Lazy-fetch the settings for extensions (microsoft#38844)

This PR stops us from synchronously initializing the settings page for every extension (including built-in's) on startup. That incurs a small penalty that really adds up the more extensions a user has.

Instead, we'll now only initialize the `CommandSettings` object when we first actually need it. 

From a relatively unscientific test, this saves approximately 10% on the initialization of builtin commands, and for my setup, it trims about 28% off extension initialization (across all built-in's / extensions):

branch | Built-in load (ms) | Extension load (ms) | %Δ builtin | %Δ extensions | 
-- | -- | -- | -- | -- |
main | 1455 | 6867.6 | | |
this PR | 1309.2 | 4919 | -10.02% | -28.37%

Closes microsoft#38321

Author: zadjii-msft

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/CommandProviderWrapper.cs

@@ -66,8 +66,10 @@ public CommandProviderWrapper(ICommandProvider provider, TaskScheduler mainThrea
         DisplayName = provider.DisplayName;
         Icon = new(provider.Icon);
         Icon.InitializeProperties();
+
+        // Note: explicitly not InitializeProperties()ing the settings here. If
+        // we do that, then we'd regress GH #38321
         Settings = new(provider.Settings, this, _taskScheduler);
-        Settings.InitializeProperties();
 
         Logger.LogDebug($"Initialized command provider {ProviderId}");
     }
@@ -151,9 +153,11 @@ public async Task LoadTopLevelCommands(IServiceProvider serviceProvider, WeakRef
             Icon = new(model.Icon);
             Icon.InitializeProperties();
 
+            // Note: explicitly not InitializeProperties()ing the settings here. If
+            // we do that, then we'd regress GH #38321
             Settings = new(model.Settings, this, _taskScheduler);
-            Settings.InitializeProperties();
 
+            // We do need to explicitly initialize commands though
             InitializeCommands(commands, fallbacks, serviceProvider, pageContext);
 
             Logger.LogDebug($"Loaded commands from {DisplayName} ({ProviderId})");
@@ -194,21 +198,6 @@ private void InitializeCommands(ICommandItem[] commands, IFallbackCommandItem[]
         }
     }
 
-    /* This is a View/ExtensionHost piece
-     * public void AllowSetForeground(bool allow)
-    {
-        if (!IsExtension)
-        {
-            return;
-        }
-
-        var iextn = extensionWrapper?.GetExtensionObject();
-        unsafe
-        {
-            PInvoke.CoAllowSetForegroundWindow(iextn);
-        }
-    }*/
-
     public override bool Equals(object? obj) => obj is CommandProviderWrapper wrapper && isValid == wrapper.isValid;
 
     public override int GetHashCode() => _commandProvider.GetHashCode();

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/CommandSettingsViewModel.cs

@@ -2,18 +2,25 @@
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using ManagedCommon;
 using Microsoft.CmdPal.UI.ViewModels.Models;
 using Microsoft.CommandPalette.Extensions;
 
 namespace Microsoft.CmdPal.UI.ViewModels;
 
-public partial class CommandSettingsViewModel(ICommandSettings _unsafeSettings, CommandProviderWrapper provider, TaskScheduler mainThread)
+public partial class CommandSettingsViewModel(ICommandSettings? _unsafeSettings, CommandProviderWrapper provider, TaskScheduler mainThread)
 {
     private readonly ExtensionObject<ICommandSettings> _model = new(_unsafeSettings);
 
     public ContentPageViewModel? SettingsPage { get; private set; }
 
-    public void InitializeProperties()
+    public bool Initialized { get; private set; }
+
+    public bool HasSettings =>
+        _model.Unsafe != null && // We have a settings model AND
+        (!Initialized || SettingsPage != null); // we weren't initialized, OR we were, and we do have a settings page
+
+    private void UnsafeInitializeProperties()
     {
         var model = _model.Unsafe;
         if (model == null)
@@ -27,4 +34,27 @@ public void InitializeProperties()
             SettingsPage.InitializeProperties();
         }
     }
+
+    public void SafeInitializeProperties()
+    {
+        try
+        {
+            UnsafeInitializeProperties();
+        }
+        catch (Exception ex)
+        {
+            Logger.LogError($"Failed to load settings page", ex: ex);
+        }
+
+        Initialized = true;
+    }
+
+    public void DoOnUiThread(Action action)
+    {
+        Task.Factory.StartNew(
+            action,
+            CancellationToken.None,
+            TaskCreationOptions.None,
+            mainThread);
+    }
 }

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/ProviderSettingsViewModel.cs

@@ -18,6 +18,8 @@ public partial class ProviderSettingsViewModel(
     IServiceProvider _serviceProvider) : ObservableObject
 {
     private readonly SettingsModel _settings = _serviceProvider.GetService<SettingsModel>()!;
+    private readonly Lock _initializeSettingsLock = new();
+    private Task? _initializeSettingsTask;
 
     public string DisplayName => _provider.DisplayName;
 
@@ -34,6 +36,9 @@ public partial class ProviderSettingsViewModel(
 
     public IconInfoViewModel Icon => _provider.Icon;
 
