Added VerifyAccess call to PerspexObject. We need to do something about Dispatcher and unit tests

src/Gtk/Perspex.Gtk/GtkPlatform.cs

@@ -17,6 +17,7 @@ namespace Perspex.Gtk
     public class GtkPlatform : IPlatformThreadingInterface, IPlatformSettings
     {
         private static readonly GtkPlatform s_instance = new GtkPlatform();
+        private static Thread _uiThread;
 
         public GtkPlatform()
         {
@@ -40,6 +41,7 @@ namespace Perspex.Gtk
                 .Bind<IPlatformThreadingInterface>().ToConstant(s_instance)
                 .Bind<ISystemDialogImpl>().ToSingleton<SystemDialogImpl>();
             SharedPlatform.Register();
+            _uiThread = Thread.CurrentThread;
         }
 
         public bool HasMessages()
@@ -79,6 +81,8 @@ namespace Perspex.Gtk
             Gtk.Application.Invoke(delegate { Signaled?.Invoke(); });
         }
 
+        public bool CheckForLoopThread() => Thread.CurrentThread == _uiThread;
+
         public event Action Signaled;
     }
 }

src/Perspex.Base/PerspexObject.cs

@@ -10,6 +10,7 @@ using System.Reactive.Linq;
 using System.Reactive.Subjects;
 using System.Reflection;
 using Perspex.Reactive;
+using Perspex.Threading;
 using Perspex.Utilities;
 using Serilog;
 using Serilog.Core.Enrichers;
@@ -300,6 +301,10 @@ namespace Perspex
             }
         }
 
+        public bool CheckAccess() => Dispatcher.UIThread.CheckAccess();
+
+        public void VerifyAccess() => Dispatcher.UIThread.VerifyAccess();
+
         /// <summary>
         /// Clears a <see cref="PerspexProperty"/>'s local value.
         /// </summary>
@@ -495,7 +500,7 @@ namespace Perspex
             BindingPriority priority = BindingPriority.LocalValue)
         {
             Contract.Requires<ArgumentNullException>(property != null);
-
+            VerifyAccess();
             if (property.IsDirect)
             {
                 property = GetRegistered(property);
@@ -556,7 +561,7 @@ namespace Perspex
             BindingPriority priority = BindingPriority.LocalValue)
         {
             Contract.Requires<ArgumentNullException>(property != null);
-
+            VerifyAccess();
             if (property.IsDirect)
             {
                 property = (PerspexProperty<T>)GetRegistered(property);
@@ -590,7 +595,7 @@ namespace Perspex
             BindingPriority priority = BindingPriority.LocalValue)
         {
             Contract.Requires<ArgumentNullException>(property != null);
-
+            VerifyAccess();
             if (property.IsDirect)
             {
                 property = GetRegistered(property);
@@ -650,7 +655,7 @@ namespace Perspex
             BindingPriority priority = BindingPriority.LocalValue)
         {
             Contract.Requires<ArgumentNullException>(property != null);
-
+            VerifyAccess();
             if (property.IsDirect)
             {
                 property = (PerspexProperty<T>)GetRegistered(property);
@@ -687,6 +692,7 @@ namespace Perspex
             PerspexProperty sourceProperty,
             BindingPriority priority = BindingPriority.LocalValue)
         {
+            VerifyAccess();
             _propertyLog.Verbose(
                 "Bound two way {Property} to {Binding} with priority {Priority}",
                 property,
@@ -716,6 +722,7 @@ namespace Perspex
             ISubject<object> source,
             BindingPriority priority = BindingPriority.LocalValue)
         {
+            VerifyAccess();
             _propertyLog.Verbose(
                 "Bound two way {Property} to {Binding} with priority {Priority}",
                 property,
@@ -733,6 +740,7 @@ namespace Perspex
         /// <param name="property">The property.</param>
         public void Revalidate(PerspexProperty property)
         {
+            VerifyAccess();
             PriorityValue value;
 
             if (_values.TryGetValue(property, out value))
@@ -788,6 +796,7 @@ namespace Perspex
             BindingPriority priority)
         {
             Contract.Requires<ArgumentNullException>(property != null);
+            VerifyAccess();
 
