SIGQUIT toggles VM service HTTP server

runtime/bin/vmservice/server.dart

Index: runtime/bin/vmservice/server.dart
diff --git a/runtime/bin/vmservice/server.dart b/runtime/bin/vmservice/server.dart
index 4d2587a2defca6c58c4736daee0fcd06853eb562..d50727fc03ab7241ea717070774b32d1f680430b 100644
--- a/runtime/bin/vmservice/server.dart
+++ b/runtime/bin/vmservice/server.dart
@@ -80,14 +80,19 @@ class HttpRequestClient extends Client {
 
 class Server {
   static const WEBSOCKET_PATH = '/ws';
-  String observatoryPath = '/index.html';
-  final String ip;
-  int port;
+  static const ROOT_REDIRECT_PATH = '/index.html';
+
+  final VMService _service;
+  final String _ip;
+  final int _port;
 
-  final VMService service;
   HttpServer _server;
+  bool get running => _server != null;
+  bool _displayMessages = false;
 
-  Server(this.service, this.ip, this.port);
+  Server(this._service, this._ip, this._port) {
+    _displayMessages = (_ip != '127.0.0.1' || _port != 8181);
+  }
 
   bool _shouldServeObservatory(HttpRequest request) {
     if (request.headers['Observatory-Version'] != null) {
@@ -117,18 +122,18 @@ class Server {
     }
 
     final String path =
-          request.uri.path == '/' ? observatoryPath : request.uri.path;
+          request.uri.path == '/' ? ROOT_REDIRECT_PATH : request.uri.path;
 
     if (path == WEBSOCKET_PATH) {
       WebSocketTransformer.upgrade(request).then((WebSocket webSocket) {
-        new WebSocketClient(webSocket, service);
+        new WebSocketClient(webSocket, _service);
       });
       return;
     }
 
     var resource = Resource.resources[path];
     if (resource == null && _shouldServeObservatory(request)) {
-      resource = Resource.resources[observatoryPath];
+      resource = Resource.resources[ROOT_REDIRECT_PATH];
       assert(resource != null);
     }
     if (resource != null) {
@@ -140,22 +145,56 @@ class Server {
       return;
     }
     var message = new Message.fromUri(request.uri);
-    var client = new HttpRequestClient(request, service);
+    var client = new HttpRequestClient(request, _service);
     client.onMessage(null, message);
   }
 
-  Future startServer() {
-    return HttpServer.bind(ip, port).then((s) {
-      // Only display message when port is automatically selected.
-      var display_message = (ip != '127.0.0.1' || port != 8181);
-      // Retrieve port.
-      port = s.port;
+  Future startup() {
+    if (_server != null) {
+      // Already running.
+      return new Future.value(this);
+    }
+
+    // Startup HTTP server.
+    return HttpServer.bind(_ip, _port).then((s) {
       _server = s;
       _server.listen(_requestHandler);
-      if (display_message) {
+      if (_displayMessages) {
+        var ip = _server.address.address.toString();
+        var port = _server.port.toString();
         print('Observatory listening on http://$ip:$port');
       }
-      return s;
+      // Server is up and running.
+      return this;
+    }).catchError((e, st) {
+      print('Could not start Observatory HTTP server:\n$e\n$st\n');
+      return this;
+    });
+  }
+
+  Future shutdown(bool forced) {
+    if (_server == null) {
+      // Not started.
+      return new Future.value(this);
+    }
+
+    // Force displaying of status messages if we are forcibly shutdown.
+    _displayMessages = _displayMessages || forced;
+
+    // Shutdown HTTP server and subscription.
+    var ip = _server.address.address.toString();
+    var port = _server.port.toString();
+    return _server.close(force: forced).then((_) {
+      if (_displayMessages) {
+        print('Observatory no longer listening on http://$ip:$port');
+      }
+      _server = null;
+      return this;
+    }).catchError((e, st) {
+      _server = null;
+      print('Could not shutdown Observatory HTTP server:\n$e\n$st\n');
+      return this;
     });
   }
+
 }