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

[Spyridon (Spyros) Mastorakis]

Hi,

we do that because the data will be inserted to the content store. When this data is retrieved from CS by future requests, it should get a new hop tag initialized to 0, since it was retrieved from CS and not the consumer.

Thanks,

Spyridon (Spyros) Mastorakis
Personal Website: http://cs.ucla.edu/~mastorakis/ <http://cs.ucla.edu/~mastorakis/>
Internet Research Laboratory
Computer Science Department
UCLA

> On Apr 26, 2017, at 1:13 PM, Amir Ibrahim <a.ibrahim at fci-cu.edu.eg> wrote:
> 
> 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 <mailto: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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