[Nix-dev] garbage collection and nix-push

[Michael Raskin]

>Hi all,
>
>The hardware I use for building my channel is not very powerful. It
>does a good job of building derivations, but packing nar files with xz
>takes ages.
>
>My channel is nothing special, It just builds the configurations for a
>few home machines and laptops and some packages that hydra doesn't
>build with the optional dependencies I like.
>
>By registering the outputs as gc roots, I made sure no extensive
>rebuilds are performed when I don't change much.
>However, after a garbage collector run, all nar outputs get removed,
>leading to long push times on the next run.
>
>So for now, I just lowered the garbage-collection cronjob to once a week.
>
>Does anyone have a suggestion on how to work around this?
>For example registering the nar outputs as (temp/indirect) gc roots or
>steering the garbage collector not to remove outputs that were built
>less than 48 hours ago or something?

I am not too familiar with precise nix-push inside. Does the idea of 
building a directory with symlinks of NARs (wo it depends on them all),
calling it something that includes current date, and removing 
100-hour-old link sets in cron look hard ot easy to implement?