Databasing framework with LINQ support

using System;
using System.Threading;

namespace Pfz.Extensions.ReaderWriterLockExtensions
{
	/// <summary>
	/// Adds methods to use ReaderWriterLockSlim easily to acquire locks,
	/// always with time-outs to avoid dead-locks.
	/// See PfzLockConfiguration class if you want to log dead-locks.
	/// </summary>
	public static class PfzReaderWriterLockExtensions
	{
		#region ReadLock
			/// <summary>
			/// Acquires a read-lock using the default time-out.
			/// </summary>
			public static IDisposable ReadLock(this ReaderWriterLockSlim lockObject)
			{
				return ReadLock(lockObject, PfzLockConfiguration.DefaultLockTimeout);
			}
			
			/// <summary>
			/// Acquires a read-lock, using the given time-out.
			/// </summary>
			public static IDisposable ReadLock(this ReaderWriterLockSlim lockObject, TimeSpan timeout)
			{
				IDisposable result = new p_ReadLock(lockObject);
				if (lockObject.TryEnterReadLock(timeout))
					return result;
				
				throw PfzLockConfiguration.i_LockTimedOutException(PfzLockConfiguration.LockType.Read);
			}
			
			/// <summary>
			/// Tries to acquire a read-lock on the given object using the default timeout. 
			/// If it fails, returns null.
			/// </summary>
			/// <param name="lockObject">The object to lock.</param>
			/// <returns>A disposable object to release the lock, or null.</returns>
			public static IDisposable TryReadLock(this ReaderWriterLockSlim lockObject)
			{
				return TryReadLock(lockObject, PfzLockConfiguration.DefaultLockTimeout);
			}
			
			/// <summary>
			/// Tries to acquire a read-lock on the given object using the specified timeout. 
			/// If it fails, returns null.
			/// </summary>
			/// <param name="lockObject">The object to lock.</param>
			/// <param name="timeout">The timeout to try for the lock.</param>
			/// <returns>A disposable object to release the lock, or null.</returns>
			public static IDisposable TryReadLock(this ReaderWriterLockSlim lockObject, TimeSpan timeout)
			{
				IDisposable result = new p_ReadLock(lockObject);
				if (lockObject.TryEnterReadLock(timeout))
					return result;
				
				PfzLockConfiguration.i_LockTimedOutNoException(PfzLockConfiguration.LockType.Read);
				return null;
			}
						
			private sealed class p_ReadLock:
				IDisposable
			{
				private ReaderWriterLockSlim fLockObject;
				
				public p_ReadLock(ReaderWriterLockSlim lockObject)
				{
					fLockObject = lockObject;
				}
				public void Dispose()
				{
					ReaderWriterLockSlim lockObject = fLockObject;
					if (lockObject != null)
					{
						lockObject.ExitReadLock();
						fLockObject = null;
					}
				}
			}
		#endregion
		#region UpgradeableLock
			/// <summary>
			/// Acquires an upgradeable-lock using the default time-out.
			/// </summary>
			public static IDisposable UpgradeableLock(this ReaderWriterLockSlim lockObject)
			{
				return UpgradeableLock(lockObject, PfzLockConfiguration.DefaultLockTimeout);
			}
			
			/// <summary>
			/// Acquires an upgradeable-lock, using the given time-out.
			/// </summary>
			public static IDisposable UpgradeableLock(this ReaderWriterLockSlim lockObject, TimeSpan timeout)
			{
				IDisposable result = new p_UpgradeableLock(lockObject);
				if (lockObject.TryEnterUpgradeableReadLock(timeout))
					return result;
				
				throw PfzLockConfiguration.i_LockTimedOutException(PfzLockConfiguration.LockType.Upgradeable);
			}
			
			/// <summary>
			/// Tries to acquire an upgradeable lock on the given object, using the default timeout.
			/// If it fails, returns null.
			/// </summary>
			/// <param name="lockObject">The object to try to lock.</param>
			/// <returns>An disposable object to release the lock, or null if the locks fails.</returns>
			public static IDisposable TryUpgradeableLock(this ReaderWriterLockSlim lockObject)
			{
				return TryUpgradeableLock(lockObject, PfzLockConfiguration.DefaultLockTimeout);
			}
			
