Rework error handling in the service protocol and in Observatory.

runtime/observatory/lib/src/app/application.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 app;
 
+class Notification {
+  Notification.fromEvent(this.event);
+  Notification.fromException(this.exception, this.stacktrace);
+
+  ServiceEvent event;
+  var exception;
+  var stacktrace;
+}
+
 /// The observatory application. Instances of this are created and owned
 /// by the observatory_application custom element.
 class ObservatoryApplication extends Observable {
   static ObservatoryApplication app;
   final _pageRegistry = new List<Page>();
   LocationManager _locationManager;
   LocationManager get locationManager => _locationManager;
   @observable Page currentPage;
   VM _vm;
   VM get vm => _vm;
@@ skipping 15 matching lines @@
           targets.add(vm.target);
         }
         _removeDisconnectEvents();
       });
 
       vm.onDisconnect.then((String reason) {
         if (this.vm != vm) {
           // This disconnect event occured *after* a new VM was installed.
           return;
         }
-        notifications.add(new ServiceEvent.connectionClosed(reason));
+        notifications.add(
+            new Notification.fromEvent(
+                new ServiceEvent.connectionClosed(reason)));
       });
 
-      vm.errors.stream.listen(_onError);
       vm.events.stream.listen(_onEvent);
-      vm.exceptions.stream.listen(_onException);
     }
     _vm = vm;
   }
   final TargetManager targets;
   @reflectable final ObservatoryApplicationElement rootElement;
 
   TraceViewElement _traceView = null;
 
   @reflectable ServiceObject lastErrorOrException;
-  @observable ObservableList<ServiceEvent> notifications =
-      new ObservableList<ServiceEvent>();
+  @observable ObservableList<Notification> notifications =
+      new ObservableList<Notification>();
 
   void _initOnce() {
     assert(app == null);
     app = this;
     _registerPages();
     Analytics.initialize();
     // Visit the current page.
     locationManager._visit();
   }
 
   void removePauseEvents(Isolate isolate) {
-    bool isPauseEvent(var event) {
+    bool isPauseEvent(ServiceEvent event) {

[Cutch, 2015/05/13 17:50:09]

this method should be on event.

[turnidge, 2015/05/14 17:53:42]

Done.

       return (event.eventType == ServiceEvent.kPauseStart ||
               event.eventType == ServiceEvent.kPauseExit ||
               event.eventType == ServiceEvent.kPauseBreakpoint ||
               event.eventType == ServiceEvent.kPauseInterrupted ||
               event.eventType == ServiceEvent.kPauseException);
     }
 
-    notifications.removeWhere((oldEvent) {
-        return (oldEvent.isolate == isolate &&
-                isPauseEvent(oldEvent));
+    notifications.removeWhere((notification) {
+        var event = notification.event;
+        return (event != null &&
+                event.isolate == isolate &&
+                isPauseEvent(event));
       });
   }
 
   void _onEvent(ServiceEvent event) {
     switch(event.eventType) {
       case ServiceEvent.kIsolateStart:
       case ServiceEvent.kIsolateUpdate:
       case ServiceEvent.kGraph:
       case ServiceEvent.kBreakpointAdded:
       case ServiceEvent.kBreakpointResolved:
       case ServiceEvent.kBreakpointRemoved:
       case ServiceEvent.kGC:
         // Ignore for now.
         break;
 
       case ServiceEvent.kIsolateExit:
       case ServiceEvent.kResume:
         removePauseEvents(event.isolate);
         break;
 
       case ServiceEvent.kPauseStart:
       case ServiceEvent.kPauseExit:
       case ServiceEvent.kPauseBreakpoint:
       case ServiceEvent.kPauseInterrupted:
       case ServiceEvent.kPauseException:
         removePauseEvents(event.isolate);
-        notifications.add(event);
+        notifications.add(new Notification.fromEvent(event));
         break;
 
       case ServiceEvent.kInspect:
-        notifications.add(event);
+        notifications.add(new Notification.fromEvent(event));
         break;
 
       default:
         // Ignore unrecognized events.
         Logger.root.severe('Unrecognized event: $event');
         break;
     }
   }
 
   void _registerPages() {
     _pageRegistry.add(new VMPage(this));
     _pageRegistry.add(new FlagsPage(this));
     _pageRegistry.add(new InspectPage(this));
     _pageRegistry.add(new ClassTreePage(this));
     _pageRegistry.add(new DebuggerPage(this));
     _pageRegistry.add(new CpuProfilerPage(this));
     _pageRegistry.add(new TableCpuProfilerPage(this));
     _pageRegistry.add(new AllocationProfilerPage(this));
     _pageRegistry.add(new HeapMapPage(this));
     _pageRegistry.add(new VMConnectPage(this));
     _pageRegistry.add(new IsolateReconnectPage(this));
     _pageRegistry.add(new ErrorViewPage(this));
     _pageRegistry.add(new MetricsPage(this));
     // Note that ErrorPage must be the last entry in the list as it is
     // the catch all.
     _pageRegistry.add(new ErrorPage(this));
   }
 
-  void _onError(ServiceError error) {
-    lastErrorOrException = error;
-    _visit(Uri.parse('error/'), null);
-  }
-
-  void _onException(ServiceException exception) {
-    lastErrorOrException = exception;
-    if (exception.kind == 'NetworkException') {
-      // Got a network exception, visit the vm-connect page.
-      this.vm = null;
-      locationManager.go(locationManager.makeLink('/vm-connect'));
-    } else {
-      _visit(Uri.parse('error/'), {});
-    }
-  }
-
   void _visit(Uri uri, Map internalArguments) {
     if (internalArguments['trace'] != null) {
       var traceArg = internalArguments['trace'];
       if (traceArg == 'on') {
         Tracer.start();
       } else if (traceArg == 'off') {
         Tracer.stop();
       }
     }
     if (Tracer.current != null) {
@@ skipping 45 matching lines @@
   }
 
   ObservatoryApplication(this.rootElement) :
       targets = new TargetManager() {
     _locationManager = new LocationManager(this);
     vm = new WebSocketVM(targets.defaultTarget);
     _initOnce();
   }
 
   void _removeDisconnectEvents() {
-    notifications.removeWhere((oldEvent) {
-        return (oldEvent.eventType == ServiceEvent.kConnectionClosed);
+    notifications.removeWhere((notification) {
+        var event = notification.event;
+        return (event != null &&
+                event.eventType == ServiceEvent.kConnectionClosed);
       });
   }
 
   loadCrashDump(Map crashDump) {
     this.vm = new FakeVM(crashDump['result']);
     app.locationManager.go('#/vm');
   }
+
+  void handleException(e, st) {
+    // TODO(turnidge): Report this failure via analytics.
+    Logger.root.warning('Caught exception: ${e}\n${st}');
+    notifications.add(new Notification.fromException(e, st));
+  }
 }