`borg --verbose prune` could print archive counts

[drws]

borg --verbose prune currently doesn't output anything useful during a normal run. It could print some archive counts:

• number of archives (in the repository)
• number of glob-matched archives (if --glob-archives is used)
• number of pruned archives (in a separate line at the end if unknown at the beginning)

[Konmous04]

Hi, I am interested in working on this issue. Is it acceptable if I try to implement this print feature?

[ThomasWaldmann]

@Konmous04 sure, thanks for helping!

Sounds like statistics, so guess there could be a --stats option?

Do a PR against 1.4-maint branch.

[drws]

--stats outputs byte statistics only also in other commands, so it might be preferrable it remains as-is. As said in OP, the problem is also that --verbose prune doesn't print anything. The proposed archive counts could also be printed if any of the two (--verbose or --stats) is set.

[ThomasWaldmann]

@drws @Konmous04 I have reviewed the existing code and also thought about how it should behave:

We have a stats object in there and already output some statistics at the end of prune, so --stats is already used and should not be changed.

So guess what we want is that it just is a bit more verbose on log level INFO while it does its work, like:

Found X normal archives and X checkpoint archives.
Applying rules...
Keeping X archives and X checkpoints, pruning X archives and X checkpoints...

This will be output early, before the loop where it actually deletes stuff, so it generates reasonable output with and without the --list option, with and without the --progress option, with and without the --stats option.

@Konmous04 can you please update your PR according to that?

[drws]

So guess what we want is that it just is a bit more verbose on log level INFO while it does its work, like:

Found X normal archives and X checkpoint archives.
Applying rules...
Keeping X archives and X checkpoints, pruning X archives and X checkpoints...

This is a great improvement, however, please consider displaying both the total number of archives in the repository, as well as the number of glob-matched (considered) archives. For example, the first 2 lines could read:

Repository contains X normal archives and X checkpoint archives.
Applying rules to the matching X archives and X checkpoints...

[ThomasWaldmann]

Reopening for this TODO.