Basic implementation of AsyncManualResetEvent

Author: danielmarbach

projects/RabbitMQ.Client/client/impl/AsyncManualResetEvent.cs

@@ -0,0 +1,108 @@
+// This source code is dual-licensed under the Apache License, version
+// 2.0, and the Mozilla Public License, version 2.0.
+//
+// The APL v2.0:
+//
+//---------------------------------------------------------------------------
+//   Copyright (c) 2007-2024 Broadcom. All Rights Reserved.
+//
+//   Licensed under the Apache License, Version 2.0 (the "License");
+//   you may not use this file except in compliance with the License.
+//   You may obtain a copy of the License at
+//
+//       https://www.apache.org/licenses/LICENSE-2.0
+//
+//   Unless required by applicable law or agreed to in writing, software
+//   distributed under the License is distributed on an "AS IS" BASIS,
+//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//   See the License for the specific language governing permissions and
+//   limitations under the License.
+//---------------------------------------------------------------------------
+//
+// The MPL v2.0:
+//
+//---------------------------------------------------------------------------
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+//
+//  Copyright (c) 2007-2024 Broadcom. All Rights Reserved.
+//---------------------------------------------------------------------------
+
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace RabbitMQ.Client.client.impl
+{
+    /// <summary>
+    /// Inspired by http://blogs.msdn.com/b/pfxteam/archive/2012/02/11/10266920.aspx
+    /// </summary>
+    sealed class AsyncManualResetEvent
+    {
+        public AsyncManualResetEvent(bool initialState)
+        {
+            if (initialState)
+            {
+                _taskCompletionSource.SetResult(true);
+            }
+        }
+
+        public bool IsSet => _taskCompletionSource.Task.IsCompleted;
+
+        public async Task WaitAsync(CancellationToken cancellationToken)
+        {
+            CancellationTokenRegistration tokenRegistration =
+#if NET6_0_OR_GREATER
+                cancellationToken.UnsafeRegister(
+                    state => ((TaskCompletionSource<bool>)state!).TrySetCanceled(), _taskCompletionSource);
+#else
+                cancellationToken.Register(
+                    state => ((TaskCompletionSource<bool>)state!).TrySetCanceled(),
+                    state: _taskCompletionSource, useSynchronizationContext: false);
+#endif
+            try
+            {
+                await _taskCompletionSource.Task.ConfigureAwait(false);
+            }
+            finally
+            {
+#if NET6_0_OR_GREATER
+                await tokenRegistration.DisposeAsync()
+                    .ConfigureAwait(false);
+#else
+                tokenRegistration.Dispose();
+#endif
+            }
+        }
+
+        public void Set()
+        {
+            _taskCompletionSource.TrySetResult(true);
+        }
+
+        public void Reset()
+        {
+            var sw = new SpinWait();
+
+            do
+            {
+                var currentTaskCompletionSource = _taskCompletionSource;
+                if (!currentTaskCompletionSource.Task.IsCompleted)
+                {
+                    return;
+                }
+
+                var nextTaskCompletionSource = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);
+                if (Interlocked.CompareExchange(ref _taskCompletionSource, nextTaskCompletionSource, currentTaskCompletionSource) == currentTaskCompletionSource)
+                {
+                    return;
+                }
+
+                sw.SpinOnce();
+            }
+            while (true);
+        }
+
+        volatile TaskCompletionSource<bool> _taskCompletionSource = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);
+    }
+}