ContextWindow: Change renew context event handling

Elwig/Windows/ContextWindow.cs

@@ -7,30 +7,32 @@ using System.Windows.Threading;
 namespace Elwig.Windows {
     public abstract class ContextWindow : Window {
 
+        public static readonly int RenewSec = 10;
+
         protected AppDbContext Context { get; private set; }
         protected bool LockContext { get; set; } = false;
 
-        private readonly DispatcherTimer ContextRenewTimer;
-        private static readonly int ContextRenewSec = 10;
+        private readonly DispatcherTimer _timer;
+        private bool _renewPending = false;
 
         public ContextWindow() : base() {
-            ContextRenewTimer = new DispatcherTimer();
-            ContextRenewTimer.Tick += new EventHandler(OnRenewContext);
-            ContextRenewTimer.Interval = new TimeSpan(0, 0, ContextRenewSec);
-            ContextRenewTimer.Start();
+            _timer = new DispatcherTimer();
+            _timer.Tick += new EventHandler(OnShouldRenewContext);
+            _timer.Interval = new TimeSpan(0, 0, RenewSec);
+            _timer.Start();
             Context = new();
             Loaded += OnLoaded;
         }
 
-        private void OnRenewContext(object? sender, EventArgs evt) {
-            if (LockContext || !Context.HasBackendChanged) return;
-            Context.Dispose();
-            Context = new();
-            RenewContext().GetAwaiter().GetResult();
+        private async void OnShouldRenewContext(object? sender, EventArgs evt) {
+            if (!Context.HasBackendChanged) return;
+            _renewPending = true;
+            if (LockContext) return;
+            await RenewContext();
         }
 
         private void OnLoaded(object sender, RoutedEventArgs evt) {
-            RenewContext().GetAwaiter().GetResult();
+            OnRenewContext().GetAwaiter().GetResult();
         }
 
         protected override void OnClosed(EventArgs evt) {
@@ -38,6 +40,14 @@ namespace Elwig.Windows {
             Context.Dispose();
         }
 
-        abstract protected Task RenewContext();
+        protected async Task RenewContext() {
+            if (!_renewPending) return;
+            Context.Dispose();
+            Context = new();
+            await OnRenewContext();
+            _renewPending = false;
+        }
+
+        abstract protected Task OnRenewContext();
     }
 }