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/* -*- 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/>.
*/
#ifndef NDN_UTIL_NOTIFICATION_SUBSCRIBER_HPP
#define NDN_UTIL_NOTIFICATION_SUBSCRIBER_HPP
#include "event-emitter.hpp"
#include "../face.hpp"
#include "concepts.hpp"
#include <boost/concept_check.hpp>
namespace ndn {
namespace util {
/** \brief provides a subscriber of Notification Stream
* \sa http://redmine.named-data.net/projects/nfd/wiki/Notification
* \tparam Notification type of Notification item, appears in payload of Data packets
*/
template<typename Notification>
class NotificationSubscriber : noncopyable
{
public:
BOOST_CONCEPT_ASSERT((boost::DefaultConstructible<Notification>));
BOOST_CONCEPT_ASSERT((WireDecodable<Notification>));
/** \brief construct a NotificationSubscriber
* \note The subscriber is not started after construction.
* User should add one or more handlers to onNotification, and invoke .start().
*/
NotificationSubscriber(Face& face, const Name& prefix,
const time::milliseconds& interestLifetime = time::milliseconds(60000))
: m_face(face)
, m_prefix(prefix)
, m_isRunning(false)
, m_lastSequenceNo(std::numeric_limits<uint64_t>::max())
, m_lastInterestId(0)
, m_interestLifetime(interestLifetime)
{
}
virtual
~NotificationSubscriber()
{
}
/** \return InterestLifetime of Interests to retrieve notifications
* \details This must be greater than FreshnessPeriod of Notification Data packets,
* to ensure correct operation of this subscriber implementation.
*/
time::milliseconds
getInterestLifetime() const
{
return m_interestLifetime;
}
bool
isRunning() const
{
return m_isRunning;
}
/** \brief start or resume receiving notifications
* \note onNotification must have at least one listener,
* otherwise this operation has no effect.
*/
void
start()
{
if (m_isRunning) // already running
return;
m_isRunning = true;
this->sendInitialInterest();
}
/** \brief stop receiving notifications
*/
void
stop()
{
if (!m_isRunning) // not running
return;
m_isRunning = false;
if (m_lastInterestId != 0)
m_face.removePendingInterest(m_lastInterestId);
m_lastInterestId = 0;
}
public: // subscriptions
/** \brief fires when a Notification is received
* \note Removing all handlers will cause the subscriber to stop.
*/
EventEmitter<Notification> onNotification;
/** \brief fires when no Notification is received within .getInterestLifetime period
*/
EventEmitter<> onTimeout;
/** \brief fires when a Data packet in the Notification Stream cannot be decoded as Notification
*/
EventEmitter<Data> onDecodeError;
private:
void
sendInitialInterest()
{
if (this->shouldStop())
return;
shared_ptr<Interest> interest = make_shared<Interest>(m_prefix);
interest->setMustBeFresh(true);
interest->setChildSelector(1);
interest->setInterestLifetime(getInterestLifetime());
m_lastInterestId = m_face.expressInterest(*interest,
bind(&NotificationSubscriber<Notification>::afterReceiveData, this, _2),
bind(&NotificationSubscriber<Notification>::afterTimeout, this));
}
void
sendNextInterest()
{
if (this->shouldStop())
return;
BOOST_ASSERT(m_lastSequenceNo !=
std::numeric_limits<uint64_t>::max());// overflow or missing initial reply
Name nextName = m_prefix;
nextName.appendSequenceNumber(m_lastSequenceNo + 1);
shared_ptr<Interest> interest = make_shared<Interest>(nextName);
interest->setInterestLifetime(getInterestLifetime());
m_lastInterestId = m_face.expressInterest(*interest,
bind(&NotificationSubscriber<Notification>::afterReceiveData, this, _2),
bind(&NotificationSubscriber<Notification>::afterTimeout, this));
}
/** \brief Check if the subscriber is or should be stopped.
* \return true if the subscriber is stopped.
*/
bool
shouldStop()
{
if (!m_isRunning)
return true;
if (onNotification.isEmpty()) {
this->stop();
return true;
}
return false;
}
void
afterReceiveData(const Data& data)
{
if (this->shouldStop())
return;
Notification notification;
try {
m_lastSequenceNo = data.getName().get(-1).toSequenceNumber();
notification.wireDecode(data.getContent().blockFromValue());
}
catch (tlv::Error&) {
this->onDecodeError(data);
this->sendInitialInterest();
return;
}
this->onNotification(notification);
this->sendNextInterest();
}
void
afterTimeout()
{
if (this->shouldStop())
return;
this->onTimeout();
this->sendInitialInterest();
}
private:
Face& m_face;
Name m_prefix;
bool m_isRunning;
uint64_t m_lastSequenceNo;
const PendingInterestId* m_lastInterestId;
time::milliseconds m_interestLifetime;
};
} // namespace util
} // namespace ndn
#endif // NDN_UTIL_NOTIFICATION_SUBSCRIBER_HPP