paketkoll - Check installed distro files for changes (much faster than paccheck)

It very much is (as I even acknowledge at the end of the github README). 😀

I have only implemented for checking all packages at the current point in time (as that is what I need later on). It could be possible to add support for checking a single package.

Thank you for reminding me of pacman -Qkk though, I had forgotten it existed.

I just did a test of pacman -Qk and pacman -Qkk (with no package, so checking all of them) and paketkoll is much faster. Based on the man page:

• pacman -Qk only checks file exists. I don't have that option, I always check file properties at least, but have the option to skip checking the file hash if the mtime and size matches (paketkoll --trust-mtime). Even though I check more in this scenario I'm still about 4x faster.
• pacman -Qkk checks checksum as well (similar to plain paketkoll). It is unclear to me if pacman will check the checksum if the mtime and size matches.

I can report that paketkoll handily beats pacman in both scenarios (pacman -Qk is slower than paketkoll --trust-mtime, and pacman -Qkk is much slower than plain paketkoll). Below are the output of using the hyperfine benchmarking tool:

$ hyperfine -i -N --warmup=1 "paketkoll --trust-mtime" "paketkoll" "pacman -Qk" "pacman -Qkk"
Benchmark 1: paketkoll --trust-mtime
  Time (mean ± σ):     246.4 ms ±   7.5 ms    [User: 1223.3 ms, System: 1247.7 ms]
  Range (min … max):   238.2 ms … 261.7 ms    11 runs
 
  Warning: Ignoring non-zero exit code.
 
Benchmark 2: paketkoll
  Time (mean ± σ):      5.312 s ±  0.387 s    [User: 17.321 s, System: 13.461 s]
  Range (min … max):    4.907 s …  6.058 s    10 runs
 
  Warning: Ignoring non-zero exit code.
 
Benchmark 3: pacman -Qk
  Time (mean ± σ):     976.7 ms ±   5.0 ms    [User: 101.9 ms, System: 873.5 ms]
  Range (min … max):   970.3 ms … 984.6 ms    10 runs
 
Benchmark 4: pacman -Qkk
  Time (mean ± σ):     86.467 s ±  0.160 s    [User: 53.327 s, System: 16.404 s]
  Range (min … max):   86.315 s … 86.819 s    10 runs
 
  Warning: Ignoring non-zero exit code.

It appears that pacman -Qkk is much slower than paccheck --file-properties --sha256sum even. I don't know how that is possible!

The above benchmarks were executed on an AMD Ryzen 5600X with 32 GB RAM and an Gen3 NVME SSD. pacman -Syu executed as of yesterday most recently. Disk cache was hot in between runs for all the tools, that would make the first run a bit slower for all the tools (but not to a large extent on a SSD, I can imagine it would dominate on a mechanical HDD though)

In conclusion:

• When checking just file properties paketkoll is 3.96 times faster than pacman checking just if the files exist
• When checking checksums paketkoll is 16.3 times faster than pacman checking file properties. This is impressive on a 6 core/12 thread CPU. pacman must be doing something exceedingly stupid here (might be worth looking into, perhaps it is checking both sha256sum and md5sum, which is totally unneeded). Compared to paccheck I see a 7x speedup in that scenario which is more in line with what I would expect.