Connect forwarder cache hit and miss signals

This lets the CsTracer provide stats again after their
removal in commit 8fbcc64.

Author: migrax

utils/tracers/ndn-cs-tracer.cpp

@@ -18,6 +18,8 @@
  **/
 
 #include "ndn-cs-tracer.hpp"
+#include "fw/forwarder.hpp"
+#include "model/ndn-l3-protocol.hpp"
 #include "ns3/node.h"
 #include "ns3/packet.h"
 #include "ns3/config.h"
@@ -199,10 +201,14 @@ CsTracer::~CsTracer(){};
 void
 CsTracer::Connect()
 {
-  // // @TODO Do the same with NFD content store...
-  // Ptr<ContentStore> cs = m_nodePtr->GetObject<ContentStore>();
-  // cs->TraceConnectWithoutContext("CacheHits", MakeCallback(&CsTracer::CacheHits, this));
-  // cs->TraceConnectWithoutContext("CacheMisses", MakeCallback(&CsTracer::CacheMisses, this));
+  auto l3proto = m_nodePtr->GetObject<ndn::L3Protocol>();
+  auto fwd = l3proto->getForwarder();
+
+  fwd->afterCsHit.connect(
+      [this](Interest interest, Data data) { CacheHits(interest, data); });
+
+  fwd->afterCsMiss.connect(
+      [this](Interest interest) { CacheMisses(interest); });
 
   Reset();
 }
@@ -259,13 +265,13 @@ CsTracer::Print(std::ostream& os) const
 }
 
 void
-CsTracer::CacheHits(shared_ptr<const Interest>, shared_ptr<const Data>)
+CsTracer::CacheHits(const Interest&, const Data&)
 {
   m_stats.m_cacheHits++;
 }
 
 void
-CsTracer::CacheMisses(shared_ptr<const Interest>)
+CsTracer::CacheMisses(const Interest&)
 {
   m_stats.m_cacheMisses++;
 }

utils/tracers/ndn-cs-tracer.hpp

@@ -173,10 +173,10 @@ class CsTracer : public SimpleRefCount<CsTracer> {
   Connect();
 
   void
-  CacheHits(shared_ptr<const Interest>, shared_ptr<const Data>);
+  CacheHits(const Interest&, const Data&);
 
   void
-  CacheMisses(shared_ptr<const Interest>);
+  CacheMisses(const Interest&);
 
 private:
   void