forked from cawka/ndn.cxx
diff --git a/ndn-cpp/trie/policies/lfu-policy.h b/ndn-cpp/trie/policies/lfu-policy.h
new file mode 100644
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+++ b/ndn-cpp/trie/policies/lfu-policy.h
@@ -0,0 +1,149 @@
+/* -*- 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 LFU_POLICY_H_
+#define LFU_POLICY_H_
+
+#include <boost/intrusive/options.hpp>
+#include <boost/intrusive/set.hpp>
+
+namespace ndn {
+namespace trie {
+
+/**
+ * @brief Traits for LFU replacement policy
+ */
+struct lfu_policy_traits
+{
+ /// @brief Name that can be used to identify the policy (e.g., for 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_;
+ };
+ };
+};
+
+} // trie
+} // ndn
+
+#endif // LFU_POLICY_H