[ndnSIM] Access outgoing data pipeline from strategy

Tue Jul 11 19:52:00 PDT 2017

Hi Rakesh,

I have cc’d Junxiao here. He is one of the main developers of NFD and he should be able to let us know what would be the most appropriate way to do that.

Thanks,

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

> On Jul 9, 2017, at 4:03 PM, Rakesh Ranjan Jha <rakeshranjan.jha at gmail.com> wrote:
> 
> 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 <mailto: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/ <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 <mailto: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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