Limit the added APIs by removing event cancellation.

Author: ilonatommy

src/Components/Components/src/NavigationManager.cs

@@ -54,10 +54,6 @@ public event EventHandler<EventArgs> NotFoundEvent
 
     private EventHandler<EventArgs>? _notFound;
 
-    private readonly List<Func<NotFoundContext, ValueTask>> _notFoundHandlers = new();
-
-    private CancellationTokenSource? _notFoundCts;
-
     // For the baseUri it's worth storing as a System.Uri so we can do operations
     // on that type. System.Uri gives us access to the original string anyway.
     private Uri? _baseUri;
@@ -487,126 +483,6 @@ protected async ValueTask<bool> NotifyLocationChangingAsync(string uri, string?
         }
     }
 
-    /// <summary>
-    /// Notifies the registered handlers of the current ot found event.
-    /// </summary>
-    /// <returns>A <see cref="ValueTask{TResult}"/> representing the completion of the operation. If the result is <see langword="true"/>, the navigation should continue.</returns>
-    protected async ValueTask<bool> NotifyNotFoundAsync()
-    {
-        _notFoundCts?.Cancel();
-        _notFoundCts = null;
-
-        var handlerCount = _notFoundHandlers.Count;
-
-        if (handlerCount == 0)
-        {
-            return true;
-        }
-
-        var cts = new CancellationTokenSource();
-
-        _notFoundCts = cts;
-
-        var cancellationToken = cts.Token;
-        var context = new NotFoundContext
-        {
-            CancellationToken = cancellationToken,
-        };
-
-        try
-        {
-            if (handlerCount == 1)
-            {
-                var handlerTask = InvokeNotFoundHandlerAsync(_notFoundHandlers[0], context);
-
-                if (handlerTask.IsFaulted)
-                {
-                    await handlerTask;
-                    return false; // Unreachable because the previous line will throw.
-                }
-
-                if (context.DidPreventRendering)
-                {
-                    return false;
-                }
-
-                if (!handlerTask.IsCompletedSuccessfully)
-                {
-                    await handlerTask.AsTask().WaitAsync(cancellationToken);
-                }
-            }
-            else
-            {
-                var notFoundHandlersCopy = ArrayPool<Func<NotFoundContext, ValueTask>>.Shared.Rent(handlerCount);
-
-                try
-                {
-                    _notFoundHandlers.CopyTo(notFoundHandlersCopy);
-
-                    var notFoundTasks = new HashSet<Task>();
-
-                    for (var i = 0; i < handlerCount; i++)
-                    {
-                        var handlerTask = InvokeNotFoundHandlerAsync(notFoundHandlersCopy[i], context);
-
-                        if (handlerTask.IsFaulted)
-                        {
-                            await handlerTask;
-                            return false; // Unreachable because the previous line will throw.
-                        }
-
-                        if (context.DidPreventRendering)
-                        {
-                            return false;
-                        }
-
-                        notFoundTasks.Add(handlerTask.AsTask());
-                    }
-
-                    while (notFoundTasks.Count != 0)
-                    {
-                        var completedHandlerTask = await Task.WhenAny(notFoundTasks).WaitAsync(cancellationToken);
-
-                        if (completedHandlerTask.IsFaulted)
-                        {
-                            await completedHandlerTask;
-                            return false; // Unreachable because the previous line will throw.
-                        }
-
-                        notFoundTasks.Remove(completedHandlerTask);
-                    }
-                }
-                finally
-                {
-                    ArrayPool<Func<NotFoundContext, ValueTask>>.Shared.Return(notFoundHandlersCopy);
-                }
-            }
-
-            return !context.DidPreventRendering;
-        }
-        catch (TaskCanceledException ex)
-        {
-            if (ex.CancellationToken == cancellationToken)
-            {
-                // This navigation was in progress when a successive navigation occurred.
-                // We treat this as a canceled navigation.
-                return false;
-            }
-
-            throw;
-        }
-        finally
-        {
-            cts.Cancel();
-            cts.Dispose();
-
-            if (_notFoundCts == cts)
-        {
-                _notFoundCts = null;
-            }
-        }
-    }
-
     private async ValueTask InvokeLocationChangingHandlerAsync(Func<LocationChangingContext, ValueTask> handler, LocationChangingContext context)
     {
         try
@@ -623,22 +499,6 @@ private async ValueTask InvokeLocationChangingHandlerAsync(Func<LocationChanging
         }
     }
 
