Issue #25 Replacing usage of TCP RTT estimator with a customized version
In the current commit, RTT estimator does not implement Karn's algorithm
and takes into account all RTT samples, including ambiguous samples from
retransmitted Interests.
diff --git a/utils/ndn-rtt-estimator.h b/utils/ndn-rtt-estimator.h
new file mode 100644
index 0000000..6bf6aa8
--- /dev/null
+++ b/utils/ndn-rtt-estimator.h
@@ -0,0 +1,172 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+//
+// Copyright (c) 2006 Georgia Tech Research Corporation
+//
+// 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: Rajib Bhattacharjea<raj.b@gatech.edu>
+//
+
+// Georgia Tech Network Simulator - Round Trip Time Estimation Class
+// George F. Riley. Georgia Tech, Spring 2002
+
+// THIS IS A COPY OF rtt-estimator.h from internet module with minor modifications
+
+#ifndef NDN_RTT_ESTIMATOR_H
+#define NDN_RTT_ESTIMATOR_H
+
+#include <deque>
+#include "ns3/sequence-number.h"
+#include "ns3/nstime.h"
+#include "ns3/object.h"
+
+namespace ns3 {
+
+namespace ndn {
+
+/**
+ * \ingroup tcp
+ *
+ * \brief Helper class to store RTT measurements
+ */
+class RttHistory {
+public:
+ RttHistory (SequenceNumber32 s, uint32_t c, Time t);
+ RttHistory (const RttHistory& h); // Copy constructor
+public:
+ SequenceNumber32 seq; // First sequence number in packet sent
+ uint32_t count; // Number of bytes sent
+ Time time; // Time this one was sent
+ bool retx; // True if this has been retransmitted
+};
+
+typedef std::deque<RttHistory> RttHistory_t;
+
+/**
+ * \ingroup tcp
+ *
+ * \brief Base class for all RTT Estimators
+ */
+class RttEstimator : public Object {
+public:
+ static TypeId GetTypeId (void);
+
+ RttEstimator();
+ RttEstimator (const RttEstimator&);
+
+ virtual ~RttEstimator();
+
+ /**
+ * \brief Note that a particular sequence has been sent
+ * \param seq the packet sequence number.
+ * \param size the packet size.
+ */
+ virtual void SentSeq (SequenceNumber32 seq, uint32_t size);
+
+ /**
+ * \brief Note that a particular ack sequence has been received
+ * \param ackSeq the ack sequence number.
+ * \return The measured RTT for this ack.
+ */
+ virtual Time AckSeq (SequenceNumber32 ackSeq);
+
+ /**
+ * \brief Clear all history entries
+ */
+ virtual void ClearSent ();
+
+ /**
+ * \brief Add a new measurement to the estimator. Pure virtual function.
+ * \param t the new RTT measure.
+ */
+ virtual void Measurement (Time t) = 0;
+
+ /**
+ * \brief Returns the estimated RTO. Pure virtual function.
+ * \return the estimated RTO.
+ */
+ virtual Time RetransmitTimeout () = 0;
+
+ virtual Ptr<RttEstimator> Copy () const = 0;
+
+ /**
+ * \brief Increase the estimation multiplier up to MaxMultiplier.
+ */
+ virtual void IncreaseMultiplier ();
+
+ /**
+ * \brief Resets the estimation multiplier to 1.
+ */
+ virtual void ResetMultiplier ();
+
+ /**
+ * \brief Resets the estimation to its initial state.
+ */
+ virtual void Reset ();
+
+ /**
+ * \brief Sets the Minimum RTO.
+ * \param minRto The minimum RTO returned by the estimator.
+ */
+ void SetMinRto (Time minRto);
+
+ /**
+ * \brief Get the Minimum RTO.
+ * \return The minimum RTO returned by the estimator.
+ */
+ Time GetMinRto (void) const;
+
+ /**
+ * \brief Sets the Maximum RTO.
+ * \param minRto The maximum RTO returned by the estimator.
+ */
+ void SetMaxRto (Time maxRto);
+
+ /**
+ * \brief Get the Maximum RTO.
+ * \return The maximum RTO returned by the estimator.
+ */
+ Time GetMaxRto (void) const;
+
+ /**
+ * \brief Sets the current RTT estimate (forcefully).
+ * \param estimate The current RTT estimate.
+ */
+ void SetCurrentEstimate (Time estimate);
+
+ /**
+ * \brief gets the current RTT estimate.
+ * \return The current RTT estimate.
+ */
+ Time GetCurrentEstimate (void) const;
+
+private:
+ SequenceNumber32 m_next; // Next expected sequence to be sent
+ uint16_t m_maxMultiplier;
+ Time m_initialEstimatedRtt;
+
+protected:
+ Time m_currentEstimatedRtt; // Current estimate
+ Time m_minRto; // minimum value of the timeout
+ Time m_maxRto; // maximum value of the timeout
+ uint32_t m_nSamples; // Number of samples
+ uint16_t m_multiplier; // RTO Multiplier
+ RttHistory_t m_history; // List of sent packet
+};
+
+} // namespace ndn
+
+} // namespace ns3
+
+#endif /* RTT_ESTIMATOR_H */