Addressed empty NCA lockup

- Updated LoadGuestApplication to use a CancellationTokenSource so we can properly asynchronously cancel and not hang (other things could listen to this too, or cancel it).
- Moved PrepareLoadScreen() to later in the pipeline (because cancelling LoadGuestApplication causes issues).
- Added Metadata read/write logging.
- Made AppHost inherit Disposable interface so that the garbage collector kicks in (side effect: made private Dispose() public)
- Added a WaitHandle to wait on either gpuDoneEvent or gpuCTS.Cancel event (LoadGuestApplication cancellation).
- Set invalid title ID for metadata.

src/Ryujinx.HLE/Loaders/Processes/ProcessLoader.cs

@@ -14,6 +14,7 @@ using Ryujinx.HLE.Loaders.Executables;
 using Ryujinx.HLE.Loaders.Processes.Extensions;
 using System;
 using System.Collections.Concurrent;
+using System.Collections.Generic;
 using System.IO;
 using Path = System.IO.Path;
 
@@ -27,10 +28,15 @@ namespace Ryujinx.HLE.Loaders.Processes
 
         private ulong _latestPid;
 
-        public ProcessResult ActiveApplication
+        public ProcessResult? ActiveApplication
         {
             get
             {
+                return _processesByPid.GetValueOrDefault(_latestPid);
+                
+                // Using this if statement locks up the UI and prevents a new game from loading.
+                // Haven't quite deduced why yet.
+                
                 if (!_processesByPid.TryGetValue(_latestPid, out ProcessResult value))
                     throw new RyujinxException(
                         $"The HLE Process map did not have a process with ID {_latestPid}. Are you missing firmware?");

src/Ryujinx.HLE/Loaders/Processes/ProcessResult.cs

@@ -4,7 +4,6 @@ using LibHac.Ns;
 using Ryujinx.Common.Logging;
 using Ryujinx.Cpu;
 using Ryujinx.HLE.HOS.SystemState;
-using Ryujinx.HLE.Loaders.Processes.Extensions;
 using Ryujinx.Horizon.Common;
 
 namespace Ryujinx.HLE.Loaders.Processes
@@ -52,6 +51,7 @@ namespace Ryujinx.HLE.Loaders.Processes
 
             if (metaLoader is not null)
             {
+                Logger.Info?.Print(LogClass.Application,$"metaLoader: {metaLoader}");
                 ulong programId = metaLoader.ProgramId;
 
                 Name = ApplicationControlProperties.Title[(int)titleLanguage].NameString.ToString();
@@ -73,6 +73,13 @@ namespace Ryujinx.HLE.Loaders.Processes
                 Is64Bit = metaLoader.IsProgram64Bit;
             } 
             
+            else
+            {
+                Logger.Error?.Print(LogClass.Application,$"metaLoader is null !!!");
+                ProcessId = 0;
+                return;
+            }
+            
             DiskCacheEnabled = diskCacheEnabled;
             AllowCodeMemoryForJit = allowCodeMemoryForJit;
         }

src/Ryujinx/Systems/AppHost.cs

@@ -61,7 +61,7 @@ using VSyncMode = Ryujinx.Common.Configuration.VSyncMode;
 
 namespace Ryujinx.Ava.Systems
 {
-    internal class AppHost
+    internal class AppHost : IDisposable // notate this
     {
         private const int CursorHideIdleTime = 5; // Hide Cursor seconds.
         private const float MaxResolutionScale = 4.0f; // Max resolution hotkeys can scale to before wrapping.
@@ -437,7 +437,7 @@ namespace Ryujinx.Ava.Systems
 
                         SaveBitmapAsPng(bitmapToSave, path);
 
-                        Logger.Notice.Print(LogClass.Application, $"Screenshot saved to {path}", "Screenshot");
+                        Logger.Notice.Print(LogClass.Application, $"Screenshot saved to {path}.", "Screenshot");
                     }
                 });
             }
@@ -612,7 +612,9 @@ namespace Ryujinx.Ava.Systems
 
