model: (Re-)Implementing ability to keep PIT records after Interest is getting satisfied

Default behavior remained the same.

As part of this commit, a small extension (and bug fix) in trie data
structure, allowing search with predicates (e.g., used to lookup a
non-empty PIT entry during Lookup on ContentObject header).
diff --git a/model/pit/ndn-pit-entry.cc b/model/pit/ndn-pit-entry.cc
index 77c7578..accfcf1 100644
--- a/model/pit/ndn-pit-entry.cc
+++ b/model/pit/ndn-pit-entry.cc
@@ -62,12 +62,12 @@
 Entry::UpdateLifetime (const Time &offsetTime)
 {
   NS_LOG_FUNCTION (offsetTime.ToDouble (Time::S));
-  
+
   Time newExpireTime = Simulator::Now () + offsetTime;
   if (newExpireTime > m_expireTime)
     m_expireTime = newExpireTime;
-  
-  NS_LOG_INFO ("Updated lifetime to " << m_expireTime.ToDouble (Time::S));
+
+  NS_LOG_INFO (this->GetPrefix () << ", Updated lifetime to " << m_expireTime.ToDouble (Time::S) << "s, " << (m_expireTime-Simulator::Now ()).ToDouble (Time::S) << "s left");
 }
 
 void
@@ -78,7 +78,7 @@
     {
       m_expireTime = Simulator::Now ();
     }
-  NS_LOG_INFO ("Offsetting lifetime to " << m_expireTime.ToDouble (Time::S));
+  NS_LOG_INFO (this->GetPrefix () << ", Offsetting lifetime to " << m_expireTime.ToDouble (Time::S) << "s, " << (m_expireTime-Simulator::Now ()).ToDouble (Time::S) << "s left");
 }
 
 
@@ -110,7 +110,7 @@
 Entry::in_iterator
 Entry::AddIncoming (Ptr<Face> face)
 {
-  std::pair<in_iterator,bool> ret = 
+  std::pair<in_iterator,bool> ret =
     m_incoming.insert (IncomingFace (face));
 
   // NS_ASSERT_MSG (ret.second, "Something is wrong");
@@ -277,7 +277,7 @@
         os << ",";
       else
         first = false;
-      
+
       os << *face.m_face;
     }
 
@@ -289,7 +289,7 @@
         os << ",";
       else
         first = false;
-      
+
       os << *face.m_face;
     }
   os << "\nNonces: ";
@@ -300,7 +300,7 @@
         os << ",";
       else
         first = false;
-      
+
       os << nonce;
     }
 
diff --git a/model/pit/ndn-pit-entry.h b/model/pit/ndn-pit-entry.h
index 259af75..9680ac2 100644
--- a/model/pit/ndn-pit-entry.h
+++ b/model/pit/ndn-pit-entry.h
@@ -75,7 +75,7 @@
 //       // boost::multi_index::ordered_non_unique<
 //       //   boost::multi_index::tag<i_retx>,
 //       //   boost::multi_index::member<OutgoingFace, uint32_t, &OutgoingFace::m_retxCount>
-//       // >    
+//       // >
 //     >
 //    > type;
 //   /// @endcond
@@ -99,7 +99,7 @@
   typedef out_container::iterator out_iterator;              ///< @brief iterator to outgoing faces
 
   typedef std::set< uint32_t > nonce_container;  ///< @brief nonce container type
-  
+
   /**
    * \brief PIT entry constructor
    * \param prefix Prefix of the PIT entry
@@ -112,33 +112,34 @@
    * @brief Virtual destructor
    */
   virtual ~Entry ();
-  
+
   /**
    * @brief Update lifetime of PIT entry
    *
-   * This function will update PIT entry lifetime to the maximum of the current lifetime and
-   * the lifetime Simulator::Now () + offsetTime
+   * @param lifetime desired lifetime of the pit entry (relative to the Simulator::Now ())
    *
-   * @param lifetime Relative time to the current moment, representing PIT entry lifetime
+   * This function will update PIT entry lifetime to the maximum of the current lifetime and
+   * the lifetime Simulator::Now () + lifetime
    */
   virtual void
   UpdateLifetime (const Time &lifetime);
 
