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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
* Copyright (c) 2014-2018 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 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 "notification-subscriber.hpp"
#include "random.hpp"
#include <cmath>
namespace ndn {
namespace util {
NotificationSubscriberBase::NotificationSubscriberBase(Face& face, const Name& prefix,
time::milliseconds interestLifetime)
: m_face(face)
, m_prefix(prefix)
, m_isRunning(false)
, m_lastSequenceNo(std::numeric_limits<uint64_t>::max())
, m_lastNackSequenceNo(std::numeric_limits<uint64_t>::max())
, m_attempts(1)
, m_scheduler(face.getIoService())
, m_nackEvent(m_scheduler)
, m_lastInterestId(nullptr)
, m_interestLifetime(interestLifetime)
{
}
NotificationSubscriberBase::~NotificationSubscriberBase() = default;
void
NotificationSubscriberBase::start()
{
if (m_isRunning) // already running
return;
m_isRunning = true;
sendInitialInterest();
}
void
NotificationSubscriberBase::stop()
{
if (!m_isRunning) // not running
return;
m_isRunning = false;
if (m_lastInterestId != nullptr)
m_face.removePendingInterest(m_lastInterestId);
m_lastInterestId = nullptr;
}
void
NotificationSubscriberBase::sendInitialInterest()
{
if (shouldStop())
return;
auto interest = make_shared<Interest>(m_prefix);
interest->setCanBePrefix(true);
interest->setMustBeFresh(true);
interest->setChildSelector(1);
interest->setInterestLifetime(getInterestLifetime());
m_lastInterestId = m_face.expressInterest(*interest,
[this] (const auto&, const auto& d) { this->afterReceiveData(d); },
[this] (const auto&, const auto& n) { this->afterReceiveNack(n); },
[this] (const auto&) { this->afterTimeout(); });
}
void
NotificationSubscriberBase::sendNextInterest()
{
if (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);
auto interest = make_shared<Interest>(nextName);
interest->setCanBePrefix(false);
interest->setInterestLifetime(getInterestLifetime());
m_lastInterestId = m_face.expressInterest(*interest,
[this] (const auto&, const auto& d) { this->afterReceiveData(d); },
[this] (const auto&, const auto& n) { this->afterReceiveNack(n); },
[this] (const auto&) { this->afterTimeout(); });
}
bool
NotificationSubscriberBase::shouldStop()
{
if (!m_isRunning)
return true;
if (!hasSubscriber() && onNack.isEmpty()) {
stop();
return true;
}
return false;
}
void
NotificationSubscriberBase::afterReceiveData(const Data& data)
{
if (shouldStop())
return;
try {
m_lastSequenceNo = data.getName().get(-1).toSequenceNumber();
}
catch (const tlv::Error&) {
onDecodeError(data);
sendInitialInterest();
return;
}
if (!decodeAndDeliver(data)) {
onDecodeError(data);
sendInitialInterest();
return;
}
sendNextInterest();
}
void
NotificationSubscriberBase::afterReceiveNack(const lp::Nack& nack)
{
if (shouldStop())
return;
onNack(nack);
time::milliseconds delay = exponentialBackoff(nack);
m_nackEvent = m_scheduler.scheduleEvent(delay, [this] { sendInitialInterest(); });
}
void
NotificationSubscriberBase::afterTimeout()
{
if (shouldStop())
return;
onTimeout();
sendInitialInterest();
}
time::milliseconds
NotificationSubscriberBase::exponentialBackoff(lp::Nack nack)
{
uint64_t nackSequenceNo;
try {
nackSequenceNo = nack.getInterest().getName().get(-1).toSequenceNumber();
}
catch (const tlv::Error&) {
nackSequenceNo = 0;
}
if (m_lastNackSequenceNo == nackSequenceNo) {
++m_attempts;
}
else {
m_attempts = 1;
}
m_lastNackSequenceNo = nackSequenceNo;
return time::milliseconds(static_cast<time::milliseconds::rep>(std::pow(2, m_attempts) * 100 +
random::generateWord32() % 100));
}
} // namespace util
} // namespace ndn