[ndnSIM] fw: Extend forwarding pipelines with beforeSatisfyInterest and beforeExpirePendingInterest signals

Change-Id: I7d8266c3c53b0b6ef791b90c9c93de216b459ad2
Refs: #2361, #2362
diff --git a/daemon/fw/forwarder.cpp b/daemon/fw/forwarder.cpp
index 300dbc8..bf1cb39 100644
--- a/daemon/fw/forwarder.cpp
+++ b/daemon/fw/forwarder.cpp
@@ -27,6 +27,7 @@
 #include "core/logger.hpp"
 #include "core/random.hpp"
 #include "strategy.hpp"
+#include "face/null-face.hpp"
 #include <boost/random/uniform_int_distribution.hpp>
 
 namespace nfd {
@@ -43,8 +44,10 @@
   , m_pit(m_nameTree)
   , m_measurements(m_nameTree)
   , m_strategyChoice(m_nameTree, fw::makeDefaultStrategy(*this))
+  , m_csFace(make_shared<NullFace>(FaceUri("contentstore://")))
 {
   fw::installStrategies(*this);
+  getFaceTable().addReserved(m_csFace, FACEID_CONTENT_STORE);
 }
 
 Forwarder::~Forwarder()
@@ -141,6 +144,10 @@
 {
   NFD_LOG_DEBUG("onContentStoreHit interest=" << interest.getName());
 
+  beforeSatisfyInterest(*pitEntry, *m_csFace, data);
+  this->dispatchToStrategy(pitEntry, bind(&Strategy::beforeSatisfyInterest, _1,
+                                          pitEntry, cref(*m_csFace), cref(data)));
+
   const_pointer_cast<Data>(data.shared_from_this())->setIncomingFaceId(FACEID_CONTENT_STORE);
   // XXX should we lookup PIT for other Interests that also match csMatch?
 
@@ -250,6 +257,7 @@
   NFD_LOG_DEBUG("onInterestUnsatisfied interest=" << pitEntry->getName());
 
   // invoke PIT unsatisfied callback
+  beforeExpirePendingInterest(*pitEntry);
   this->dispatchToStrategy(pitEntry, bind(&Strategy::beforeExpirePendingInterest, _1,
                                           pitEntry));
 
@@ -322,6 +330,7 @@
     }
 
     // invoke PIT satisfy callback
+    beforeSatisfyInterest(*pitEntry, inFace, data);
     this->dispatchToStrategy(pitEntry, bind(&Strategy::beforeSatisfyInterest, _1,
                                             pitEntry, cref(inFace), cref(data)));
 
diff --git a/daemon/fw/forwarder.hpp b/daemon/fw/forwarder.hpp
index c8bd402..61d55f2 100644
--- a/daemon/fw/forwarder.hpp
+++ b/daemon/fw/forwarder.hpp
@@ -45,6 +45,8 @@
 class Strategy;
 } // namespace fw
 
+class NullFace;
+
 /** \brief main class of NFD
  *
  *  Forwarder owns all faces and tables, and implements forwarding pipelines.
@@ -110,6 +112,17 @@
   void
   setCsFromNdnSim(ns3::Ptr<ns3::ndn::ContentStore> cs);
 
+public:
+  /** \brief trigger before PIT entry is satisfied
+   *  \sa Strategy::beforeSatisfyInterest
+   */
+  signal::Signal<Forwarder, pit::Entry, Face, Data> beforeSatisfyInterest;
+
+  /** \brief trigger before PIT entry expires
+   *  \sa Strategy::beforeExpirePendingInterest
+   */
+  signal::Signal<Forwarder, pit::Entry> beforeExpirePendingInterest;
+
 PUBLIC_WITH_TESTS_ELSE_PRIVATE: // pipelines
   /** \brief incoming Interest pipeline
    */
@@ -215,6 +228,7 @@
   Measurements   m_measurements;
   StrategyChoice m_strategyChoice;
   DeadNonceList  m_deadNonceList;
+  shared_ptr<NullFace> m_csFace;
 
   ns3::Ptr<ns3::ndn::ContentStore> m_csFromNdnSim;