Lazy with expiration time

Question

I want to implement an expiration time on a Lazy object. The expiration cooldown must start with the first retrieve of the value. If we get the value, and the expiration time is

Answer 1

I needed the same thing. But I would prefer an implementation without locked reads when there is no write.

public class ExpiringLazy
{
    private readonly Func factory;
    private readonly TimeSpan lifetime;
    private readonly ReaderWriterLockSlim locking = new ReaderWriterLockSlim(LockRecursionPolicy.NoRecursion);

    private T value;
    private DateTime expiresOn = DateTime.MinValue;

    public ExpiringLazy(Func factory, TimeSpan lifetime)
    {
        this.factory = factory;
        this.lifetime = lifetime;
    }

    public T Value
    {
        get
        {
            DateTime now = DateTime.UtcNow;
            locking.EnterUpgradeableReadLock();
            try
            {
                if (expiresOn < now)
                {
                    locking.EnterWriteLock();
                    try
                    {
                        if (expiresOn < now)
                        {
                            value = factory();
                            expiresOn = DateTime.UtcNow.Add(lifetime);
                        }
                    }
                    finally
                    {
                        locking.ExitWriteLock();
                    }
                }

                return value;
            }
            finally
            {
                locking.ExitUpgradeableReadLock();
            }
        }
    }
}