New command: hg debugrevlog

[Benoit Boissinot]

On Thu, May 12, 2011 at 6:44 PM, Sune Foldager <cryo at cyanite.org> wrote:
> I added a debugrevlog command which shows some data about a revlog (or
> filelog),
> and some statistics. My original use case was to debug generaldelta
> performance.
>
> The command shows extensive statistics about the deltas if it's a
> generaldelta
> revlog. Example output:
>
> cryo at serene:~/test$ hg debugrevlog .hg/store/00manifest.i
> format    : 1
> flags     : generaldelta
> revisions : 10194
> merges    : 3374
> chains    : 16
>
> data size (min/max/avg)                : 392850 / 611167 / 491670
> compressed snapshot size (min/max/avg) : 113171 / 151388 / 135161
> compressed delta size (min/max/avg)    : 0 / 112440 / 1300
>
> deltas against prev  : 3204
>  ..where prev = p1  : 3073
>  ..where prev = p2  : 33
>  ..other            : 98
> deltas against p1    : 6950
> deltas against p2    : 24
> deltas against other : 0
>
> The command can also be started with a filename directly, similar to
> debugindex and debugdata:
>
> cryo at serene:~/crew$ hg debugrevlog mercurial/lock.py
> format    : 1
> flags     : inline
> revisions : 32
> merges    : 2
> chains    : 1
>
> data size (min/max/avg)                : 1052 / 4373 / 2830
> compressed snapshot size (min/max/avg) : 454 / 454 / 454
> compressed delta size (min/max/avg)    : 0 / 767 / 130
>
> Notice how this, non-generaldelta revlog displays less information.

You could still show something like:
deltas against prev  : 3204
 ..where prev = p1  : 3073
 ..where prev = p2  : 33
 ..other            : 98

It would make sense I think. (and we could compare the result before
and after shrink)

Might also be nice to have %age instead of absolute numbers, easier to
interpret.

cheers,

Benoit