Dispose workers on app exit

#50

NAPS2.Lib.Tests/WinForms/DesktopControllerTests.cs

@@ -5,6 +5,7 @@ using NAPS2.ImportExport;
 using NAPS2.ImportExport.Images;
 using NAPS2.Platform.Windows;
 using NAPS2.Recovery;
+using NAPS2.Remoting.Worker;
 using NAPS2.Sdk.Tests;
 using NAPS2.Sdk.Tests.Asserts;
 using NAPS2.Update;
@@ -36,6 +37,7 @@ public class DesktopControllerTests : ContextualTests
     private readonly DesktopFormProvider _desktopFormProvider;
     private readonly Mock<IScannedImagePrinter> _scannedImagePrinter;
     private readonly ThumbnailController _thumbnailController;
+    private readonly Mock<IWorkerFactory> _workerFactory;
 
     public DesktopControllerTests()
     {
@@ -59,6 +61,7 @@ public class DesktopControllerTests : ContextualTests
         _desktopFormProvider = new DesktopFormProvider();
         _scannedImagePrinter = new Mock<IScannedImagePrinter>();
         _thumbnailController = new ThumbnailController(_thumbnailRenderQueue, _config);
+        _workerFactory = new Mock<IWorkerFactory>();
         _desktopController = new DesktopController(
             ScanningContext,
             _imageList,
@@ -78,7 +81,8 @@ public class DesktopControllerTests : ContextualTests
             _desktopImagesController,
             _desktopScanController.Object,
             _desktopFormProvider,
-            _scannedImagePrinter.Object
+            _scannedImagePrinter.Object,
+            _workerFactory.Object
         );
 
         _operationFactory.Setup(x => x.Create<RecoveryOperation>()).Returns(

NAPS2.Lib/EtoForms/Desktop/DesktopController.cs

@@ -5,6 +5,7 @@ using NAPS2.ImportExport.Images;
 using NAPS2.Platform.Windows;
 using NAPS2.Recovery;
 using NAPS2.Remoting;
+using NAPS2.Remoting.Worker;
 using NAPS2.Scan;
 using NAPS2.Update;
 
@@ -30,6 +31,7 @@ public class DesktopController
     private readonly IDesktopScanController _desktopScanController;
     private readonly DesktopFormProvider _desktopFormProvider;
     private readonly IScannedImagePrinter _scannedImagePrinter;
+    private readonly IWorkerFactory _workerFactory;
 
     private bool _closed;
     private bool _initialized;
@@ -43,7 +45,7 @@ public class DesktopController
         ImageClipboard imageClipboard, ImageListActions imageListActions,
         DialogHelper dialogHelper,
         DesktopImagesController desktopImagesController, IDesktopScanController desktopScanController,
-        DesktopFormProvider desktopFormProvider, IScannedImagePrinter scannedImagePrinter)
+        DesktopFormProvider desktopFormProvider, IScannedImagePrinter scannedImagePrinter, IWorkerFactory workerFactory)
     {
         _scanningContext = scanningContext;
         _imageList = imageList;
@@ -63,6 +65,7 @@ public class DesktopController
         _desktopScanController = desktopScanController;
         _desktopFormProvider = desktopFormProvider;
         _scannedImagePrinter = scannedImagePrinter;
+        _workerFactory = workerFactory;
     }
 
     public bool SkipRecoveryCleanup { get; set; }
@@ -167,6 +170,7 @@ public class DesktopController
         }
         _closed = true;
         _thumbnailController.Dispose();
+        _workerFactory.Dispose();
     }
 
     public bool PrepareForClosing(bool userClosing)

NAPS2.Lib/Images/ThumbnailRenderQueue.cs

@@ -127,6 +127,7 @@ public class ThumbnailRenderQueue : IDisposable
             _renderThumbnailsCompleteHandle.Set();
             _renderThumbnailsWaitHandle.WaitOne();
         }
+        worker?.Dispose();
     }
 
     private IMemoryImage RenderThumbnailWithWorker(WorkerContext worker, ProcessedImage imageToRender,

NAPS2.Sdk/Remoting/Worker/IWorkerFactory.cs

@@ -3,7 +3,7 @@
 /// <summary>
 /// A factory interface to spawn NAPS2.Worker.exe instances as needed.
 /// </summary>
-public interface IWorkerFactory
+public interface IWorkerFactory : IDisposable
 {
     void Init();
     WorkerContext Create(WorkerType workerType);

NAPS2.Sdk/Remoting/Worker/WorkerFactory.cs

@@ -161,4 +161,16 @@ public class WorkerFactory : IWorkerFactory
         worker.Service.Init(_fileStorageManager.FolderPath);
         return worker;
     }
+
+    public void Dispose()
+    {
+        if (_workerQueues == null) return;
+        foreach (var queue in _workerQueues.Values)
+        {
+            while (queue.TryTake(out var worker))
+            {
+                worker.Dispose();
+            }
+        }
+    }
 }