Hello,

I assume (well, I initially developer db_text, but db api came from other developers and I was inspired from other db module, most like to be mysql) it follows a pattern from all (most) of db connector modules. I think that one of the goals was to be able to free previous result if there is a new query on the same connection, in case someone forgot to free the result, to avoid leaks, considering that the result variables are typically local in the function.

So, at this moment I would postpone its adoption if it is not fixing anything anymore, until we can get the time to look overall db api and connectors. You should add it to the tracker, not to forget about it.

Cheers,
Daniel

On 08/09/14 16:41, Luis Azedo wrote:
Hi Daniel,

well, i think its not needed but wouldn't we all benefit from it ? binding the internal structure to the result instead of connection?

Thanks


On Mon, Sep 8, 2014 at 3:37 PM, <sr-dev-request@lists.sip-router.org> wrote:
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Today's Topics:

   1. Re: accessing database from a child forked proces
      (Daniel-Constantin Mierla)


----------------------------------------------------------------------

Message: 1
Date: Mon, 08 Sep 2014 16:37:21 +0200
From: Daniel-Constantin Mierla <miconda@gmail.com>
To: Luis Azedo <luis.azedo@factorlusitano.com>
Cc: "Kamailio \(SER\) - Development Mailing List"
        <sr-dev@lists.sip-router.org>
Subject: Re: [sr-dev] accessing database from a child forked proces
Message-ID: <540DBF21.8070802@gmail.com>
Content-Type: text/plain; charset="utf-8"; Format="flowed"

Hello,

On 08/09/14 15:29, Luis Azedo wrote:
> Hi Daniel,
>
> all problems solved with presence! i was not running child_init  and
> now there is no need for the proposed patch to presence.
ok. Given this, would the db_text patch still be required, as there
should be no database connection sharing?

