DccFileSessionManager.cs :  » Chat-Servers » Thresher » Sharkbite » Irc » C# / CSharp Open Source

/*
 * Thresher IRC client library
 * Copyright (C) 2002 Aaron Hunter <thresher@sharkbite.org>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 * 
 * See the gpl.txt file located in the top-level-directory of
 * the archive of this library for complete text of license.
*/

using System;
using System.Diagnostics;
using System.Collections;
using System.Threading;


namespace Sharkbite.Irc{
  /// <summary>
  /// This class checks each file session to see if it has not 
  /// had any activity within the timeout period so that
  /// inactive sessions can be closed.
  /// </summary>
  public sealed class DccFileSessionManager
  {
    //How long to wait
    private TimeSpan timeout;
    //A clone of the session hashtable to iterate over
    private Hashtable sessionClone;
    //A place to store the active sessions
    private Hashtable sessions;
    //Check for timeouts every 10 seconds
    private const int TimeoutCheckPeriod = 10000;
    //Default to tming out after 30 seconds of no activity.
    private const int DefaultTimeout = 30000;
    private static DccFileSessionManager defaultInstance;
    private static object lockObject = new object();
    private Timer timerThread;
    private bool timerStopped;

    private DccFileSessionManager( )
    {
      timeout = new TimeSpan( DefaultTimeout * TimeSpan.TicksPerMillisecond );
      //Create Timer but don't start it yet
      timerThread = new Timer( new TimerCallback( CheckSessions ), null, Timeout.Infinite, TimeoutCheckPeriod );
      timerStopped = true;
      sessions = Hashtable.Synchronized( new Hashtable() );
    }
  
    private Boolean TimedOut( DccFileSession session ) 
    {
      if( ( DateTime.Now - session.LastActivity ) >= timeout )
      {
        return true;
      }
      return false;
    }

    internal void AddSession( DccFileSession session ) 
    {
      sessions.Add( session.ID, session );
      if( timerStopped ) 
      {
        timerStopped = false;
        timerThread.Change(TimeoutCheckPeriod, TimeoutCheckPeriod);
      }
      Debug.WriteLineIf( DccUtil.DccTrace.TraceInfo, "[" + Thread.CurrentThread.Name +"] DccSessionManager::AddSession() ID=" + session.ID );
    }
    internal void RemoveSession( DccFileSession session ) 
    {
      sessions.Remove( session.ID );
      if( sessions.Count == 0 ) 
      {
        timerStopped = true;
        timerThread.Change( Timeout.Infinite, TimeoutCheckPeriod );
      }
      Debug.WriteLineIf( DccUtil.DccTrace.TraceInfo, "[" + Thread.CurrentThread.Name +"] DccSessionManager::RemoveSession() ID=" + session.ID );
    }
    internal void CheckSessions( object state ) 
    {
      Debug.WriteLineIf( DccUtil.DccTrace.TraceVerbose, "[" + Thread.CurrentThread.Name +"] DccSessionManager::CheckSessions()");
      sessionClone = (Hashtable) sessions.Clone();
      foreach( object session in sessionClone.Values ) 
      {
        DccFileSession fileSession = (DccFileSession) session;
        lock( fileSession ) 
        {
          if( TimedOut( fileSession ) ) 
          {
            fileSession.TimedOut();
          }
        }
      }
    }
    internal bool ContainsSession( string sessionID )
    {
      return sessions.Contains( sessionID );
    }
    internal DccFileSession LookupSession( string sessionID ) 
    {
      //Make sure this session is till active
      if( !ContainsSession( sessionID ) ) 
      {
        throw new ArgumentException( sessionID + " is not active.");
      }
      //Lookup corresponding session
      return (DccFileSession) sessions[ sessionID ];
    }

    /// <summary>
    /// Returns the singleton instance.
    /// </summary>
    public static DccFileSessionManager DefaultInstance
    {
      get 
      {
        lock( lockObject ) 
        {
          if( defaultInstance == null ) 
          {
            defaultInstance = new DccFileSessionManager();
            Debug.WriteLineIf( DccUtil.DccTrace.TraceVerbose, "[" + Thread.CurrentThread.Name +"] DccFileSessionManager::init");
          }
        }
        return defaultInstance;
      }
    }
    /// <summary>
    /// Timeout period in milliseconds
    /// </summary>
    public long TimeoutPeriod 
    {
      get
      {
        lock( defaultInstance ) 
        {
          return timeout.Ticks * TimeSpan.TicksPerMillisecond;
        }
      }
      set 
      {
        lock( defaultInstance ) 
        {
          timeout = new TimeSpan( value * TimeSpan.TicksPerMillisecond );
        }
      }
    }

  }
}