/* -*-    Mode:C++; c-basic-offset:4; tab-width:4; indent-tabs-mode:nil -*- */

/*

 * Copyright (c) 2005 INRIA

 * All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation;

 *

 * 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

 *

 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>

 */

#ifndef SCHEDULER_H

#define SCHEDULER_H

#include <stdint.h>

#include "event-id.h"

namespace ns3 {

class EventImpl;

/**

 * \brief Maintain the event list

 *

 * This base class specifies the interface used to maintain the 

 * event list. If you want to provide a new event list scheduler, 

 * you need to create a subclass of this base class and implement 

 * all the private pure virtual methods defined here. Namely:

 *   - ns3::Scheduler::realInsert

 *   - ns3::Scheduler::realIsEmpty

 *   - ns3::Scheduler::realPeekNext

 *   - ns3::Scheduler::realPeekNextKey

 *   - ns3::Scheduler::realRemoveNext

 *   - ns3::Scheduler::realRemove

 *   - ns3::Scheduler::realIsValid

 *

 * If you need to provide a new event list scheduler without

 * editing the main simulator class, you need to also implement

 * a subclass of the ns3::SchedulerFactory base class and

 * feed it to ns3::Simulator::setExternal.

 * The simplest example of a scheduler is the linked-list

 * scheduler included in ns3: see the files 

 * src/simulator/scheduler-list.h and src/simulator/scheduler-list.cc

 */

class Scheduler {

 public:

    struct EventKey {

        uint64_t m_ns;

        uint32_t m_uid;

    };

    class EventKeyCompare {

    public:

        bool operator () (struct EventKey a, struct EventKey b);

    };

    virtual ~Scheduler () = 0;

private:

    /**

     * \param event event to store in the event list

     * \param key timecode associated to this new event

     * \returns an event id which identifies the event inserted

     *

     * This method takes ownership of the event pointer.

     */

    /**

     * \returns true if the event list is empty and false otherwise.

     */

    /**

     * \returns a pointer to the next earliest event. The caller

     *      takes ownership of the returned pointer.

     *

     * This method cannot be invoked if the list is empty.

     */

    /**

     * \returns the timecode associated with the next earliest event.

     *

     * This method cannot be invoked if the list is empty.

     */

    /**

     * This method cannot be invoked if the list is empty.

     * Remove the next earliest event from the event list.

     */

    /**

     * \param id the id of the event to remove

     * \param key the timecode of the event removed

     * \returns a pointer to the event removed. The caller

     *      takes ownership of the returned pointer.

     *

     * This methods cannot be invoked if the list is empty.

     */

    /**

     * \param id event id to validate

     * \returns true if the event id identifies an existing valid

     *      event stored in the event list and false otherwise.

     */

};

}; // namespace ns3

#endif /* SCHEDULER_H */