// src/backend/policy.hh - Copyright 2005, 2006, University
//               of Padova, dept. of Pure and Applied
//               Mathematics
//
// This file is part of SGPEMv2.
//
// This 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.
//
// SGPEMv2 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 SGPEMv2; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

#ifndef POLICY_HH
#define POLICY_HH 1

#include "config.h"
#include "gettext.h"

#include "glibmm/ustring.h"

#include "scheduler.hh"
#include "policy_parameters.hh"

namespace sgpem
{

	class Policy;
	
  	/**	\brief 
	  It's a Strategy wich stay for a scheduling algorithm.
	  It implements the related scheduling policy.
	  Its goal is, usually, to keep a list of Schedulable objects
	  mantained in a SchedulableQueue.
  	*/			   
	class SG_DLLEXPORT Policy 
	{
	public:
		virtual ~Policy();
	  
		/**
		  Initialize the inner components of the policy.

		  Because it's a pure virtual method, must be re-implemented 
		  in concrete derived classes.
		 */
		virtual void	configure() = 0;

		/**
		  Sort the \ref SchedulableQueue object that contain all the Schedulable objects
		  (Processes, Threads) still active managed by the scheduler.

		  Because it's a pure virtual method, must be re-implemented 
		  in concrete derived classes.
		  \param event Call reason. Needed only by some scheduling policies.
		 */
		virtual void	sort_queue(Scheduler::event event) const = 0;

		/**
		  Gets the unique identifier (id) of this Policy.
		  \return The Policy id.
		 */
		int	get_id() const;

		/**
		  Gets a string description of the policy.

		  Because it's a pure virtual method, must be re-implemented 
		  in concrete derived classes.
		  \return String description of the policy.
		 */
		virtual Glib::ustring 	get_description() const = 0;

		/**
		  Tell if this policy is preemptible.
		  If true, for the \ref Scheduler::SCHEDULABLE_ARRIVAL event, the 
		  ready queue will contain also the running \ref Schedulable;
		  else the running Schedulable will not be in the queue.

		  Because it's a pure virtual method, must be re-implemented 
		  in concrete derived classes.
		  \return True if this policy is preemptible.
		 */
		virtual bool	is_pre_emptive() const = 0;

		/**
		  Gets the time quantum for the policy.

		  Because it's a pure virtual method, must be re-implemented 
		  in concrete derived classes.
		  \return Time quantum for the policy.
		 */
		virtual int	get_time_slice() const = 0;

		/**
		  Sets the time quantum for the policy.

		  Because it's a pure virtual method, must be re-implemented 
		  in concrete derived classes.
		  \param quantum The desired time quantum for the policy.
		 */
		virtual void	set_time_slice(const int& quantum) = 0;
	  
		/**
		  Gets the parameters related with this policy.

		  Because it's a pure virtual method, must be re-implemented 
		  in concrete derived classes.
		  \return The policy parameters.
		 */
		PolicyParameters&	get_parameters();
	  
	protected:
		PolicyParameters	_parameters;
		int			_id;
	};
	
}//~ namespace sgpem


#endif