Re: using cdb for 'update' without race condition?

Norman Ramsey <[email protected]> wrote:
>   1. My app reads a database and extracts all the key-value pairs.
>
>   2. My app produces a new set of key-value pairs.
>
>   3. I atomically make a new database. I cannot do this through a C
>      API but only via the cdbmake program.  Atomicity is guaranteed by
>      the way cdbmake uses the filesystem.

Mostly correct.  skalibs provices a C API for updates:
http://www.skarnet.org/software/skalibs/

> It appears to me that if I want to avoid losing an update via race
> conditions that my cdb file needs to be protected by some kind of
> lock, and it's up to my app to use liblockfile or something similar.

Yes, almost - since the original cdb file will be deleted during the
update, it's not a good choice of lock file.  You want to lock a
different file which will remain in place.

> I cannot find a Web archive for this list

http://news.gmane.org/gmane.comp.djb.cdb


paul