+    [ObservableProperty]
+    public partial bool LoadingSettings { get; set; } = _provider.Settings?.HasSettings ?? false;
+
     public bool IsEnabled
     {
         get => _providerSettings.IsEnabled;
@@ -56,15 +61,60 @@ public bool IsEnabled
         }
     }
 
-    private void Provider_CommandsChanged(CommandProviderWrapper sender, CommandPalette.Extensions.IItemsChangedEventArgs args)
+    /// <summary>
+    /// Gets a value indicating whether returns true if we have a settings page
+    /// that's initialized, or we are still working on initializing that
+    /// settings page. If we don't have a settings object, or that settings
+    /// object doesn't have a settings page, then we'll return false.
+    /// </summary>
+    public bool HasSettings
     {
-        OnPropertyChanged(nameof(ExtensionSubtext));
-        OnPropertyChanged(nameof(TopLevelCommands));
+        get
+        {
+            if (_provider.Settings == null)
+            {
+                return false;
+            }
+
+            if (_provider.Settings.Initialized)
+            {
+                return _provider.Settings.HasSettings;
+            }
+
+            // settings still need to be loaded.
+            return LoadingSettings;
+        }
     }
 
-    public bool HasSettings => _provider.Settings != null && _provider.Settings.SettingsPage != null;
+    /// <summary>
+    /// Gets will return the settings page, if we have one, and have initialized it.
+    /// If we haven't initialized it, this will kick off a thread to start
+    /// initializing it.
+    /// </summary>
+    public ContentPageViewModel? SettingsPage
+    {
+        get
+        {
+            if (_provider.Settings == null)
+            {
+                return null;
+            }
 
-    public ContentPageViewModel? SettingsPage => HasSettings ? _provider?.Settings?.SettingsPage : null;
+            if (_provider.Settings.Initialized)
+            {
+                LoadingSettings = false;
+                return _provider.Settings.SettingsPage;
+            }
+
+            // Don't load the settings if we're already working on it
+            lock (_initializeSettingsLock)
+            {
+                _initializeSettingsTask ??= Task.Run(InitializeSettingsPage);
+            }
+
+            return null;
+        }
+    }
 
     [field: AllowNull]
     public List<TopLevelViewModel> TopLevelCommands
@@ -90,4 +140,30 @@ private List<TopLevelViewModel> BuildTopLevelViewModels()
     }
 
     private void Save() => SettingsModel.SaveSettings(_settings);
+
+    private void InitializeSettingsPage()
+    {
+        if (_provider.Settings == null)
+        {
+            return;
+        }
+
+        _provider.Settings.SafeInitializeProperties();
+        _provider.Settings.DoOnUiThread(() =>
+        {
+            // Changing these properties will try to update XAML, and that has
+            // to be handled on the UI thread, so we need to raise them on the
+            // UI thread
+            LoadingSettings = false;
+            OnPropertyChanged(nameof(HasSettings));
+            OnPropertyChanged(nameof(LoadingSettings));
+            OnPropertyChanged(nameof(SettingsPage));
+        });
+    }
+
+    private void Provider_CommandsChanged(CommandProviderWrapper sender, CommandPalette.Extensions.IItemsChangedEventArgs args)
+    {
+        OnPropertyChanged(nameof(ExtensionSubtext));
+        OnPropertyChanged(nameof(TopLevelCommands));
+    }
 }

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/TopLevelCommandManager.cs

@@ -45,6 +45,9 @@ public TopLevelCommandManager(IServiceProvider serviceProvider)
 
     public async Task<bool> LoadBuiltinsAsync()
     {
+        var s = new Stopwatch();
+        s.Start();
+
         _builtInCommands.Clear();
 
         // Load built-In commands first. These are all in-proc, and
@@ -64,6 +67,10 @@ public async Task<bool> LoadBuiltinsAsync()
             }
         }
 
+        s.Stop();
+
+        Logger.LogDebug($"Loading built-ins took {s.ElapsedMilliseconds}ms");
+
         return true;
     }
 

src/modules/cmdpal/Microsoft.CmdPal.UI/Settings/ExtensionPage.xaml

@@ -113,7 +113,24 @@
                                     Visibility="{x:Bind ViewModel.HasSettings}" />
 
                                 <Frame x:Name="SettingsFrame" Visibility="{x:Bind ViewModel.HasSettings}">
-                                    <cmdpalUI:ContentPage ViewModel="{x:Bind ViewModel.SettingsPage, Mode=OneWay}" />
+
+                                    <controls:SwitchPresenter
+                                        HorizontalAlignment="Stretch"
+                                        TargetType="x:Boolean"
+                                        Value="{x:Bind ViewModel.LoadingSettings, Mode=OneWay}">
+                                        <controls:Case Value="True">
+                                            <ProgressRing
+                                                Width="36"
+                                                Height="36"
+                                                HorizontalAlignment="Center"
+                                                VerticalAlignment="Center"
+                                                IsIndeterminate="True" />
+                                        </controls:Case>
+                                        <controls:Case Value="False">
+                                            <cmdpalUI:ContentPage ViewModel="{x:Bind ViewModel.SettingsPage, Mode=OneWay}" />
+                                        </controls:Case>
+                                    </controls:SwitchPresenter>
+
                                 </Frame>
 
                                 <TextBlock