certmgr/certmgr/Core/Utils/AsyncLock.cs

namespace CertMgr.Core.Utils;

using System;
using System.Threading;
using System.Threading.Tasks;

public sealed class AsyncLock
{
    private readonly SemaphoreSlim _semaphore;
    private readonly Task<IDisposable> _disposer;

    public AsyncLock()
    {
        _semaphore = new SemaphoreSlim(1, 1);
        _disposer = Task.FromResult((IDisposable)new AsyncLockDisposer(this));
    }

    public Task<IDisposable> LockAsync(CancellationToken cancellation = default)
    {
        Task wait = _semaphore.WaitAsync();
        if (wait.IsCompleted)
        {
            return _disposer;
        }
        else
        {
            return wait.ContinueWith((_, state) => (IDisposable)state!, _disposer.Result, CancellationToken.None, TaskContinuationOptions.ExecuteSynchronously, TaskScheduler.Default);
        }
    }

    private sealed class AsyncLockDisposer : IDisposable
    {
        private readonly AsyncLock _owner;

        internal AsyncLockDisposer(AsyncLock owner)
        {
            _owner = owner;
        }

        public void Dispose()
        {
            _owner._semaphore.Release();
        }
    }
}