             // NOTE: The render loop is allowed to stay alive until the renderer itself is disposed, as it may handle resource dispose.
             // We only need to wait for all commands submitted during the main gpu loop to be processed.
-            _gpuDoneEvent.WaitOne();
+
+            WaitHandle.WaitAny(new []{_gpuDoneEvent, _gpuCancellationTokenSource.Token.WaitHandle}); // notate this
+            _gpuCancellationTokenSource.Dispose();
             _gpuDoneEvent.Dispose();
 
             DisplaySleep.Restore();
@@ -622,14 +624,16 @@ namespace Ryujinx.Ava.Systems
             Device.Dispose();
             
             DisposeGpu();
-
             AppExit?.Invoke(this, EventArgs.Empty);
         }
 
-        private void Dispose()
+        public void Dispose() // notate this
         {
             if (Device.Processes != null)
-                MainWindowViewModel.UpdateGameMetadata(Device.Processes.ActiveApplication.ProgramIdText, _playTimer.Elapsed);
+            {
+                MainWindowViewModel.UpdateGameMetadata(Device.Processes.ActiveApplication?.ProgramIdText ?? "<INVALID>", // notate this
+                    _playTimer.Elapsed);
+            }
             
             ConfigurationState.Instance.System.IgnoreMissingServices.Event -= UpdateIgnoreMissingServicesState;
             ConfigurationState.Instance.Graphics.AspectRatio.Event -= UpdateAspectRatioState;
@@ -645,7 +649,6 @@ namespace Ryujinx.Ava.Systems
             _topLevel.PointerExited -= TopLevel_PointerExited;
 
             _gpuCancellationTokenSource.Cancel();
-            _gpuCancellationTokenSource.Dispose();
 
             _chrono.Stop();
             _playTimer.Stop();
@@ -685,7 +688,7 @@ namespace Ryujinx.Ava.Systems
             _cursorState = CursorStates.ForceChangeCursor;
         }
 
-        public async Task<bool> LoadGuestApplication(BlitStruct<ApplicationControlProperty>? customNacpData = null)
+        public async Task LoadGuestApplication(CancellationTokenSource cts, BlitStruct<ApplicationControlProperty>? customNacpData = null)
         {
             DiscordIntegrationModule.GuestAppStartedAt = Timestamps.Now;
 
@@ -714,7 +717,8 @@ namespace Ryujinx.Ava.Systems
                                 await UserErrorDialog.ShowUserErrorDialog(userError);
                                 Device.Dispose();
 
-                                return false;
+                                cts.Cancel();
+                                throw new OperationCanceledException(cts.Token);
                             }
                         }
 
@@ -723,10 +727,11 @@ namespace Ryujinx.Ava.Systems
                             await UserErrorDialog.ShowUserErrorDialog(userError);
                             Device.Dispose();
 
-                            return false;
+                            cts.Cancel();
+                            throw new OperationCanceledException(cts.Token);
                         }
 
-                        // Tell the user that we installed a firmware for them.
+                        // Tell the user that we installed firmware for them.
                         if (userError is UserError.NoFirmware)
                         {
                             firmwareVersion = ContentManager.GetCurrentFirmwareVersion();
@@ -746,7 +751,8 @@ namespace Ryujinx.Ava.Systems
                         await UserErrorDialog.ShowUserErrorDialog(userError);
                         Device.Dispose();
 
-                        return false;
+                        cts.Cancel();
+                        throw new OperationCanceledException(cts.Token);
                     }
                 }
             }
@@ -761,7 +767,8 @@ namespace Ryujinx.Ava.Systems
                 {
                     Device.Dispose();
 
