improve measurement of completion performance

pkg/analysis_server/lib/src/services/completion/completion_manager.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 services.completion.computer;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/completion/dart_completion_manager.dart';
@@ skipping 106 matching lines @@
 class CompletionPerformance {
   final DateTime start = new DateTime.now();
   final Map<String, Duration> _startTimes = new Map<String, Duration>();
   final Stopwatch _stopwatch = new Stopwatch();
   final List<OperationPerformance> operations = <OperationPerformance>[];
 
   Source source;
   int offset;
   String contents;
   int notificationCount = -1;
-  int suggestionCount = -1;
+  int suggestionCountFirst = -1;
+  int suggestionCountLast = -1;
   Duration _firstNotification;
 
   CompletionPerformance() {
     _stopwatch.start();
   }
 
   int get elapsedInMilliseconds =>
       operations.length > 0 ? operations.last.elapsed.inMilliseconds : 0;
 
   int get firstNotificationInMilliseconds =>
@@ skipping 17 matching lines @@
       if (ch == '\r' || ch == '\n') {
         break;
       }
       ++end;
     }
     String prefix = contents.substring(start, offset);
     String suffix = contents.substring(offset, end);
     return '$prefix^$suffix';
   }
 
+  String get startTimeAndMs => '${start.millisecondsSinceEpoch} - $start';
+
+  String get suggestionCount {
+    if (notificationCount < 1) return '';
+    if (notificationCount == 1) return '$suggestionCountFirst';
+    return '$suggestionCountFirst,  $suggestionCountLast';
+  }
+
   void complete([String tag = null]) {
     _stopwatch.stop();
     _logDuration(tag != null ? tag : 'total time', _stopwatch.elapsed);
   }
 
   logElapseTime(String tag, [f() = null]) {
     Duration start;
     Duration end = _stopwatch.elapsed;
     var result;
     if (f == null) {
@@ skipping 97 matching lines @@
    */
   final String name;
 
   /**
    * The elapse time or `null` if undefined.
    */
   final Duration elapsed;
 
   OperationPerformance(this.name, this.elapsed);
 }