[PATCH] Add configurable changed tag to messages that have been changed on disk

[Austin Clements]

I should add that this code shouldn't be considered stable yet.  The
on-disk format may (and probably will) change, so don't try it on your
main notmuch database.

Quoth myself on Aug 01 at  2:55 pm:
> I have a prototype implementation of message modification times on my
> lastmod-v1 branch at
> 
>   https://github.com/aclements/notmuch/tree/lastmod-v1
> 
> It builds on my database features series that's currently awaiting
> review [1].
> 
> The series uses a monotonic revision number, rather than wall-clock
> time, for reasons related to Xapian's concurrent control and detailed
> in the main commit's commit message.  The implementation isn't quite
> useful from the CLI yet because I haven't added any way to query the
> database's current revision number.  (I'm still thinking about how I
> want to do this, since search/show don't have a good way to deliver
> "additional" information right now.  I might just add the last
> modification for each individual message/max of all messages in a
> thread, similar to what Thomas Jost's patch did long ago.)
> 
> [1] id:1406859003-11561-1-git-send-email-amdragon at mit.edu
> 
> Quoth Gaute Hope on Jul 28 at  4:37 pm:
> >    On Thu, Jul 3, 2014 at 12:42 PM, David Bremner <[1]david at tethera.net>
> >    wrote:
> > 
> >      Gaute Hope <[2]eg at gaute.vetsj.com> writes:
> > 
> >      > When one of the source files for a message is changed on disk,
> >      renamed,
> >      > deleted or a new source file is added. A configurable changed tag is
> >      > is added. The tag can be configured under the option 'changed_tags' in
> >      > the [new] section, the default is none. Tests have been updated to
> >      > accept the new config option.
> >      >
> >      > notmuch-setup now asks for a changed tag after the new tags question.
> >      >
> >      > This could be useful for for example 'afew' to detect remote changes
> >      in
> >      > IMAP folders and update the FolderNameFilter to also add tags or
> >      remove
> >      > tags when a _existing_ message has been added to or removed from a
> >      > maildir.
> > 
> >      The discussion on this proposal seems to have died out without reaching
> >      a conclusion. David M expressed a strong preference for some kind of
> >      modification time field in the database.  Gaute agreed with some caveats
> >      that such an approach could solve his problems as well. On the other
> >      hand, nobody seems to be actually working on such an approach at the
> >      moment.  Gaute and or David do you have any interest in revisiting the
> >      series [3]id:1323796305-28789-1-git-send-email-schnouki at schnouki.net and
> >      seeing if it can be reworked into mergeable shape? I suspect in
> >      particular something needs to be added with respect to message deletion
> >      Thomas, are you still running some variant of these patches?
> >      d
> > 
> >    I am afraid I don't have the chance to put in any consistent effort on
> >    this at the moment.
> > 
> >    I agree, message deletion needs to be solved somehow.
> >    Regards, Gaute

-- 
Austin Clements                               MIT/CSAIL/SB '06/PhD '14
amdragon at mit.edu                           http://web.mit.edu/amdragon
       Somewhere in the dream we call reality you will find me,
              searching for the reality we call dreams.