request-group-articles for nnimap (was: Faster, lolcat. Faster!)

[Ted Zlatanov <tzz@lifelogs.com>]

On Thu, 02 Sep 2010 16:39:11 +0200 David Engster <deng@randomsample.de> wrote: 

DE> Yes, exactly. The nnimap-request-group-articles I posted simply returns
DE> the list of available article numbers in that group (which could be
DE> further compressed into the above range notation). Requesting the range
DE> of articles can take a second for very large groups, so some kind of
DE> caching should be done.

Let the backend decide if caching is possible since it has the best
knowledge of when the data is old.  It also knows best where to cache
(on the server, in memory, on disk, etc.)  The caching policy can be set
globally, but the rest should be on the backend IMO.  Otherwise this
sounds great.

DE> Anyway, this would be an optional back end function, and Gnus can query
DE> the back end for availability and use it (if the user wants it). I for
DE> example don't have much problems with the article count, but I don't
DE> delete much and use Dovecot. But there are IMAP servers out there
DE> (Zimbra...) which use absolutely insane values for article numbers;
DE> maybe it's using those for Mersenne prime searching or something.

So there's two pieces: the general facility and support for it in
nnimap.  Let's get the nnimap piece done first and verify it works since
we're close.  Can you modify your function to do compressed ranges?  Do
you know of any alternate implementations or patches (I haven't kept track)?

Thanks
Ted