Fire and forget BlazorWebView disposal by default (#25430)

Author: MackinnonBuck

src/BlazorWebView/src/Maui/Android/BlazorWebViewHandler.Android.cs

@@ -61,9 +61,6 @@ protected override AWebView CreatePlatformView()
 
 		private const string AndroidFireAndForgetAsyncSwitch = "BlazorWebView.AndroidFireAndForgetAsync";
 
-		private static bool IsAndroidFireAndForgetAsyncEnabled =>
-			AppContext.TryGetSwitch(AndroidFireAndForgetAsyncSwitch, out var enabled) && enabled;
-
 		protected override void DisconnectHandler(AWebView platformView)
 		{
 			platformView.StopLoading();
@@ -77,19 +74,25 @@ protected override void DisconnectHandler(AWebView platformView)
 					.DisposeAsync()
 					.AsTask()!;
 
-				if (IsAndroidFireAndForgetAsyncEnabled)
-				{
-					// If the app is configured to fire-and-forget via an AppContext Switch, we'll do that.
-					disposalTask.FireAndForget();
-				}
-				else
+				// When determining whether to block on disposal, we respect the more specific AndroidFireAndForgetAsync switch
+				// if specified. If not, we fall back to the general UseBlockingDisposal switch, defaulting to false.
+				var shouldBlockOnDispose = AppContext.TryGetSwitch(AndroidFireAndForgetAsyncSwitch, out var enableFireAndForget)
+					? !enableFireAndForget
+					: IsBlockingDisposalEnabled;
+
+				if (shouldBlockOnDispose)
 				{
-					// Otherwise by default, we'll synchronously wait for the disposal to complete. This can cause
-					// a deadlock, but is the original behavior.
+					// If the app is configured to block on dispose via an AppContext switch,
+					// we'll synchronously wait for the disposal to complete. This can cause a deadlock.
 					disposalTask
 						.GetAwaiter()
 						.GetResult();
 				}
+				else
+				{
+					// Otherwise, by default, we'll fire-and-forget the disposal task.
+					disposalTask.FireAndForget(_logger);
+				}
 
 				_webviewManager = null;
 			}

src/BlazorWebView/src/Maui/BlazorWebViewHandler.cs

@@ -13,6 +13,11 @@ namespace Microsoft.AspNetCore.Components.WebView.Maui
 #endif
 	public partial class BlazorWebViewHandler
 	{
+		private const string UseBlockingDisposalSwitch = "BlazorWebView.UseBlockingDisposal";
+
+		private static bool IsBlockingDisposalEnabled =>
+			AppContext.TryGetSwitch(UseBlockingDisposalSwitch, out var enabled) && enabled;
+
 		/// <summary>
 		/// This field is part of MAUI infrastructure and is not intended for use by application code.
 		/// </summary>

src/BlazorWebView/src/Maui/Windows/BlazorWebViewHandler.Windows.cs

@@ -6,6 +6,7 @@
 using Microsoft.Extensions.FileProviders;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Maui;
 using Microsoft.Maui.Dispatching;
 using Microsoft.Maui.Handlers;
 using WebView2Control = Microsoft.UI.Xaml.Controls.WebView2;
@@ -30,13 +31,24 @@ protected override void DisconnectHandler(WebView2Control platformView)
 		{
 			if (_webviewManager != null)
 			{
-				// Dispose this component's contents and block on completion so that user-written disposal logic and
-				// Blazor disposal logic will complete.
-				_webviewManager?
+				// Start the disposal...
+				var disposalTask = _webviewManager?
 					.DisposeAsync()
-					.AsTask()
-					.GetAwaiter()
-					.GetResult();
+					.AsTask()!;
+
+				if (IsBlockingDisposalEnabled)
+				{
+					// If the app is configured to block on dispose via an AppContext switch,
+					// we'll synchronously wait for the disposal to complete. This can cause a deadlock.
+					disposalTask
+						.GetAwaiter()
+						.GetResult();
+				}
+				else
+				{
+					// Otherwise, by default, we'll fire-and-forget the disposal task.
+					disposalTask.FireAndForget();
+				}
 
 				_webviewManager = null;
 			}

src/BlazorWebView/src/Maui/iOS/BlazorWebViewHandler.iOS.cs

@@ -8,6 +8,7 @@
 using Microsoft.Extensions.FileProviders;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Maui;
 using Microsoft.Maui.Dispatching;
 using Microsoft.Maui.Handlers;
 using UIKit;
@@ -127,13 +128,24 @@ protected override void DisconnectHandler(WKWebView platformView)
 
 			if (_webviewManager != null)
 			{
-				// Dispose this component's contents and block on completion so that user-written disposal logic and
-				// Blazor disposal logic will complete.
-				_webviewManager?
+				// Start the disposal...
+				var disposalTask = _webviewManager?
 					.DisposeAsync()
-					.AsTask()
-					.GetAwaiter()
-					.GetResult();
+					.AsTask()!;
+
+				if (IsBlockingDisposalEnabled)
+				{
+					// If the app is configured to block on dispose via an AppContext switch,
+					// we'll synchronously wait for the disposal to complete. This can cause a deadlock.
+					disposalTask
+						.GetAwaiter()
+						.GetResult();
+				}
+				else
+				{
+					// Otherwise, by default, we'll fire-and-forget the disposal task.
+					disposalTask.FireAndForget(_logger);
+				}
 
 				_webviewManager = null;
 			}