Merge branch 'master' into issues/1954

src/Avalonia.Visuals/Rendering/RenderLoop.cs

@@ -19,7 +19,8 @@ namespace Avalonia.Rendering
         private readonly IDispatcher _dispatcher;
         private List<IRenderLoopTask> _items = new List<IRenderLoopTask>();
         private IRenderTimer _timer;
-        private int inTick;
+        private int _inTick;
+        private int _inUpdate;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="RenderLoop"/> class.
@@ -84,21 +85,36 @@ namespace Avalonia.Rendering
             }
         }
 
-        private async void TimerTick(TimeSpan time)
+        private void TimerTick(TimeSpan time)
         {
-            if (Interlocked.CompareExchange(ref inTick, 1, 0) == 0)
+            if (Interlocked.CompareExchange(ref _inTick, 1, 0) == 0)
             {
                 try
                 {
-                    if (_items.Any(item => item.NeedsUpdate))
+                    if (_items.Any(item => item.NeedsUpdate) &&
+                        Interlocked.CompareExchange(ref _inUpdate, 1, 0) == 0)
                     {
-                        await _dispatcher.InvokeAsync(() =>
+                        _dispatcher.Post(() =>
                         {
-                            foreach (var i in _items)
+                            for (var i = 0; i < _items.Count; ++i)
                             {
-                                i.Update(time);
+                                var item = _items[i];
+
+                                if (item.NeedsUpdate)
+                                {
+                                    try
+                                    {
+                                        item.Update(time);
+                                    }
+                                    catch (Exception ex)
+                                    {
+                                        Logger.Error(LogArea.Visual, this, "Exception in render update: {Error}", ex);
+                                    }
+                                }
                             }
-                        }, DispatcherPriority.Render).ConfigureAwait(false);
+
+                            Interlocked.Exchange(ref _inUpdate, 0);
+                        }, DispatcherPriority.Render);
                     }
 
                     foreach (var i in _items)
@@ -112,7 +128,7 @@ namespace Avalonia.Rendering
                 }
                 finally
                 {
-                    Interlocked.Exchange(ref inTick, 0);
+                    Interlocked.Exchange(ref _inTick, 0);
                 }
             }
         }

tests/Avalonia.Visuals.UnitTests/Rendering/RenderLoopTests.cs

@@ -19,14 +19,13 @@ namespace Avalonia.Visuals.UnitTests.Rendering
             bool inDispatcher = false;
 
             dispatcher.Setup(
-                d => d.InvokeAsync(It.IsAny<Action>(), DispatcherPriority.Render))
+                d => d.Post(It.IsAny<Action>(), DispatcherPriority.Render))
                 .Callback((Action a, DispatcherPriority _) =>
                 {
                     inDispatcher = true;
                     a();
                     inDispatcher = false;
-                })
-                .Returns(Task.CompletedTask);
+                });
 
             var timer = new Mock<IRenderTimer>();
 
@@ -71,14 +70,13 @@ namespace Avalonia.Visuals.UnitTests.Rendering
             var dispatcher = new Mock<IDispatcher>();
             bool inDispatcher = false;
             dispatcher.Setup(
-                d => d.InvokeAsync(It.IsAny<Action>(), DispatcherPriority.Render))
+                d => d.Post(It.IsAny<Action>(), DispatcherPriority.Render))
                 .Callback((Action a, DispatcherPriority _) =>
                 {
                     inDispatcher = true;
                     a();
                     inDispatcher = false;
-                })
-                .Returns(Task.CompletedTask);
+                });
 
             var timer = new Mock<IRenderTimer>();
             var loop = new RenderLoop(timer.Object, dispatcher.Object);
@@ -100,9 +98,8 @@ namespace Avalonia.Visuals.UnitTests.Rendering
         {
             var dispatcher = new Mock<IDispatcher>();
             dispatcher.Setup(
-                d => d.InvokeAsync(It.IsAny<Action>(), DispatcherPriority.Render))
-                .Callback((Action a, DispatcherPriority _) => a())
-                .Returns(Task.CompletedTask);
+                d => d.Post(It.IsAny<Action>(), DispatcherPriority.Render))
+                .Callback((Action a, DispatcherPriority _) => a());
 
             var timer = new Mock<IRenderTimer>();
             var loop = new RenderLoop(timer.Object, dispatcher.Object);