[sr-dev] dialog module: failed_dlgs semantics

[Timo Reimann]

Hi,

what's the dialog module's "failed_dlgs" counter variable (defined in
modules_k/dialog.c) supposed to indicate?

My understanding would be that it shows the number of dialogs that could
not reach the "confirmed" call state, i.e., calls for which the caller
received a non-2xx final response after the initial INVITE during
routing. However, the variable is increased in situations for which a
dialog could not be set up in the very first place due to either

- malformed SIP headers in the INVITE request,
- lack of shared memory, and
- unsuccessful callback registrations to the rr or tm module

which are all checked in dlg_handler.c's dlg_new_dialog() function prior
to any further response processing.

What I'd prefer to do to the least is additionally update the counter
variable every time a non-2xx final response has been received to
indicate call failure in the SIP sense. Going one step further, I'd
remove the update code from its current place because I do not see much
meaning in running statistics on hard errors as given above. The cases
are already covered by ERROR-level log messages so they will be reported
anyway.

To sum up my goal: If no one objects, I will change the code such that
hard errors are not covered by failed_dlgs anymore but failure to
establish SIP sessions are.


Cheers,

--Timo