model+utils: New implementation (realization) of PIT, implementing limiting based on Interest packet sizes, not the number of entries

Also, small reorganization with policies
diff --git a/model/pit/custom-policies/serialized-size-policy.h b/model/pit/custom-policies/serialized-size-policy.h
new file mode 100644
index 0000000..0050ac6
--- /dev/null
+++ b/model/pit/custom-policies/serialized-size-policy.h
@@ -0,0 +1,174 @@
+/* -*-  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 SERIALIZED_POLICY_H_
+#define SERIALIZED_POLICY_H_
+
+#include <boost/intrusive/options.hpp>
+#include <boost/intrusive/set.hpp>
+
+namespace ns3 {
+namespace ndn {
+namespace ndnSIM {
+
+/**
+ * @brief Traits for Least Recently Used replacement policy
+ */
+struct serialized_size_policy_traits
+{
+  /// @brief Name that can be used to identify the policy (for NS-3 object model and logging)
+  static std::string GetName () { return "SerializedSize"; }
+
+  struct policy_hook_type : public boost::intrusive::set_member_hook<> { uint32_t size; };
+
+  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_size (typename Container::iterator item)
+    {
+      return static_cast<typename policy_container::value_traits::hook_type*>
+        (policy_container::value_traits::to_node_ptr(*item))->size;
+    }
+
+    static const uint32_t& get_size (typename Container::const_iterator item)
+    {
+      return static_cast<const typename policy_container::value_traits::hook_type*>
+        (policy_container::value_traits::to_node_ptr(*item))->size;
+    }
+
+    template<class Key>
+    struct MemberHookLess
+    {
+      bool operator () (const Key &a, const Key &b) const
+      {
+        return get_size (&a) < get_size (&b);
+      }
+    };
+
+    typedef typename boost::intrusive::multiset< Container,
+                                                 boost::intrusive::compare< MemberHookLess< Container > >,
+                                                 Hook > policy_container;
+
+    // could be just typedef
+    class type : public policy_container
+    {
+    public:
+      typedef Container parent_trie;
+
+      type (Base &base)
+        : base_ (base)
+        , max_size_ (10000) // size in bytes. Default ~10 kilobytes
+        , current_space_used_ (0)
+      {
+      }
+
+      inline void
+      update (typename parent_trie::iterator item)
+      {
+        // in case size got changed
+        current_space_used_ -= get_size (item);
+        policy_container::erase (*item);
+
+        get_order (item) = item->payload ()->GetInterest ()->GetSerializedSize ();
+        current_space_used_ += get_size (item); // this operation can violate policy constraint, so in some case
+                                                // it may be necessary to remove some other element
+        policy_container::insert (*item);
+      }
+
+      inline bool
+      insert (typename parent_trie::iterator item)
+      {
+        if (max_size_ != 0 && current_space_used_ >= max_size_)
+          {
+            // the current version just fails to add an element, but it also possible
+            // to remove the largest element (last element in multi_map policy container)
+            return false;
+          }
+
+        get_size (item) = item->payload ()->GetInterest ()->GetSerializedSize ();
+        current_space_used_ += get_size (item);
+
+        policy_container::insert (*item);
+        return true;
+      }
+
+      inline void
+      lookup (typename parent_trie::iterator item)
+      {
+        // do nothing
+      }
+
+      inline void
+      erase (typename parent_trie::iterator item)
+      {
+        current_space_used_ -= get_size (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 uint32_t
+      get_current_space_used () const
+      {
+        return current_space_used_;
+      }
+
+    private:
+      type () : base_(*((Base*)0)) { };
+
+    private:
+      Base &base_;
+      uint32_t max_size_;
+      uint32_t current_space_used_;
+    };
+  };
+};
+
+} // ndnSIM
+} // ndn
+} // ns3
+
+#endif