feat: Introduce RegistryLoader class with Lazy<T> and async registry settings loading

- Added the RegistryLoader class to handle loading of registry settings.
- Implemented Lazy<T> for singleton pattern to ensure only one instance of RegistryLoader is created.
- Added support for asynchronous loading of registry settings to improve performance in async workflows.
- Designed the class with thread safety in mind, leveraging ConcurrentDictionary for storage.
- Included logging of debug messages to track the load process and timing.

mRemoteNG/App/Startup.cs

@@ -1,5 +1,4 @@
 using System;
-using System.ComponentModel;
 using System.Diagnostics;
 using System.Globalization;
 using System.Runtime.Versioning;
@@ -8,6 +7,7 @@ using mRemoteNG.App.Info;
 using mRemoteNG.App.Initialization;
 using mRemoteNG.App.Update;
 using mRemoteNG.Config.Connections.Multiuser;
+using mRemoteNG.Config.Settings.Registry;
 using mRemoteNG.Connection;
 using mRemoteNG.Messages;
 using mRemoteNG.Properties;
@@ -22,6 +22,7 @@ namespace mRemoteNG.App
     [SupportedOSPlatform("windows")]
     public class Startup
     {
+        private RegistryLoader _RegistryLoader;
         private AppUpdater _appUpdate;
         private readonly ConnectionIconLoader _connectionIconLoader;
         private readonly FrmMain _frmMain = FrmMain.Default;
@@ -30,6 +31,7 @@ namespace mRemoteNG.App
 
         private Startup()
         {
+            _RegistryLoader = RegistryLoader.Instance; //created instance
             _appUpdate = new AppUpdater(); 
             _connectionIconLoader = new ConnectionIconLoader(GeneralAppInfo.HomePath + "\\Icons\\");
         }

