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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
/*
* Copyright (c) 2013, Regents of the University of California
* Alexander Afanasyev
*
* BSD license, See the LICENSE file for more information
*
* Author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
*/
#ifndef RANDOM_POLICY_H_
#define RANDOM_POLICY_H_
#include "ns3/random-variable.h"
#include <boost/intrusive/options.hpp>
#include <boost/intrusive/set.hpp>
namespace ndn {
namespace trie {
/**
* @brief Traits for random replacement policy
*/
struct random_policy_traits
{
/// @brief Name that can be used to identify the policy (e.g., for logging)
static std::string GetName () { return "Random"; }
struct policy_hook_type : public boost::intrusive::set_member_hook<> { uint32_t randomOrder; };
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 uint32_t& get_order (typename Container::iterator item)
{
return static_cast<typename policy_container::value_traits::hook_type*>
(policy_container::value_traits::to_node_ptr(*item))->randomOrder;
}
static const uint32_t& get_order (typename Container::const_iterator item)
{
return static_cast<const typename policy_container::value_traits::hook_type*>
(policy_container::value_traits::to_node_ptr(*item))->randomOrder;
}
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)
, u_rand (0, std::numeric_limits<uint32_t>::max ())
, max_size_ (100)
{
}
inline void
update (typename parent_trie::iterator item)
{
// do nothing. it's random policy
}
inline bool
insert (typename parent_trie::iterator item)
{
get_order (item) = u_rand.GetValue ();
if (max_size_ != 0 && policy_container::size () >= max_size_)
{
if (MemberHookLess<Container>() (*item, *policy_container::begin ()))
{
// std::cout << "Cannot add. Signaling fail\n";
// just return false. Indicating that insert "failed"
return false;
}
else
{
// removing some random element
base_.erase (&(*policy_container::begin ()));
}
}
policy_container::insert (*item);
return true;
}
inline void
lookup (typename parent_trie::iterator item)
{
// do nothing. it's random policy
}
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_;
ns3::UniformVariable u_rand;
size_t max_size_;
};
};
};
} // trie
} // ndn
#endif // RANDOM_POLICY_H