util: Porting NotificationSubscriber, FaceMonitor, and NotificationStream from NFD

New generic classes:
- `util::NotificationSubscriber` (`util/notification-subscriber.hpp`)
- `util::NotificationStream` (`util/notification-stream.hpp`)

NFD Face monitoring class:
- `nfd::FaceMonitor` (`management/nfd-face-monitor.hpp`)

Change-Id: I2ab0a2cd9d7e3ac07036f290f0b4de5eb16e6e38
diff --git a/tests/unit-tests/util/notification-subscriber.cpp b/tests/unit-tests/util/notification-subscriber.cpp
new file mode 100644
index 0000000..1633ccf
--- /dev/null
+++ b/tests/unit-tests/util/notification-subscriber.cpp
@@ -0,0 +1,240 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * 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.
+ */
+
+/**
+ * Original copyright notice from NFD:
+ *
+ * Copyright (c) 2014,  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 "util/notification-subscriber.hpp"
+#include "util/notification-stream.hpp"
+#include "simple-notification.hpp"
+
+#include "boost-test.hpp"
+#include "../dummy-client-face.hpp"
+
+namespace ndn {
+namespace tests {
+
+BOOST_AUTO_TEST_SUITE(UtilNotificationSubscriber)
+
+class EndToEndFixture
+{
+public:
+  EndToEndFixture()
+    : streamPrefix("ndn:/NotificationSubscriberTest")
+    , publisherFace(makeDummyClientFace())
+    , notificationStream(*publisherFace, streamPrefix, publisherKeyChain)
+    , subscriberFace(makeDummyClientFace())
+    , subscriber(*subscriberFace, streamPrefix, time::seconds(1))
+  {
+  }
+
+  /** \brief post one notification and deliver to subscriber
+   */
+  void
+  deliverNotification(const std::string& msg)
+  {
+    publisherFace->m_sentDatas.clear();
+    SimpleNotification notification(msg);
+    notificationStream.postNotification(notification);
+    publisherFace->processEvents();
+    BOOST_REQUIRE_EQUAL(publisherFace->m_sentDatas.size(), 1);
+
+    lastDeliveredSeqNo = publisherFace->m_sentDatas[0].getName().at(-1).toSequenceNumber();
+
+    lastNotification.setMessage("");
+    subscriberFace->receive(publisherFace->m_sentDatas[0]);
+  }
+
+  void
+  afterNotification(const SimpleNotification& notification)
+  {
+    lastNotification = notification;
+  }
+
+  void
+  clearNotificationHandlers()
+  {
+    subscriber.onNotification.clear();
+  }
+
+  void
+  afterTimeout()
+  {
+    hasTimeout = true;
+  }
+
+  void
+  afterDecodeError(const Data& data)
+  {
+    lastDecodeErrorData = data;
+  }
+
+  /** \return true if subscriberFace has an initial request (first sent Interest)
+   */
+  bool
+  hasInitialRequest() const
+  {
+    if (subscriberFace->m_sentInterests.empty())
+      return 0;
+
+    const Interest& interest = subscriberFace->m_sentInterests[0];
+    return interest.getName() == streamPrefix &&
+           interest.getChildSelector() == 1 &&
+           interest.getMustBeFresh() &&
+           interest.getInterestLifetime() == subscriber.getInterestLifetime();
+  }
+
+  /** \return sequence number of the continuation request sent from subscriberFace
+   *          or 0 if there's no such request as sole sent Interest
+   */
+  uint64_t
+  getRequestSeqNo() const
+  {
+    if (subscriberFace->m_sentInterests.size() != 1)
+      return 0;
+
+    const Interest& interest = subscriberFace->m_sentInterests[0];
+    const Name& name = interest.getName();
+    if (streamPrefix.isPrefixOf(name) &&
+        name.size() == streamPrefix.size() + 1 &&
+        interest.getInterestLifetime() == subscriber.getInterestLifetime())
+      return name[-1].toSequenceNumber();
+    else
+      return 0;
+  }
+
