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

/*

 * Copyright (c) 2005,2006 INRIA

 *

 * 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>

 */

#include "simulator.h"

#include "default-simulator-impl.h"

#include "scheduler.h"

#include "event-impl.h"

#include "ptr.h"

#include "pointer.h"

#include "assert.h"

#include "log.h"

#include <cmath>

/**

 * \file

 * \ingroup simulator

 * Implementation of class ns3::DefaultSimulatorImpl.

 */

namespace ns3 {

// Note:  Logging in this file is largely avoided due to the

// number of calls that are made to these functions and the possibility

// of causing recursions leading to stack overflow

NS_LOG_COMPONENT_DEFINE ("DefaultSimulatorImpl");

NS_OBJECT_ENSURE_REGISTERED (DefaultSimulatorImpl);

TypeId

DefaultSimulatorImpl::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::DefaultSimulatorImpl")

    .SetParent<SimulatorImpl> ()

    .SetGroupName ("Core")

    .AddConstructor<DefaultSimulatorImpl> ()

  ;

  return tid;

}

DefaultSimulatorImpl::DefaultSimulatorImpl ()

{

  NS_LOG_FUNCTION (this);

  m_stop = false;

  // uids are allocated from 4.

  // uid 0 is "invalid" events

  // uid 1 is "now" events

  // uid 2 is "destroy" events

  m_uid = 4;

  // before ::Run is entered, the m_currentUid will be zero

  m_currentUid = 0;

  m_currentTs = 0;

  m_currentContext = 0xffffffff;

  m_unscheduledEvents = 0;

  m_eventsWithContextEmpty = true;

  m_main = SystemThread::Self();

}

DefaultSimulatorImpl::~DefaultSimulatorImpl ()

{

  NS_LOG_FUNCTION (this);

}

void

DefaultSimulatorImpl::DoDispose (void)

{

  NS_LOG_FUNCTION (this);

  ProcessEventsWithContext ();

  while (!m_events->IsEmpty ())

    {

      Scheduler::Event next = m_events->RemoveNext ();

      next.impl->Unref ();

    }

  m_events = 0;

  SimulatorImpl::DoDispose ();

}

void

DefaultSimulatorImpl::Destroy ()

{

  NS_LOG_FUNCTION (this);

  while (!m_destroyEvents.empty ()) 

    {

      Ptr<EventImpl> ev = m_destroyEvents.front ().PeekEventImpl ();

      m_destroyEvents.pop_front ();

      NS_LOG_LOGIC ("handle destroy " << ev);

      if (!ev->IsCancelled ())

        {

          ev->Invoke ();

        }

    }

}

void

DefaultSimulatorImpl::SetScheduler (ObjectFactory schedulerFactory)

{

  NS_LOG_FUNCTION (this << schedulerFactory);

  Ptr<Scheduler> scheduler = schedulerFactory.Create<Scheduler> ();

  if (m_events != 0)

    {

      while (!m_events->IsEmpty ())

        {

          Scheduler::Event next = m_events->RemoveNext ();

          scheduler->Insert (next);

        }

    }

  m_events = scheduler;

}

// System ID for non-distributed simulation is always zero

uint32_t 

DefaultSimulatorImpl::GetSystemId (void) const

{

  return 0;

}

void

DefaultSimulatorImpl::ProcessOneEvent (void)

{

  Scheduler::Event next = m_events->RemoveNext ();

  NS_ASSERT (next.key.m_ts >= m_currentTs);

  m_unscheduledEvents--;

  NS_LOG_LOGIC ("handle " << next.key.m_ts);

  m_currentTs = next.key.m_ts;

  m_currentContext = next.key.m_context;

  m_currentUid = next.key.m_uid;

  next.impl->Invoke ();

  next.impl->Unref ();

  ProcessEventsWithContext ();

}

bool 

DefaultSimulatorImpl::IsFinished (void) const

{

  return m_events->IsEmpty () || m_stop;

}

void

DefaultSimulatorImpl::ProcessEventsWithContext (void)

{

  if (m_eventsWithContextEmpty)

    {

      return;

    }

  // swap queues

  EventsWithContext eventsWithContext;

  {

    CriticalSection cs (m_eventsWithContextMutex);

    m_eventsWithContext.swap(eventsWithContext);

    m_eventsWithContextEmpty = true;

  }

  while (!eventsWithContext.empty ())

    {

       EventWithContext event = eventsWithContext.front ();

       eventsWithContext.pop_front ();

       Scheduler::Event ev;

       ev.impl = event.event;

       ev.key.m_ts = m_currentTs + event.timestamp;

       ev.key.m_context = event.context;

       ev.key.m_uid = m_uid;

       m_uid++;

       m_unscheduledEvents++;

       m_events->Insert (ev);

    }

}

void

DefaultSimulatorImpl::Run (void)

{

  NS_LOG_FUNCTION (this);

  // Set the current threadId as the main threadId

  m_main = SystemThread::Self();

  ProcessEventsWithContext ();

  m_stop = false;

  while (!m_events->IsEmpty () && !m_stop) 

    {

      ProcessOneEvent ();

    }

  // If the simulator stopped naturally by lack of events, make a

  // consistency test to check that we didn't lose any events along the way.

  NS_ASSERT (!m_events->IsEmpty () || m_unscheduledEvents == 0);

}

void 

DefaultSimulatorImpl::Stop (void)

{

  NS_LOG_FUNCTION (this);

  m_stop = true;

}

void 

DefaultSimulatorImpl::Stop (Time const &delay)

{

  NS_LOG_FUNCTION (this << delay.GetTimeStep ());

  Simulator::Schedule (delay, &Simulator::Stop);

}

//

// Schedule an event for a _relative_ time in the future.

