m_subscriptions is not cleaned up when closing a session

[reddwarf69]

I would have expected m_subscriptions to have been cleaned up by the time I get the closed_future. Not sure if this could be a more serious issue (can the session be reopened and have old sessions? could it be considered a memory leak?). But for me it's an issue because my on_event_fn (indirectly) contains a reference to my wamp_session shared_ptr. So if I don't make sure to UNSUBSCRIBE all the subscriptions before closing the wamp_session the std::shared_ptr<wamp_session> reference counter never reaches zero and wamp_session is never destroyed.

Edit: Actually AFAICS the subscription in only removed from m_subscriptions in process_inbound_unsubscribed(). So I depend on my peer behaving and sending me the reply. If the connection dies for some reason and I can't get the UNSUBSCRIBED message back I'm out of luck.

[darrenjs]

Hi ... how about storing a weak_ptr inside your on_event_fn instead of the shared_ptr. The problem is the underlying connection can terminate uncleanly at any point (eg network disconnect), and I'm not sure it would make sense to invoke the on_event_fn to indicate an UNSUBSCRIBED has been received.

Or maybe, the library could be altered to release all internal state upon internal closure (e.g., I think this could be done in wampcc::transition_to_closed, although there might be synchronisation considerations to bare in mind, e.g., what locks need to be taken etc).

But, back to my initial thought. I think it's wrong to use a shared_pointer as you are doing. Shared pointers convey resource ownership semantics, and so by the wamp session holding a reference to itself, it kinds of means it controls its own lifetime! So I think weak pointer will work, you just need to promote it to shared pointer during each callback (infact, a raw pointer would work also).