-    private async ValueTask InvokeNotFoundHandlerAsync(Func<NotFoundContext, ValueTask> handler, NotFoundContext context)
-    {
-        try
-        {
-            await handler(context);
-        }
-        catch (OperationCanceledException)
-        {
-            // Ignore exceptions caused by cancellations.
-        }
-        catch (Exception ex)
-        {
-            HandleNotFoundHandlerException(ex, context);
-        }
-    }
-
     /// <summary>
     /// Handles exceptions thrown in location changing handlers.
     /// </summary>
@@ -647,14 +507,6 @@ private async ValueTask InvokeNotFoundHandlerAsync(Func<NotFoundContext, ValueTa
     protected virtual void HandleLocationChangingHandlerException(Exception ex, LocationChangingContext context)
         => throw new InvalidOperationException($"To support navigation locks, {GetType().Name} must override {nameof(HandleLocationChangingHandlerException)}");
 
-    /// <summary>
-    /// Handles exceptions thrown in NotFound rendering handlers.
-    /// </summary>
-    /// <param name="ex">The exception to handle.</param>
-    /// <param name="context">The context passed to the handler.</param>
-    protected virtual void HandleNotFoundHandlerException(Exception ex, NotFoundContext context)
-        => throw new InvalidOperationException($"To support not found rendering locks, {GetType().Name} must override {nameof(HandleNotFoundHandlerException)}");
-
     /// <summary>
     /// Sets whether navigation is currently locked. If it is, then implementations should not update <see cref="Uri"/> and call
     /// <see cref="NotifyLocationChanged(bool)"/> until they have first confirmed the navigation by calling

src/Components/Components/src/PublicAPI.Unshipped.txt

@@ -3,15 +3,8 @@ Microsoft.AspNetCore.Components.IEndpointHtmlRenderer
 Microsoft.AspNetCore.Components.IEndpointHtmlRenderer.SetNotFoundResponse() -> void
 Microsoft.AspNetCore.Components.NavigationManager.NotFoundEvent -> System.EventHandler<System.EventArgs!>!
 Microsoft.AspNetCore.Components.NavigationManager.NotifyNotFound() -> void
-Microsoft.AspNetCore.Components.NavigationManager.NotifyNotFoundAsync() -> System.Threading.Tasks.ValueTask<bool>
 Microsoft.AspNetCore.Components.NotFoundRenderingException
 Microsoft.AspNetCore.Components.NotFoundRenderingException.NotFoundRenderingException(string! message, System.Exception! innerException) -> void
 Microsoft.AspNetCore.Components.Routing.IHostEnvironmentNavigationManager.Initialize(string! baseUri, string! uri, Microsoft.AspNetCore.Components.IEndpointHtmlRenderer! renderer) -> void
-Microsoft.AspNetCore.Components.Routing.NotFoundContext
-Microsoft.AspNetCore.Components.Routing.NotFoundContext.CancellationToken.get -> System.Threading.CancellationToken
-Microsoft.AspNetCore.Components.Routing.NotFoundContext.CancellationToken.init -> void
-Microsoft.AspNetCore.Components.Routing.NotFoundContext.NotFoundContext() -> void
-Microsoft.AspNetCore.Components.Routing.NotFoundContext.PreventRendering() -> void
-virtual Microsoft.AspNetCore.Components.NavigationManager.HandleNotFoundHandlerException(System.Exception! ex, Microsoft.AspNetCore.Components.Routing.NotFoundContext! context) -> void
 virtual Microsoft.AspNetCore.Components.NavigationManager.NotFound() -> void
 virtual Microsoft.AspNetCore.Components.NavigationManager.NotFoundCore() -> void

src/Components/Components/src/Routing/NotFoundContext.cs

@@ -165,26 +165,14 @@ protected override void NotFoundCore()
     {
         Log.RequestingNotFound(_logger);
 
