notification-subscriber.hpp

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
#ifndef NDN_UTIL_NOTIFICATION_SUBSCRIBER_HPP
#define NDN_UTIL_NOTIFICATION_SUBSCRIBER_HPP

#include "../face.hpp"
#include "signal.hpp"
#include "concepts.hpp"
#include "time.hpp"
#include "scheduler.hpp"
#include "scheduler-scoped-event-id.hpp"
#include <boost/concept_check.hpp>

namespace ndn {
namespace util {

class NotificationSubscriberBase : noncopyable
{
public:
  virtual
  ~NotificationSubscriberBase();

  time::milliseconds
  getInterestLifetime() const
  {
    return m_interestLifetime;
  }

  bool
  isRunning() const
  {
    return m_isRunning;
  }

  void
  start();

  void
  stop();

protected:
  NotificationSubscriberBase(Face& face, const Name& prefix,
                             time::milliseconds interestLifetime);

private:
  void
  sendInitialInterest();

  void
  sendNextInterest();

  virtual bool
  hasSubscriber() const = 0;

  bool
  shouldStop();

  void
  afterReceiveData(const Data& data);

  virtual bool
  decodeAndDeliver(const Data& data) = 0;

  void
  afterReceiveNack(const lp::Nack& nack);

  void
  afterTimeout();

  time::milliseconds
  exponentialBackoff(lp::Nack nack);

public:
  signal::Signal<NotificationSubscriberBase, lp::Nack> onNack;

  signal::Signal<NotificationSubscriberBase> onTimeout;

  signal::Signal<NotificationSubscriberBase, Data> onDecodeError;

private:
  Face& m_face;
  Name m_prefix;
  bool m_isRunning;
  uint64_t m_lastSequenceNo;
  uint64_t m_lastNackSequenceNo;
  uint64_t m_attempts;
  util::scheduler::Scheduler m_scheduler;
  util::scheduler::ScopedEventId m_nackEvent;
  const PendingInterestId* m_lastInterestId;
  time::milliseconds m_interestLifetime;
};

template<typename Notification>
class NotificationSubscriber : public NotificationSubscriberBase
{
public:
  BOOST_CONCEPT_ASSERT((boost::DefaultConstructible<Notification>));
  BOOST_CONCEPT_ASSERT((WireDecodable<Notification>));

  NotificationSubscriber(Face& face, const Name& prefix,
                         time::milliseconds interestLifetime = time::seconds(60))
    : NotificationSubscriberBase(face, prefix, interestLifetime)
  {
  }

public:
  signal::Signal<NotificationSubscriber, Notification> onNotification;

private:
  bool
  hasSubscriber() const override
  {
    return !onNotification.isEmpty();
  }

  bool
  decodeAndDeliver(const Data& data) override
  {
    Notification notification;
    try {
      notification.wireDecode(data.getContent().blockFromValue());
    }
    catch (const tlv::Error&) {
      return false;
    }

    onNotification(notification);
    return true;
  }
};

} // namespace util
} // namespace ndn

#endif // NDN_UTIL_NOTIFICATION_SUBSCRIBER_HPP