NFD

It depends on when the face is destructed... unfortunately there is no guarantee on that, but it seems cleaner to me if the FaceTable removes its subscriptions when it's done with the face. And this covers onReceive(Interest|Data) and onFail.

As far as onSend(Interest|Data) are concerned, I don't know why they are cleared in the current code, maybe for the same reason as #1718?

On the other hand, wouldn't it be more appropriate to use a weak_ptr in those cases?

More generally, we should really define who owns the various face objects... FaceTable or the protocol factories? or someone else? Right now they aren't really owned by anyone... in fact they're collectively owned by anything that has a shared_ptr to them, which doesn't give many guarantees, and that makes it harder to reason about object lifetime, destruction and ownership cycles.

I somewhat agree with note-8, however that's out of scope of this Task.

The solution to #1718 regression is:

• use weak_ptr or reference instead of shared_ptr in bound handlers
• if shared_ptr is desirable, store the Connection, and cancel it in onFail
• use connectSingleShot (#2331) for onFail handlers