use proper function for state destruction

[shaitan]

dnet_state_destroy() releases memory allocated for st->addrs and fills st's memory with 0xff.

[kletkavrubashku]

dnet_state_destroy calls pthread_mutex_lock(&st->trans_lock) as example. It'll be work correctly after destroy of mutex?

[shaitan]

Yes, you're right. I will add WIP label and rework it

[sabramkin]

It's undetermined what refcnt will left after dnet_state_move_to_dht call. In case of error, dnet_state_move_to_dht can put (-EEXIST) or not to put (other errorcode) the net state. So you can't know how many puts you must do at this line.

I think the good practic is to do like shared_ptr: we lock the resource in the component where we use this resource (in dnet_state_create), and don't do refcounting for another components. These another components must do clear refcounting by themself. For example: dnet_state_create must have scoped single refcnt-lock, and dnet_state_move_to_dht should inc (if success) or don't inc (if fail) refcnt. The same way in dnet_state_create: if success, we return net state and don't decrement refcnt; if fail, decrement refcnt and return NULL. The caller of dnet_state_create must keep the result object, or throw it away via put.