IdentityCacheObject.cs

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using System;
using System.Threading;
using System.Threading.Tasks;
 
using Tgstation.Server.Host.Utils;
 
namespace Tgstation.Server.Host.Security
{
    sealed class IdentityCacheObject : IAsyncDisposable
    {
        public ISystemIdentity SystemIdentity { get; }
 
        readonly CancellationTokenSource cancellationTokenSource;
 
        readonly Task task;
 
        public IdentityCacheObject(ISystemIdentity systemIdentity, IAsyncDelayer asyncDelayer, Action onExpiry, DateTimeOffset expiry)
        {
            SystemIdentity = systemIdentity ?? throw new ArgumentNullException(nameof(systemIdentity));
 
            ArgumentNullException.ThrowIfNull(asyncDelayer);
 
            ArgumentNullException.ThrowIfNull(onExpiry);
            var now = DateTimeOffset.UtcNow;
            if (expiry < now)
                throw new ArgumentOutOfRangeException(nameof(expiry), expiry, "expiry must be greater than DateTimeOffset.UtcNow!");
 
            cancellationTokenSource = new CancellationTokenSource();
 
            async Task DisposeOnExipiry(CancellationToken cancellationToken)
            {
                using (SystemIdentity)
                    try
                    {
                        await asyncDelayer.Delay(expiry - now, cancellationToken);
                    }
                    catch (OperationCanceledException)
                    {
                    }
                    finally
                    {
                        onExpiry();
                    }
            }
 
            task = DisposeOnExipiry(cancellationTokenSource.Token);
        }
 
        public async ValueTask DisposeAsync()
        {
            cancellationTokenSource.Cancel();
            cancellationTokenSource.Dispose();
            await task;
        }
    }
}