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From: James Leifer <James.Leifer@inria.fr>
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Subject: Re: concurrent synchronization of nnmaildir directories
Date: Tue, 09 Dec 2003 22:10:02 +0100
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prj@po.cwru.edu (Paul Jarc) writes:

(snipping liberally)

>> * Modify the marks of an existing message, i.e. add and delete entries
>>   in foo/.nnmaildir/marks/{read,reply,...}
>
> Safe.

Paul, thanks for your reply.

Let me clarify this last point...

Suppose a message uniq has the set of flags F when the group is
opened.

Suppose in gnus I add the set of the flags X0 and remove the set Y0.
Now, when nnmaildir flushes its state, it will change the on-disc flag
set to

   F \ Y0 U X0

(using \ for set difference and U for set union).  Suppose instead
that before it flushes its state, an external program adds the set of
flags X1 and removes the set Y1, leaving the state on disc

   F \ Y1 U X1

Now what will nnmaildir do when it flushes its changes?  The reason I
ask is as follows: some of the flags it would normally delete (in Y0)
are no longer there on disc; others it would add (in X0) are already
there.

Warm regards,
-James

P.S. If you get a chance, could you have a look at my
performance/design question concerning constant messages
(http://article.gmane.org/gmane.emacs.gnus.general/55114/)?