| /* |
| * 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 |
| * |
| * http://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. |
| */ |
| |
| namespace DotPulsar.Internal |
| { |
| using Abstractions; |
| using Exceptions; |
| using System; |
| using System.Collections.Generic; |
| using System.Threading; |
| using System.Threading.Tasks; |
| |
| public sealed class AsyncQueue<T> : IEnqueue<T>, IDequeue<T>, IDisposable |
| { |
| private readonly object _lock; |
| private readonly Queue<T> _queue; |
| private readonly LinkedList<CancelableCompletionSource<T>> _pendingDequeues; |
| private int _isDisposed; |
| |
| public AsyncQueue() |
| { |
| _lock = new object(); |
| _queue = new Queue<T>(); |
| _pendingDequeues = new LinkedList<CancelableCompletionSource<T>>(); |
| } |
| |
| public void Enqueue(T item) |
| { |
| lock (_lock) |
| { |
| ThrowIfDisposed(); |
| |
| if (_pendingDequeues.Count > 0) |
| { |
| var tcs = _pendingDequeues.First; |
| _pendingDequeues.RemoveFirst(); |
| tcs.Value.SetResult(item); |
| } |
| else |
| _queue.Enqueue(item); |
| } |
| } |
| |
| public ValueTask<T> Dequeue(CancellationToken cancellationToken = default) |
| { |
| LinkedListNode<CancelableCompletionSource<T>>? node = null; |
| |
| lock (_lock) |
| { |
| ThrowIfDisposed(); |
| |
| if (_queue.Count > 0) |
| return new ValueTask<T>(_queue.Dequeue()); |
| |
| node = _pendingDequeues.AddLast(new CancelableCompletionSource<T>()); |
| } |
| |
| node.Value.SetupCancellation(() => Cancel(node), cancellationToken); |
| return new ValueTask<T>(node.Value.Task); |
| } |
| |
| public void Dispose() |
| { |
| lock (_lock) |
| { |
| if (Interlocked.Exchange(ref _isDisposed, 1) != 0) |
| return; |
| |
| foreach (var pendingDequeue in _pendingDequeues) |
| pendingDequeue.Dispose(); |
| |
| _pendingDequeues.Clear(); |
| _queue.Clear(); |
| } |
| } |
| |
| private void Cancel(LinkedListNode<CancelableCompletionSource<T>> node) |
| { |
| lock (_lock) |
| { |
| try |
| { |
| node.Value.Dispose(); |
| _pendingDequeues.Remove(node); |
| } |
| catch |
| { |
| // ignored |
| } |
| } |
| } |
| |
| private void ThrowIfDisposed() |
| { |
| if (_isDisposed != 0) |
| throw new AsyncQueueDisposedException(); |
| } |
| } |
| } |