In the past I was very active with Python packaging.
For several years now I was hardly around as maintainer,
so it does not make sense I am listed as a maintainer for
these makes. Looking back, I should have removed myself
as maintainer already much longer ago. Anyway, better late
than never.
It's been a fun ride, and I do intend to occasionally contribute
to Nixpkgs, but not in the same way it once was.
Currently, nix-support/propagated-build-inputs is parsed by splitting on
a single space. This means that if this file contains multiple spaces
separating two paths, the build_inputs list will end up containing an
empty string.
Instead, call split() with no arguments, which splits on runs of
whitespace and also ignores whitespace at the beginning and end of the
string, eliminating the need for strip().
Now that we only visit each path once, a few things can be simplified.
We no longer have to keep a list of different dependency chains leading
to a package, since only one chain will ever be found. Also, the already
visited check also takes care of cycles, so the other cycle check can be
removed.
The hook performs a depth first search on the graph defined by
propagatedBuildInputs. This traverses all paths through the graph,
except for any cycles. In the worst case with a highly connected graph,
this search can take exponential time. In practice, this means that in
cases with long dependency chains and multiple packages depending on the
same package, the hook can take several hours to run.
Avoid this problem by keeping track of already visited paths and only
visiting each path once. This makes the search complete in linear time.
The visible effect of this change is that, if a conflict is found, only
one dependency chain that leads to the conflicting package is printed,
rather than all the possible dependency chains.
Add a test where a conflicting package can be found at the end of
multiple dependency chains. This is far too simple an example to
demonstrate the ill effects of exponential time complexity, but does
serve to demonstrate how the error output changes when each path is only
visited once.
This was achieved using the following command:
sd 'wrapGAppsHook\b' wrapGAppsHook3 (rg -l 'wrapGAppsHook\b')
And then manually reverted the following changes:
- alias in top-level.nix
- function name in wrap-gapps-hook.sh
- comment in postFixup of at-spi2-core
- comment in gtk4
- comment in preFixup of 1password-gui/linux.nix
- comment in postFixup of qgis/unwrapped-ltr.nix and qgis/unwrapped.nix
- comment in postFixup of telegram-desktop
- comment in postFixup of fwupd
- buildCommand of mongodb-compass
- postFixup of xflux-gui
- comment in a patch in kdePackages.kde-gtk-config and plasma5Packages.kde-gtk-config
- description of programs.sway.wrapperFeatures.gtk NixOS option (manual rebuild)
