Don't remove indexing operations on potential source changes.

pkg/analysis_server/lib/src/analysis_server.dart

Index: pkg/analysis_server/lib/src/analysis_server.dart
diff --git a/pkg/analysis_server/lib/src/analysis_server.dart b/pkg/analysis_server/lib/src/analysis_server.dart
index a99cbebf283fbd1f90efff3f07513df32eeea9ba..b33ccd8efa912bf8520d959f105fdf01df9083dc 100644
--- a/pkg/analysis_server/lib/src/analysis_server.dart
+++ b/pkg/analysis_server/lib/src/analysis_server.dart
@@ -661,7 +661,6 @@ class AnalysisServer {
    * 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) {
@@ -1030,18 +1029,21 @@ class AnalysisServer {
           // 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);
             }