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 051ea43ff64eed6d97a83ea3b0b961a65516dae4..8fc5a8773a227cdda9fe55289f743b5bfc65b7f8 100644
--- a/runtime/bin/vmservice/server.dart
+++ b/runtime/bin/vmservice/server.dart
@@ -80,21 +80,27 @@ class HttpRequestClient extends Client {
 
 class Server {
   static const WEBSOCKET_PATH = '/ws';
-  String defaultPath = '/index.html';
-  final String ip;
-  int port;
+  static const SLASH_PATH = '/index.html';

[Anders Johnsen, 2014/05/23 06:06:36]

Maybe ROOT_REDIRECT_PATH is more descriptive.

[Cutch, 2014/06/16 22:21:12]

Done.

+
+  final VMService _service;
+  final String _ip;
+  final int _port;
 
-  final VMService service;
   HttpServer _server;
+  var _subscription;
+  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);
+  }
 
   void _requestHandler(HttpRequest request) {
     // Allow cross origin requests.
     request.response.headers.add('Access-Control-Allow-Origin', '*');
 
     final String path =
-          request.uri.path == '/' ? defaultPath : request.uri.path;
+          request.uri.path == '/' ? SLASH_PATH : request.uri.path;
 
     var resource = Resource.resources[path];
     if (resource != null) {
@@ -108,28 +114,64 @@ class Server {
 
     if (path == WEBSOCKET_PATH) {
       WebSocketTransformer.upgrade(request).then((WebSocket webSocket) {
-        new WebSocketClient(webSocket, service);
+        new WebSocketClient(webSocket, _service);
       });
       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) {

[Anders Johnsen, 2014/05/23 06:06:36]

_server is not non-null until the bind is complete. We should introduce a new
field to guard this, so we don't bind twice, on a very fast series of signals.

[Cutch, 2014/06/16 22:21:12]

This is guarded against in the SIGQUIT handler.

+      // 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) {
+      _subscription = _server.listen(_requestHandler);
+      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;

[Anders Johnsen, 2014/05/23 06:06:36]

Do we really want to override the _displayMessages field? Perhaps just a local
variable would be sufficient.

[Cutch, 2014/06/16 22:21:12]

We need to track the state across multiple calls.

+
+    // Shutdown HTTP server and subscription.
+    var ip = _server.address.address.toString();
+    var port = _server.port.toString();
+    _subscription.cancel();

[Anders Johnsen, 2014/05/23 06:06:36]

No need to cancel subscription when closing the server. I don't think we can do
this without the subscription at all.

[Cutch, 2014/06/16 22:21:12]

Done.

+    _subscription = null;
+    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;
+    });
+  }
+
 }