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/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
/*
* Copyright (c) 2011 University of California, Los Angeles
*
* 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: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
*/
#ifndef LFU_POLICY_H_
#define LFU_POLICY_H_
#include <boost/intrusive/options.hpp>
#include <boost/intrusive/set.hpp>
namespace ns3 {
namespace ndn {
namespace ndnSIM {
/**
* @brief Traits for LFU replacement policy
*/
struct lfu_policy_traits
{
/// @brief Name that can be used to identify the policy (for NS-3 object model and logging)
static std::string GetName () { return "Lfu"; }
struct policy_hook_type : public boost::intrusive::set_member_hook<> { double frequency; };
template<class Container>
struct container_hook
{
typedef boost::intrusive::member_hook< Container,
policy_hook_type,
&Container::policy_hook_ > type;
};
template<class Base,
class Container,
class Hook>
struct policy
{
static double& get_order (typename Container::iterator item)
{
return static_cast<policy_hook_type*>
(policy_container::value_traits::to_node_ptr(*item))->frequency;
}
static const double& get_order (typename Container::const_iterator item)
{
return static_cast<const policy_hook_type*>
(policy_container::value_traits::to_node_ptr(*item))->frequency;
}
template<class Key>
struct MemberHookLess
{
bool operator () (const Key &a, const Key &b) const
{
return get_order (&a) < get_order (&b);
}
};
typedef boost::intrusive::multiset< Container,
boost::intrusive::compare< MemberHookLess< Container > >,
Hook > policy_container;
// could be just typedef
class type : public policy_container
{
public:
typedef policy policy_base; // to get access to get_order methods from outside
typedef Container parent_trie;
type (Base &base)
: base_ (base)
, max_size_ (100)
{
}
inline void
update (typename parent_trie::iterator item)
{
policy_container::erase (policy_container::s_iterator_to (*item));
get_order (item) += 1;
policy_container::insert (*item);
}
inline bool
insert (typename parent_trie::iterator item)
{
get_order (item) = 0;
if (max_size_ != 0 && policy_container::size () >= max_size_)
{
// this erases the "least frequently used item" from cache
base_.erase (&(*policy_container::begin ()));
}
policy_container::insert (*item);
return true;
}
inline void
lookup (typename parent_trie::iterator item)
{
policy_container::erase (policy_container::s_iterator_to (*item));
get_order (item) += 1;
policy_container::insert (*item);
}
inline void
erase (typename parent_trie::iterator item)
{
policy_container::erase (policy_container::s_iterator_to (*item));
}
inline void
clear ()
{
policy_container::clear ();
}
inline void
set_max_size (size_t max_size)
{
max_size_ = max_size;
}
inline size_t
get_max_size () const
{
return max_size_;
}
private:
type () : base_(*((Base*)0)) { };
private:
Base &base_;
size_t max_size_;
};
};
};
} // ndnSIM
} // ndn
} // ns3
#endif // LFU_POLICY_H