SemaphoreSlimContext.cs

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

namespace Tgstation.Server.Host.Core
{
    public sealed class SemaphoreSlimContext : IDisposable
    {
        public static async Task<SemaphoreSlimContext> Lock(SemaphoreSlim semaphore, CancellationToken cancellationToken)
        {
            if (semaphore == null)
                throw new ArgumentNullException(nameof(semaphore));
            cancellationToken.ThrowIfCancellationRequested();
            await semaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
            return new SemaphoreSlimContext(semaphore);
        }

        readonly SemaphoreSlim lockedSemaphore;

        readonly object disposeLock;

        bool disposed;

        SemaphoreSlimContext(SemaphoreSlim lockedSemaphore)
        {
            this.lockedSemaphore = lockedSemaphore;
            disposeLock = new object();
        }

#pragma warning disable CA1821 // Remove empty Finalizers //TODO remove this when https://github.com/dotnet/roslyn-analyzers/issues/1241 is fixed
        ~SemaphoreSlimContext() => Dispose();
#pragma warning restore CA1821 // Remove empty Finalizers

        public void Dispose()
        {
            lock (disposeLock)
            {
                if (disposed)
                    return;
                disposed = true;
            }

            GC.SuppressFinalize(this);
            lockedSemaphore.Release();
        }
    }
}