Re: Cache/Agent unification

[Simon Josefsson <jas@extundo.com>]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

>> Hm.  Maybe there still is a gap though -- cached articles (not
>> persistant ones) are kept around (and shown in summary buffers) even
>> when they have expired on the server, if `gnus-cache-remove-articles'
>> is nil (or something).  But this is probably a bug.  A cache should
>> cache things, not change semantics.
>
> Says who?  :-)
>
> It's definitely a feature, and it's a feature that's shared by the
> Agent.  Neither the Agent nor the cache cares one whit whether
> articles are expired on the server.  They'll keep articles around
> until the user makes them go away.

If the cache also contain persistent articles we'll have a problem
when people want to backup the cache directory (to have backups of
server-expired articles) but not their agent directory.  Unifying the
agent and cache is no good then.  Admittedly, the articles could still
be in separate directories and the agent (or the cache) could look
into the cache's (or the agent's) directory before storing/fetching
articles, but that's sort of yucky (and also a problem when articles
are removed in one of the cache/agent but not the other).  I thought
it would be nice if we could have ~/News/persistant/ and ~/News/agent/
only.

But I'm not sure what the usage pattern is here.  Maybe it's enough to
separate persistent articles into a directory that people can backup.

Hm. I'm assuming that you want a agent mode that synched the agent
with what's on the server.  If you read mail on a remote server (IMAP)
you kind of expect that articles you've deleted from the server (with
another client or Gnus instance) are deleted from the agent.  Then you
could use the cache to keep expired articles around.  OTOH you could
also use persistent articles for that.  If the latter is OK, we could
remove the persistentness thing from the cache, which would make it
possible to merge the cache and agent directories.

Maybe there the persistent article store could be a `expiry-target'.
So when cache/agent articles expire from the server, the local copies
are run through this process and people that want to keep them around
can make them end up in the persistent article store.

Err. Or something.