/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2008 University of Washington

 *

 * 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

 */

#ifndef REALTIME_SIMULATOR_IMPL_H

#define REALTIME_SIMULATOR_IMPL_H

#include "simulator-impl.h"

#include "scheduler.h"

#include "synchronizer.h"

#include "event-impl.h"

#include "ns3/ptr.h"

#include "ns3/assert.h"

#include "ns3/log.h"

#include <list>

#include <fstream>

namespace ns3 {

class RealtimeEventLock : public EventLock

{

public:

  void Lock (void);

  void Unlock (void);

private:

  SystemMutex m_eventMutex;

};

class RealtimeSimulatorImpl : public SimulatorImpl

{

public:

  static TypeId GetTypeId (void);

  /**

   * Enumeration of the types of packets supported in the class.

   *

   */

  enum SynchronizationMode {

    SYNC_BEST_EFFORT, /** Make a best effort to keep synced to real-time */

    SYNC_HARD_LIMIT, /** Keep to real-time within a tolerance or die trying */

  };

  RealtimeSimulatorImpl ();

  ~RealtimeSimulatorImpl ();

  void Destroy ();

  void EnableLogTo (char const *filename);

  bool IsFinished (void) const;

  Time Next (void) const;

  void Stop (void);

  void Stop (Time const &time);

  EventId Schedule (Time const &time, const Ptr<EventImpl> &event);

  EventId ScheduleNow (const Ptr<EventImpl> &event);

  EventId ScheduleDestroy (const Ptr<EventImpl> &event);

  void Remove (const EventId &ev);

  void Cancel (const EventId &ev);

  bool IsExpired (const EventId &ev) const;

  virtual void RunOneEvent (void);

  void Run (void);

  Time Now (void) const;

  Time GetDelayLeft (const EventId &id) const;

  Time GetMaximumSimulationTime (void) const;

  void SetScheduler (Ptr<Scheduler> scheduler);

  Ptr<Scheduler> GetScheduler (void) const;

  void SetSynchronizationMode (RealtimeSimulatorImpl::SynchronizationMode mode);

  RealtimeSimulatorImpl::SynchronizationMode GetSynchronizationMode (void) const;

  void SetHardLimit (Time limit);

  Time GetHardLimit (void) const;

private:

  bool Running (void) const;

  bool Realtime (void) const;

  void ProcessOneEvent (void);

  uint64_t NextTs (void) const;

  typedef std::list<EventId> DestroyEvents;

  DestroyEvents m_destroyEvents;

  uint64_t m_stopAt;

  bool m_stop;

  bool m_running;

  // The following variables are protected using the m_mutex

  Ptr<Scheduler> m_events;

  int m_unscheduledEvents;

  uint32_t m_uid;

  uint32_t m_currentUid;

  uint64_t m_currentTs;

  mutable SystemMutex m_mutex;

  RealtimeEventLock m_eventLock;

  Ptr<Synchronizer> m_synchronizer;

  /*

   * In calls to Simulator::Now we have a basic choice to make.  We can either

   * report back the time the simulator thinks it should be, or we can report 

   * the time it actually is.

   *

   * The synchronizer will make an attempt to cause these two numbers to be as

   * close as possible to each other, but they will never be exactly the same.

   * We give the client a choice in this respect.  

   *

   * If the client sets m_reportSimulatedTime to true, the behavior will be that 

   * the simulator runs as close as possible to real time, but reports back to the

   * client that it is running at exactly real time, and consuming no real time 

   * as each event executes.  This allows for deterministic execution times and

   * repeatable trace files.

   *

   * If the client sets m_reportSimulatedTime to false, the behavior will be that 

   * the simulator runs as close as possible to real time, and reports back to the

   * client the real wall-clock time whenever it asks.  Real time will be consumed

   * as each event executes.  This allows for non-deterministic execution times and

   * real variations in event executions.  Simulation time will be influenced by

   * variations in host process scheduling, for example.

   */

  bool m_reportSimulatedTime;

  /**

   * The policy to use if the simulation cannot keep synchronized to real-time.

   */

  SynchronizationMode m_synchronizationMode;

  /**

   * The maximum allowable drift from real-time in SYNC_HARD_LIMIT mode.

   */

  Time m_hardLimit;

};

} // namespace ns3

#endif /* REALTIME_SIMULATOR_IMPL_H */