[PATCH] lib: Fix gencache_del

[Volker Lendecke]

On Sun, Mar 06, 2016 at 04:57:01PM +0100, Ralph Boehme wrote:
> On Fri, Mar 04, 2016 at 01:18:47PM +0100, Volker Lendecke wrote:
> > On Fri, Mar 04, 2016 at 08:15:51AM +0100, Volker Lendecke wrote:
> > > On Thu, Mar 03, 2016 at 07:08:18PM +0100, Michael Adam wrote:
> > > > Unfortunately, this fails make test due to a slight
> > > > change in semantics of delete:
> > > 
> > > Attached find a patchset that survived a private autobuild for me.
> > > 
> > > Comments welcome!
> > 
> > Not a good day for me today. Working on the next version of this
> > patchset.
> 
> maybe we should get rid of the double (or tripple with memcache) cache
> layering and use lmdb for the gencache.

There's a reason for the double-caching: The stuff that's in
gencache.tdb survives crashes even under writes. The
saf_join cache might be among the more important ones, but I
could imagine that other entries might also be valuable.

With the current 2-db architecture we can write and get
"eventual consistency" across crashes. I'm not sure lmdb
without sync keeps the stuff that was last sync'ed always
consistent, even under subsequent write traffic.

Volker

-- 
SerNet GmbH, Bahnhofsallee 1b, 37081 Göttingen
phone: +49-551-370000-0, fax: +49-551-370000-9
AG Göttingen, HRB 2816, GF: Dr. Johannes Loxen
http://www.sernet.de, mailto:kontakt at sernet.de