if (server.shouldSendErrorsNotificationFor(file)) {
     server.scheduleOperation(
         new _NotificationErrorsOperation(context, file, lineInfo, errors));
   }
 }
 
 void sendAnalysisNotificationAnalyzedFiles(AnalysisServer server) {
   _sendNotification(server, () {
+    // TODO(paulberry): if it proves to be too inefficient to recompute the set
+    // of analyzed files each time analysis is complete, consider modifying the
+    // analysis engine to update this set incrementally as analysis is
+    // performed.
     LibraryDependencyCollector collector =
         new LibraryDependencyCollector(server.getAnalysisContexts().toList());
-    Set<String> directories = collector.collectLibraryDependencies();
+    Set<String> analyzedFiles = collector.collectLibraryDependencies();
+    Set<String> prevAnalyzedFiles = server.prevAnalyzedFiles;
+    if (prevAnalyzedFiles != null &&
+        prevAnalyzedFiles.length == analyzedFiles.length &&
+        prevAnalyzedFiles.difference(analyzedFiles).isEmpty) {
+      // No change to the set of analyzed files.  No need to send another
+      // notification.
+      return;
+    }
+    server.prevAnalyzedFiles = analyzedFiles;
     protocol.AnalysisAnalyzedFilesParams params =
-        new protocol.AnalysisAnalyzedFilesParams(directories.toList());
+        new protocol.AnalysisAnalyzedFilesParams(analyzedFiles.toList());
     server.sendNotification(params.toNotification());
   });
 }
 
 void sendAnalysisNotificationErrors(AnalysisServer server, String file,
     LineInfo lineInfo, List<AnalysisError> errors) {
   _sendNotification(server, () {
     if (errors == null) {
       errors = <AnalysisError>[];
     }
@@ skipping 334 matching lines @@
 abstract class _SingleFileOperation extends SourceSensitiveOperation {
   final String file;
 
   _SingleFileOperation(AnalysisContext context, this.file) : super(context);
 
   @override
   bool shouldBeDiscardedOnSourceChange(Source source) {
     return source.fullName == file;
   }
 }