fw: RetxSuppressionExponential

refs #1913

Change-Id: I9bb2bae8d7600722920534f646cc8056b3d4843a
diff --git a/daemon/fw/retx-suppression-exponential.cpp b/daemon/fw/retx-suppression-exponential.cpp
new file mode 100644
index 0000000..a462f8a
--- /dev/null
+++ b/daemon/fw/retx-suppression-exponential.cpp
@@ -0,0 +1,97 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2015,  Regents of the University of California,
+ *                           Arizona Board of Regents,
+ *                           Colorado State University,
+ *                           University Pierre & Marie Curie, Sorbonne University,
+ *                           Washington University in St. Louis,
+ *                           Beijing Institute of Technology,
+ *                           The University of Memphis.
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NFD 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
+ * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "retx-suppression-exponential.hpp"
+
+namespace nfd {
+namespace fw {
+
+const RetxSuppressionExponential::Duration RetxSuppressionExponential::DEFAULT_INITIAL_INTERVAL =
+    time::milliseconds(1);
+const float RetxSuppressionExponential::DEFAULT_MULTIPLIER = 2.0;
+const RetxSuppressionExponential::Duration RetxSuppressionExponential::DEFAULT_MAX_INTERVAL =
+    time::milliseconds(250);
+
+class RetxSuppressionExponential::PitInfo : public StrategyInfo
+{
+public:
+  static constexpr int
+  getTypeId()
+  {
+    return 1020;
+  }
+
+  explicit
+  PitInfo(const Duration& initialInterval)
+    : suppressionInterval(initialInterval)
+  {
+  }
+
+public:
+  /** \brief if last transmission occurred within suppressionInterval,
+   *         retransmission will be suppressed
+   */
+  Duration suppressionInterval;
+};
+
+RetxSuppressionExponential::RetxSuppressionExponential(const Duration& initialInterval,
+                                                       float multiplier,
+                                                       const Duration& maxInterval)
+  : m_initialInterval(initialInterval)
+  , m_multiplier(multiplier)
+  , m_maxInterval(maxInterval)
+{
+  BOOST_ASSERT(initialInterval > time::milliseconds::zero());
+  BOOST_ASSERT(multiplier >= 1.0);
+  BOOST_ASSERT(maxInterval >= initialInterval);
+}
+
+RetxSuppression::Result
+RetxSuppressionExponential::decide(const Face& inFace, const Interest& interest,
+                                   pit::Entry& pitEntry) const
+{
+  bool isNewPitEntry = !pitEntry.hasUnexpiredOutRecords();
+  if (isNewPitEntry) {
+    return NEW;
+  }
+
+  time::steady_clock::TimePoint lastOutgoing = this->getLastOutgoing(pitEntry);
+  time::steady_clock::TimePoint now = time::steady_clock::now();
+  time::steady_clock::Duration sinceLastOutgoing = now - lastOutgoing;
+
+  shared_ptr<PitInfo> pi = pitEntry.getOrCreateStrategyInfo<PitInfo>(m_initialInterval);
+  bool shouldSuppress = sinceLastOutgoing < pi->suppressionInterval;
+
+  if (shouldSuppress) {
+    return SUPPRESS;
+  }
+
+  pi->suppressionInterval = std::min(m_maxInterval,
+      time::duration_cast<Duration>(pi->suppressionInterval * m_multiplier));
+  return FORWARD;
+}
+
+} // namespace fw
+} // namespace nfd