wip/pkgchkxx: a complete reimplementation of pkg_chk and pkg_rolling-replace

[PHO <pho%cielonegro.org@localhost>]

Hi all,

I just created a new package wip/pkgchkxx. This is a complete 
reimplementation of pkgtools/pkg_chk and pkgtools/pkg_rolling_replace in 
C++17.

This implementation achieves better performance by using a faster 
language, better algorithms, and making use of many CPUs whenever 
possible. The latter is the primary reason why a complete rewrite was 
needed: doing it in POSIX shell was simply not feasible.

When you update your pkgsrc tree on a running system and you have like 
200 outdated packages to update, the chance of pkg_rr -u completing 
without any failures is somewhere between 5% and 0%. You usually have to 
fix broken things here and there, re-run pkg_rr repeatedly, and waste 
your time staring at "Checking for xxx packages (xxx=YES)" for several 
seconds each time you restart pkg_rr. I wanted to change that.

* pkgchkxx(8) takes options fully compatible with pkg_chk(8).
* pkgrrxx(8) takes options fully compatible with pkg_rolling-replace(8).
* Unlike pkg_rr, you can run pkgrrxx as a non-root user. It makes use of 
${ROOT_CMD} whenever it needs a root access.
* "pkgrrxx -u" runs roughly N times faster than "pkg_rolling-replace -u" 
where N is the number of CPUs you have.
* "pkgrrxx -sn" runs 14.8x faster than "pkg_rolling-replace -sn".
* "pkgchkxx -aur -b" runs 11x faster than "pkg_chk -aur -b" when 
pkg_summary file is available.
* "pkgchkxx -aur -s" runs roughly N times faster than "pkg_chk -aur -s" 
on a system with N CPUs.
* "pkgchkxx -l" runs 185x faster than "pkg_chk -l" when pkg_summary file 
is available, and runs 24.8x faster when it's unavailable (and needs to 
scan archives).
* "pkgchkxx -p" runs 1.3x faster than "pkg_chk -p".
* "pkgchkxx -g" runs 1.6x faster than "pkg_chk -g".
* "pkgchkxx -N" runs 22x faster than "pkg_chk -N".

Please consider the package as experimental. Do not forget to backup 
your /usr/pkg (I recommend sysutils/bup for that) before using it in 
case it messes up your system.

Also do not question the value of faster pkg_rr when the most 
time-consuming part of its job is to actually rebuild packages!