Reader/writer lock with auto guard support

GuardedReaderWriterLock.cs

using System;
using System.Threading;


/// <summary>
/// Simple ReaderWriterLockShim wrapper that exposes read and write
/// guards.
/// </summary>
public class GuardedReaderWriterLock
{
  private readonly ReaderWriterLockSlim _lock;
	private readonly AutoGuard _readGuard;
	private readonly AutoGuard _writeGuard;
	private readonly UpgradeGuard _upgradeGuard;

	class AutoGuard : IDisposable
	{
		private readonly ReaderWriterLockSlim _lock;
		private readonly bool _isWriteGuard;
		
		public AutoGuard(ReaderWriterLockSlim @lock, bool isWriteGuard)
		{
			_lock = @lock;
			_isWriteGuard = isWriteGuard;
		}
		
		public IDisposable Enter()
		{
			if (_isWriteGuard)
			{
				_lock.EnterWriteLock();
			}
			else
			{
				_lock.EnterReadLock();
			}
			
			return this;
		}

		public void Dispose()
		{
			if (_isWriteGuard)
			{
				_lock.ExitWriteLock();
			}
			else
			{
				_lock.ExitReadLock();
			}				
		}
	}

	class UpgradeGuard : IDisposable
	{
		private readonly ReaderWriterLockSlim _lock;

		public UpgradeGuard(ReaderWriterLockSlim @lock)
		{
			_lock = @lock;
		}

		public IDisposable Enter()
		{
			_lock.EnterUpgradeableReadLock();

			return this;
		}

		public void Dispose()
		{
			_lock.ExitUpgradeableReadLock();
		}
	}

	public ReaderWriterLockSlim UnderlyingLock
	{
		get { return _lock; }
	}

	public GuardedReaderWriterLock()
	{
		_lock = new ReaderWriterLockSlim();
		_readGuard = new AutoGuard(_lock, false);
		_writeGuard = new AutoGuard(_lock, true);
		_upgradeGuard = new UpgradeGuard(_lock);
	}

	public GuardedReaderWriterLock(LockRecursionPolicy recursionPolicy)
	{
		_lock = new ReaderWriterLockSlim(recursionPolicy);
		_readGuard = new AutoGuard(_lock, false);
		_writeGuard = new AutoGuard(_lock, true);
		_upgradeGuard = new UpgradeGuard(_lock);
	}

	public IDisposable Read
	{
		get { return _readGuard.Enter(); }
	}

	public IDisposable ReadUpgradable
	{
		get { return _upgradeGuard.Enter(); }
	}

	public IDisposable Write
	{
		get { return _writeGuard.Enter(); }
	}
}