Xdnd: add timeout waiting for XdndFinished

src/Avalonia.X11/Selections/DragDrop/DragDropDataProvider.cs

@@ -5,11 +5,11 @@ namespace Avalonia.X11.Selections.DragDrop;
 
 internal sealed class DragDropDataProvider : SelectionDataProvider
 {
+    public Action? Activity { get; set; }
+
     public DragDropDataProvider(AvaloniaX11Platform platform, IAsyncDataTransfer dataTransfer)
         : base(platform, platform.Info.Atoms.XdndSelection)
-    {
+        => DataTransfer = dataTransfer;
-        DataTransfer = dataTransfer;
-    }
 
     public new IntPtr GetOwner()
         => base.GetOwner();
@@ -17,8 +17,13 @@ internal sealed class DragDropDataProvider : SelectionDataProvider
     public new void SetOwner(IntPtr window)
         => base.SetOwner(window);
 
+    protected override void OnActivity()
+        => Activity?.Invoke();
+
     public override void Dispose()
     {
+        Activity = null;
+
         DataTransfer?.Dispose();
         DataTransfer = null;
     }

src/Avalonia.X11/Selections/DragDrop/DragDropTimeoutManager.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Threading;
+
+namespace Avalonia.X11.Selections.DragDrop;
+
+internal sealed class DragDropTimeoutManager : IDisposable
+{
+    private readonly TimeSpan _timeout;
+    private readonly Timer _timer;
+
+    public DragDropTimeoutManager(TimeSpan timeout, Action onTimeout)
+    {
+        _timeout = timeout;
+
+        _timer = new Timer(
+            static state => ((Action)state!)(),
+            onTimeout,
+            Timeout.InfiniteTimeSpan,
+            Timeout.InfiniteTimeSpan);
+    }
+
+    public void Restart()
+    {
+        try
+        {
+            _timer.Change(_timeout, Timeout.InfiniteTimeSpan);
+        }
+        catch (ObjectDisposedException)
+        {
+        }
+    }
+
+    public void Dispose()
+        => _timer.Dispose();
+}

src/Avalonia.X11/Selections/DragDrop/X11DragSource.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.Threading.Tasks;
 using Avalonia.Controls;
 using Avalonia.Input;
@@ -49,6 +50,7 @@ internal sealed class X11DragSource(AvaloniaX11Platform platform) : IPlatformDra
         private bool _pointerGrabbed;
         private XdndTargetInfo? _lastTarget;
         private DragDropEffects _currentEffects;
+        private DragDropTimeoutManager? _timeoutManager;
 
         public Handler(
             AvaloniaX11Platform platform,
@@ -68,7 +70,7 @@ internal sealed class X11DragSource(AvaloniaX11Platform platform) : IPlatformDra
             if (!platform.Windows.TryGetValue(sourceWindow, out var sourceWindowInfo))
             {
                 _formatAtoms = [];
-                _completionSource.TrySetResult(DragDropEffects.None);
+                Complete(DragDropEffects.None);
                 return;
             }
 
@@ -92,7 +94,7 @@ internal sealed class X11DragSource(AvaloniaX11Platform platform) : IPlatformDra
             if (grabResult != GrabResult.GrabSuccess)
             {
                 _formatAtoms = [];
-                _completionSource.TrySetResult(DragDropEffects.None);
+                Complete(DragDropEffects.None);
                 return;
             }
 
@@ -198,11 +200,22 @@ internal sealed class X11DragSource(AvaloniaX11Platform platform) : IPlatformDra
                 var rootPosition = new PixelPoint(button.x_root, button.y_root);
                 ProcessRawDragEvent(lastTarget.InProcessWindow, RawDragEventType.Drop, rootPosition);
                 _lastTarget = null;
-                _completionSource.TrySetResult(_currentEffects);
+                Complete(_currentEffects);
             }
             else
             {
                 _dataProvider.SetOwner(_sourceWindow);
+
+                Debug.Assert(_timeoutManager is null);
+
+                _timeoutManager = new DragDropTimeoutManager(SelectionHelper.Timeout, () =>
+                {
+                    DisposeTimeoutManager();
+                    Complete(DragDropEffects.None);
+                });
+
+                _dataProvider.Activity = _timeoutManager.Restart;
+
                 SendXdndDrop(lastTarget, button.time);
             }
         }
@@ -224,6 +237,7 @@ internal sealed class X11DragSource(AvaloniaX11Platform platform) : IPlatformDra
                 return;
 
             _lastTarget = null;
+            DisposeTimeoutManager();
 
             if (lastTarget.Version >= 5)
             {
@@ -233,7 +247,7 @@ internal sealed class X11DragSource(AvaloniaX11Platform platform) : IPlatformDra
                 UpdateCurrentEffects(effects & _allowedEffects);
             }
 