//

EventId

DefaultSimulatorImpl::Schedule (Time const &delay, EventImpl *event)

{

  NS_LOG_FUNCTION (this << delay.GetTimeStep () << event);

  NS_ASSERT_MSG (SystemThread::Equals (m_main), "Simulator::Schedule Thread-unsafe invocation!");

  Time tAbsolute = delay + TimeStep (m_currentTs);

  NS_ASSERT (tAbsolute.IsPositive ());

  NS_ASSERT (tAbsolute >= TimeStep (m_currentTs));

  Scheduler::Event ev;

  ev.impl = event;

  ev.key.m_ts = (uint64_t) tAbsolute.GetTimeStep ();

  ev.key.m_context = GetContext ();

  ev.key.m_uid = m_uid;

  m_uid++;

  m_unscheduledEvents++;

  m_events->Insert (ev);

  return EventId (event, ev.key.m_ts, ev.key.m_context, ev.key.m_uid);

}

void

DefaultSimulatorImpl::ScheduleWithContext (uint32_t context, Time const &delay, EventImpl *event)

{

  NS_LOG_FUNCTION (this << context << delay.GetTimeStep () << event);

  if (SystemThread::Equals (m_main))

    {

      Time tAbsolute = delay + TimeStep (m_currentTs);

      Scheduler::Event ev;

      ev.impl = event;

      ev.key.m_ts = (uint64_t) tAbsolute.GetTimeStep ();

      ev.key.m_context = context;

      ev.key.m_uid = m_uid;

      m_uid++;

      m_unscheduledEvents++;

      m_events->Insert (ev);

    }

  else

    {

      EventWithContext ev;

      ev.context = context;

      // Current time added in ProcessEventsWithContext()

      ev.timestamp = delay.GetTimeStep ();

      ev.event = event;

      {

        CriticalSection cs (m_eventsWithContextMutex);

        m_eventsWithContext.push_back(ev);

        m_eventsWithContextEmpty = false;

      }

    }

}

EventId

DefaultSimulatorImpl::ScheduleNow (EventImpl *event)

{

  NS_ASSERT_MSG (SystemThread::Equals (m_main), "Simulator::ScheduleNow Thread-unsafe invocation!");

  Scheduler::Event ev;

  ev.impl = event;

  ev.key.m_ts = m_currentTs;

  ev.key.m_context = GetContext ();

  ev.key.m_uid = m_uid;

  m_uid++;

  m_unscheduledEvents++;

  m_events->Insert (ev);

  return EventId (event, ev.key.m_ts, ev.key.m_context, ev.key.m_uid);

}

EventId

DefaultSimulatorImpl::ScheduleDestroy (EventImpl *event)

{

  NS_ASSERT_MSG (SystemThread::Equals (m_main), "Simulator::ScheduleDestroy Thread-unsafe invocation!");

  EventId id (Ptr<EventImpl> (event, false), m_currentTs, 0xffffffff, 2);

  m_destroyEvents.push_back (id);

  m_uid++;

  return id;

}

Time

DefaultSimulatorImpl::Now (void) const

{

  // Do not add function logging here, to avoid stack overflow

  return TimeStep (m_currentTs);

}

Time 

DefaultSimulatorImpl::GetDelayLeft (const EventId &id) const

{

  if (IsExpired (id))

    {

      return TimeStep (0);

    }

  else

    {

      return TimeStep (id.GetTs () - m_currentTs);

    }

}

void

DefaultSimulatorImpl::Remove (const EventId &id)

{

  if (id.GetUid () == 2)

    {

      // destroy events.

      for (DestroyEvents::iterator i = m_destroyEvents.begin (); i != m_destroyEvents.end (); i++)

        {

          if (*i == id)

            {

              m_destroyEvents.erase (i);

              break;

            }

        }

      return;

    }

  if (IsExpired (id))

    {

      return;

    }

  Scheduler::Event event;

  event.impl = id.PeekEventImpl ();

  event.key.m_ts = id.GetTs ();

  event.key.m_context = id.GetContext ();

  event.key.m_uid = id.GetUid ();

  m_events->Remove (event);

  event.impl->Cancel ();

  // whenever we remove an event from the event list, we have to unref it.

  event.impl->Unref ();

  m_unscheduledEvents--;

}

void

DefaultSimulatorImpl::Cancel (const EventId &id)

{

  if (!IsExpired (id))

    {

      id.PeekEventImpl ()->Cancel ();

    }

}

bool

DefaultSimulatorImpl::IsExpired (const EventId &id) const

{

  if (id.GetUid () == 2)

    {

      if (id.PeekEventImpl () == 0 ||

          id.PeekEventImpl ()->IsCancelled ())

        {

          return true;

        }

      // destroy events.

      for (DestroyEvents::const_iterator i = m_destroyEvents.begin (); i != m_destroyEvents.end (); i++)

        {

          if (*i == id)

            {

              return false;

            }

        }

      return true;

    }

  if (id.PeekEventImpl () == 0 ||

      id.GetTs () < m_currentTs ||

      (id.GetTs () == m_currentTs &&

       id.GetUid () <= m_currentUid) ||

      id.PeekEventImpl ()->IsCancelled ()) 

    {

      return true;

    }

  else

    {

      return false;

    }

}

Time 

DefaultSimulatorImpl::GetMaximumSimulationTime (void) const

{

  /// \todo I am fairly certain other compilers use other non-standard

  /// post-fixes to indicate 64 bit constants.

  return TimeStep (0x7fffffffffffffffLL);

}

uint32_t

DefaultSimulatorImpl::GetContext (void) const

{

  return m_currentContext;

}

} // namespace ns3