Support stacktrace and objecthistogram service commands

runtime/bin/vmservice/server.dart

 // Copyright (c) 2013, 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.
 
 part of vmservice;
 
 class Server {
   int port;
   static ContentType jsonContentType = ContentType.parse('application/json');
   final VmService service;
@@ skipping 16 matching lines @@
       request.response.close();
       return;
     }
 
     var serviceRequest = new ServiceRequest();
     var r = serviceRequest.parse(request.uri);
     if (!r) {
       // Did not understand the request uri.
       serviceRequest.setErrorResponse('Invalid request uri: ${request.uri}');
     } else {
-      r = service.runningIsolates.route(serviceRequest);
-      if (!r) {
+      var f = service.runningIsolates.route(serviceRequest);
+      if (f != null) {
+        f.then((_) {
+          request.response.headers.contentType = jsonContentType;
+          request.response.write(serviceRequest.response);
+          request.response.close();
+        }).catchError((e) { });
+        return;
+      } else {
         // Nothing responds to this type of request.
         serviceRequest.setErrorResponse('No route for: $path');
       }
     }
 
-    // Send response back over HTTP.
     request.response.headers.contentType = jsonContentType;
     request.response.write(serviceRequest.response);
     request.response.close();
   }
 
   Future startServer() {
     return HttpServer.bind(InternetAddress.LOOPBACK_IP_V4, port).then((s) {
       // Only display message when port is automatically selected.
       var display_message = (port == 0);
       // Retrieve port.
       port = s.port;
       _server = s;
       _server.listen(_requestHandler);
       if (display_message) {
         print('VmService listening on port $port');
       }
       return s;
     });
   }
 }
-