Re: offlineimap imap<->imap reliability?

[James Leifer <James.Leifer@xxxxxxxx>]

John,

First of all, thanks for your detailed reply.

Let me just clarify a few points.

> Even if a state file is corrupted (and likely this would just result in it
> being truncated), the worst that will happen is your mail will be
> duplicated.

Are state files overwritten as the sync goes or are they written to a
temporary file and then atomically moved into place a the end of the
sync?

Are the internal integrity of state files verified when loaded by
offlineimap?

> There is one small potential race condition that I hope to fix for
> OfflineIMAP 5.0:  If a new message arrives on the remote end, and the remote
> server tells OfflineIMAP about it when it asks for a list of messages in the
> folder, but it gets deleted from the remote before OfflineIMAP can download
> it, OfflineIMAP will exit with an error.

OK, good to know.  Here's another scenario where this might occur:
there's a spam filter running concurrently with offlineimap that opens
a connection to the remote server and walks through the files, moving
suspected spams to another folder.

When you say ``deleted'' does that include ``moved to another folder''?

>> * What happens if ``conflicts'' arise, i.e. each replica has different
>>   flags modified for a particular message since the last sync?
>
> Flags are handled on an as-changed basis; so if the local system added the
> seen flag and the remote added replied, the message should end up with both. 
> (I'll have to verify this is the case, but I think it is.)

And if on one replica a message is moved to another folder and on the
other replica, the message is not moved but receives new flags, what
does the synced state look like? Is it moved+flags changed, or just
one or just the other, or something else?  Does it matter whether the
move is local and the flag change remote or vice versa?

> Otherwise, local changes override remote ones.

So if flag foo is added on the local side and removed on the remote
then in the newly synced state foo is present on both?

> Hope this helps.  You've got some honest answers on plusses and minuses of

I really appreciate your reply.  Thank you again.

James