[OpenSIPS-Users] Logic behind check of current_turn in presence module?

[Bogdan-Andrei Iancu]

Hi Surya,

This question is more appropriate for the devel mailing list :).

The "turns" is a mechanism to force OpenSIPS to process the PUBLISH 
requests in the some order as they were received. OpenSIPS is a 
multi-processes application and requests received in a certain order 
from the network level may end up being processed in a totally different 
one. This was breaking the whole presence philosophy, especially in 
dialog-info, where the PUBLISH-ing is done fast and order is really 
important.

The two variables are used as a ticketing system for order - each 
incoming PUBLISH will take a turn ticket (based on its arrival) and it 
will wait to be handled only when all the previously received PUBLISHes 
are processed.

Regards,

Bogdan-Andrei Iancu
OpenSIPS Founder and Developer
http://www.opensips-solutions.com

On 10.09.2015 10:16, surya wrote:
> Hi All,
>
> Here I am referring opensips1.8.4
>
> I am not able to understand the use of current_turn and last_turn variables
> in update_presentity function.
>
> As I understand:
>
> For initial request current_turn=0  and last_turn=0
>
> and for subsequent requests where etag matches and found in hash, each will
> be incremented by 1.
>
>
> I have two questions:
>
> 1. What is the use of this check?
> 2. When will be the current_turn and last_turn become unequal?
>
> Also, I see this was not present in the version 1.8.3.
>
> Please help me understanding the logic behind this functionality.
>
> Thanks & Regards
> Surya
>
>
>
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