Don't remove indexing operations on potential source changes.

pkg/analysis_server/lib/src/analysis_server.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 analysis.server;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:math' show max;
 
@@ skipping 643 matching lines @@
       completer = new Completer<AnalysisDoneReason>();
       contextAnalysisDoneCompleters[context] = completer;
     }
     return completer.future;
   }
 
   /**
    * Perform the next available [ServerOperation].
    */
   void performOperation() {
-    assert(performOperationPending);

[Paul Berry, 2015/02/27 22:05:00]

Why remove this assertion?  AFAICT this invariant should still hold, and if it
doesn't we are likely introducing a bug.

[scheglov, 2015/02/28 01:34:35]

I found the problem in my test code.
And you are right, this assertion actually helper my to avoid having two
parallel Future sequences.
We cannot call performOperation() directly, we have to rely on the existing
scheduled instance and have another way to be notified after a single operation
execution.

     PerformanceTag.UNKNOWN.makeCurrent();
     performOperationPending = false;
     if (!running) {
       // An error has occurred, or the connection to the client has been
       // closed, since this method was scheduled on the event queue.  So
       // don't do anything.  Instead clear the operation queue.
       operationQueue.clear();
       return;
     }
     // prepare next operation
@@ skipping 348 matching lines @@
             oldContents,
             newContents,
             true)) {
           schedulePerformAnalysisOperation(context);
         } else {
           // When the client sends any change for a source, we should resend
           // subscribed notifications, even if there were no changes in the
           // source contents.
           // TODO(scheglov) consider checking if there are subscriptions.
           if (AnalysisEngine.isDartFileName(file)) {
-            CompilationUnit dartUnit =
-                context.ensureAnyResolvedDartUnit(source);
-            if (dartUnit != null) {
+            List<CompilationUnit> dartUnits =
+                context.ensureResolvedDartUnits(source);
+            if (dartUnits != null) {
               AnalysisErrorInfo errorInfo = context.getErrors(source);
-              scheduleNotificationOperations(
-                  this,
-                  file,
-                  errorInfo.lineInfo,
-                  context,
-                  null,
-                  dartUnit,
-                  errorInfo.errors);
+              for (var dartUnit in dartUnits) {
+                scheduleNotificationOperations(
+                    this,
+                    file,
+                    errorInfo.lineInfo,
+                    context,
+                    null,
+                    dartUnit,
+                    errorInfo.errors);
+                scheduleIndexOperation(this, file, context, dartUnit);
+              }
             } else {
               schedulePerformAnalysisOperation(context);
             }
           }
         }
       }
     });
   }
 
   /**
@@ skipping 317 matching lines @@
   /**
    * The [PerformanceTag] for time spent in server request handlers.
    */
   static PerformanceTag serverRequests = new PerformanceTag('serverRequests');
 
   /**
    * The [PerformanceTag] for time spent in split store microtasks.
    */
   static PerformanceTag splitStore = new PerformanceTag('splitStore');
 }