Cheers,
Daniel
>
> Thank you
>
>
>
> On Mon, Sep 8, 2014 at 2:13 PM, Luis Azedo
> <luis.azedo@factorlusitano.com <mailto:luis.azedo@factorlusitano.com>>
> wrote:
>
>     Hi Daniel,
>
>     this is the way we are creating the child processes (1 manager and
>     n workers)
>     the problem is with the workers.
>     the worker will call a event-route and in the script config we try
>     to call pres_refresh_watchers and that's where we get the pa_db =
>     NULL.
>
>     as i understand from your email, if we change PROC_NOCHLDINIT and
>     let the child_init execute for the forked process then it will
>     also execute child_init in other modules ? it makes sense.
>
>     going to try this.
>
>
>     static int mod_child_init(int rank)
>     {
>     int pid;
>     int i;
>
>     fire_init_event(rank);
>
>     if (rank==PROC_MAIN) {
>     pid=fork_process(PROC_NOCHLDINIT, "AMQP Manager", 1);
>     if (pid<0)
>     return -1; /* error */
>     if(pid==0){
>     kz_amqp_manager_loop(0);
>     }
>     else {
>     for(i=0; i < dbk_consumer_processes; i++) {
>     pid=fork_process(PROC_NOCHLDINIT, "AMQP Consumer", 1);
>     if (pid<0)
>     return -1; /* error */
>     if(pid==0){
>     mod_consumer_proc(i+1);
>     }
>     }
>     }
>     }
>
>     return 0;
>     }
>
>
>
>     On Mon, Sep 8, 2014 at 1:11 PM, Daniel-Constantin Mierla
>     <miconda@gmail.com <mailto:miconda@gmail.com>> wrote:
>
>         Hello,
>
>         the database connection should not be shared beween processes,
>         because it can bring unexpected results in may places.
>
>         Right now, the rule is to have one connection per process,
>         shared by all modules in that process.
>
>         To achieve that, at mod_init each module opens database
>         connection and closes it before ending the function. Then in
>         child_init() the connection is opened again. Another module
>         that will have to open in child_init() will get the same
>         connection now.
>
>         When you create a new process, you tell the type of child and
>         based on that child_init() from the other modules are executed.
>
>         What is the function do you use for creating a new process?
>         Maybe you can paste it here exactly how you do it and I can
>         see if something can be done.
>
>         Cheers,
>         Daniel
>
>
>         On 03/09/14 12:09, Luis Azedo wrote:
>>         Hi Jason,
>>
>>         thanks for the reply.
>>
>>         the last 2 statements in presence module mod_init close the
>>         connection and set pa_db to NULL. when my module main process
>>         forks the extra processes the pa_db in presence is NULL, so
>>         when it calls pres_refresh_watchers it fails because pa_db is
>>         NULL.
>>         i commented these last statements in presence mod_init and i
>>         got it to work.
>>
>>         // pa_dbf.close(pa_db);
>>         // pa_db = NULL;
>>
>>         does this have any implications on how the module works ? is
>>         it ok to merge this change ?
>>
>>         Thank you
>>
>>
>>
>>             ----------------------------------------------------------------------
>>
>>             Message: 1
>>             Date: Sun, 31 Aug 2014 09:40:49 +0200
>>             From: Jason Penton <jason.penton@gmail.com
>>             <mailto:jason.penton@gmail.com>>
>>             To: "Kamailio (SER) - Development Mailing List"
>>                     <sr-dev@lists.sip-router.org
>>             <mailto:sr-dev@lists.sip-router.org>>
>>             Subject: Re: [sr-dev] accessing database from a child
>>             forked process
>>             Message-ID:
>>
>>             <CALoGXNWvHhCAO91Tfa0w8W3eYQRvfV7Qkgte7dBnD+ciNr_Kpg@mail.gmail.com
>>             <mailto:CALoGXNWvHhCAO91Tfa0w8W3eYQRvfV7Qkgte7dBnD%2BciNr_Kpg@mail.gmail.com>>
>>             Content-Type: text/plain; charset="utf-8"
>>
>>             To confirm exactly what processes are being used, maybe
>>             check the log file
>>             and take note of process id at each log event. For
>>             example you could check
>>             the process id of the messages showing you the connection
>>             is null. Then run
>>             kamcmd ps to show the process list with a description of
>>             each Kamailio
>>             process. That will probably point you in the correct
>>             direction.
>>
>>             Cheers
>>             Jason
>>
>>
>>             On Fri, Aug 29, 2014 at 3:53 PM, Luis Azedo
>>             <luis.azedo@factorlusitano.com
>>             <mailto:luis.azedo@factorlusitano.com>>
>>             wrote:
>>
>>             > Hi,
>>             >
>>             > i have a module that creates 1 extra process where it
>>             processes stuff in a
>>             > loop.
>>             > on some condition i fire a route_event with a fakemsg
>>             and its up to the
>>             > user of the module to take action, it tries to work
>>             like dispatcher module
>>             > or htable (mod-init) events.
>>             >
>>             > the problem that i have is that, if i call some
>>             function on some module
>>             > that performs a database action, the connection is null
>>             when it calls
>>             > use_table.
>>             >
>>             > in this case i'm making this call
>>             > event_route[my_module:my_event]
>>             > {
>>             >  $var(my_uri) = <<result of some operations>>;
>>             > pres_refresh_watchers("$var(my_uri)", "dialog", 1);
>>             > }
>>             > presence module makes the call to use_table but this
>>             call fails because
>>             > the connection is null. presence module is working fine
>>             besides this.
>>             >
>>             > if i make this call inside
>>             event_route[dispatcher:dst-up] it works.
>>             >
>>             > i think that dispatcher fires the event inside a
>>             callback from a
>>             > registered timer, so, i think (may be wrong) that it
>>             comes from a different
>>             > process ?
>>             >
>>             > i wonder if i'm missing something from child_init ?
>>             need to register
>>             > something ?
>>             >
>>             > thanks for your help.
>>             >
>>             >
>>             >
>>             >
>>             >
>>             >
>>             > _______________________________________________
>>             > sr-dev mailing list
>>             > sr-dev@lists.sip-router.org
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>>             > http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-dev
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>
>         --
>         Daniel-Constantin Mierla
>         http://twitter.com/#!/miconda  <http://twitter.com/#%21/miconda>  -http://www.linkedin.com/in/miconda
>         Next Kamailio Advanced Trainings 2014 -http://www.asipto.com
>         Sep 22-25, Berlin, Germany
>
>
>

--
Daniel-Constantin Mierla
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Next Kamailio Advanced Trainings 2014 - http://www.asipto.com
Sep 22-25, Berlin, Germany

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Daniel-Constantin Mierla
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Next Kamailio Advanced Trainings 2014 - http://www.asipto.com
Sep 22-25, Berlin, Germany