+protected:
+  Name streamPrefix;
+  shared_ptr<DummyClientFace> publisherFace;
+  ndn::KeyChain publisherKeyChain;
+  util::NotificationStream<SimpleNotification> notificationStream;
+  shared_ptr<DummyClientFace> subscriberFace;
+  util::NotificationSubscriber<SimpleNotification> subscriber;
+
+  uint64_t lastDeliveredSeqNo;
+
+  SimpleNotification lastNotification;
+  bool hasTimeout;
+  Data lastDecodeErrorData;
+};
+
+BOOST_FIXTURE_TEST_CASE(EndToEnd, EndToEndFixture)
+{
+  BOOST_REQUIRE_EQUAL(subscriber.isRunning(), false);
+
+  // has no effect because onNotification has no handler
+  subscriber.start();
+  BOOST_REQUIRE_EQUAL(subscriber.isRunning(), false);
+
+  subscriber.onNotification += bind(&EndToEndFixture::afterNotification, this, _1);
+  subscriber.onTimeout += bind(&EndToEndFixture::afterTimeout, this);
+  subscriber.onDecodeError += bind(&EndToEndFixture::afterDecodeError, this, _1);
+
+  // not received when subscriber is not running
+  this->deliverNotification("n1");
+  subscriberFace->processEvents(time::milliseconds(10));
+  BOOST_CHECK(lastNotification.getMessage().empty());
+  BOOST_CHECK_EQUAL(subscriberFace->m_sentInterests.size(), 0);
+
+  subscriberFace->m_sentInterests.clear();
+  subscriber.start();
+  subscriberFace->processEvents(time::milliseconds(10));
+  BOOST_REQUIRE_EQUAL(subscriber.isRunning(), true);
+  BOOST_CHECK(this->hasInitialRequest());
+
+  // respond to initial request
+  subscriberFace->m_sentInterests.clear();
+  this->deliverNotification("n2");
+  subscriberFace->processEvents(time::milliseconds(10));
+  BOOST_CHECK_EQUAL(lastNotification.getMessage(), "n2");
+  BOOST_CHECK_EQUAL(this->getRequestSeqNo(), lastDeliveredSeqNo + 1);
+
+  // respond to continuation request
+  subscriberFace->m_sentInterests.clear();
+  this->deliverNotification("n3");
+  subscriberFace->processEvents(time::milliseconds(10));
+  BOOST_CHECK_EQUAL(lastNotification.getMessage(), "n3");
+  BOOST_CHECK_EQUAL(this->getRequestSeqNo(), lastDeliveredSeqNo + 1);
+
+  // timeout
+  subscriberFace->m_sentInterests.clear();
+  lastNotification.setMessage("");
+  subscriberFace->processEvents(2 * subscriber.getInterestLifetime());
+  BOOST_CHECK(lastNotification.getMessage().empty());
+  BOOST_CHECK_EQUAL(hasTimeout, true);
+  BOOST_CHECK(this->hasInitialRequest());
+
+  // decode error on sequence number
+  Name wrongName = streamPrefix;
+  wrongName.append("%07%07");
+  Data wrongData(wrongName);
+  publisherKeyChain.sign(wrongData);
+  subscriberFace->receive(wrongData);
+  subscriberFace->m_sentInterests.clear();
+  lastNotification.setMessage("");
+  subscriberFace->processEvents(time::milliseconds(10));
+  BOOST_CHECK(lastNotification.getMessage().empty());
+  BOOST_CHECK_EQUAL(lastDecodeErrorData.getName(), wrongName);
+  BOOST_CHECK(this->hasInitialRequest());
+
+  // decode error in payload
+  subscriberFace->m_sentInterests.clear();
+  lastNotification.setMessage("");
+  this->deliverNotification("\x07n4");
+  subscriberFace->processEvents(time::milliseconds(10));
+  BOOST_CHECK(lastNotification.getMessage().empty());
+  BOOST_CHECK(this->hasInitialRequest());
+
+  // stop if handlers are cleared
+  subscriber.onNotification += bind(&EndToEndFixture::clearNotificationHandlers, this);
+  subscriberFace->m_sentInterests.clear();
+  this->deliverNotification("n5");
+  subscriberFace->processEvents(time::milliseconds(10));
+  BOOST_CHECK_EQUAL(subscriberFace->m_sentInterests.size(), 0);
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // namespace tests
+} // namespace ndn