Merge branch 'master' into MikeCodesDotNET-readme-update

src/Avalonia.Base/Threading/Dispatcher.Invoke.cs

@@ -248,11 +248,11 @@ public partial class Dispatcher
     ///     An operation representing the queued delegate to be invoked.
     /// </returns>
     /// <remarks>
-    ///     Note that the default priority is DispatcherPriority.Normal.
+    ///     Note that the default priority is DispatcherPriority.Default.
     /// </remarks>
     public DispatcherOperation InvokeAsync(Action callback)
     {
-        return InvokeAsync(callback, DispatcherPriority.Normal, CancellationToken.None);
+        return InvokeAsync(callback, default, CancellationToken.None);
     }
 
     /// <summary>
@@ -326,11 +326,11 @@ public partial class Dispatcher
     ///     An operation representing the queued delegate to be invoked.
     /// </returns>
     /// <remarks>
-    ///     Note that the default priority is DispatcherPriority.Normal.
+    ///     Note that the default priority is DispatcherPriority.Default.
     /// </remarks>
     public DispatcherOperation<TResult> InvokeAsync<TResult>(Func<TResult> callback)
     {
-        return InvokeAsync(callback, DispatcherPriority.Normal, CancellationToken.None);
+        return InvokeAsync(callback, DispatcherPriority.Default, CancellationToken.None);
     }
 
     /// <summary>
@@ -541,6 +541,18 @@ public partial class Dispatcher
         InvokeAsyncImpl(new DispatcherOperation(this, priority, action, true), CancellationToken.None);
     }
 
+    /// <summary>
+    ///     Executes the specified Func&lt;Task&gt; asynchronously on the
+    ///     thread that the Dispatcher was created on
+    /// </summary>
+    /// <param name="callback">
+    ///     A Func&lt;Task&gt; delegate to invoke through the dispatcher.
+    /// </param>
+    /// <returns>
+    ///     An task that completes after the task returned from callback finishes.
+    /// </returns>
+    public Task InvokeAsync(Func<Task> callback) => InvokeAsync(callback, DispatcherPriority.Default);
+    
     /// <summary>
     ///     Executes the specified Func&lt;Task&gt; asynchronously on the
     ///     thread that the Dispatcher was created on
@@ -556,11 +568,29 @@ public partial class Dispatcher
     /// <returns>
     ///     An task that completes after the task returned from callback finishes
     /// </returns>
-    public Task InvokeAsync(Func<Task> callback, DispatcherPriority priority = default)
+    public Task InvokeAsync(Func<Task> callback, DispatcherPriority priority)
     {
         _ = callback ?? throw new ArgumentNullException(nameof(callback));
         return InvokeAsync<Task>(callback, priority).GetTask().Unwrap();
     }
+
+    /// <summary>
+    ///     Executes the specified Func&lt;Task&lt;TResult&gt;&gt; asynchronously on the
+    ///     thread that the Dispatcher was created on
+    /// </summary>
+    /// <param name="action">
+    ///     A Func&lt;Task&lt;TResult&gt;&gt; delegate to invoke through the dispatcher.
+    /// </param>
+    /// <param name="priority">
+    ///     The priority that determines in what order the specified
+    ///     callback is invoked relative to the other pending operations
+    ///     in the Dispatcher.
+    /// </param>
+    /// <returns>
+    ///     An task that completes after the task returned from callback finishes
+    /// </returns>
+    public Task<TResult> InvokeAsync<TResult>(Func<Task<TResult>> action) =>
+        InvokeAsync(action, DispatcherPriority.Default);
     
     /// <summary>
     ///     Executes the specified Func&lt;Task&lt;TResult&gt;&gt; asynchronously on the
@@ -577,7 +607,7 @@ public partial class Dispatcher
     /// <returns>
     ///     An task that completes after the task returned from callback finishes
     /// </returns>
-    public Task<TResult> InvokeAsync<TResult>(Func<Task<TResult>> action, DispatcherPriority priority = default)
+    public Task<TResult> InvokeAsync<TResult>(Func<Task<TResult>> action, DispatcherPriority priority)
     {
         _ = action ?? throw new ArgumentNullException(nameof(action));
         return InvokeAsync<Task<TResult>>(action, priority).GetTask().Unwrap();

