Hey Timo,

Ok, I agree with you on the reference counting - this can be avoided by keeping the h_entry:h_id pair instead of a pointer to dlg. The reason I was doing the ref was to make sure that the dialog module does not delete a dialog under a modules feet (in which case a module would hold a pointer to memory that has been freed). However, to avoid this we can just call lookup_dlg passing in the entry:id pair. (another reason why we would need lookup_dlg to be exposed ;)

Ok Scenarios:

If we just use as one example the Ro interface we have built. Effectivley Ro is used in the IMS world for online charging (i.e. realtime charing during the call). So naturally, this module is dialog aware. What we do is keep a mapping between the dialog and the particular Ro session (Ro session exists between Kamailio and an OCS (online charging system). This is the reason for storing the dialog pointer or id pairs. Now, when we run out of credit - the OCS will deny a new batch of requested credit. In this case we lookup the corresponding dialog associated to the Ro session and tear it down, using terminate_dlg function

I hope this explains one of the scenarios.

We have a similar scenario with the Rx interface where we store links between dialogs and PCC (policy and charging control) sessions - think of this as QoS bandwidth reservation on EPC network.

Hope this makes sense.

I really think there are a number of scenarios where these extended API functions could be used so as to ensure modules don't have to replicate what alrady exists in the dialog module, from both memory and processing perspective.

Cheers
Jason


On Fri, Aug 12, 2011 at 12:58 PM, Timo Reimann <timo.reimann@1und1.de> wrote:
Hey Jason,


On 12.08.2011 12:54, Jason Penton wrote:
> this wont be available to configuration users but to other modules
> through API.

Ok, thanks for clarifying this. Still, allowing other modules to fiddle
with referencing counting is a no-go IMHO.


> On phone now so will respond to use cases when I'm back at my PC

Sounds good!


Cheers,

--Timo



> On Aug 12, 2011 12:48 PM, "Timo Reimann" <timo.reimann@1und1.de
> <mailto:timo.reimann@1und1.de>> wrote:
>> Hey,
>>
>>
>> On 12.08.2011 12:33, Jason Penton wrote:
>>> We are currently refactoring and cleaning the various IMS modules for
>>> inclusion into SR, diameter_rx, diameter_cxdx, diameter_ro, etc.
>>>
>>> One thing we have noticed is that the use of dialog module functions
>>> would make the code alot better and cleaner, so 2 questions:
>>>
>>> 1. why is the Dialog module not exposing more if its methods?
>>> 2. Can we put in a patch to expose the ones we require.
>>>
>>> Currently, we have exposed and are using the following:
>>>
>>> lookup_dlg;
>>> terminate_dlg;
>>> get_dlg;
>>> unref_dlg;
>>> ref_dlg;
>>
>> I strongly opt against exporting any functions related to reference
>> management. It's already hard to handle reference counting properly
>> inside the module; allowing configuration users to touch that part of
>> the module will likely result in all kinds of ugly bugs. IMHO, it's best
>> to keep it internal and provide functions to whatever feature you like.
>> There's already a bunch of dialog PVs and (more recently) the very
>> generic dialog variable mechanism which allows you to do a series of
> things.
>>
>> Regarding the other functions you mentioned, can you outline what your
>> use case for those is?
>>
>>
>> Cheers,
>>
>> --Timo

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