CreditWaiter.cs

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using System.Runtime.ExceptionServices;
using System.Threading;
using System.Threading.Tasks;
using System.Threading.Tasks.Sources;
 
namespace System.Net.Http;
 
internal sealed class CreditWaiter : IValueTaskSource<int>
{
    private CancellationToken _cancellationToken;
 
    private CancellationTokenRegistration _registration;
 
    private ManualResetValueTaskSourceCore<int> _source;
 
    public int Amount;
 
    public CreditWaiter Next;
 
    public CreditWaiter(CancellationToken cancellationToken)
    {
        _source.RunContinuationsAsynchronously = true;
        RegisterCancellation(cancellationToken);
    }
 
    public void ResetForAwait(CancellationToken cancellationToken)
    {
        _source.Reset();
        RegisterCancellation(cancellationToken);
    }
 
    private void RegisterCancellation(CancellationToken cancellationToken)
    {
        _cancellationToken = cancellationToken;
        _registration = cancellationToken.UnsafeRegister(delegate(object s, CancellationToken cancellationToken)
        {
            ((CreditWaiter)s)._source.SetException(ExceptionDispatchInfo.SetCurrentStackTrace(new OperationCanceledException(cancellationToken)));
        }, this);
    }
 
    public ValueTask<int> AsValueTask()
    {
        return new ValueTask<int>(this, _source.Version);
    }
 
    public bool TrySetResult(int result)
    {
        if (UnregisterAndOwnCompletion())
        {
            _source.SetResult(result);
            return true;
        }
        return false;
    }
 
    public void Dispose()
    {
        if (UnregisterAndOwnCompletion())
        {
            _source.SetException(ExceptionDispatchInfo.SetCurrentStackTrace(new ObjectDisposedException("CreditManager", System.SR.net_http_disposed_while_in_use)));
        }
    }
 
    private bool UnregisterAndOwnCompletion()
    {
        if (!_registration.Unregister())
        {
            return !_cancellationToken.CanBeCanceled;
        }
        return true;
    }
 
    int IValueTaskSource<int>.GetResult(short token)
    {
        return _source.GetResult(token);
    }
 
    ValueTaskSourceStatus IValueTaskSource<int>.GetStatus(short token)
    {
        return _source.GetStatus(token);
    }
 
    void IValueTaskSource<int>.OnCompleted(Action<object> continuation, object state, short token, ValueTaskSourceOnCompletedFlags flags)
    {
        _source.OnCompleted(continuation, state, token, flags);
    }
}