segment-publisher.hpp

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

#include "common.hpp"

#include <ndn-cxx/encoding/encoding-buffer.hpp>
#include <ndn-cxx/security/key-chain.hpp>

namespace nfd {

template <class FaceBase>
class SegmentPublisher : noncopyable
{
public:
  SegmentPublisher(FaceBase& face,
                   const Name& prefix,
                   ndn::KeyChain& keyChain,
                   const time::milliseconds& freshnessPeriod = getDefaultFreshness())
    : m_face(face)
    , m_prefix(prefix)
    , m_keyChain(keyChain)
    , m_freshnessPeriod(freshnessPeriod)
  {
  }

  virtual
  ~SegmentPublisher()
  {
  }

  static size_t
  getMaxSegmentSize()
  {
    static const size_t MAX_SEGMENT_SIZE = ndn::MAX_NDN_PACKET_SIZE >> 1;
    return MAX_SEGMENT_SIZE;
  }

  static constexpr time::milliseconds
  getDefaultFreshness()
  {
    return time::milliseconds(1000);
  }

  void
  publish()
  {
    ndn::EncodingBuffer buffer;
    generate(buffer);

    const uint8_t* rawBuffer = buffer.buf();
    const uint8_t* segmentBegin = rawBuffer;
    const uint8_t* end = rawBuffer + buffer.size();

    Name segmentPrefix(m_prefix);
    segmentPrefix.appendVersion();

    uint64_t segmentNo = 0;
    do {
      const uint8_t* segmentEnd = segmentBegin + getMaxSegmentSize();
      if (segmentEnd > end) {
        segmentEnd = end;
      }

      Name segmentName(segmentPrefix);
      segmentName.appendSegment(segmentNo);

      shared_ptr<Data> data = make_shared<Data>(segmentName);
      data->setContent(segmentBegin, segmentEnd - segmentBegin);
      data->setFreshnessPeriod(m_freshnessPeriod);

      segmentBegin = segmentEnd;
      if (segmentBegin >= end) {
        data->setFinalBlockId(segmentName[-1]);
      }

      publishSegment(data);
      ++segmentNo;
    } while (segmentBegin < end);
  }

protected:
  virtual size_t
  generate(ndn::EncodingBuffer& outBuffer) = 0;

private:
  void
  publishSegment(shared_ptr<Data>& data)
  {
    m_keyChain.sign(*data);
    m_face.put(*data);
  }

private:
  FaceBase& m_face;
  const Name m_prefix;
  ndn::KeyChain& m_keyChain;
  const time::milliseconds m_freshnessPeriod;
};

} // namespace nfd

#endif // NFD_CORE_SEGMENT_PUBLISHER_HPP