src/Avalonia.Base/Threading/DispatcherFrame.cs

@@ -91,31 +91,44 @@ public class DispatcherFrame
 
     internal void Run(IControlledDispatcherImpl impl)
     {
-        // Since the actual platform run loop is controlled by a Cancellation token, we are restarting 
-        // it if frame still needs to run
-        while (Continue)
-            RunCore(impl);
-    }
-
-    private void RunCore(IControlledDispatcherImpl impl)
-    {
-        if (_isRunning)
-            throw new InvalidOperationException("This frame is already running");
-        _isRunning = true;
-        try
-        {
-            _cancellationTokenSource = new CancellationTokenSource();
-            // Wake up the dispatcher in case it has pending jobs
-            Dispatcher.RequestProcessing();
-            impl.RunLoop(_cancellationTokenSource.Token);
-        }
-        finally
+        Dispatcher.VerifyAccess();
+        
+        // Since the actual platform run loop is controlled by a Cancellation token, we have an
+        // outer loop that restarts the platform one in case Continue was set to true after being set to false
+        while (true)
         {
-            _isRunning = false;
-            _cancellationTokenSource?.Cancel();
-            _cancellationTokenSource = null;
+            // Take the instance lock since `Continue` is changed from one too
+            lock (Dispatcher.InstanceLock)
+            {
+                if (!Continue)
+                    return;
+                
+                if (_isRunning)
+                    throw new InvalidOperationException("This frame is already running");
+
+                _cancellationTokenSource = new CancellationTokenSource();
+                _isRunning = true;
+            }
+
+            try
+            {
+                // Wake up the dispatcher in case it has pending jobs
+                Dispatcher.RequestProcessing();
+                impl.RunLoop(_cancellationTokenSource.Token);
+            }
+            finally
+            {
+                lock (Dispatcher.InstanceLock)
+                {
+                    _isRunning = false;
+                    _cancellationTokenSource?.Cancel();
+                    _cancellationTokenSource?.Dispose();
+                    _cancellationTokenSource = null;
+                }
+            }
         }
     }
+    
 
     internal void MaybeExitOnDispatcherRequest()
     {

src/Avalonia.Controls/Platform/ManagedDispatcherImpl.cs

@@ -58,6 +58,10 @@ public class ManagedDispatcherImpl : IControlledDispatcherImpl
     
     public void RunLoop(CancellationToken token)
     {
+        CancellationTokenRegistration registration = default;
+        if (token.CanBeCanceled) 
+            registration = token.Register(() => _wakeup.Set());
+
         while (!token.IsCancellationRequested)
         {
             bool signaled;
@@ -105,5 +109,7 @@ public class ManagedDispatcherImpl : IControlledDispatcherImpl
             else
                 _wakeup.WaitOne();
         }
+
+        registration.Dispose();
     }
 }

tests/Avalonia.Base.UnitTests/DispatcherTests.cs

@@ -3,6 +3,8 @@ using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
 using System.Threading;
+using System.Threading.Tasks;
+using Avalonia.Controls.Platform;
 using Avalonia.Threading;
 using Avalonia.Utilities;
 using Xunit;
@@ -458,4 +460,46 @@ public class DispatcherTests
         }
     }
 
+    [Fact]
+    public void DispatcherInvokeAsyncUnwrapsTasks()
+    {
+        int asyncMethodStage = 0;
+        
+        async Task AsyncMethod()
+        {
+            asyncMethodStage = 1;
+            await Task.Delay(200);
+            asyncMethodStage = 2;
+        }
+        
+        async Task<int> AsyncMethodWithResult()
+        {
+            await Task.Delay(100);
+            return 1;
+        }
+        
+        async Task Test()
+        {
+            await Dispatcher.UIThread.InvokeAsync(AsyncMethod);
+            Assert.Equal(2, asyncMethodStage);
+            Assert.Equal(1, await Dispatcher.UIThread.InvokeAsync(AsyncMethodWithResult));
+            asyncMethodStage = 0;
+            
+            await Dispatcher.UIThread.InvokeAsync(AsyncMethod, DispatcherPriority.Default);
+            Assert.Equal(2, asyncMethodStage);
+            Assert.Equal(1, await Dispatcher.UIThread.InvokeAsync(AsyncMethodWithResult, DispatcherPriority.Default));
+            
+            Dispatcher.UIThread.ExitAllFrames();
+        }
+        
+        using (new DispatcherServices(new ManagedDispatcherImpl(null)))
+        {
+            var t = Test();
+            var cts = new CancellationTokenSource();
+            Task.Delay(3000).ContinueWith(_ => cts.Cancel());
+            Dispatcher.UIThread.MainLoop(cts.Token);
+            Assert.True(t.IsCompletedSuccessfully);
+            t.GetAwaiter().GetResult();
+        }
+    }
 }