/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
* Copyright (c) 2005 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>
*/
#ifndef SCHEDULER_H
#define SCHEDULER_H
#include <stdint.h>
#include "ns3/object.h"
namespace ns3 {
class EventImpl;
/**
* \ingroup simulator
* \defgroup scheduler Scheduler
*/
/**
* \ingroup scheduler
* \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 pure virtual methods defined here.
*
* The only tricky aspect of this API is the memory management of
* the EventImpl pointer which is a member of the Event data structure.
* The lifetime of this pointer is assumed to always be longer than
* the lifetime of the Scheduler class which means that the caller
* is responsible for ensuring that this invariant holds through
* calling EventImpl::Ref and EventImpl::Unref at the right time.
* Typically, ::Ref is called before Insert and ::Unref is called
* after a call to one of the Remove methods.
*/
class Scheduler : public Object
{
public:
static TypeId GetTypeId (void);
struct EventKey {
uint64_t m_ts;
uint32_t m_uid;
};
struct Event {
EventImpl *impl;
EventKey key;
};
virtual ~Scheduler () = 0;
/**
* \param ev event to store in the event list
*/
virtual void Insert (const Event &ev) = 0;
/**
* \returns true if the event list is empty and false otherwise.
*/
virtual bool IsEmpty (void) const = 0;
/**
* \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.
*/
virtual Event PeekNext (void) const = 0;
/**
* This method cannot be invoked if the list is empty.
* Remove the next earliest event from the event list.
*/
virtual Event RemoveNext (void) = 0;
/**
* \param ev the event to remove
*
* This methods cannot be invoked if the list is empty.
*/
virtual void Remove (const Event &ev) = 0;
};
/* Note the invariants which this function must provide:
* - irreflexibility: f (x,x) is false)
* - antisymmetry: f(x,y) = !f(y,x)
* - transitivity: f(x,y) and f(y,z) => f(x,z)
*/
inline bool operator < (const Scheduler::EventKey &a, const Scheduler::EventKey &b)
{
if (a.m_ts < b.m_ts)
{
return true;
}
else if (a.m_ts == b.m_ts &&
a.m_uid < b.m_uid)
{
return true;
}
else
{
return false;
}
}
inline bool operator < (const Scheduler::Event &a, const Scheduler::Event &b)
{
return a.key < b.key;
}
} // namespace ns3
#endif /* SCHEDULER_H */