Re: ‘core-updates’ is back!

[ludo@gnu.org (Ludovic Courtès)]

iyzsong@member.fsf.org (宋文武) skribis:

> Andy Wingo <wingo@igalia.com> writes:
>
>> On Tue 29 Aug 2017 00:01, ludo@gnu.org (Ludovic Courtès) writes:
>>
>>> Yup, I just created a new ‘core-updates’ branch by pushing
>>> <https://bugs.gnu.org/27849>.  Enjoy!
>>>
>>> Let’s freeze in one month, say Oct. 1st?
>>
>> It would be pretty cool if we could fix our O(n^2) problems in search
>> paths in this core-updates -- basically whenever you go to create an
>> environment, instead of making e.g. VAR=A:B:C:..., for all VARs
>> (LIBRARY_PATH, PKG_CONFIG_PATH, etc), instead we make a union directory
>> Z containing the union of A, B, C, etc and set VAR=Z.  The goal would be
>> to fix quadratic run-time lookup costs by replacing it with a
>> compile-time computation.  This applies to many lookups: PATH, -rpath,
>> etc.
>
> The runtime references scanner of daemon will be inefficient if the
> union gets recorded with all the inputs contained, and we likely won't
> apply this to packages with multiple outputs (eg: fcitx) which will make
> every output including the union into its runtime reference.

Indeed, good point.

Ludo’.