-        _ = NotFoundAsync();
-
-        async Task NotFoundAsync()
+        try
         {
-            try
-            {
-                bool shouldContinueRendering = await NotifyNotFoundAsync();
-                if (!shouldContinueRendering)
-                {
-                    Log.NotFoundRenderCanceled(_logger);
-                    return;
-                }
-
-                NotifyNotFound();
-            }
-            catch (Exception ex)
-            {
-                Log.NotFoundRenderFailed(_logger, ex);
-                UnhandledException?.Invoke(this, ex);
-            }
+            NotifyNotFound();
+        }
+        catch (Exception ex)
+        {
+            Log.NotFoundRenderFailed(_logger, ex);
+            UnhandledException?.Invoke(this, ex);
         }
     }
 
@@ -248,8 +236,5 @@ public static void RequestingNavigation(ILogger logger, string uri, NavigationOp
 
         [LoggerMessage(7, LogLevel.Debug, "Navigation stopped because the session ended when navigating to {Uri}", EventName = "NavigationStoppedSessionEnded")]
         public static partial void NavigationStoppedSessionEnded(ILogger logger, string uri);
-
-        [LoggerMessage(3, LogLevel.Debug, "Rendering of NotFound canceled", EventName = "NotFoundRenderCanceled")]
-        public static partial void NotFoundRenderCanceled(ILogger logger);
     }
 }

src/Components/Server/src/Circuits/RemoteNavigationManager.cs

@@ -88,28 +88,13 @@ public override void Refresh(bool forceReload = false)
     /// <inheritdoc />
     protected override void NotFoundCore()
     {
-        _ = PerformNotFoundAsync();
-
-        async Task PerformNotFoundAsync()
+        try
         {
-            try
-            {
-                var shouldContinueNotFound = await NotifyNotFoundAsync();
-
-                if (!shouldContinueNotFound)
-                {
-                    Log.NotFoundRenderCanceled(_logger);
-                    return;
-                }
-
-                NotifyNotFound();
-            }
-            catch (Exception ex)
-            {
-                // We shouldn't ever reach this since exceptions thrown from handlers are handled in HandleNotFoundHandlerException.
-                // But if some other exception gets thrown, we still want to know about it.
-                Log.NotFoundRenderFailed(_logger, ex);
-            }
+            NotifyNotFound();
+        }
+        catch (Exception ex)
+        {
+            Log.NotFoundRenderFailed(_logger, ex);
         }
     }
 
@@ -118,11 +103,6 @@ protected override void HandleLocationChangingHandlerException(Exception ex, Loc
         Log.NavigationFailed(_logger, context.TargetLocation, ex);
     }
 
-    protected override void HandleNotFoundHandlerException(Exception ex, NotFoundContext context)
-    {
-        Log.NotFoundRenderFailed(_logger, ex);
-    }
-
     protected override void SetNavigationLockState(bool value)
         => InternalJSImportMethods.Instance.NavigationManager_SetHasLocationChangingListeners((int)WebRendererId.WebAssembly, value);
 
@@ -136,8 +116,5 @@ private static partial class Log
 
         [LoggerMessage(5, LogLevel.Error, "Failed to render NotFound", EventName = "NotFoundRenderFailed")]
         public static partial void NotFoundRenderFailed(ILogger logger, Exception exception);
-
-        [LoggerMessage(1, LogLevel.Debug, "NotFound render canceled", EventName = "NotFoundRenderCanceled")]
-        public static partial void NotFoundRenderCanceled(ILogger logger);
     }
 }