[sr-dev] Question about config framework (ser)

[marius zbihlei]

Andrei Pelinescu-Onciul wrote:
> On Feb 16, 2010 at 12:47, marius zbihlei <marius.zbihlei at 1and1.ro> wrote:
>   
> You need this callback to be called the moment the value is set (1),
>  in each process, before the updated config is used (2) or once, before
> the updated config is use the 1st time (by the first process that needs
> to access it) (3)?
>
> If (2) is ok, then use the on_set_child_cb (next field in the cfg_def).
> If (3) is ok, then set CFG_CB_ONLY_ONCE among the flag and use the
>  on_set_child_cb, like for (2).
>
>   
Hello,
What I really wanted was 1, when the cfg value was change the statistics 
are also updated. But I guess this can't be easy done (requires changes 
to cfg framework).  As I only need the value changed once, and 
statistics aren't per process, I guess 3 is the better option.

I don't completely understand the whole "before the updated config is 
used". This means a cfg_update() is required or I don't have to do 
anything the update being done transparently from the user(myself) point 
of view. If I issue a sercmd cfg.set_now_int this will mean that the 
child_cb will be called at the time of the update(the value being 
changed now ?!) ?!

If I need to call cfg_update(), then I can call it from the "save" 
function export of the registrar module(and all other function exports 
called from ser cfg script). If this will make the child_cb to get 
called, then I can update the statistics from there. The window between 
the cfg value is changed and the changed is reflected to statistics is 
limited by the next call to a registrar function export when a sip 
messages is processed.

Another thing. Do I need to use cfg_update() periodically to ensure that 
values from cfg framework are consistent in the modules?! After looking 
at some examples in modules/tm I presumed that a call to cfg_get(...) is 
enough to get the updated value (Note that I don't have any child 
processes in the module - if there were children I would call 
cfg_update() from the infinite loop of the child).

> So far I guess nobody had a fixup that didn't change the value :-)
>   

I can think of two cases when the value is not changed/transformed

1. A change in cfg framework generates some internal module changes 
(like a reread of a database, update of statistics). I think this can be 
achieved via child_cb.
2. The fixup tests to see if the value is correct (like expecting a 
string from a already known lists of strings). No changes are possible 
and if the user gave smth wrong, sercmd will inform it at once . This 
can't be achieved via child_cb.

Thanks for the help

Marius
>> Any ideas welcome.
>>     
>
>   

> In the long run we have to fix somehow the var. w/ fixup unreadable
> problem. Maybe we should add a cfg_on_display callback (but then we
> would have to update a lot of cfg_defs).
>
> Andrei
>
>