NS-3 based Named Data Networking (NDN) simulator
ndnSIM 2.3: NDN, CCN, CCNx, content centric networks
API Documentation
ndn-rtt-estimator.cpp
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1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
2 //
3 // Copyright (c) 2006 Georgia Tech Research Corporation
4 //
5 // This program is free software; you can redistribute it and/or modify
6 // it under the terms of the GNU General Public License version 2 as
7 // published by the Free Software Foundation;
8 //
9 // This program is distributed in the hope that it will be useful,
10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 // GNU General Public License for more details.
13 //
14 // You should have received a copy of the GNU General Public License
15 // along with this program; if not, write to the Free Software
16 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17 //
18 // Author: Rajib Bhattacharjea<raj.b@gatech.edu>
19 //
20 
21 // THIS IS A COPY OF rtt-estimator.cc from internet module with minor modifications
22 
23 // Ported from:
24 // Georgia Tech Network Simulator - Round Trip Time Estimation Class
25 // George F. Riley. Georgia Tech, Spring 2002
26 
27 // Implements several variations of round trip time estimators
28 
29 #include <iostream>
30 
31 #include "ndn-rtt-estimator.hpp"
32 #include "ns3/simulator.h"
33 #include "ns3/double.h"
34 #include "ns3/integer.h"
35 #include "ns3/uinteger.h"
36 #include "ns3/log.h"
37 
38 NS_LOG_COMPONENT_DEFINE("ndn.RttEstimator");
39 
40 namespace ns3 {
41 
42 namespace ndn {
43 
45 
46 TypeId
48 {
49  static TypeId tid =
50  TypeId("ns3::ndn::RttEstimator")
51  .SetParent<Object>()
52  .AddAttribute("MaxMultiplier", "Maximum RTO Multiplier", UintegerValue(64),
53  MakeUintegerAccessor(&RttEstimator::m_maxMultiplier),
54  MakeUintegerChecker<uint16_t>())
55  .AddAttribute("InitialEstimation", "Initial RTT estimation", TimeValue(Seconds(1.0)),
56  MakeTimeAccessor(&RttEstimator::m_initialEstimatedRtt), MakeTimeChecker())
57  .AddAttribute("MinRTO", "Minimum retransmit timeout value",
58  TimeValue(
59  Seconds(0.2)), // RFC2988 says min RTO=1 sec, but Linux uses 200ms. See
60  // http://www.postel.org/pipermail/end2end-interest/2004-November/004402.html
62  MakeTimeChecker())
63  .AddAttribute("MaxRTO", "Maximum retransmit timeout value", TimeValue(Seconds(200.0)),
65  MakeTimeChecker());
66  return tid;
67 }
68 
69 void
71 {
72  NS_LOG_FUNCTION(this << minRto);
73  m_minRto = minRto;
74 }
75 Time
77 {
78  return m_minRto;
79 }
80 
81 void
83 {
84  NS_LOG_FUNCTION(this << maxRto);
85  m_maxRto = maxRto;
86 }
87 Time
89 {
90  return m_maxRto;
91 }
92 
93 void
95 {
96  NS_LOG_FUNCTION(this << estimate);
97  m_currentEstimatedRtt = estimate;
98 }
99 Time
101 {
102  return m_currentEstimatedRtt;
103 }
104 
105 // RttHistory methods
106 RttHistory::RttHistory(SequenceNumber32 s, uint32_t c, Time t)
107  : seq(s)
108  , count(c)
109  , time(t)
110  , retx(false)
111 {
112  NS_LOG_FUNCTION(this);
113 }
114 
116  : seq(h.seq)
117  , count(h.count)
118  , time(h.time)
119  , retx(h.retx)
120 {
121  NS_LOG_FUNCTION(this);
122 }
123 
124 // Base class methods
125 
127  : m_next(1)
128  , m_nSamples(0)
129  , m_multiplier(1)
130  , m_history()
131 {
132  NS_LOG_FUNCTION(this);
133  // note next=1 everywhere since first segment will have sequence 1
134 
135  // We need attributes initialized here, not later, so use the
136  // ConstructSelf() technique documented in the manual
137  ObjectBase::ConstructSelf(AttributeConstructionList());
138  m_currentEstimatedRtt = m_initialEstimatedRtt;
139  NS_LOG_DEBUG("Initialize m_currentEstimatedRtt to " << m_currentEstimatedRtt.GetSeconds()
140  << " sec.");
141 }
142 
144  : Object(c)
145  , m_next(c.m_next)
146  , m_maxMultiplier(c.m_maxMultiplier)
147  , m_initialEstimatedRtt(c.m_initialEstimatedRtt)
149  , m_minRto(c.m_minRto)
150  , m_maxRto(c.m_maxRto)
153  , m_history(c.m_history)
154 {
155  NS_LOG_FUNCTION(this);
156 }
157 
159 {
160  NS_LOG_FUNCTION(this);
161 }
162 
163 TypeId
165 {
