wip

src/libraries/System.Runtime.InteropServices.JavaScript/src/System/Runtime/InteropServices/JavaScript/JSWebWorker.cs

@@ -59,7 +59,7 @@ internal sealed class JSWebWorkerInstance<T> : IDisposable
 
             public JSWebWorkerInstance(Func<Task<T>> bodyRes, CancellationToken cancellationToken)
             {
-                _taskCompletionSource = new TaskCompletionSource<T>(TaskCreationOptions.RunContinuationsAsynchronously);
+                _taskCompletionSource = new TaskCompletionSource<T>(TaskCreationOptions.DenyChildAttach | TaskCreationOptions.RunContinuationsAsynchronously | TaskCreationOptions.HideScheduler);
                 _thread = new Thread(ThreadMain);
                 _resultTask = null;
                 _cancellationToken = cancellationToken;
@@ -75,14 +75,19 @@ public Task<T> Start()
                     // give browser chance to load more threads
                     // until there at least one thread loaded, it doesn't make sense to `Start`
                     // because that would also hang, but in a way blocking the UI thread, much worse.
-                    JavaScriptImports.ThreadAvailable().ContinueWith(t =>
+                    JavaScriptImports.ThreadAvailable().ContinueWith(static (t, o) =>
                     {
+                        var self = (JSWebWorkerInstance<T>)o!;
                         if (t.IsCompletedSuccessfully)
                         {
-                            _thread.Start();
+                            self._thread.Start();
                         }
-                        return t;
-                    }, _cancellationToken, TaskContinuationOptions.ExecuteSynchronously, TaskScheduler.FromCurrentSynchronizationContext());
+                        if (t.IsCanceled)
+                        {
+                            throw new OperationCanceledException(self._cancellationToken);
+                        }
+                        throw t.Exception!;
+                    }, this, _cancellationToken, TaskContinuationOptions.None, TaskScheduler.FromCurrentSynchronizationContext());
                 }
                 else
                 {
@@ -97,16 +102,17 @@ private void ThreadMain()
                 {
                     if (_cancellationToken.IsCancellationRequested)
                     {
-                        PropagateCompletionAndDispose(Task.FromException<T>(new OperationCanceledException(_cancellationToken)));
+                        PropagateCompletionAndDispose(Task.FromCanceled<T>(_cancellationToken));
                         return;
                     }
 
                     // receive callback when the cancellation is requested
-                    _cancellationRegistration = _cancellationToken.Register(() =>
+                    _cancellationRegistration = _cancellationToken.Register(static (o) =>
                     {
+                        var self = (JSWebWorkerInstance<T>)o!;
                         // this could be executing on any thread
-                        PropagateCompletionAndDispose(Task.FromException<T>(new OperationCanceledException(_cancellationToken)));
-                    });
+                        self.PropagateCompletionAndDispose(Task.FromCanceled<T>(self._cancellationToken));
+                    }, this);
 
                     // JSSynchronizationContext also registers to _cancellationToken
                     _jsSynchronizationContext = JSSynchronizationContext.InstallWebWorkerInterop(false, _cancellationToken);

src/libraries/System.Runtime.InteropServices.JavaScript/src/System/Runtime/InteropServices/JavaScript/Marshaling/JSMarshalerArgument.Task.cs

@@ -49,7 +49,7 @@ public unsafe void ToManaged(out Task? value)
             lock (ctx)
             {
                 PromiseHolder holder = ctx.GetPromiseHolder(slot.GCHandle);
-                TaskCompletionSource tcs = new TaskCompletionSource(holder);
+                TaskCompletionSource tcs = new TaskCompletionSource(holder, TaskCreationOptions.DenyChildAttach | TaskCreationOptions.RunContinuationsAsynchronously);
                 ToManagedCallback callback = (JSMarshalerArgument* arguments_buffer) =>
                 {
                     if (arguments_buffer == null)
@@ -98,7 +98,7 @@ public unsafe void ToManaged<T>(out Task<T>? value, ArgumentToManagedCallback<T>
             lock (ctx)
             {
                 var holder = ctx.GetPromiseHolder(slot.GCHandle);
-                TaskCompletionSource<T> tcs = new TaskCompletionSource<T>(holder);
+                TaskCompletionSource<T> tcs = new TaskCompletionSource<T>(holder, TaskCreationOptions.DenyChildAttach | TaskCreationOptions.RunContinuationsAsynchronously);
                 ToManagedCallback callback = (JSMarshalerArgument* arguments_buffer) =>
                 {
                     if (arguments_buffer == null)

src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System.Runtime.InteropServices.JavaScript.Tests.csproj

@@ -1,5 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
+<!--
+
   <Import Condition="'$(TargetOS)' == 'browser'" Project="$(CommonTestPath)System/Net/Prerequisites/LocalEchoServer.props" />
+-->
   <PropertyGroup>
     <TargetPlatformIdentifier>$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)'))</TargetPlatformIdentifier>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>

src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/WebWorkerTest.cs

@@ -30,10 +30,33 @@ namespace System.Runtime.InteropServices.JavaScript.Tests
 
     public class WebWorkerTest : IAsyncLifetime
     {
-        const int TimeoutMilliseconds = 300;
+        const int TimeoutMilliseconds = 5000;
+
+        public static bool _isWarmupDone;
+
+        public async Task InitializeAsync()
+        {
+            if (_isWarmupDone)
+            {
+                return;
+            }
+            await Task.Delay(500);
+            _isWarmupDone = true;
+        }
+
+        public Task DisposeAsync() => Task.CompletedTask;
 
         #region Executors
 
+        private CancellationTokenSource CreateTestCaseTimeoutSource()
+        {
+            var cts = new CancellationTokenSource(TimeoutMilliseconds);
+            cts.Token.Register(() => {
+                Console.WriteLine($"Unexpected test case timeout at {DateTime.Now.ToString("u")} ManagedThreadId:{Environment.CurrentManagedThreadId}");
+            });
+            return cts;
+        }
+
         public static IEnumerable<object[]> GetTargetThreads()
         {
             return Enum.GetValues<ExecutorType>().Select(type => new object[] { new Executor(type) });
@@ -677,19 +700,5 @@ await Assert.ThrowsAsync<TaskCanceledException>(async () =>
         }
 
         #endregion
-
-        public static bool _isWarmupDone;
-
-        public async Task InitializeAsync()
-        {
-            if (_isWarmupDone)
-            {
-                return;
-            }
-            await Task.Delay(500);
-            _isWarmupDone = true;
-        }
-
-        public Task DisposeAsync() => Task.CompletedTask;
     }
 }