			/// <summary>
			/// Tries to acquire an upgradeable lock on the given object, using the specified timeout.
			/// If it fails, returns null.
			/// </summary>
			/// <param name="lockObject">The object to try to lock.</param>
			/// <param name="timeout">The maximum time to wait for the lock.</param>
			/// <returns>An disposable object to release the lock, or null if the locks fails.</returns>
			public static IDisposable TryUpgradeableLock(this ReaderWriterLockSlim lockObject, TimeSpan timeout)
			{
				IDisposable result = new p_UpgradeableLock(lockObject);
				if (lockObject.TryEnterUpgradeableReadLock(timeout))
					return result;
				
				PfzLockConfiguration.i_LockTimedOutNoException(PfzLockConfiguration.LockType.Upgradeable);
				return null;
			}
			
			private sealed class p_UpgradeableLock:
				IDisposable
			{
				private ReaderWriterLockSlim fLockObject;
				
				public p_UpgradeableLock(ReaderWriterLockSlim lockObject)
				{
					fLockObject = lockObject;
				}
				public void Dispose()
				{
					ReaderWriterLockSlim lockObject = fLockObject;
					if (lockObject != null)
					{
						lockObject.ExitUpgradeableReadLock();
						fLockObject = null;
					}
				}
			}
		#endregion
		#region WriteLock
			/// <summary>
			/// Acquires a write-lock using the default time-out.
			/// </summary>
			public static IDisposable WriteLock(this ReaderWriterLockSlim lockObject)
			{
				return WriteLock(lockObject, PfzLockConfiguration.DefaultLockTimeout);
			}
			
			/// <summary>
			/// Acquires a write-lock, using the given time-out.
			/// </summary>
			public static IDisposable WriteLock(this ReaderWriterLockSlim lockObject, TimeSpan timeout)
			{
				IDisposable result = new p_WriteLock(lockObject);
				if (lockObject.TryEnterWriteLock(timeout))
					return result;
				
				throw PfzLockConfiguration.i_LockTimedOutException(PfzLockConfiguration.LockType.Write);
			}
			
			/// <summary>
			/// Tries to acquire a write-lock on the given object using the default timeout.
			/// If it fails, returns null.
			/// </summary>
			/// <param name="lockObject">The object to lock.</param>
			/// <returns>A disposable object to release the lock, or null.</returns>
			public static IDisposable TryWriteLock(this ReaderWriterLockSlim lockObject)
			{
				return TryWriteLock(lockObject, PfzLockConfiguration.DefaultLockTimeout);
			}
			
			/// <summary>
			/// Tries to acquire a write-lock on the given object using the specified timeout.
			/// If it fails, returns null.
			/// </summary>
			/// <param name="lockObject">The object to lock.</param>
			/// <param name="timeout">The maximum time to wait for the lock.</param>
			/// <returns>A disposable object to release the lock, or null.</returns>
			public static IDisposable TryWriteLock(this ReaderWriterLockSlim lockObject, TimeSpan timeout)
			{
				IDisposable result = new p_WriteLock(lockObject);
				if (lockObject.TryEnterWriteLock(timeout))
					return result;
				
				PfzLockConfiguration.i_LockTimedOutNoException(PfzLockConfiguration.LockType.Write);
				return null;
			}
			
			private sealed class p_WriteLock:
				IDisposable
			{
				private ReaderWriterLockSlim fLockObject;
				
				public p_WriteLock(ReaderWriterLockSlim lockObject)
				{
					fLockObject = lockObject;
				}
				public void Dispose()
				{
					ReaderWriterLockSlim lockObject = fLockObject;
					if (lockObject != null)
					{
						lockObject.ExitWriteLock();
						fLockObject = null;
					}
				}
			}
		#endregion
	}
}