Code Quality: Pin WinRT server object to prevent object reference being invalid (#15324)

Author: hez2010

src/Files.App.Server/AppInstanceMonitor.cs

@@ -1,13 +1,15 @@
 // Copyright (c) 2024 Files Community
 // Licensed under the MIT License. See the LICENSE.
 
+using System.Collections.Concurrent;
 using System.Diagnostics;
 
 namespace Files.App.Server;
 
 public sealed class AppInstanceMonitor
 {
 	private static int processCount = 0;
+	internal static ConcurrentDictionary<int, ConcurrentBag<IDisposable>> AppInstanceResources = new();
 
 	public static void StartMonitor(int processId)
 	{
@@ -19,10 +21,18 @@ public static void StartMonitor(int processId)
 
 	private static void Process_Exited(object? sender, EventArgs e)
 	{
-		if (sender is Process process)
+		if (sender is Process { Id: var processId } process)
 		{
 			process.Dispose();
 
+			if (AppInstanceResources.TryRemove(processId, out var instances))
+			{
+				foreach (var instance in instances)
+				{
+					instance.Dispose();
+				}
+			}
+
 			if (Interlocked.Decrement(ref processCount) == 0)
 			{
 				Program.ExitSignalEvent.Set();

src/Files.App.Server/Database/FileTagsDatabase.cs

@@ -6,6 +6,7 @@
 using LiteDB;
 using Microsoft.Win32;
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 using System.Runtime.InteropServices.WindowsRuntime;
 using System.Text;
 using Windows.ApplicationModel;
@@ -17,13 +18,16 @@
 
 namespace Files.App.Server.Database
 {
-	public sealed class FileTagsDatabase
+	public sealed class FileTagsDatabase : IDisposable
 	{
 		private readonly static string FileTagsKey = @$"Software\Files Community\{Package.Current.Id.FullName}\v1\FileTags";
 
 		private readonly static string FileTagsDbPath = Path.Combine(ApplicationData.Current.LocalFolder.Path, "filetags.db");
 		private const string FileTagsCollectionName = "taggedfiles";
 
+		private readonly GCHandle _handle;
+		private bool _disposed = false;
+
 		static FileTagsDatabase()
 		{
 			if (File.Exists(FileTagsDbPath))
@@ -44,6 +48,25 @@ static FileTagsDatabase()
 			}
 		}
 
+		public FileTagsDatabase()
+		{
+			throw new NotSupportedException($"Instantiating {nameof(FileTagsDatabase)} by non-parameterized constructor is not supported.");
+		}
+
+		public FileTagsDatabase(int processId)
+		{
+			_handle = GCHandle.Alloc(this, GCHandleType.Pinned);
+
+			if (AppInstanceMonitor.AppInstanceResources.TryGetValue(processId, out var instances))
+			{
+				instances.Add(this);
+			}
+			else
+			{
+				AppInstanceMonitor.AppInstanceResources[processId] = [this];
+			}
+		}
+
 		private static void UpdateDb(LiteDatabase database)
 		{
 			if (database.UserVersion == 0)
@@ -279,5 +302,14 @@ private void IterateKeys(List<TaggedFile> list, string path, int depth)
 				IterateKeys(list, CombineKeys(path, subKey), depth + 1);
 			}
 		}
+
+		public void Dispose()
+		{
+			if (!_disposed)
+			{
+				_disposed = true;
+				_handle.Free();
+			}
+		}
 	}
 }

src/Files.App.Server/Database/LayoutPreferencesDatabase.cs

@@ -5,6 +5,7 @@
 using LiteDB;
 using Microsoft.Win32;
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 using Windows.ApplicationModel;
 using Windows.Storage;
 using static Files.App.Server.Data.LayoutPreferencesRegistry;
@@ -13,13 +14,16 @@
 
 namespace Files.App.Server.Database
 {
-	public sealed class LayoutPreferencesDatabase
+	public sealed class LayoutPreferencesDatabase : IDisposable
 	{
 		private readonly static string LayoutSettingsKey = @$"Software\Files Community\{Package.Current.Id.FullName}\v1\LayoutPreferences";
 
 		private readonly static string LayoutSettingsDbPath = Path.Combine(ApplicationData.Current.LocalFolder.Path, "user_settings.db");
 		private const string LayoutSettingsCollectionName = "layoutprefs";
 
+		private readonly GCHandle _handle;
+		private bool _disposed = false;
+
 		static LayoutPreferencesDatabase()
 		{
 			if (File.Exists(LayoutSettingsDbPath))
@@ -37,6 +41,25 @@ static LayoutPreferencesDatabase()
 			}
 		}
 
+		public LayoutPreferencesDatabase()
+		{
+			throw new NotSupportedException($"Instantiating {nameof(LayoutPreferencesDatabase)} by non-parameterized constructor is not supported.");
+		}
+
+		public LayoutPreferencesDatabase(int processId)
+		{
+			_handle = GCHandle.Alloc(this, GCHandleType.Pinned);
+
+			if (AppInstanceMonitor.AppInstanceResources.TryGetValue(processId, out var instances))
+			{
+				instances.Add(this);
+			}
+			else
+			{
+				AppInstanceMonitor.AppInstanceResources[processId] = [this];
+			}
+		}
+
 		public LayoutPreferencesItem? GetPreferences(string filePath, ulong? frn)
 		{
 			return FindPreferences(filePath, frn)?.LayoutPreferencesManager;
@@ -197,5 +220,14 @@ private void IterateKeys(List<LayoutPreferences> list, string path, int depth)
 
 			return null;
 		}
+
+		public void Dispose()
+		{
+			if (!_disposed)
+			{
+				_disposed = true;
+				_handle.Free();
+			}
+		}
 	}
 }

src/Files.App/Helpers/Layout/LayoutPreferencesDatabaseManager.cs

@@ -11,7 +11,7 @@ namespace Files.App.Helpers
 	public class LayoutPreferencesDatabaseManager
 	{
 		// Fields
-		private readonly Server.Database.LayoutPreferencesDatabase _database = new();
+		private readonly Server.Database.LayoutPreferencesDatabase _database = new(Environment.ProcessId);
 
 		private DetailsLayoutColumnItem FromDatabaseEntity(Server.Data.ColumnPreferencesItem entry)
 		{

src/Files.App/Utils/FileTags/FileTagsHelper.cs

@@ -12,9 +12,9 @@ namespace Files.App.Utils.FileTags
 {
 	public static class FileTagsHelper
 	{
-		private static readonly Lazy<Server.Database.FileTagsDatabase> dbInstance = new(() => new());
+		private static readonly Server.Database.FileTagsDatabase dbInstance = new(Environment.ProcessId);
 
-		public static Server.Database.FileTagsDatabase GetDbInstance() => dbInstance.Value;
+		public static Server.Database.FileTagsDatabase GetDbInstance() => dbInstance;
 
 		public static string[] ReadFileTag(string filePath)
 		{