[ndnSIM] In content-store-impl.hpp (add method) trying to get the hopCount field in Data Packet

[Amir Ibrahim]

I found the reason:

in the NFD/fw/forwarder.cpp

the hopCount field is removed before calling content-store-impl Add()
method.
void
Forwarder::onIncomingData(Face& inFace, const Data& data)
{
  // receive Data
  NFD_LOG_DEBUG("onIncomingData face=" << inFace.getId() << " data=" <<
data.getName());
  data.setTag(make_shared<lp::IncomingFaceIdTag>(inFace.getId()));
  ++m_counters.nInData;

  // /localhost scope control
  bool isViolatingLocalhost = inFace.getScope() ==
ndn::nfd::FACE_SCOPE_NON_LOCAL &&

scope_prefix::LOCALHOST.isPrefixOf(data.getName());
  if (isViolatingLocalhost) {
    NFD_LOG_DEBUG("onIncomingData face=" << inFace.getId() <<
                  " data=" << data.getName() << " violates /localhost");
    // (drop)
    return;
  }

  // PIT match
  pit::DataMatchResult pitMatches = m_pit.findAllDataMatches(data);
  if (pitMatches.begin() == pitMatches.end()) {
    // goto Data unsolicited pipeline
    this->onDataUnsolicited(inFace, data);
    return;
  }

  shared_ptr<Data> dataCopyWithoutTag = make_shared<Data>(data);
  dataCopyWithoutTag->removeTag<lp::HopCountTag>();

  // CS insert
  if (m_csFromNdnSim == nullptr)
    m_cs.insert(*dataCopyWithoutTag);
  else
    m_csFromNdnSim->Add(dataCopyWithoutTag);



My question is why is the hopCount field removed?

On Wed, Apr 26, 2017 at 3:50 PM, Amir Ibrahim <a.ibrahim at fci-cu.edu.eg>
wrote:

> Dear ndnSim users and experts,
>            I'm trying to modify the caching strategy in a way that
> requires accessing the hopCount field in the data packet.
>
> Below is my trial to access the hopCount field in data packet:
>
> in  content-store-impl.hpp (add method):
>
> template<class Policy>
> bool
> ContentStoreImpl<Policy>::Add(shared_ptr<const Data> data)
> {
>   NS_LOG_FUNCTION(this << data->getName());
>
>   int TSB = 0;
>   auto TSBTag = data->getTag<lp::HopCountTag>();
>   if (TSBTag != nullptr) {
>    TSB = *TSBTag;
>     }
>   std::cout<<"in CS Impl, found HopCount = "<<TSB<<" \n";
>
>   Ptr<entry> newEntry = Create<entry>(this, data);
>   std::pair<typename super::iterator, bool> result =
> super::insert(data->getName(), newEntry);
>
>   if (result.first != super::end()) {
>     if (result.second) {
>       newEntry->SetTrie(result.first);
>
>       m_didAddEntry(newEntry);
>       std::cout<<"inside contentStoreImpl, new entry is added"<<"\n";
>       return true;
>     }
>     else {
>       // should we do anything?
>       // update payload? add new payload?
>       return false;
>     }
>   }
>   else
>     return false; // cannot insert entry
> }
>
> The problem is that, the pointer (TSBTag) is always null.
>
> Is there any clue why is this happening? any suggestions how to get the
> hop count field of data packet from within the content-store-impl.hpp Add
> method.
>
> --
>    Regards
> Amir I. Mohamad
> Assistant Lecturer
> Faculty of Computers & Information
> IT Dept. Cairo University
>



-- 
   Regards
Amir I. Mohamad
Assistant Lecturer
Faculty of Computers & Information
IT Dept. Cairo University

-- 

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