Coda File System

Re: Coda spinning

From: <>
Date: Wed, 16 May 2007 09:29:28 +0200
Hi Jan,

On Tue, May 15, 2007 at 11:35:15PM -0400, Jan Harkes wrote:
> Another approach is to replace the existing hoard mechanism, the current
> implementation is both flexible but also quite complex. It combines both
> cache-replacement policy, in the way of hoard priority, with a demand
> fetch preference which indicates which files need to be automatically
> refetched when they are changed on the server.

seen with my eyes, the current implementation despite its flexibility
and presumable correctness is hardly usable in practice,
so some possibly less functional but usable and hence useful replacement
would be very nice to have.

With the arrival of cache access across reboots/token expiry
it becomes important to have startup files pinned down in the cache,
otherwise my small .xsession, which is not referenced at all except
during login time, can become forgotten and then I can not log in
without going failsafe, clog, and then login again...
There are other files used during login which can be forgotten as well.

For some few files the existing hoard would be sufficient,
but it does not seem to be friendly to a "big collection" scenario.

For such and similar reasons I would love, say, having an option of
"the files right now in the cache shall be there forever".
I think a similar result can be achieved by making a lookaside cache
of Venus cache. What happens if I hardlink the container files
into a shadow tree? If Venus does not notice that, it would allow
a space-efficient preservation of current cache for lookaside.

Of course, for generality the criteria for pinning down the files
should/might be extended. Say, "the files accessed since the begin-hoard-def
command are to be pinned/hoarded" - which gives us a very simple interface
to definition of hoard sets (shortcutting spy->config and combining
the definition and the actual fetch).

Again, my primary concern is not about keeping files fresh,
but about ensuring their presense.

An explicit find command or a dedicated tool, aware of hoard sets,
can be used at will for keeping the files updated,
but it should not be the default repeating action for the pinned files.

Best regards,
Received on 2007-05-16 03:29:37