             PerspexPropertyChangedEventArgs e = new PerspexPropertyChangedEventArgs(
                 this,
@@ -824,6 +833,7 @@ namespace Perspex
         /// </returns>
         protected bool SetAndRaise<T>(PerspexProperty<T> property, ref T field, T value)
         {
+            VerifyAccess();
             if (!object.Equals(field, value))
             {
                 var old = field;

src/Perspex.Base/Platform/IPlatformThreadingInterface.cs

@@ -26,6 +26,8 @@ namespace Perspex.Platform
         /// </summary>
         void Signal();
 
+        bool CheckForLoopThread();
+
         event Action Signaled;
 
     }

src/Perspex.Base/Threading/Dispatcher.cs

@@ -26,10 +26,21 @@ namespace Perspex.Threading
         public Dispatcher(IPlatformThreadingInterface platform)
         {
             _platform = platform;
+            if(_platform == null)
+                //TODO: Unit test mode, fix that somehow
+                return;
             _jobRunner = new JobRunner(platform);
             _platform.Signaled += _jobRunner.RunJobs;
         }
 
+        public bool CheckAccess() => _platform?.CheckForLoopThread() ?? true;
+
+        public void VerifyAccess()
+        {
+            if (!CheckAccess())
+                throw new InvalidOperationException("Call from invalid thread");
+        }
+
 
         /// <summary>
         /// Runs the dispatcher's main loop.
@@ -49,7 +60,7 @@ namespace Perspex.Threading
         /// </summary>
         public void RunJobs()
         {
-            _jobRunner.RunJobs();
+            _jobRunner?.RunJobs();
         }
 
         /// <summary>
@@ -60,7 +71,7 @@ namespace Perspex.Threading
         /// <returns>A task that can be used to track the method's execution.</returns>
         public Task InvokeTaskAsync(Action action, DispatcherPriority priority = DispatcherPriority.Normal)
         {
-            return _jobRunner.InvokeAsync(action, priority);
+            return _jobRunner?.InvokeAsync(action, priority);
         }
 
         /// <summary>
@@ -70,7 +81,7 @@ namespace Perspex.Threading
         /// <param name="priority">The priority with which to invoke the method.</param>
         public void InvokeAsync(Action action, DispatcherPriority priority = DispatcherPriority.Normal)
         {
-            _jobRunner.Post(action, priority);
+            _jobRunner?.Post(action, priority);
         }
     }
 }

src/Perspex.Base/Threading/SingleThreadDispatcher.cs

@@ -37,6 +37,11 @@ namespace Perspex.Threading
                     () => _timerJobRunner.Post(tick, DispatcherPriority.Normal));
 
             public void Signal() => _evnt.Set();
+            public bool CheckForLoopThread()
+            {
+                //TODO: Actually perform check
+                return true;
+            }
 
             public event Action Signaled;
         }

src/Windows/Perspex.Win32/Win32Platform.cs

@@ -21,6 +21,7 @@ namespace Perspex.Win32
     public class Win32Platform : IPlatformThreadingInterface, IPlatformSettings
     {
         private static readonly Win32Platform s_instance = new Win32Platform();
+        private static Thread _uiThread;
 
         private UnmanagedMethods.WndProc _wndProcDelegate;
 
@@ -52,6 +53,7 @@ namespace Perspex.Win32
                 .Bind<ISystemDialogImpl>().ToSingleton<SystemDialogImpl>();
 
             SharedPlatform.Register();
+            _uiThread = Thread.CurrentThread;
         }
 
         public static void Initialize()
@@ -124,6 +126,8 @@ namespace Perspex.Win32
                 new IntPtr(SignalL));
         }
 
+        public bool CheckForLoopThread() => _uiThread == Thread.CurrentThread;
+
         public event Action Signaled;
 
         [SuppressMessage("Microsoft.StyleCop.CSharp.NamingRules", "SA1305:FieldNamesMustNotUseHungarianNotation", Justification = "Using Win32 naming for consistency.")]