[Kamailio-Devel] dialog callback - locks?

[Klaus Darilion]

Ovidiu Sas wrote:
> On Wed, Oct 15, 2008 at 11:12 AM, Klaus Darilion
> <klaus.mailinglists at pernau.at> wrote:
>>
>> Ovidiu Sas schrieb:
>>> On Mon, Oct 13, 2008 at 12:01 PM, Klaus Darilion
>>> <klaus.mailinglists at pernau.at> wrote:
>>>> Hi Ovidiu!
>>>>
>>>> Ovidiu Sas schrieb:
>>>>> [osas]
>>>>> I think you will need to lock the dialog if you want to access the
>>>>> content of the dialog structure during subsequent dialog callbacks.
>>>>> One option would be to copy all the info that you might need during
>>>>> the first callback from the dialog context into your module context
>>>>> and then use then local one.  This will avoid the necessity to lock
>>>>> the dialog context.  The whole purpose of passing a pointer back to
>>>>> the dialog module during the initial dialog callback is to create a
>>>>> link back into the local module context.
>>>> This works for most of the dlg_cell parameters, except lifetime. How can
>>>> I
>>>> read dlg->lifetime in hte callback in a safe way?
>>>>
>>> The params structure should be enhanced and the lifetime should be
>>> passed via the existing API (see how CURR_DLG_LIFETIME is computed
>>> inside dlg_handlers.c:dlg_onroute() ).
>>> BTW, the lifetime is available in the script via $DLG_lifetime pv.
>> If I got it right: accessing params is fine during callback and those the
>> dialog module should copy the lifetime into the params struct for other
>> modules to access it.
> 
> That is correct.  The params are initialized just before being passed
> to the calling module.
> 
> 
>> btw: if accessing dlg_cell in callback is not safe, why is it even signaled
>> to the callback handler? (of course except DLG_CREATED handler)
> 
> I don't know for sure ... just to keep a unique interface for all callbacks ...

Ok. I will try to enhance the documentation of the dialog module.

One thing left: the to-tag. My callback handler can not access the totag 
(tag[1]) from dlg_cell as it is not available in the DLG_CREATED 
callback. What do you think is the preferred way for getting the totag? 
Currently I parse param->msg->... to get the totag manually. Do think it 
makes sense to extend the param struct for the totag too?

regards
klaus