wefts_subscription.h

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/*
   wefts_subscription.h
   Subscribe + notify system implementation

   $Id: wefts_subscription.h,v 1.9 2004/03/08 20:28:53 jonnymind Exp $
----------------------------------------------
   Begin      : 2003-08-02 00:10
   Author     : Giancarlo Niccolai

   Last modified because:

*/

/**************************************************************************
*   This program is free software; you can redistribute it and/or modify  *
*   it under the terms of the GNU Library General Public License as       *
*   published by the Free Software Foundation; either version 2.1 of the  *
*   License, or (at your option) any later version.                       *
***************************************************************************/

#ifndef WT_SUBSCRIPTION_H
#define WT_SUBSCRIPTION_H

#include <wefts_os.h>
#include <wefts_thread.h>
#include <wefts_cleanup.h>
#include <wefts_fastcond.h>
#include <wefts_referenced.h>
#include <list>

namespace Wefts {


class Subscription: public CleanupHandler
{
private:
   Mutex m_mutex;
   Condition m_condNotify;

   Condition m_condFinish;

   std::list<Referenced *> m_items;
   std::list<OSThread *> m_waiting;
   bool m_front;

   int m_notifyAll;
   /* Count of subscribed threads (to spare time with trespect to list::size()*/
   int m_subscribed;
   /* Count of ready items */
   int m_notifies;
   int m_limbo;

   bool subscribeInternal( double time, Referenced **result );

protected:

   virtual inline bool subscriberCanGo( OSThread &pself )
   {
      return (m_front && pself.equal(**(m_waiting.begin() ) ))|| ! m_front;
   }

   void limboSubscribe();

public:
   Subscription( bool fairPolicy = true);

   bool subscribe( double time = -1.0, Referenced **result=0 );

   bool subscribeNow( double time = -1.0, Referenced ** result=0 );

   bool subscribe(Referenced ** result ) { return subscribe( -1.0, result ); }

   bool subscribeNow(Referenced ** result ) { return subscribeNow( -1.0, result ); }

   void notify( Referenced *data = 0 );

   void notifyAll( Referenced *data = 0 );

   int subscribers() { return m_subscribed; }

   void setPolicy( bool fair )
   {
      m_mutex.lock();
      m_front = fair; // some subscriber may have waited for that.
      if ( m_subscribed > 0 )
         m_condNotify.signal();
      m_mutex.unlock();
   }

   virtual void handleCleanup( int, void * );
};

}

#endif
/* end of wefts_subscription.h */

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