utils: draft implementation for queue drop tracer
diff --git a/utils/tracers/l2-rate-tracer.cc b/utils/tracers/l2-rate-tracer.cc
new file mode 100644
index 0000000..823977b
--- /dev/null
+++ b/utils/tracers/l2-rate-tracer.cc
@@ -0,0 +1,155 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2013 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>
+ */
+
+#include "l2-rate-tracer.h"
+#include "ns3/node.h"
+#include "ns3/packet.h"
+#include "ns3/config.h"
+#include "ns3/callback.h"
+#include "ns3/simulator.h"
+#include "ns3/node-list.h"
+#include "ns3/node.h"
+#include "ns3/log.h"
+
+#include <boost/lexical_cast.hpp>
+#include <fstream>
+
+using namespace boost;
+using namespace std;
+
+NS_LOG_COMPONENT_DEFINE ("L2RateTracer");
+
+namespace ns3 {
+
+boost::tuple< boost::shared_ptr<std::ostream>, std::list<Ptr<L2RateTracer> > >
+L2RateTracer::InstallAll (const std::string &file, Time averagingPeriod/* = Seconds (0.5)*/)
+{
+  std::list<Ptr<L2RateTracer> > tracers;
+  boost::shared_ptr<std::ofstream> outputStream (new std::ofstream ());
+  outputStream->open (file.c_str (), std::ios_base::out | std::ios_base::trunc);
+
+  if (!outputStream->is_open ())
+    return boost::make_tuple (outputStream, tracers);
+
+  for (NodeList::Iterator node = NodeList::Begin ();
+       node != NodeList::End ();
+       node++)
+    {
+      NS_LOG_DEBUG ("Node: " << lexical_cast<string> ((*node)->GetId ()));
+
+      Ptr<L2RateTracer> trace = Create<L2RateTracer> (outputStream, *node);
+      trace->SetAveragingPeriod (averagingPeriod);
+      tracers.push_back (trace);
+    }
+
+  if (tracers.size () > 0)
+    {
+      // *m_l3RateTrace << "# "; // not necessary for R's read.table
+      tracers.front ()->PrintHeader (*outputStream);
+      *outputStream << "\n";
+    }
+
+  return boost::make_tuple (outputStream, tracers);
+}
+
+
+L2RateTracer::L2RateTracer (boost::shared_ptr<std::ostream> os, Ptr<Node> node)
+  : L2Tracer (node)
+  , m_os (os)
+{
+  SetAveragingPeriod (Seconds (1.0));
+}
+
+L2RateTracer::~L2RateTracer ()
+{
+  m_printEvent.Cancel ();
+}
+
+void
+L2RateTracer::SetAveragingPeriod (const Time &period)
+{
+  m_period = period;
+  m_printEvent.Cancel ();
+  m_printEvent = Simulator::Schedule (m_period, &L2RateTracer::PeriodicPrinter, this);
+}
+
+void
+L2RateTracer::PeriodicPrinter ()
+{
+  Print (*m_os);
+  Reset ();
+
+  m_printEvent = Simulator::Schedule (m_period, &L2RateTracer::PeriodicPrinter, this);
+}
+
+void
+L2RateTracer::PrintHeader (std::ostream &os) const
+{
+  os << "Time" << "\t"
+
+     << "Node" << "\t"
+     << "Interface" << "\t"
+
+     << "Type" << "\t"
+     << "Packets" << "\t"
+     << "Kilobytes";
+}
+
+void
+L2RateTracer::Reset ()
+{
+  m_stats.get<0> ().Reset ();
+  m_stats.get<1> ().Reset ();
+}
+
+const double alpha = 0.8;
+
+#define STATS(INDEX) m_stats.get<INDEX> ()
+#define RATE(INDEX, fieldName) STATS(INDEX).fieldName / m_period.ToDouble (Time::S)
+
+#define PRINTER(printName, fieldName, interface)                        \
+STATS(2).fieldName = /*new value*/alpha * RATE(0, fieldName) + /*old value*/(1-alpha) * STATS(2).fieldName; \
+STATS(3).fieldName = /*new value*/alpha * RATE(1, fieldName) / 1024.0 + /*old value*/(1-alpha) * STATS(3).fieldName; \
+                                                                        \
+ os << time.ToDouble (Time::S) << "\t"                                  \
+ << m_node << "\t"                                                      \
+ << interface << "\t"                                                  \
+ << printName << "\t"                                                   \
+ << STATS(2).fieldName  << "\t"                                         \
+ << STATS(3).fieldName << "\n";
+
+void
+L2RateTracer::Print (std::ostream &os) const
+{
+  Time time = Simulator::Now ();
+
+  PRINTER ("Drop", m_drop, "combined");
+}
+
+void
+L2RateTracer::Drop (Ptr<const Packet> packet)
+{
+  // no interface information... this should be part of this L2Tracer object data
+
+  m_stats.get<0> ().m_drop ++;
+  m_stats.get<1> ().m_drop += packet->GetSize ();
+}
+
+} // namespace ns3