   /**
    * @brief Offset the currently set PIT lifetime (allowed both negative and positive offsets)
+   *
    * @param offsetTime positive or negative offset for the PIT lifetime.
    *
    * If PIT expire time becomes less than Simulator::Now, then it is adjusted to Simulator::Now.
    */
   virtual void
   OffsetLifetime (const Time &offsetTime);
-  
+
   /**
    * @brief Get prefix of the PIT entry
    */
   const NameComponents &
   GetPrefix () const;
-  
+
   /**
    * @brief Get current expiration time of the record
    *
@@ -146,7 +147,7 @@
    */
   const Time &
   GetExpireTime () const;
-  
+
   /**
    * @brief Check if nonce `nonce` for the same prefix has already been seen
    *
@@ -154,7 +155,7 @@
    */
   bool
   IsNonceSeen (uint32_t nonce) const;
-  
+
   /**
    * @brief Add `nonce` to the list of seen nonces
    *
@@ -164,7 +165,7 @@
    */
   virtual void
   AddSeenNonce (uint32_t nonce);
-  
+
   /**
    * @brief Add `face` to the list of incoming faces
    *
@@ -200,10 +201,10 @@
    */
   virtual void
   ClearOutgoing ();
-  
+
   /**
    * @brief Remove all references to face.
-   * 
+   *
    * This method should be called before face is completely removed from the stack.
    * Face is removed from the lists of incoming and outgoing faces
    */
@@ -217,7 +218,7 @@
   // SetWaitingInVain (out_iterator face);
   virtual void
   SetWaitingInVain (Ptr<Face> face);
-  
+
   /**
    * @brief Check if all outgoing faces are NACKed
    */
@@ -266,7 +267,7 @@
    */
   uint32_t
   GetOutgoingCount () const;
-  
+
   /**
    * @brief Add new forwarding strategy tag
    */
@@ -295,14 +296,14 @@
 
 private:
   friend std::ostream& operator<< (std::ostream& os, const Entry &entry);
-  
+
 protected:
   Pit &m_container; ///< @brief Reference to the container (to rearrange indexes, if necessary)
 
   Ptr<const InterestHeader> m_interest; ///< \brief Interest of the PIT entry (if several interests are received, then nonce is from the first Interest)
   Ptr<fib::Entry> m_fibEntry;     ///< \brief FIB entry related to this prefix
-  
-  nonce_container m_seenNonces;  ///< \brief map of nonces that were seen for this prefix  
+
+  nonce_container m_seenNonces;  ///< \brief map of nonces that were seen for this prefix
   in_container  m_incoming;      ///< \brief container for incoming interests
   out_container m_outgoing;      ///< \brief container for outgoing interests
 
@@ -314,6 +315,15 @@
   std::list< boost::shared_ptr<fw::Tag> > m_fwTags; ///< @brief Forwarding strategy tags
 };
 
+struct EntryIsNotEmpty
+{
+  bool
+  operator () (Ptr<Entry> entry)
+  {
+    return !entry->GetIncoming ().empty ();
+  }
+};
+
 std::ostream& operator<< (std::ostream& os, const Entry &entry);
 
 inline void
diff --git a/model/pit/ndn-pit-impl.cc b/model/pit/ndn-pit-impl.cc
index 3b693f8..27fcab2 100644
--- a/model/pit/ndn-pit-impl.cc
+++ b/model/pit/ndn-pit-impl.cc
@@ -185,7 +185,7 @@
 PitImpl<Policy>::Lookup (const ContentObjectHeader &header)
 {
   /// @todo use predicate to search with exclude filters
-  typename super::iterator item = super::longest_prefix_match (header.GetName ());
+  typename super::iterator item = super::longest_prefix_match_if (header.GetName (), EntryIsNotEmpty ());
 
   if (item == super::end ())
     return 0;
@@ -249,8 +249,14 @@
 void
 PitImpl<Policy>::MarkErased (Ptr<Entry> item)
 {
-  // entry->SetExpireTime (Simulator::Now () + m_PitEntryPruningTimout);
-  super::erase (StaticCast< entry > (item)->to_iterator ());
+  if (this->m_PitEntryPruningTimout.IsZero ())
+    {
+      super::erase (StaticCast< entry > (item)->to_iterator ());
+    }
+  else
+    {
+      item->OffsetLifetime (this->m_PitEntryPruningTimout - item->GetExpireTime () + Simulator::Now ());
+    }
 }
 
 
diff --git a/model/pit/ndn-pit.cc b/model/pit/ndn-pit.cc
index ad8f4a2..224e013 100644
--- a/model/pit/ndn-pit.cc
+++ b/model/pit/ndn-pit.cc
@@ -24,7 +24,7 @@
 #include "ns3/ndn-content-object.h"
 
 #include "ns3/log.h"
-#include "ns3/string.h"
+#include "ns3/nstime.h"
 #include "ns3/uinteger.h"
 #include "ns3/simulator.h"
 
@@ -44,10 +44,10 @@
   static TypeId tid = TypeId ("ns3::ndn::Pit")
     .SetGroupName ("Ndn")
     .SetParent<Object> ()
-    
+
     .AddAttribute ("PitEntryPruningTimout",
                    "Timeout for PIT entry to live after being satisfied. To make sure recently satisfied interest will not be satisfied again",
-                   StringValue ("100ms"),
+                   TimeValue (), // by default, PIT entries are removed instantly
                    MakeTimeAccessor (&Pit::m_PitEntryPruningTimout),
                    MakeTimeChecker ())
     ;