async handling of dependency load in app

Author: ibetitsmike

App/App.xaml.cs

@@ -46,6 +46,8 @@ public partial class App : Application
 
     private readonly ISettingsManager _settingsManager;
 
+    private readonly IHostApplicationLifetime _appLifetime;
+
     public App()
     {
         var builder = Host.CreateApplicationBuilder();
@@ -119,6 +121,7 @@ public App()
         _logger = (ILogger<App>)_services.GetService(typeof(ILogger<App>))!;
         _uriHandler = (IUriHandler)_services.GetService(typeof(IUriHandler))!;
         _settingsManager = (ISettingsManager)_services.GetService(typeof(ISettingsManager))!;
+        _appLifetime = (IHostApplicationLifetime)_services.GetRequiredService<IHostApplicationLifetime>();
 
         InitializeComponent();
     }
@@ -140,71 +143,73 @@ protected override void OnLaunched(LaunchActivatedEventArgs args)
     {
         _logger.LogInformation("new instance launched");
 
-        // Load the credentials in the background.
-        var credentialManagerCts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
+        _ = InitializeServicesAsync(_appLifetime.ApplicationStopping);
+
+        // Prevent the TrayWindow from closing, just hide it.
+        var trayWindow = _services.GetRequiredService<TrayWindow>();
+        trayWindow.Closed += (_, closedArgs) =>
+        {
+            if (!_handleWindowClosed) return;
+            closedArgs.Handled = true;
+            trayWindow.AppWindow.Hide();
+        };
+    }
+
+    /// <summary>
+    /// Loads stored VPN credentials, reconnects the RPC controller,
+    /// and (optionally) starts the VPN tunnel on application launch.
+    /// </summary>
+    private async Task InitializeServicesAsync(CancellationToken cancellationToken = default)
+    {
         var credentialManager = _services.GetRequiredService<ICredentialManager>();
-        credentialManager.LoadCredentials(credentialManagerCts.Token).ContinueWith(t =>
+        var rpcController = _services.GetRequiredService<IRpcController>();
+
+        using var credsCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+        credsCts.CancelAfter(TimeSpan.FromSeconds(15));
+
+        Task loadCredsTask = credentialManager.LoadCredentials(credsCts.Token);
+        Task reconnectTask = rpcController.Reconnect(cancellationToken);
+
+        try
         {
-            if (t.Exception != null)
-            {
-                _logger.LogError(t.Exception, "failed to load credentials");
-#if DEBUG
-                Debug.WriteLine(t.Exception);
-                Debugger.Break();
-#endif
-            }
+            await Task.WhenAll(loadCredsTask, reconnectTask);
+        }
+        catch (Exception)
+        {
+            if (loadCredsTask.IsFaulted)
+                _logger.LogError(loadCredsTask.Exception!.GetBaseException(),
+                                 "Failed to load credentials");
 
-            credentialManagerCts.Dispose();
-        });
+            if (reconnectTask.IsFaulted)
+                _logger.LogError(reconnectTask.Exception!.GetBaseException(),
+                                 "Failed to connect to VPN service");
 
+            return;
+        }
 
-        // Start connecting to the manager in the background.
-        var rpcController = _services.GetRequiredService<IRpcController>();
-        _ = rpcController.Reconnect(CancellationToken.None).ContinueWith(t =>
+        if (_settingsManager.ConnectOnLaunch)
         {
-            if (t.Exception != null)
+            try
             {
-                _logger.LogError(t.Exception, "failed to connect to VPN service");
-#if DEBUG
-                Debug.WriteLine(t.Exception);
-                Debugger.Break();
-#endif
-                return;
+                await rpcController.StartVpn(cancellationToken);
             }
-            if (_settingsManager.ConnectOnLaunch)
+            catch (Exception ex)
             {
-                _logger.LogInformation("RPC lifecycle is disconnected, but ConnectOnLaunch is enabled; attempting to connect");
-                _ = rpcController.StartVpn(CancellationToken.None).ContinueWith(connectTask =>
-                {
-                    if (connectTask.Exception != null)
-                    {
-                        _logger.LogError(connectTask.Exception, "failed to connect on launch");
-                    }
-                });
+                _logger.LogError(ex, "Failed to connect on launch");
             }
-        });
+        }
 
         // Initialize file sync.
         var syncSessionCts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
         var syncSessionController = _services.GetRequiredService<ISyncSessionController>();
-        _ = syncSessionController.RefreshState(syncSessionCts.Token).ContinueWith(t =>
+        try
         {
-            if (t.IsCanceled || t.Exception != null)
-            {
-                _logger.LogError(t.Exception, "failed to refresh sync state (canceled = {canceled})", t.IsCanceled);
-            }
-
-            syncSessionCts.Dispose();
-        }, CancellationToken.None);
-
-        // Prevent the TrayWindow from closing, just hide it.
-        var trayWindow = _services.GetRequiredService<TrayWindow>();
-        trayWindow.Closed += (_, closedArgs) =>
+            await syncSessionController.RefreshState(syncSessionCts.Token);
+        }
+        catch(Exception ex)
         {
-            if (!_handleWindowClosed) return;
-            closedArgs.Handled = true;
-            trayWindow.AppWindow.Hide();
-        };
+            _logger.LogError($"Failed to refresh sync session state {ex.Message}", ex);
+        }
     }
 
     public void OnActivated(object? sender, AppActivationArguments args)