-                    return false;
+                    cts.Cancel();
+                    throw new OperationCanceledException(cts.Token);
                 }
             }
             else if (Directory.Exists(ApplicationPath))
@@ -781,20 +788,24 @@ namespace Ryujinx.Ava.Systems
 
                     if (!Device.LoadCart(ApplicationPath, romFsFiles[0]))
                     {
+                        ContentDialogHelper.CreateErrorDialog(
+                            "Please specify an unpacked game directory with a valid exefs or NSO/NRO.");
                         Device.Dispose();
 
-                        return false;
+                        cts.Cancel();
+                        throw new OperationCanceledException(cts.Token);
                     }
                 }
                 else
                 {
                     Logger.Info?.Print(LogClass.Application, "Loading as cart WITHOUT RomFS.");
-
                     if (!Device.LoadCart(ApplicationPath))
                     {
+                        ContentDialogHelper.CreateErrorDialog(
+                            "Please specify an unpacked game directory with a valid exefs or NSO/NRO.");
                         Device.Dispose();
-
+                        cts.Cancel();
-                        return false;
+                        throw new OperationCanceledException(cts.Token);
                     }
                 }
             }
@@ -812,7 +823,8 @@ namespace Ryujinx.Ava.Systems
                             {
                                 Device.Dispose();
 
-                                return false;
+                                cts.Cancel();
+                                throw new OperationCanceledException(cts.Token);
                             }
 
                             break;
@@ -825,7 +837,8 @@ namespace Ryujinx.Ava.Systems
                             {
                                 Device.Dispose();
 
-                                return false;
+                                cts.Cancel();
+                                throw new OperationCanceledException(cts.Token);
                             }
 
                             break;
@@ -839,7 +852,8 @@ namespace Ryujinx.Ava.Systems
                             {
                                 Device.Dispose();
 
-                                return false;
+                                cts.Cancel();
+                                throw new OperationCanceledException(cts.Token);
                             }
 
                             break;
@@ -854,7 +868,8 @@ namespace Ryujinx.Ava.Systems
                                 {
                                     Device.Dispose();
 
-                                    return false;
+                                    cts.Cancel();
+                                    throw new OperationCanceledException(cts.Token);
                                 }
                             }
                             catch (ArgumentOutOfRangeException)
@@ -863,7 +878,8 @@ namespace Ryujinx.Ava.Systems
 
                                 Device.Dispose();
 
-                                return false;
+                                cts.Cancel();
+                                throw new OperationCanceledException(cts.Token);
                             }
 
                             break;
@@ -872,19 +888,18 @@ namespace Ryujinx.Ava.Systems
             }
             else
             {
-                Logger.Warning?.Print(LogClass.Application, "Please specify a valid XCI/NCA/NSP/PFS0/NRO file.");
+                Logger.Warning?.Print(LogClass.Application, "Please specify a valid XCI/NCA/NSP/PFS0/NSO/NRO file.");
 
                 Device.Dispose();
 
-                return false;
+                cts.Cancel();
+                throw new OperationCanceledException(cts.Token);
             }
 
             ApplicationLibrary.LoadAndSaveMetaData(Device.Processes.ActiveApplication.ProgramIdText,
                 appMetadata => appMetadata.UpdatePreGame()
             );
             _playTimer.Start();
-
-            return true;
         }
 
         internal void Resume()
@@ -894,7 +909,7 @@ namespace Ryujinx.Ava.Systems
             _viewModel.IsPaused = false;
             _playTimer.Start();
             _viewModel.Title = TitleHelper.ActiveApplicationTitle(Device?.Processes.ActiveApplication, Program.Version, !ConfigurationState.Instance.ShowOldUI);
-            Logger.Info?.Print(LogClass.Emulation, "Emulation was resumed");
+            Logger.Info?.Print(LogClass.Emulation, "Emulation was resumed.");
         }
 
