util: add afterMeasurement signal to RttEstimator

Refs: #4887
Change-Id: Ie48871a346f2960a7894c45a9386c52f3e1d9af2
diff --git a/tests/unit/util/rtt-estimator.t.cpp b/tests/unit/util/rtt-estimator.t.cpp
new file mode 100644
index 0000000..01fe4f8
--- /dev/null
+++ b/tests/unit/util/rtt-estimator.t.cpp
@@ -0,0 +1,183 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2016-2019, Regents of the University of California,
+ *                          Colorado State University,
+ *                          University Pierre & Marie Curie, Sorbonne University.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "ndn-cxx/util/rtt-estimator.hpp"
+
+#include "tests/boost-test.hpp"
+
+#include <cmath>
+
+namespace ndn {
+namespace util {
+namespace tests {
+
+BOOST_AUTO_TEST_SUITE(Util)
+BOOST_AUTO_TEST_SUITE(TestRttEstimator)
+
+using Millis = RttEstimator::MillisecondsDouble;
+
+BOOST_AUTO_TEST_CASE(MinAvgMaxRtt)
+{
+  RttEstimator rttEstimator;
+
+  // check initial values
+  BOOST_CHECK_CLOSE(rttEstimator.getMinRtt().count(), std::numeric_limits<double>::max(), 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getAvgRtt().count(), 0.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getMaxRtt().count(), std::numeric_limits<double>::min(), 0.001);
+
+  // start with three samples
+  rttEstimator.addMeasurement(Millis(100), 1);
+  rttEstimator.addMeasurement(Millis(400), 1);
+  rttEstimator.addMeasurement(Millis(250), 1);
+
+  BOOST_CHECK_CLOSE(rttEstimator.getMinRtt().count(), 100.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getAvgRtt().count(), 250.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getMaxRtt().count(), 400.0, 0.001);
+
+  // add another sample (new minimum)
+  rttEstimator.addMeasurement(Millis(50), 2);
+  BOOST_CHECK_CLOSE(rttEstimator.getMinRtt().count(), 50.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getAvgRtt().count(), 200.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getMaxRtt().count(), 400.0, 0.001);
+
+  // add another sample (new maximum)
+  rttEstimator.addMeasurement(Millis(700), 1);
+  BOOST_CHECK_CLOSE(rttEstimator.getMinRtt().count(), 50.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getAvgRtt().count(), 300.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getMaxRtt().count(), 700.0, 0.001);
+}
+
+BOOST_AUTO_TEST_CASE(EstimatedRto)
+{
+  RttEstimator::Options opts;
+  opts.initialRto = Millis(1000);
+  opts.maxRto = Millis(4000);
+  RttEstimator rttEstimator(opts);
+
+  // check initial values
+  BOOST_CHECK(std::isnan(rttEstimator.m_sRtt.count()));
+  BOOST_CHECK(std::isnan(rttEstimator.m_rttVar.count()));
+  BOOST_CHECK_CLOSE(rttEstimator.getEstimatedRto().count(), 1000.0, 0.001);
+
+  // first measurement
+  rttEstimator.addMeasurement(Millis(100), 1);
+
+  BOOST_CHECK_CLOSE(rttEstimator.m_sRtt.count(), 100.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.m_rttVar.count(), 50.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getEstimatedRto().count(), 300.0, 0.001);
+
+  rttEstimator.m_sRtt = Millis(500);
+  rttEstimator.m_rttVar = Millis(100);
+  rttEstimator.m_rto = Millis(900);
+
+  rttEstimator.addMeasurement(Millis(100), 1);
+
