Re: [naviserver-devel] ns_atstartup and order of execution?

[Zoran V. <zv...@ar...>]

Am 19.10.2005 um 18:16 schrieb Zoran Vasiljevic:

> Hi !
>
> We have a pretty elaborate (and sometimes confusing) mechanism
> for running various atXXX scripts.
>
> So, if I would like to:
>
>   ns_atstartup X
>   ns_atstartup Y
>   ns_atstartup Z
>
> then the server will execute:
>
>   Z
>   Y
>   X
>
> i.e. in the *reverse* order. This is because all of those
> are just entered in a single-linked list and the head of
> the list points always to the *last* registered item.
>
> This is suboptimal.
>
> In many real world scenarios, I will like to use the ns_atstartup
> to schedule couple of scripts to do various initialization things.
> It is often so that Y will depend on X and Z on Y to be successfull.
> At the moment, I'm (mis)using the ns_job with a single thread and
> post the jobs there, because it will then exectue them in FIFO fashion
> (which is what I need). BUT: this is of course not optimal as it runs
> parallely with the server startup and I have to be carefull to  
> accomodate
> for that.
>
> So, I'm all for reversing the logic of script execution i.e. doing the
> more natural way of runing them in FIFO fashion (now we have LIFO).
> But, I'm afraid of the potential compatibility problems. What I would
> like to see is if any of you would have objections to reversing the
> logic, and if yes, ideas how we could make this compatible?
> One idea would be:
>
>    ns_atXXX ?-tail? $theScript
>
> I'd rather go after FIFO list walk then adding yet-another-option,
> but I'm open to suggestions...

I've done the coding.

All ns_atXXX EXCEPT ns_atshutdown will now execute callbacks in FIFO
fashion. The ns_atshutdown will execute the callbacks in LIFO fashion.
This seems more natural to me. If nobody has anyhing against
(Vlad already expressed himself) I will commit this.

Cheers
Zoran