Re: Executing a file only on later passes

[Mark . Burgess]

The double pass removes the responsibilty from the user to
remember to force multple passes. Nothing else is different.

M

On  3 Nov, Wipf, Stefan wrote:
> We've disabled the second pass. I can't think of all the reasons
> just now, but the ones that immediately come to mind are:
> 
> 
> - Relying on the second pass to resolve hidden dependencies is
>   not reliable and just seems wrong.
> - it obscures dependencies and can make an already complex
>   configuration very convoluted.
> - Often order does matter.  Sometimes things do not get done
>   unless the order is right
> - Most importantly, there does not seem to be a real need for it.
>   There is nothing stopping us from explicitly forcing as many
>   passes as needed on a per action basis in in the action sequence.
>   This gives more refined control than to brute force a global
>   second pass.
> 
> 
> 
> Mark.Burgess@iu.hio.no wrote:
>> 
>> Chip, John,
>> 
>> The second pass is just like the next invocation of cfagent.
>> Nothing will change by eliminating it except that the system will
>> not be completely configured in a single iteration. The ordering
>> of events is nothing to do with this. It just speeds up convergence
>> for 90% of cases with hidden dependencies.
>> 
>> > OK.  It does cause things to sometimes (rarely) be executed in an
>> > unexpected order, however.  Life might be made easier if we made this a
>> > bit more user-accessible; for example, define a 'laterpass' class (or
>> > something similar) after the first pass is done.  This would aid in
>> > debugging (add a !laterpass condition and see if the problem persists
>> > and the like) and allow for some clever hacks.
>> 
>> The second pass is only used if there are classes defined that have
>> restricted the first pass, leaving some potentially unexecuted actions
>> that would not be possible to evaluate.
>> 
>> If you want to control the order of things (which should not be
>> necessary if you just trust the agent) then reorganize the
>> input files. But who cares what the order is if it gets done?
>> 
>> > This isn't a major problem, but it can be frustrating.  No doubt this
>> > frustration is exacerbated by a lack of grokking on my own part.
>> >
>> 
>> Yup. Whern things get complex they are hard to understand.
>> M
>> 
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> Work: +47 22453272            Email:  Mark.Burgess@iu.hio.no
>> Fax : +47 22453205            WWW  :  http://www.iu.hio.no/~mark
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> 
>> _______________________________________________
>> Help-cfengine mailing list
>> Help-cfengine@gnu.org
>> http://mail.gnu.org/mailman/listinfo/help-cfengine



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Work: +47 22453272            Email:  Mark.Burgess@iu.hio.no
Fax : +47 22453205            WWW  :  http://www.iu.hio.no/~mark
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~