model: Adding experimental support for caching policies with probability caching
This caching can be enabled, for example, for LRU policy with caching
probability 50%:
ndnHelper.SetContentStore ("ns3::ndn::cs::Probability::Lru",
"MaxSize", "100",
"CacheProbability", "0.5");
Similar way, probability can be enabled for other existing caching policies.
diff --git a/model/cs/custom-policies/probability-policy.h b/model/cs/custom-policies/probability-policy.h
new file mode 100644
index 0000000..0c3088c
--- /dev/null
+++ b/model/cs/custom-policies/probability-policy.h
@@ -0,0 +1,150 @@
+/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2012 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 PROBABILITY_POLICY_H_
+#define PROBABILITY_POLICY_H_
+
+#include <boost/intrusive/options.hpp>
+#include <boost/intrusive/list.hpp>
+
+#include <ns3/random-variable.h>
+
+namespace ns3 {
+namespace ndn {
+namespace ndnSIM {
+
+/**
+ * @brief Traits for freshness policy
+ */
+struct probability_policy_traits
+{
+ static std::string GetName () { return "ProbabilityImpl"; }
+
+ struct policy_hook_type : public boost::intrusive::list_member_hook<> {};
+
+ 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
+ {
+ typedef typename boost::intrusive::list< Container, Hook > policy_container;
+
+ class type : public policy_container
+ {
+ public:
+ typedef policy policy_base; // to get access to get_freshness methods from outside
+ typedef Container parent_trie;
+
+ type (Base &base)
+ : base_ (base)
+ , max_size_ (100)
+ , probability_ (1.0)
+ {
+ }
+
+ inline void
+ update (typename parent_trie::iterator item)
+ {
+ }
+
+ inline bool
+ insert (typename parent_trie::iterator item)
+ {
+ if (ns3_rand_.GetValue () < probability_)
+ {
+ policy_container::push_back (*item);
+
+ // allow caching
+ return true;
+ }
+ else
+ {
+ // don't allow caching
+ return false;
+ }
+ }
+
+ 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_;
+ }
+
+ inline void
+ set_probability (double probability)
+ {
+ probability_ = probability;
+ }
+
+ inline double
+ get_probability () const
+ {
+ return probability_;
+ }
+
+ private:
+ type () : base_(*((Base*)0)) { };
+
+ private:
+ Base &base_;
+ size_t max_size_;
+ double probability_;
+ UniformVariable ns3_rand_;
+ };
+ };
+};
+
+} // ndnSIM
+} // ndn
+} // ns3
+
+#endif // PROBABILITY_POLICY_H