+  BOOST_CHECK_CLOSE(rttEstimator.m_sRtt.count(), 450.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.m_rttVar.count(), 175.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getEstimatedRto().count(), 1150.0, 0.001);
+
+  // expected samples larger than 1
+  rttEstimator.addMeasurement(Millis(100), 5);
+
+  BOOST_CHECK_CLOSE(rttEstimator.m_sRtt.count(), 441.25, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.m_rttVar.count(), 183.75, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getEstimatedRto().count(), 1176.25, 0.001);
+
+  rttEstimator.m_sRtt = Millis(100.0);
+  rttEstimator.m_rttVar = Millis(30.0);
+  rttEstimator.m_rto = Millis(220.0);
+
+  // check if minRto works
+  rttEstimator.addMeasurement(Millis(100), 1);
+
+  BOOST_CHECK_CLOSE(rttEstimator.m_sRtt.count(), 100.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.m_rttVar.count(), 22.5, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getEstimatedRto().count(), 200.0, 0.001);
+
+  rttEstimator.m_sRtt = Millis(2000);
+  rttEstimator.m_rttVar = Millis(400);
+  rttEstimator.m_rto = Millis(3600);
+
+  // check if maxRto works
+  rttEstimator.addMeasurement(Millis(100), 1);
+
+  BOOST_CHECK_CLOSE(rttEstimator.m_sRtt.count(), 1762.5, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.m_rttVar.count(), 775.0, 0.001);
+  BOOST_CHECK_CLOSE(rttEstimator.getEstimatedRto().count(), 4000.0, 0.001);
+}
+
+BOOST_AUTO_TEST_CASE(BackoffRto)
+{
+  RttEstimator::Options opts;
+  opts.initialRto = Millis(500);
+  opts.maxRto = Millis(4000);
+  RttEstimator rttEstimator(opts);
+
+  rttEstimator.backoffRto();
+  BOOST_CHECK_CLOSE(rttEstimator.getEstimatedRto().count(), 1000.0, 0.001);
+
+  // check if minRto works
+  rttEstimator.m_rto = Millis(10);
+  rttEstimator.backoffRto();
+  BOOST_CHECK_CLOSE(rttEstimator.getEstimatedRto().count(), 200.0, 0.001);
+
+  // check if maxRto works
+  rttEstimator.m_rto = Millis(3000);
+  rttEstimator.backoffRto();
+  BOOST_CHECK_CLOSE(rttEstimator.getEstimatedRto().count(), 4000.0, 0.001);
+}
+
+BOOST_AUTO_TEST_CASE(AfterMeasurement)
+{
+  RttEstimator rttEstimator;
+
+  int nHandlerInvocations = 0;
+  rttEstimator.afterMeasurement.connectSingleShot([&nHandlerInvocations] (const auto& sample) {
+    ++nHandlerInvocations;
+    BOOST_CHECK_CLOSE(sample.rtt.count(), 80.0, 0.001);
+    BOOST_CHECK_CLOSE(sample.sRtt.count(), 80.0, 0.001);
+    BOOST_CHECK_CLOSE(sample.rttVar.count(), 40.0, 0.001);
+    BOOST_CHECK_CLOSE(sample.rto.count(), 240.0, 0.001);
+    BOOST_CHECK(!sample.segNum.has_value());
+  });
+  rttEstimator.addMeasurement(Millis(80), 1);
+  BOOST_CHECK_EQUAL(nHandlerInvocations, 1);
+
+  rttEstimator.afterMeasurement.connectSingleShot([&nHandlerInvocations] (const auto& sample) {
+    ++nHandlerInvocations;
+    BOOST_CHECK_CLOSE(sample.rtt.count(), 40.0, 0.001);
+    BOOST_CHECK_CLOSE(sample.sRtt.count(), 75.0, 0.001);
+    BOOST_CHECK_CLOSE(sample.rttVar.count(), 40.0, 0.001);
+    BOOST_CHECK_CLOSE(sample.rto.count(), 235.0, 0.001);
+    BOOST_CHECK(sample.segNum == 42U);
+  });
+  rttEstimator.addMeasurement(Millis(40), 1, 42);
+  BOOST_CHECK_EQUAL(nHandlerInvocations, 2);
+}
+
+BOOST_AUTO_TEST_SUITE_END() // TestRttEstimator
+BOOST_AUTO_TEST_SUITE_END() // Util
+
+} // namespace tests
+} // namespace util
+} // namespace ndn