text: /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
  /*
   * Copyright (c) 2016 ResiliNets, ITTC, University of Kansas
   *
   * 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: Truc Anh N. Nguyen <annguyen@ittc.ku.edu>
   *
   * James P.G. Sterbenz <jpgs@ittc.ku.edu>, director
   * ResiliNets Research Group  http://wiki.ittc.ku.edu/resilinets
   * Information and Telecommunication Technology Center (ITTC)
   * and Department of Electrical Engineering and Computer Science
   * The University of Kansas Lawrence, KS USA.
   */
  
  #include "ns3/test.h"
  #include "ns3/log.h"
  #include "ns3/tcp-congestion-ops.h"
  #include "ns3/tcp-socket-base.h"
  #include "ns3/tcp-vegas.h"
  
  using namespace ns3;
  
  NS_LOG_COMPONENT_DEFINE ("TcpVegasTestSuite");
  
  /**
   * \brief TcpVegas congestion control algorithm test
   */
  class TcpVegasTest : public TestCase
  {
  public:
    /**
     * \brief Constructor.
     * \param cWnd Congestion window.
     * \param segmentSize Segment size.
     * \param ssThresh Slow Start Threshold.
     * \param rtt The RTT.
     * \param segmentsAcked Number of segments ACKed.
     * \param nextTxSeq Next Tx sequence number.
     * \param lastAckedSeq Last ACKed sequence number.
     * \param name Test description.
     */
    TcpVegasTest (uint32_t cWnd,
                  uint32_t segmentSize,
                  uint32_t ssThresh,
                  Time rtt,
                  uint32_t segmentsAcked,
                  SequenceNumber32 nextTxSeq,
                  SequenceNumber32 lastAckedSeq,
                  const std::string &name);
  
  private:
    virtual void DoRun (void);
    /**
     * \brief Increases the TCP window.
     * \param cong The congestion control.
     */
    void IncreaseWindow (Ptr<TcpVegas> cong);
    /**
     * brief Get and check the SSH threshold.
     * \param cong The congestion control.
     */
    void GetSsThresh (Ptr<TcpVegas> cong);
  
    uint32_t m_cWnd;        //!< Congestion window.
    uint32_t m_segmentSize; //!< Segment size.
    uint32_t m_ssThresh;    //!< Slow Start Threshold.
    Time m_rtt;             //!< RTT.
    uint32_t m_segmentsAcked; //!< Number of segments ACKed.
    SequenceNumber32 m_nextTxSeq; //!< Next Tx sequence number.
    SequenceNumber32 m_lastAckedSeq;  //!< Last ACKed sequence number.
  
    Ptr<TcpSocketState> m_state;  //!< TCP socket state.
  };
  
  TcpVegasTest::TcpVegasTest (uint32_t cWnd,
                              uint32_t segmentSize,
                              uint32_t ssThresh,
                              Time rtt,
                              uint32_t segmentsAcked,
                              SequenceNumber32 nextTxSeq,
                              SequenceNumber32 lastAckedSeq,
                              const std::string &name)
    : TestCase (name),
      m_cWnd (cWnd),
      m_segmentSize (segmentSize),
      m_ssThresh (ssThresh),
      m_rtt (rtt),
      m_segmentsAcked (segmentsAcked),
      m_nextTxSeq (nextTxSeq),
      m_lastAckedSeq (lastAckedSeq)
  {
  }
  
  void
  TcpVegasTest::DoRun ()
  {
    m_state = CreateObject<TcpSocketState> ();
  
    m_state->m_cWnd = m_cWnd;
    m_state->m_segmentSize = m_segmentSize;
    m_state->m_ssThresh = m_ssThresh;
    m_state->m_nextTxSequence = m_nextTxSeq;
    m_state->m_lastAckedSeq = m_lastAckedSeq;
  
    Ptr<TcpVegas> cong = CreateObject <TcpVegas> ();
  
    // Set baseRtt to 100 ms
    cong->PktsAcked (m_state, m_segmentsAcked, MilliSeconds (100));
  
    // Re-set Vegas to assign a new value of minRtt
    cong->CongestionStateSet (m_state, TcpSocketState::CA_OPEN);
    cong->PktsAcked (m_state, m_segmentsAcked, m_rtt);
  
    // 2 more calls to PktsAcked to increment cntRtt beyond 2
    cong->PktsAcked (m_state, m_segmentsAcked, m_rtt);
    cong->PktsAcked (m_state, m_segmentsAcked, m_rtt);
  
