[rbldnsd] [RFC] zlib support in rbldnsd

[Michael Tokarev]

Another request-for-comments.

I'm thinking about including zlib support into rbldnsd (the
changes are pretty trivial, about 10 lines of code), to be
able to read gzip-compressed data files directly.

After recent problems with CBL, when, due to whatever reasons
(mostly rsync-unfriendly ordering of the records), every update
ends up in transferring the whole file, taking significant
bandwidth and CPU time.  In this situation (unless something's
done to make the data file more rsync-friendly), it's better
to grab compressed data (a bit less bandwidth needed, and alot
less CPU usage on both sides), and rbldnsd could be learned to
read .gz file directly.

Additionally, it takes less resources to update compressed file
(less disk I/O), and to read it (again, less disk I/O).

And another point is -- when the original data already is rsync-
friendly (more or less), using gzip --rsyncable on it still allows
to use rsync with almost the same (if not better, due to reduced
file size) effectiveness, while keeping everything smaller...

Zlib support adds almost nothing for the "normal" case of
uncompressed files (just one extra cmp per data line).

How do you think, is such support valuable/worth it?

Thanks.

/mjt