[Nix-dev] Fwd: Re: Gratuitous generations

[Tomasz Kontusz]

Argh, responded to the wrong address again :-/


-------- Wiadomość oryginalna --------
Od: Tomasz Kontusz <tomasz.kontusz at gmail.com>
Wysłane: Tue Mar 31 08:37:07 CEST 2015
Do: Serge Kosyrev <_deepfire at feelingofgreen.ru>
Temat: Re: [Nix-dev] Gratuitous generations

Cool idea! I'm sure you'll be happy to know that's how nix profiles (the system one too) work already :-)

Serge Kosyrev <_deepfire at feelingofgreen.ru> napisał:
>Christian Theune <ct at flyingcircus.io> writes:
>>> We could add an option to suppress creating a new generation if
>nothing has changed.
>>
>> Sounds like an idea to start working on this. If your main concern is
>to avoid
>> accidentally breaking the switch/rollback semantics while providing
>this then
>> maybe at some point the option could be dropped.
>>
>> Mulling over this: I’m not sure what the clear expectation is on the
>> switch/rollback scenario when nothing is changing. Knowing that
>rolback always
>> gets me to the point prior to the last switch (independently whether
>something was
>> changed or not) is a simple rule (which is good). I can also see that
>rollback
>> fixes the last change. This would require users to understand when a
>rebuild
>> introduced a change or not. This would require an additional concept
>to be
>> present, the overhead of that is currently unclear to me.
>
>Just a somewhat silly idea..
>
>What if we had a more pervasive content-addressing (CAS) --
>i.e. generations were named by a hash of its contents -- hashes of the
>constituent derivatations and relevant meta information?
>
>In the case nothing truly changed, we'd get the same hash.
>
>Mapping the hashes to a monotonic progression of numbers could then be
>added atop.
>
>-- 
>regards,
>Серёга Косырев
>_______________________________________________
>nix-dev mailing list
>nix-dev at lists.science.uu.nl
>http://lists.science.uu.nl/mailman/listinfo/nix-dev

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