Re: Caching IMAP articles

[Simon Josefsson]

Edi Weitz <spamtrap@agharta.de> writes:

> I'm reading mail on my laptop from a remote IMAP server. The remote
> server is at home on an ADSL line which is kind of slow upstream, and
> sometimes I'm even offline. So, I'm looking for a solution to keep my
> IMAP server but make mail reading faster if I'm not at home. I've used
> offlineimap[1] for a while but I didn't really like this setup.
>
> Now I thought that maybe this might be doable with Gnus alone. What I
> want is the following: Every IMAP message that I've read with Gnus
> should be stored locally. Whenever I try to read this message again,
> whether online or offline, Gnus should fetch it from the local storage
> and don't contact the IMAP server again.

These are my agent configuration to achieve this:

 '(gnus-agent-consider-all-articles t)
 '(gnus-agent-enable-expiration (quote DISABLE))
 '(gnus-select-article-hook (quote (gnus-agent-fetch-selected-article ...

Perhaps there should be a simpler way to request that articles are
entered into the cache when you read them than adding a function to a
hook variable.

> I've played around with various combinations of gnus-use-cache and
> gnus-agent-cache but unless I set both of them to nil the IMAP groups
> aren't updated by Gnus, no matter if I'm online or not, i.e. if I've
> deleted an IMAP message with another client it's still shown by Gnus
> although I can't select it. (Nor can I delete it from Gnus, of
> course.) I'm probably missing something simple but I'm stuck.

It sounds like a Gnus agent overview cache problem.

> I also have to admit that I don't fully understand the difference
> between cache and agent-cache.

Originally they were two separate features, but are now in the state
where it is difficult to tell them apart.  The intention was that the
cache can be used to store articles locally, forever, even when the
articles has been removed on the server.  The agent-cache is only used
to speed up normal operations.  To enter articles into the cache, you
have to request it for each article, but entering articles into the
agent cache can be done more automatically.  Perhaps it is useful to
think of the cache as a manual user-controlled caching mechanism, and
the agent-cache as a Gnus controlled caching mechanism.