NFD

FIB/PIT/Measurements entry should contain shared_ptr<NameTree>.

I suggest an API like:

namespace name_tree {
class Entry;
}
namespace fib {
class Entry {
private:
  shared_ptr<name_tree::Entry> m_nameTreeNode;
  friend class NameTree;
};
}
namespace pit {
class Entry {
private:
  shared_ptr<name_tree::Entry> m_nameTreeNode;
  friend class NameTree;
};
}
namespace measurements {
class Entry {
private:
  shared_ptr<name_tree::Entry> m_nameTreeNode;
  friend class NameTree;
};
}
class NameTree
{
  shared_ptr<name_tree::Entry> get(const fib::Entry& fibEntry);
  shared_ptr<name_tree::Entry> get(const pit::Entry& pitEntry);
  shared_ptr<name_tree::Entry> get(const measurements::Entry& measurementsEntry);
};

I think the following three functions could be implemented at each fib/pit/measurements-entry.hpp, and probably should not in NameTree class.

  shared_ptr<name_tree::Entry> get(const fib::Entry& fibEntry);
  shared_ptr<name_tree::Entry> get(const pit::Entry& pitEntry);
  shared_ptr<name_tree::Entry> get(const measurements::Entry& measurementsEntry);

My idea is, forwarding/strategy should not know about name_tree::Entry. Therefore, it's a private field, and class NameTree is a friend.

Yes, name_tree/NameTree is "internal optimization" that should not be really exposed in the interface, unless there is a very good reason to do so.

Yes, the NameTree should not be exposed in the interface to /fw or /strategy.

What I was trying to say is, if the shared_ptr<name_tree::Entry> get(const fib::Entry& fibEntry); is used only internally in fib/pit/measurements.cpp, then it is probably easier to just return fib->m_nameTreeEntry or fib->getNameTreeEntry(), since you already have the fibEntry pointer. (alternatively, you could call m_nameTree->get(fibEntry), which then returns fibEntry->m_nameTreeEntry). It shouldn't matter much in this case...

The nice part of having these three functions in NameTree is that the interface get() is simple and unified.

pit::Entry::m_nameTreeEntry is not only used by Pit.

Measurements::get(pit::Entry) would like to get the name_tree::Entry from PIT entry, and follow the pointer to find Measurements entry.

However, it's strange to make class Measurements a friend of pit::Entry, therefore this should go through NameTree::get.