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Lazy Alternatives - LazyAndWeak and BackgroundLoader

, 1 Dec 2011 CPOL
This article will present two alternatives to Lazy.
LazyAlternatives.zip
LazyAlternatives
LazyAlternatives.suo
LazyAlternativesSample
Properties
Settings.settings
Pfz
Caching
Collections
DataTypes
DynamicObjects
Internal
Extensions
Factoring
Pfz.csproj.user
Pfz.Phone.csproj.user
Pfz.ruleset
Pfz.Silverlight.csproj.user
Pfz.snk
Pfz.suo
PhoneSpecific
Properties
Remoting
Instructions
Internal
Serializers
Udp
Serialization
BinaryBuiltIn
Threading
Contexts
Disposers
Unsafe
using System;
using System.IO;
using Pfz.Extensions;
using Pfz.Threading;

namespace Pfz.Remoting.Udp
{
	/// <summary>
	/// TcpIp connection that has an UDP connection bound to it, so you can opt to send guaranteed and ordered packets or
	/// udp (optional) packets. Also allows you to configure it so it can use a guaranteed udp version, in which case
	/// packets are unordered, but are guaranteed to arrive.
	/// </summary>
	public sealed class TcpWithUdpConnection:
		ThreadSafeDisposable,
		IConnection,
		IGuaranteedUdpConnection
	{
		#if !WINDOWS_PHONE
			private TcpWithUdpListener _listener;
		#endif

		private DisposableTcpConnection _connection;
		private GuaranteedUdpConnection _udp;

		/// <summary>
		/// Creates and configures a new TcpWithUdpConnection instance.
		/// </summary>
		public TcpWithUdpConnection(string hostname, int port, bool useTcpDelay=true, int bufferedWriteStreamSize=-1, int pendingGuaranteedDeliveryCount=57)
		{
			try
			{
				_udp = new GuaranteedUdpConnection(hostname, port+1, pendingGuaranteedDeliveryCount);

				var startedEvent = new ManagedManualResetEvent();
				byte[] bytes = null;

				UnlimitedThreadPool.Run
				(
					() =>
					{
						try
						{
							bytes = _udp.UdpReceive();
						}
						catch
						{
							Dispose();
						}
						finally
						{
							startedEvent.Set();
						}
					}
				);

				if (!startedEvent.WaitOne(60000))
					throw new TimeoutException("UDP handshaking timed-out.");

				if (bytes == null)
					throw new IOException("Can't stablish UDP connection.");

				if (bytes.Length != _udp.UdpHeaderSize + 16)
					throw new IOException("The other side sent an invalid handshaking packet.");

				_connection = new DisposableTcpConnection(hostname, port, useTcpDelay, bufferedWriteStreamSize);
				var stream = _connection.Stream;
				stream.Write(bytes, _udp.UdpHeaderSize);
				stream.Flush();
			}
			catch
			{
				Dispose();
				throw;
			}
		}

		#if !WINDOWS_PHONE
			internal TcpWithUdpConnection(TcpWithUdpListener listener, DisposableTcpConnection connection, GuaranteedUdpConnection udp)
			{
				_listener = listener;
				_connection = connection;
				_udp = udp;
			}
		#endif

		/// <summary>
		/// Releases the tcp and udp connections.
		/// </summary>
		protected override void Dispose(bool disposing)
		{
			if (disposing)
			{
				#if !WINDOWS_PHONE
					var listener = _listener;
					if (listener != null)
					{
						_listener = null;

						lock(listener.DisposeLock)
							if (!listener.WasDisposed)
								listener._activeConnections.Remove(this);
					}
				#endif

				Disposer.Dispose(ref _connection);
				Disposer.Dispose(ref _udp);
			}

			base.Dispose(disposing);
		}

		/// <summary>
		/// Gets the local endpoint.
		/// </summary>
		public string LocalEndpoint
		{
			get
			{
				var connection = _connection;
				if (connection == null)
					return null;

				return connection.LocalEndpoint;
			}
		}

		/// <summary>
		/// Gets the remote endpoint.
		/// </summary>
		public string RemoteEndpoint
		{
			get
			{
				var connection = _connection;
				if (connection == null)
					return null;

				return connection.RemoteEndpoint;
			}
		}

		/// <summary>
		/// Gets or sets the stream used for the ordered (tcp/ip) communication.
		/// </summary>
		public Stream Stream
		{
			get
			{
				var connection = _connection;
				if (connection == null)
					return null;

				return connection.Stream;
			}
			set
			{
				lock(DisposeLock)
				{
					CheckUndisposed();

					_connection.Stream = value;
				}
			}
		}

		/// <summary>
		/// Sends an UDP packet. This packet can be lost.
		/// </summary>
		public void UdpSend(byte[] buffer, int offset, int count)
		{
			lock(DisposeLock)
			{
				CheckUndisposed();

				_udp.UdpSend(buffer, offset, count);
			}
		}

		/// <summary>
		/// Receives an UDP packet. Note that it may include a header, so check the UdpHeaderSize property.
		/// </summary>
		public byte[] UdpReceive()
		{
			var udp = _udp;
			if (udp == null)
				return null;

			return udp.UdpReceive();
		}

		/// <summary>
		/// Gets the size of the header added to all packets.
		/// </summary>
		public int UdpHeaderSize
		{
			get
			{
				var udp = _udp;
				if (udp == null)
					return 0;

				return udp.UdpHeaderSize;
			}
		}

		/// <summary>
		/// Sends a message with guarantee of delivery. It does not guarantees the order, however.
		/// </summary>
		public void GuaranteedSend(byte[] buffer, int offset, int count)
		{
			lock(DisposeLock)
			{
				CheckUndisposed();

				_udp.GuaranteedSend(buffer, offset, count);
			}
		}

		/// <summary>
		/// Checks if a packet was sent as guaranteed (true) or not.
		/// </summary>
		public bool IsGuaranteedPacket(byte[] packet)
		{
			lock(DisposeLock)
			{
				CheckUndisposed();

				return _udp.IsGuaranteedPacket(packet);
			}
		}
	}
}

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This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Paulo Zemek
Engineer Microsoft Corporation
United States United States
I started to program computers when I was 11 years old, as a hobbist, programming in AMOS Basic and Blitz Basic for Amiga.
At 12 I had my first try with assembler, but it was too difficult at the time. Then, in the same year, I learned C and, after learning C, I was finally able to learn assembler (for Motorola 680x0).
Not sure, but probably between 12 and 13, I started to learn C++. I always programmed "in an object oriented way", but using function pointers instead of virtual methods.
 
At 15 I started to learn Pascal at school and to use Delphi. At 16 I started my first internship (using Delphi). At 18 I started to work professionally using C++ and since then I've developed my programming skills as a professional developer in C++ and C#, generally creating libraries that help other developers do they work easier, faster and with less errors.
 
Now I just started working as a Senior Software Engineer at Microsoft.
 
Want more info or simply want to contact me?
Take a look at: http://paulozemek.azurewebsites.net/
Or e-mail me at: paulozemek@outlook.com
 
Codeproject MVP 2012, 2015
Microsoft MVP 2013-2014

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