[bug#29928] [PATCH 0/5] Optimize profile hooks

[宋文武]

address@hidden (Ludovic Courtès) writes:

> Hi,
>
> address@hidden (宋文武) skribis:
>
>> address@hidden (Ludovic Courtès) writes:
>
> [...]
>
>>>> One drawback is 'guix package --dry-run' no longer report the derivations 
>>>> of
>>>> profile hooks, and the derivation of profile it reports is not the real 
>>>> one.
>>>> Addition files will be built when the profiles hooks are run.
>>>
>>> FWIW I’m not entirely convinced by the approach.
>>
>> Well.. these patches modify package hooks to:
>>
>> 1. build all manifest inputs first.
>>
>> 2. filter manifest inputs to get interested ones.
>>
>> 3. run hook with its interested inputs.
>>
>> I think reducing the inputs of hook from the whole manifest to its
>> interested ones is the only way to avoid unneeded reruns.
>
> Agreed.
>
>>> As discussed earlier, I’d like to experiment with a notion of “build
>>> rounds”: the first round would build a profile without any hooks, the
>>> second round would, depending on what the profile contains, rebuild it
>>> with certain hooks.
>>
>> I think "build rounds" would improve the UI/UX, and by changing inputs
>> from manifest inputs to a built profile, it would simply the current
>> implementations of profile hooks, but it won't avoid unneeded reruns
>> compare to the filtered interested inputs way.
>>
>> Is my understanding correct?
>
> A “build round” is something that computes derivations based on the
> output of previously-built derivations.  So it’s just another way to
> structure steps 1/2/3 above; it should not reduce expressivity.
>
> Build rounds would allow us to ensure that ‘build-derivations’ is not
> called right in the middle of Guix, and is instead always under the
> control of the “top level”.
>

I see, looking forward it, thanks!