Fix rolling averages in diagnostic status.

pkg/analysis_server/lib/src/status/get_handler.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.src.status.get_handler;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
@@ skipping 166 matching lines @@
    * Buffer containing strings printed by the analysis server.
    */
   List<String> _printBuffer;
 
   /**
    * Contents of overlay files.
    */
   final Map<String, String> _overlayContents = <String, String>{};
 
   /**
+   * Handler for diagnostics requests.
+   */
+  DiagnosticDomainHandler _diagnosticHandler;
+
+  /**
    * Initialize a newly created handler for GET requests.
    */
   GetHandler(this._server, this._printBuffer);
 
+  DiagnosticDomainHandler get diagnosticHandler {
+    if (_diagnosticHandler == null) {
+      _diagnosticHandler = new DiagnosticDomainHandler(_server.analysisServer);
+    }
+    return _diagnosticHandler;
+  }
+
   /**
    * Return the active [CompletionDomainHandler]
    * or `null` if either analysis server is not running
    * or there is no completion domain handler.
    */
   CompletionDomainHandler get _completionDomainHandler {
     AnalysisServer analysisServer = _server.analysisServer;
     if (analysisServer == null) {
       return null;
     }
@@ skipping 1276 matching lines @@
         sent to the client in the first notification, followed by a comma,
         followed by the number of suggestions send to the client
         in the last notification. If there is only one notification,
         then there will be only one number in this column.''');
   }
 
   /**
    * Write the status of the diagnostic domain to the given [buffer].
    */
   void _writeDiagnosticStatus(StringBuffer buffer) {
-    DiagnosticDomainHandler handler =
-        new DiagnosticDomainHandler(_server.analysisServer);
-
     var request = new DiagnosticGetDiagnosticsParams().toRequest('0');
 
     var stopwatch = new Stopwatch();
     stopwatch.start();
-    var response = handler.handleRequest(request);
+    var response = diagnosticHandler.handleRequest(request);
     stopwatch.stop();
 
     int elapsedMs = stopwatch.elapsedMilliseconds;
     _diagnosticCallAverage.addSample(elapsedMs);
 
     buffer.write('<h3>Timing</h3>');
 
     buffer.write('<p>');
     buffer.write('getDiagnostic (last call): $elapsedMs (ms)');
     buffer.write('<p>');
@@ skipping 516 matching lines @@
    */
   static String makeLink(
       String path, Map<String, String> params, String innerHtml,
       [bool hasError = false]) {
     Uri uri = new Uri(path: path, queryParameters: params);
     String href = HTML_ESCAPE.convert(uri.toString());
     String classAttribute = hasError ? ' class="error"' : '';
     return '<a href="$href"$classAttribute>$innerHtml</a>';
   }
 }