-            _completionSource.TrySetResult(_currentEffects);
+            Complete(_currentEffects);
         }
 
         private XdndTargetInfo? FindXdndTarget(PixelPoint rootPosition)
@@ -433,6 +447,16 @@ internal sealed class X11DragSource(AvaloniaX11Platform platform) : IPlatformDra
             return _platform.Info.DefaultCursor;
         }
 
+        private void Complete(DragDropEffects resultEffects)
+            => _completionSource.TrySetResult(resultEffects);
+
+        private void DisposeTimeoutManager()
+        {
+            _dataProvider.Activity = null;
+            _timeoutManager?.Dispose();
+            _timeoutManager = null;
+        }
+
         public void Dispose()
         {
             if (_pointerGrabbed)
@@ -448,6 +472,8 @@ internal sealed class X11DragSource(AvaloniaX11Platform platform) : IPlatformDra
             _lastTarget = null;
             _currentEffects = DragDropEffects.None;
 
+            DisposeTimeoutManager();
+
             if (_dataProvider.GetOwner() == _sourceWindow)
                 _dataProvider.SetOwner(0);
 

src/Avalonia.X11/Selections/SelectionDataProvider.cs

@@ -63,6 +63,7 @@ internal abstract class SelectionDataProvider : IDisposable
         }
 
         XSendEvent(Platform.Display, request.requestor, false, new IntPtr((int)EventMask.NoEventMask), ref response);
+        OnActivity();
 
         IntPtr WriteTargetToProperty(IntPtr target, IntPtr window, IntPtr property)
         {
@@ -196,6 +197,7 @@ internal abstract class SelectionDataProvider : IDisposable
             ref size, 1);
 
         var buffer = ArrayPool<byte>.Shared.Rent((int)Math.Min(_maximumPropertySize, data.Length));
+        var gotTimeout = false;
 
         while (true)
         {
@@ -204,22 +206,29 @@ internal abstract class SelectionDataProvider : IDisposable
                     x.type == XEventName.PropertyNotify &&
                     x.PropertyEvent.atom == property &&
                     x.PropertyEvent.state == 1,
-                TimeSpan.FromMinutes(1));
+                SelectionHelper.Timeout);
 
             if (evt is null)
+            {
+                gotTimeout = true;
                 break;
+            }
 
             var read = await data.ReadAsync(buffer, 0, buffer.Length);
             if (read == 0)
                 break;
 
             XChangeProperty(Platform.Display, window, property, target, 8, PropertyMode.Replace, buffer, read);
+            OnActivity();
         }
 
         ArrayPool<byte>.Shared.Return(buffer);
 
         // Finish the transfer
         XChangeProperty(Platform.Display, window, property, target, 8, PropertyMode.Replace, 0, 0);
+
+        if (!gotTimeout)
+            OnActivity();
     }
 
     private Task SendDataToClientAsync(IntPtr window, IntPtr property, IntPtr target, byte[] bytes)
@@ -228,6 +237,7 @@ internal abstract class SelectionDataProvider : IDisposable
         {
             XChangeProperty(Platform.Display, window, property, target, 8, PropertyMode.Replace,
                 bytes, bytes.Length);
+            OnActivity();
             return Task.CompletedTask;
         }
 
@@ -242,5 +252,9 @@ internal abstract class SelectionDataProvider : IDisposable
         return [atoms.TARGETS, atoms.MULTIPLE, ..formatAtoms];
     }
 
+    protected virtual void OnActivity()
+    {
+    }
+
     public abstract void Dispose();
 }

src/Avalonia.X11/Selections/SelectionHelper.cs

@@ -0,0 +1,8 @@
+using System;
+
+namespace Avalonia.X11.Selections;
+
+internal static class SelectionHelper
+{
+    public static TimeSpan Timeout { get; } = TimeSpan.FromSeconds(5);
+}

src/Avalonia.X11/Selections/SelectionReadSession.cs

@@ -42,7 +42,7 @@ internal sealed class SelectionReadSession(
                   ev.SelectionEvent.requestor == window &&
                   ev.SelectionEvent.selection == selection &&
                   ev.SelectionEvent.property == property,
-            TimeSpan.FromSeconds(5));
+            SelectionHelper.Timeout);
         
         if (ev == null)
             return null;
@@ -108,7 +108,7 @@ internal sealed class SelectionReadSession(
                 x => x is { type: XEventName.PropertyNotify, PropertyEvent.state: 0 } &&
                      x.PropertyEvent.window == window &&
                      x.PropertyEvent.atom == property,
-                TimeSpan.FromSeconds(5));
+                SelectionHelper.Timeout);
             
             if (ev == null)
                 return null;