         internal void Pause()
@@ -904,7 +919,7 @@ namespace Ryujinx.Ava.Systems
             _viewModel.IsPaused = true;
             _playTimer.Stop();
             _viewModel.Title = TitleHelper.ActiveApplicationTitle(Device?.Processes.ActiveApplication, Program.Version, !ConfigurationState.Instance.ShowOldUI, LocaleManager.Instance[LocaleKeys.Paused]);
-            Logger.Info?.Print(LogClass.Emulation, "Emulation was paused");
+            Logger.Info?.Print(LogClass.Emulation, "Emulation was paused.");
         }
 
         private void InitEmulatedSwitch()

src/Ryujinx/Systems/AppLibrary/ApplicationLibrary.cs

@@ -1168,6 +1168,7 @@ namespace Ryujinx.Ava.Systems.AppLibrary
             
             if (!File.Exists(metadataFile))
             {
+                Logger.Info?.Print(LogClass.Application, $"Metadata file does not exist. Creating metadata for {titleId}...");
                 Directory.CreateDirectory(metadataFolder);
 
                 appMetadata = new ApplicationMetadata();
@@ -1177,12 +1178,12 @@ namespace Ryujinx.Ava.Systems.AppLibrary
 
             try
             {
+                Logger.Debug?.Print(LogClass.Application, $"Deserializing metadata for {titleId}...");
                 appMetadata = JsonHelper.DeserializeFromFile(metadataFile, _serializerContext.ApplicationMetadata);
             }
             catch (JsonException)
             {
                 Logger.Warning?.Print(LogClass.Application, $"Failed to parse metadata json for {titleId}. Loading defaults.");
-
                 appMetadata = new ApplicationMetadata();
             }
 

src/Ryujinx/UI/ViewModels/MainWindowViewModel.cs

@@ -1700,11 +1700,6 @@ namespace Ryujinx.Ava.UI.ViewModels
 
             Logger.RestartTime();
 
-            SelectedIcon ??= ApplicationLibrary.GetApplicationIcon(application.Path,
-                ConfigurationState.Instance.System.Language, application.Id);
-
-            PrepareLoadScreen();
-
             RendererHostControl = new RendererHost();
 
             AppHost = new AppHost(
@@ -1719,18 +1714,36 @@ namespace Ryujinx.Ava.UI.ViewModels
                 this,
                 TopLevel);
             
-            if (!await AppHost.LoadGuestApplication(customNacpData))
+            // Needs a new name to better fit code styling
+            CancellationTokenSource cts = new CancellationTokenSource();
+
+            try
             {
+                await AppHost.LoadGuestApplication(cts, customNacpData);
+            }
+            catch (OperationCanceledException exception)
+            {
+                Logger.Info?.Print(LogClass.Application,
+                    "LoadGuestApplication was interrupted !!! " + exception.Message);
                 AppHost.DisposeContext();
                 AppHost = null;
-
                 return;
             }
+            finally
+            {
+                cts.Dispose();
+            }
             
             CanUpdate = false;
 
             application.Name ??= AppHost.Device.Processes.ActiveApplication.Name;
             
+            // notate this
+            SelectedIcon ??= ApplicationLibrary.GetApplicationIcon(application.Path,
+                ConfigurationState.Instance.System.Language, application.Id);
+
+            PrepareLoadScreen();
+
             LoadHeading = LocaleManager.Instance.UpdateAndGetDynamicValue(LocaleKeys.LoadingHeading, application.Name);
 
             SwitchToRenderer(startFullscreen);
@@ -1752,7 +1765,8 @@ namespace Ryujinx.Ava.UI.ViewModels
             });
 
         public static void UpdateGameMetadata(string titleId, TimeSpan playTime) 
-            => ApplicationLibrary.LoadAndSaveMetaData(titleId, appMetadata => appMetadata.UpdatePostGame(playTime));
+            =>ApplicationLibrary.LoadAndSaveMetaData(titleId, appMetadata => appMetadata.UpdatePostGame(playTime));
+            
 
         public void RefreshFirmwareStatus()
         {