[ndnSIM] Access outgoing data pipeline from strategy

[Rakesh Ranjan Jha]

Hi Spyridon,

Thanks for answering. Let me clarify my statements:

m_forwarder currently in Strategy base class, Strategy.cpp is a private
member and hence can't be accessed from derived class.
class Strategy : public enable_shared_from_this<Strategy>, noncopyable
{
...
private:
  Name m_name;

  /** \brief reference to the forwarder
   *
   *  Triggers can access forwarder indirectly via actions.
   */
  Forwarder& m_forwarder;
...
}

Also currently forwarder class has only Strategy base class as friend.

class Forwarder
{
...
  // allow Strategy (base class) to enter pipelines
  friend class fw::Strategy;
};

So, as I mentioned earlier to work around these I made m_forwarder a
protected member and also added my strategy class as friend to forwarder as
well.

With these changes now I can access the pipeline as well as access private
members of m_fowarder but then I see the error when trying to access the
content store and send the fetched data in the outgoing pipeline. What I
wasn't sure is that similar call in forwarder passes but fails in my
strategy class

//fowarder.cpp - This passes
    if (m_csFromNdnSim == nullptr) {
      m_cs.find(interest,
                bind(&Forwarder::onContentStoreHit, this, ref(inFace),
pitEntry, _1, _2),
                bind(&Forwarder::onContentStoreMiss, this, ref(inFace),
pitEntry, _1));
    }

//myStrategy.cpp - This fails
    if (m_forwarder.m_csFromNdnSim == nullptr) {
        /* m_forwarder is a reference to forwarder */
m_forwarder.m_cs.find(pe->getInterest(),
                  bind(&Forwarder::onContentStoreHit, &m_forwarder,
ref(face), pe, _1, _2),
  bind(&Forwarder::onContentStoreMiss, &m_forwarder, ref(face), pe, _1));
     }


Also if there is a better way to access the CS and outgoing pipeline from
strategy please let me know.

Thanks again,
Rakesh


On Sun, Jul 9, 2017 at 6:47 PM, Spyridon (Spyros) Mastorakis <
mastorakis at cs.ucla.edu> wrote:

> Hi Rakesh,
>
> I would like to make 2 comments about your code:
>
> 1) m_forwarder is already a reference to an object of type Forwarder, so
> you tried to get a reference out of a reference.
>
> 2) The m_cs attribute is declared as a private member of the Forwarder
> class.
>
> Please let me know if you have any questions.
>
> Thank you,
>
> Spyridon (Spyros) Mastorakis
> Personal Website: http://cs.ucla.edu/~mastorakis/
> Internet Research Laboratory
> Computer Science Department
> UCLA
>
> On Jul 9, 2017, at 10:30 AM, Rakesh Ranjan Jha <rakeshranjan.jha at gmail.com>
> wrote:
>
> Hi,
>
> I'm trying to spontaneously inject a cached data (based on a previously
> unfulfilled interest present in PIT and so I have an interest handle to
> fetch data) from content store.
>
> However, I'm facing some issues:
>
> 1) Derived strategy doesn't seem to have any handle to fowarder although
> base strategy has a handle and is friend to forwarder to access pipelines.
> In order to workaround this I added my strategy also as a friend and gave
> it a reference to forwarder, similar to base strategy. Is there a better
> way to access pipeline from strategy?
>
> 2) To access data from CS and feed it to outgoing data pipeline, I follow
> similar mechanism as done on receiving valid interest from forwarder:
> //fowarder.cpp
>     if (m_csFromNdnSim == nullptr) {
>       m_cs.find(interest,
>                 bind(&Forwarder::onContentStoreHit, this, ref(inFace),
> pitEntry, _1, _2),
>                 bind(&Forwarder::onContentStoreMiss, this, ref(inFace),
> pitEntry, _1));
>     }
>
> //myStrategy.cpp
>     if (m_forwarder.m_csFromNdnSim == nullptr) {
>         /* m_forwarder is a reference to forwarder */
> m_forwarder.m_cs.find(pe->getInterest(),
>                   bind(&Forwarder::onContentStoreHit, &m_forwarder,
> ref(face), pe, _1, _2),
>  bind(&Forwarder::onContentStoreMiss, &m_forwarder, ref(face), pe, _1));
>      }
>
> However this fails compilation and I get error as below:
>
> ../src/ndnSIM/NFD/daemon/fw/my_strategy.cpp: In member function ‘virtual
> void nfd::fw::MyStrategy::beforeSatisfyInterest(std::shared_ptr<nfd::pit::Entry>,
> const nfd::Face&, const ndn::Data&)’:
> ../src/ndnSIM/NFD/daemon/fw/my_strategy.cpp:243:75: error: no matching
> function for call to ‘nfd::cs::Cs::find(const ndn::Interest&,
> std::_Bind_helper<false, void (nfd::Forwarder::*)(const nfd::Face&,
> std::shared_ptr<nfd::pit::Entry>, const ndn::Interest&, const
> ndn::Data&), nfd::Forwarder*, std::reference_wrapper<int>,
> std::shared_ptr<nfd::pit::Entry>&, const std::_Placeholder<1>&, const
> std::_Placeholder<2>&>::type, std::_Bind_helper<false, void
> (nfd::Forwarder::*)(const nfd::Face&, std::shared_ptr<nfd::pit::Entry>,
> const ndn::Interest&), nfd::Forwarder*, std::reference_wrapper<int>,
> std::shared_ptr<nfd::pit::Entry>&, const std::_Placeholder<1>&>::type)’
>       bind(&Forwarder::onContentStoreMiss, &m_forwarder, ref(face), pe,
> _1));
>
>  ^
> In file included from ../src/ndnSIM/NFD/daemon/fw/forwarder.hpp:35:0,
>                  from ../src/ndnSIM/NFD/daemon/fw/strategy.hpp:29,
>                  from ../src/ndnSIM/NFD/daemon/fw/my_strategy.hpp:24,
>                  from ../src/ndnSIM/NFD/daemon/fw/my_strategy.cpp:21:
> ../src/ndnSIM/NFD/daemon/fw/../table/cs.hpp:88:3: note: candidate: void
> nfd::cs::Cs::find(const ndn::Interest&, const HitCallback&, const
> MissCallback&) const
>    find(const Interest& interest,
>    ^
> ../src/ndnSIM/NFD/daemon/fw/../table/cs.hpp:88:3: note:   no known
> conversion for argument 2 from ‘std::_Bind_helper<false, void
> (nfd::Forwarder::*)(const nfd::Face&, std::shared_ptr<nfd::pit::Entry>,
> const ndn::Interest&, const ndn::Data&), nfd::Forwarder*,
> std::reference_wrapper<int>, std::shared_ptr<nfd::pit::Entry>&, const
> std::_Placeholder<1>&, const std::_Placeholder<2>&>::type {aka
> std::_Bind<std::_Mem_fn<void (nfd::Forwarder::*)(const nfd::Face&,
> std::shared_ptr<nfd::pit::Entry>, const ndn::Interest&, const
> ndn::Data&)>(nfd::Forwarder*, std::reference_wrapper<int>,
> std::shared_ptr<nfd::pit::Entry>, std::_Placeholder<1>,
> std::_Placeholder<2>)>}’ to ‘const HitCallback& {aka const
> std::function<void(const ndn::Interest&, const ndn::Data&)>&}’
>
> Can somebody help me figure out why this fails when similar invocation
> from forwarder passes?
>
> Thanks in advance,
> Rakesh
>
>
>
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