mRemoteNG/Config/Settings/Registry/RegistryLoader.cs

@@ -0,0 +1,187 @@
+using mRemoteNG.App;
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Runtime.Versioning;
+using System.Threading.Tasks;
+
+namespace mRemoteNG.Config.Settings.Registry
+{
+    [SupportedOSPlatform("windows")]
+    public class RegistryLoader : IDisposable
+    {
+        /// <summary>
+        /// This instance is used to load registry settings at program startup.cs, ensuring that 
+        /// these settings are applied to regular configurations and can override them as needed.
+        /// Once the settings are loaded, this lazy instance will primarily be used for configuring 
+        /// the options page. After this initialization phase, the lazy instance may no longer be necessary and get disposed.
+        /// </summary>
+        private static readonly Lazy<RegistryLoader> instance =
+                new(() => new RegistryLoader());
+
+        /// <summary>
+        /// Singleton instance of the RegistryMultiLoader class.
+        /// </summary>
+        public static RegistryLoader Instance => instance.Value;
+
+        /// <summary>
+        /// Dictionary to store settings for all registry pages.
+        /// </summary>
+        public static ConcurrentDictionary<Type, object> RegistrySettings { get; private set; }
+
+        /// <summary>
+        /// Static constructor that initializes the registry settings dictionary 
+        /// and starts loading settings asynchronously at startup.
+        /// </summary>
+        static RegistryLoader()
+        {
+            RegistrySettings = new ConcurrentDictionary<Type, object>();
+            // Start loading asynchronously on startup
+            _ = LoadAllAsync();
+        }
+
+        /// <summary>
+        /// Cleans up the registry settings by removing entries of a specified type.
+        /// </summary>
+        /// <param name="deleteEntries">The type of entries to remove from the dictionary.</param>
+        /// <remarks>
+        /// If the dictionary becomes empty after removal and the singleton instance has been created,
+        /// it disposes of the instance to free resources.
+        /// </remarks>
+        public static void Cleanup(Type deleteEntries)
+        {
+            // Remove the registry setting from the dictionary
+            RegistrySettings?.TryRemove(deleteEntries, out _);
+
+            if (RegistrySettings.IsEmpty && instance.IsValueCreated)
+            {
+                Instance.Dispose();
+            }
+        }
+
+        /// <summary>
+        /// Asynchronously loads and applies multiple registry classes in parallel.
+        /// </summary>
+        /// <returns>A task representing the asynchronous operation.</returns>
+        /// <remarks>
+        /// This method creates a list of tasks, each responsible for initializing 
+        /// and applying a specific registry class. It awaits the completion of all tasks 
+        /// using Task.WhenAll.
+        /// </remarks>
+        private static async Task LoadAllAsync()
+        {
+#if DEBUG
+            Stopwatch stopwatch = Stopwatch.StartNew();
+#endif
+
+            try
+            {
+                // Create a list of tasks to initialize and apply each registry class asynchronously
+                var tasks = new List<Task>
+            {
+                LoadAndApplyAsync<OptRegistryAppearancePage>(),
+                LoadAndApplyAsync<OptRegistryConnectionsPage>(),
+                LoadAndApplyAsync<OptRegistryCredentialsPage>(),
+                LoadAndApplyAsync<OptRegistryNotificationsPage>(),
+                LoadAndApplyAsync<OptRegistrySecurityPage>(),
+                LoadAndApplyAsync<OptRegistrySqlServerPage>(),
+                LoadAndApplyAsync<OptRegistryStartupExitPage>(),
+                LoadAndApplyAsync<OptRegistryTabsPanelsPage>(),
+                LoadAndApplyAsync<OptRegistryUpdatesPage>()
+            };
+
+                // Await all tasks to complete
+                await Task.WhenAll(tasks);
+
+                Runtime.MessageCollector.AddMessage(Messages.MessageClass.DebugMsg,
+                    $"Registry settings loaded and applied asynchronously in {typeof(RegistryLoader).Name}", true);
+            }
+            catch (Exception ex)
+            {
+                Runtime.MessageCollector.AddMessage(Messages.MessageClass.DebugMsg,
+                    $"Registry settings error during load: {ex.Message}", true);
+            }
+
+#if DEBUG
+            stopwatch.Stop();
+            Runtime.MessageCollector.AddMessage(Messages.MessageClass.DebugMsg,
+                $"Registry settings total async load time: {stopwatch.ElapsedMilliseconds} ms", true);
+#endif
+        }
+
+        /// <summary>
+        /// Asynchronously initializes and applies registry settings for a specified type.
+        /// </summary>
+        /// <typeparam name="T">The type of the registry settings class, which must have a parameterless constructor.</typeparam>
+        /// <returns>A task representing the asynchronous operation.</returns>
+        /// <remarks>
+        /// This method creates an instance of the specified type T, stores it in a dictionary 
+        /// using its type as the key, and completes the task. 
+        /// </remarks>
+        private static async Task LoadAndApplyAsync<T>() where T : new()
+        {
+            try
+            {
+                // create an instance of setting
+                var instance = new T();
+
+                // Store the instance in the dictionary using its type as key
+                RegistrySettings[typeof(T)] = instance;
+
+                // complete task
+                await Task.CompletedTask;
+            }
+            catch (Exception ex)
+            {
+                Runtime.MessageCollector.AddMessage(Messages.MessageClass.DebugMsg,
+                    $"Registry settings error during load {typeof(T).Name}: {ex.Message}", true);
+            }
+        }
+
+        #region IDisposable Support
+
+        /// <summary>
+        /// Implements the IDisposable pattern for resource cleanup.
+        /// </summary>
+        private bool disposedValue = false; // To detect redundant calls
+
+        /// <summary>
+        /// Releases the resources used by the object.
+        /// </summary>
+        public void Dispose()
+        {
+            if (disposedValue)
+                return;
+
+            Dispose(true);
+            GC.SuppressFinalize(this);
+
+            disposedValue = true;
+
+            Runtime.MessageCollector.AddMessage(Messages.MessageClass.DebugMsg,
+                $"Registry settings lazy instance of {typeof(RegistryLoader).Name} has been disposed.", true);
+        }
+
+        /// <summary>
+        /// Performs the actual resource cleanup.
+        /// </summary>
+        /// <param name="disposing">True if managed resources should be released.</param>
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (disposing)
+                RegistrySettings?.Clear();
+        }
+
+        /// <summary>
+        /// Finalizer that is called to free unmanaged resources.
+        /// </summary>
+        ~RegistryLoader()
+        {
+            Dispose(false);
+        }
+
+        #endregion IDisposable Support
+    }
+}

mRemoteNG/Tools/WindowsRegistry/WinRegistryEntry.cs

@@ -300,6 +300,9 @@ namespace mRemoteNG.Tools.WindowsRegistry
                 AllowedValues = allowedValues;
             }
 
+            if (ElementType == typeof(string) && privateValue != null)
+                privateValue = EnforceStringInputValidity(privateValue);
+
             return this;
         }