improve measurement of completion performance

pkg/analysis_server/lib/src/domain_completion.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 domain.completion;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/constants.dart';
@@ skipping 39 matching lines @@
 
   /**
    * A list of code completion peformance measurements for the latest
    * completion operation up to [performanceListMaxLength] measurements.
    */
   final List<CompletionPerformance> performanceList =
       new List<CompletionPerformance>();
 
   /**
    * The maximum number of performance measurements to keep.
-   * This defaults to zero for efficiency, but clients may change this.
    */
-  int performanceListMaxLength = 0;
+  static const int performanceListMaxLength = 50;
 
   /**
    * Performance for the last priority change event.
    */
   CompletionPerformance priorityChangedPerformance;
 
   /**
    * Initialize a new request handler for the given [server].
    */
   CompletionDomainHandler(this.server) {
@@ skipping 105 matching lines @@
       performance.logElapseTime("notification $notificationCount send", () {
         sendCompletionNotification(
             completionId,
             result.replacementOffset,
             result.replacementLength,
             result.suggestions,
             result.last);
       });
       if (notificationCount == 1) {
         performance.logFirstNotificationComplete('notification 1 complete');
+        performance.suggestionCountFirst = result.suggestions.length;
       }
       if (result.last) {
         performance.notificationCount = notificationCount;
-        performance.suggestionCount = result.suggestions.length;
+        performance.suggestionCountLast = result.suggestions.length;
         performance.complete();
       }
     });
     // initial response without results
     return new CompletionGetSuggestionsResult(
         completionId).toResponse(request.id);
   }
 
   /**
    * If tracking code completion performance over time, then
@@ skipping 65 matching lines @@
     if (_sourcesChangedSubscription != null) {
       _sourcesChangedSubscription.cancel();
       _sourcesChangedSubscription = null;
     }
     if (_manager != null) {
       _manager.dispose();
       _manager = null;
     }
   }
 }