overview index cache

[Igor Timkin]

Katsuhiro Kondou writes:
> 
> Seeing from my server in production, not a few reader issue
> HEAD and BODY to retrieve articles.  Current article retrieval
> in nnrpd calls OVgetartinfo() for each article to get token.
> I believe it's quite wasteful for some overview method(yes,
> I mean buffindexed).  I'm thinking of having overivew index
> cache to reduce this, but some methods may not care those
> behavior.  All methods may not need.  To match both I'll add
> new feature into OVctl() which will do something like madvise(),
> to inform method to keep or free cache for index.  For method
> which does not care, just returns with doing nothing.  Any
> comments?
> -- 
> Katsuhiro Kondou
> 
> 

Looks fine. I'll use cache on my news.gamma.ru which overloaded.