166  return GetTypeId();
167 }
168 
169 void
170 RttEstimator::SentSeq(SequenceNumber32 seq, uint32_t size)
171 {
172  NS_LOG_FUNCTION(this << seq << size);
173  // Note that a particular sequence has been sent
174  if (seq == m_next) { // This is the next expected one, just log at end
175  m_history.push_back(RttHistory(seq, size, Simulator::Now()));
176  m_next = seq + SequenceNumber32(size); // Update next expected
177  }
178  else { // This is a retransmit, find in list and mark as re-tx
179  for (RttHistory_t::iterator i = m_history.begin(); i != m_history.end(); ++i) {
180  if ((seq >= i->seq) && (seq < (i->seq + SequenceNumber32(i->count)))) { // Found it
181  i->retx = true;
182  // One final test..be sure this re-tx does not extend "next"
183  if ((seq + SequenceNumber32(size)) > m_next) {
184  m_next = seq + SequenceNumber32(size);
185  i->count = ((seq + SequenceNumber32(size)) - i->seq); // And update count in hist
186  }
187  break;
188  }
189  }
190  }
191 }
192 
193 Time
194 RttEstimator::AckSeq(SequenceNumber32 ackSeq)
195 {
196  NS_LOG_FUNCTION(this << ackSeq);
197  // An ack has been received, calculate rtt and log this measurement
198  // Note we use a linear search (O(n)) for this since for the common
199  // case the ack'ed packet will be at the head of the list
200  Time m = Seconds(0.0);
201  if (m_history.size() == 0)
202  return (m); // No pending history, just exit
203  RttHistory& h = m_history.front();
204  if (!h.retx && ackSeq >= (h.seq + SequenceNumber32(h.count))) { // Ok to use this sample
205  m = Simulator::Now() - h.time; // Elapsed time
206  Measurement(m); // Log the measurement
207  ResetMultiplier(); // Reset multiplier on valid measurement
208  }
209  // Now delete all ack history with seq <= ack
210  while (m_history.size() > 0) {
211  RttHistory& h = m_history.front();
212  if ((h.seq + SequenceNumber32(h.count)) > ackSeq)
213  break; // Done removing
214  m_history.pop_front(); // Remove
215  }
216  return m;
217 }
218 
219 void
221 {
222  NS_LOG_FUNCTION(this);
223  // Clear all history entries
224  m_next = 1;
225  m_history.clear();
226 }
227 
228 void
230 {
231  NS_LOG_FUNCTION(this);
232  m_multiplier = (m_multiplier * 2 < m_maxMultiplier) ? m_multiplier * 2 : m_maxMultiplier;
233  NS_LOG_DEBUG("Multiplier increased to " << m_multiplier);
234 }
235 
236 void
238 {
239  NS_LOG_FUNCTION(this);
240  m_multiplier = 1;
241 }
242 
243 void
245 {
246  NS_LOG_FUNCTION(this);
247  // Reset to initial state
248  m_next = 1;
249  m_currentEstimatedRtt = m_initialEstimatedRtt;
250  m_history.clear(); // Remove all info from the history
251  m_nSamples = 0;
252  ResetMultiplier();
253 }
254 
255 } // namespace ndn
256 } // namespace ns3
RttHistory(SequenceNumber32 s, uint32_t c, Time t)
virtual void SentSeq(SequenceNumber32 seq, uint32_t size)
Note that a particular sequence has been sent.
Copyright (c) 2011-2015 Regents of the University of California.
Time GetCurrentEstimate(void) const
gets the current RTT estimate.
static TypeId GetTypeId(void)
NS_OBJECT_ENSURE_REGISTERED(ContentStore)
void SetMaxRto(Time maxRto)
Sets the Maximum RTO.
virtual void Measurement(Time t)=0
Add a new measurement to the estimator.
virtual Time AckSeq(SequenceNumber32 ackSeq)
Note that a particular ack sequence has been received.
virtual void Reset()
Resets the estimation to its initial state.
virtual void ClearSent()
Clear all history entries.
void SetMinRto(Time minRto)
Sets the Minimum RTO.
Table::const_iterator iterator
Definition: cs-internal.hpp:41
void SetCurrentEstimate(Time estimate)
Sets the current RTT estimate (forcefully).
Time GetMaxRto(void) const
Get the Maximum RTO.
virtual TypeId GetInstanceTypeId(void) const
virtual void IncreaseMultiplier()
Increase the estimation multiplier up to MaxMultiplier.
virtual void ResetMultiplier()
Resets the estimation multiplier to 1.
Copyright (c) 2011-2015 Regents of the University of California.
Base class for all RTT Estimators.
Helper class to store RTT measurements.
ndn RttEstimator
Time GetMinRto(void) const
Get the Minimum RTO.