Hi Sebastian!

Thanks for your response!

In our system we have: - usrloc with db_mode=1 (Write-Through scheme. All changes to usrloc are immediately reflected in database too. ) - sqlite DB, to store location info (sqlite is blocking for the time of write, and if there are 2 write attempts by 2 workers - one of them fails)

In this scheme - I definitely need to process only one REGISTER at the same time (In our setup kamailio are not high loaded)

And locking - seemed to me the safest workaround for production (as turned out - it did not).

What I am doing now - is testing my kamailio with usrloc db_mode=2 (Write-Back scheme.) (and this is going to be production solution soon)

I posted the topic - to discuss my case - and make some changes (sources or documentation) - to prevent someone else in future to encounter something similar.

cheers

a registrar module working

Sebastian Damm-2 wrote

Hi,

indeed, when a function returns with 0, Kamailio immediately ends the processing of the packet. So that's why the unlock statement is never executed.

I am wondering, why you are using locks at this point. That way, only one REGISTER can be processed at the same time, since they all share the same lock. I've never seen somebody do this before, and multiple REGISTERs being processed in parallel should be no problem. What problem do you try to solve by surrounding the save command with locks?

Best Regards, Sebastian

On Thu, Oct 12, 2017 at 6:03 PM, Vasiliy Ganchev <

vancecezar@

> wrote:

...

Hi, community!

I have in my Kamailio script following block (while REGISTER processing, after auth succeed):

..... /* Save to usrloc */ lock("LOCATION_LOCK"); if (!save("location")) { unlock("LOCATION_LOCK"); sl_reply_error(); exit(); } unlock("LOCATION_LOCK");

......

According to module documentation - if "save" - failed (for any reason) - I expected the control to be returned to the script with error code "-1"

But, there are cases - when this does not happen - which lead to deadlock for workers processing REGISTERs (I never unlock("LOCATION_LOCK")):

• module answers with internal error - and return 0 from "save" function:

https://github.com/kamailio/kamailio/blob/master/src/modules/registrar/save....

• line 1013

My use case happened due to malfunctioning device that in some moment of time:

• send REGISTER update
• kamailio answers 200OK
• device retransmit the same REGISTER (same CSeq)
• during 20 seconds (hardcoded value in registrar module) - kamailio

answers 200OK (and everything is ok)

• if retransmission continue more than 20s - kamailio answered 400 Bad

request, and did not return control to script (as a result I had no chance to unlock("LOCATION_LOCK") from code above)

Tested it on kamailio 4.2.5 and 5.0.3.

as for me, possible solutions are:

• return -1 instead of 0 from "save" by default
• if there are some reasons not to do this - we should change

documentation, and explicitly mention that there are cases - when script execution is stopped.

thanks in advance!

cheers

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Hello,

On 30.10.17 09:21, Vasiliy Ganchev wrote:

Hi there again!

@Daniel, can you comment what do you think about the topic?

I changed to return -1. Not sure what was the reason to return 0 there, but was not the expected behaviour. Patch pushed to master and 5.0 branches for now.

Cheers, Daniel