Pfz.Caching - ViewIds instead of ViewStates

using System;
using System.Collections.Specialized;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Binary;
using System.Web;
using System.Web.SessionState;
using Pfz.Threading;

namespace Pfz.Caching
{
	/// <summary>
	/// Class that provides session management features using CacheDictionary class.
	/// </summary>
	public sealed class PfzSessionStateStoreProvider:
		SessionStateStoreProviderBase
	{
		private IPfzSessionStateStoreProvider fProvider;
		private static string fSessionIdPrefix;
		
		internal static string GetId(string id)
		{
			if (fSessionIdPrefix == null)
				return id;
			
			return fSessionIdPrefix + id;
		}
		
		/// <summary>
		/// Connects to the SessionStateServer.
		/// </summary>
		public override void Initialize(string name, NameValueCollection config)
		{
			base.Initialize(name, config);
			
			string host = config.Get("host");
			int port = int.Parse(config.Get("port"));
			
			fSessionIdPrefix = config.Get("group");
			if (fSessionIdPrefix != null)
				fSessionIdPrefix += ':';
			
			string fullHost = string.Format("tcp://{0}:{1}/IPfzSessionStateStoreProvider", host, port);
			fProvider = (IPfzSessionStateStoreProvider)Activator.GetObject(typeof(IPfzSessionStateStoreProvider), fullHost);
		}
	
		/// <summary>
		/// Does nothing.
		/// </summary>
		public override void Dispose()
		{
			fProvider = null;
		}

		/// <summary>
		/// Only initializes an empty dictionary.
		/// </summary>
		public override SessionStateStoreData CreateNewStoreData(HttpContext context, int timeout)
		{
			var items = new PfzSessionStateItemCollection();
			var staticObjects = SessionStateUtility.GetSessionStaticObjects(context);
			return new SessionStateStoreData(items, staticObjects, timeout);
		}

		/// <summary>
		/// Does nothing.
		/// </summary>
		public override void CreateUninitializedItem(HttpContext context, string id, int timeout)
		{
		}

		/// <summary>
		/// Does nothing.
		/// </summary>
		public override void EndRequest(HttpContext context)
		{
		}

		/// <summary>
		/// Loads a session from disk. The values are then loaded from disk or memory.
		/// </summary>
		public override SessionStateStoreData GetItem(HttpContext context, string id, out bool locked, out TimeSpan lockAge, out object lockId, out SessionStateActions actions)
		{
			actions = SessionStateActions.None;
			
			TimeSpan timeout;
			long longLockId;
			byte[] bytes = fProvider.GetItem(GetId(id), out longLockId, out lockAge, out timeout);
			
			locked = (longLockId != 0);
			if (locked)
				lockId = longLockId;
			else
				lockId = null;
			
			if (bytes == null)
				return null;
			
			PfzSessionStateItemCollection dictionary = null;
			BinaryFormatter binaryFormatter = new BinaryFormatter();
			
			try
			{
				AbortSafe.Using
				(
					() => new MemoryStream(bytes),
					(stream) => dictionary = (PfzSessionStateItemCollection)binaryFormatter.Deserialize(stream)
				);
			}
			catch(SerializationException)
			{
				return null;
			}
			
			var staticObjects = SessionStateUtility.GetSessionStaticObjects(context);
			return new SessionStateStoreData(dictionary, staticObjects, (int)timeout.TotalMinutes);
		}

		/// <summary>
		/// Loads a session from disk and renames (locks) it. The values are then 
		/// loaded from disk or memory.
		/// </summary>
		public override SessionStateStoreData GetItemExclusive(HttpContext context, string id, out bool locked, out TimeSpan lockAge, out object lockId, out SessionStateActions actions)
		{
			actions = SessionStateActions.None;
		
			TimeSpan timeout;
			long longLockId;
			
			byte[] bytes = fProvider.GetItemExclusive(GetId(id), out longLockId, out locked, out lockAge, out timeout);
			
			if (longLockId == 0)
				lockId = null;
			else
				lockId = longLockId;
			
			if (bytes == null && lockId != null)
				return null;
			
			PfzSessionStateItemCollection dictionary = null;
			
			if (bytes == null)
				dictionary = new PfzSessionStateItemCollection();
			else
			{
				BinaryFormatter binaryFormatter = new BinaryFormatter();
				
				try
				{
					AbortSafe.Using
					(
						() => new MemoryStream(bytes),
						(stream) => dictionary = (PfzSessionStateItemCollection)binaryFormatter.Deserialize(stream)
					);
				}
				catch(SerializationException)
				{
					return null;
				}
			}
			
			var staticObjects = SessionStateUtility.GetSessionStaticObjects(context);
			return new SessionStateStoreData(dictionary, staticObjects, (int)timeout.TotalMinutes);
		}

		/// <summary>
		/// Does nothing.
		/// </summary>
		public override void InitializeRequest(HttpContext context)
		{
		}

		/// <summary>
		/// Only executed on exceptions.
		/// </summary>
		public override void ReleaseItemExclusive(HttpContext context, string id, object lockId)
		{
			long longLockId = 0;
			if (lockId != null)
				longLockId = (long)lockId;
			
			fProvider.ReleaseItem(GetId(id), longLockId);
		}

		/// <summary>
		/// Delete the file from disk.
		/// </summary>
		public override void RemoveItem(HttpContext context, string id, object lockId, SessionStateStoreData item)
		{
			fProvider.RemoveItem(GetId(id), (long)lockId);
		}
		
		/// <summary>
		/// Does a keep alive to the session.
		/// </summary>
		/// <param name="context"></param>
		/// <param name="id"></param>
		public override void ResetItemTimeout(HttpContext context, string id)
		{
			fProvider.KeepAlive(GetId(id));
		}

		/// <summary>
		/// Saves the session to the disk.
		/// </summary>
		public override void SetAndReleaseItemExclusive(HttpContext context, string id, SessionStateStoreData data, object lockId, bool newItem)
		{
			byte[] bytes = null;

			BinaryFormatter binaryFormatter = new BinaryFormatter();
			AbortSafe.Using
			(
				() => new MemoryStream(),
				(stream) =>
				{
					binaryFormatter.Serialize(stream, data.Items);
					bytes = stream.ToArray();
				}
			);
			
			long longLockId = 0;
			if (lockId != null)
				longLockId = (long)lockId;
				
			fProvider.SetAndReleaseItem(GetId(id), longLockId, bytes);
		}

		/// <summary>
		/// Does nothing. The callback is not registered.
		/// </summary>
		public override bool SetItemExpireCallback(SessionStateItemExpireCallback expireCallback)
		{
			return false;
		}
	}
}