    // Update cwnd using Vegas algorithm
    cong->IncreaseWindow (m_state, m_segmentsAcked);
  
    // Our calculation of cwnd
    IncreaseWindow (cong);
  
    NS_TEST_ASSERT_MSG_EQ (m_state->m_cWnd.Get (), m_cWnd,
                           "CWnd has not updated correctly");
    NS_TEST_ASSERT_MSG_EQ (m_state->m_ssThresh.Get (), m_ssThresh,
                           "SsThresh has not updated correctly");
  }
  
  void
  TcpVegasTest::IncreaseWindow (Ptr<TcpVegas> cong)
  {
    Time baseRtt = MilliSeconds (100);
    uint32_t segCwnd = m_cWnd / m_segmentSize;
  
    // Calculate expected throughput
    uint64_t expectedCwnd;
    expectedCwnd = (uint64_t) segCwnd * (double) baseRtt.GetMilliSeconds () / (double) m_rtt.GetMilliSeconds ();
  
    // Calculate the difference between actual and expected throughput
    uint32_t diff;
    diff = segCwnd - expectedCwnd;
  
    // Get the alpha,beta, and gamma attributes
    UintegerValue alpha, beta, gamma;
    cong->GetAttribute ("Alpha", alpha);
    cong->GetAttribute ("Beta", beta);
    cong->GetAttribute ("Gamma", gamma);
  
    if (diff > gamma.Get () && (m_cWnd < m_ssThresh))
      { // Change from slow-start to linear increase/decrease mode
        segCwnd = std::min (segCwnd, (uint32_t) expectedCwnd + 1);
        m_cWnd = segCwnd * m_segmentSize;
        GetSsThresh (cong);
      }
    else if (m_cWnd < m_ssThresh)
      { // Execute Reno slow start
        if (m_segmentsAcked >= 1)
          {
            m_cWnd += m_segmentSize;
            m_segmentsAcked--;
          }
      }
    else
      { // Linear increase/decrease mode
        if (diff > beta.Get ())
          {
            m_cWnd = (segCwnd - 1) * m_segmentSize;
            GetSsThresh (cong);
          }
        else if (diff < alpha.Get ())
          {
            m_cWnd = (segCwnd + 1) * m_segmentSize;
          }
        else
          {
          }
      }
    m_ssThresh = std::max (m_ssThresh, 3 * m_cWnd / 4);
  }
  
  void
  TcpVegasTest::GetSsThresh (Ptr<TcpVegas> cong)
  {
    m_ssThresh = std::max (std::min (m_ssThresh, m_cWnd - m_segmentSize), 2 * m_segmentSize);
  }
  
  
  /**
   * \ingroup internet-test
   * \ingroup tests
   *
   * \brief TCP Vegas TestSuite
   */
  class TcpVegasTestSuite : public TestSuite
  {
  public:
    TcpVegasTestSuite () : TestSuite ("tcp-vegas-test", UNIT)
    {
      AddTestCase (new TcpVegasTest (38 * 1446, 1446, 40 * 1446, MilliSeconds (106), 1, SequenceNumber32 (2893), SequenceNumber32 (5785),
                                     "Vegas test on cWnd and ssThresh when in slow start and diff > gamma"),
                   TestCase::QUICK);
      AddTestCase (new TcpVegasTest (5 * 536, 536, 10 * 536, MilliSeconds (118), 1, SequenceNumber32 (3216), SequenceNumber32 (3753),
                                     "Vegas test on cWnd and ssThresh when in slow start and diff < gamma"),
                   TestCase::QUICK);
      AddTestCase (new TcpVegasTest (60 * 346, 346, 40 * 346, MilliSeconds (206), 1, SequenceNumber32 (20761), SequenceNumber32 (21107),
                                     "Vegas test on cWnd and ssThresh when diff > beta"),
                   TestCase::QUICK);
      AddTestCase (new TcpVegasTest (15 * 1446, 1446, 10 * 1446, MilliSeconds (106), 1, SequenceNumber32 (21691), SequenceNumber32 (24583),
                                     "Vegas test on cWnd and ssThresh when diff < alpha"),
                   TestCase::QUICK);
      AddTestCase (new TcpVegasTest (20 * 746, 746, 10 * 746, MilliSeconds (109), 1, SequenceNumber32 (14921), SequenceNumber32 (15667),
                                     "Vegas test on cWnd and ssThresh when alpha <= diff <= beta"),
                   TestCase::QUICK);
    }
  };
  
  static TcpVegasTestSuite g_tcpVegasTest; //!< Static variable for test initialization
  