Re: Determing Threads

2005-04-21 13:16:51
On April 19, 2005 at 19:37, East Coast Coder wrote:

Have you looked at the $TSLICE$ resource variable?  I.e.  If you
provide more info on what you are trying to do, there may already
be features that do what you need.

I'm experimenting with a format where, instead of rebuilding the
entire tree, new messages are output incrementally.  I think this
would be necessary for using MHonArc for formats other than HTML
archives (RSS feeds, perhaps, or text messages).  I'd like to be able
to process a mbox, take the new messages, and output them - but
identify each message with a unique id to its thread, so that the
final output device (aggregator, phone, whatever) can associate it.

Mhonarc does not assume that it will process messages in the correct
order.  For example, a follow-up to a message may be processed before
its reference(s).  Also, mhonarc was initially coded in Perl 4,
so leveraging complex data structures was not necessarily trivial.
Therefore, mhonarc just recomputes threads after each update to
an archive.  There may be ways to optimize threading computation
with the existing code base, but I have not bothered to look into it.
Some of the main hash structures have been "Perl 5'ed", but in general,
most of mhonarc's data structures are flat.

As for your immediate need, you can write a wrapper program that
invokes mhonarc for the main work and then does some post-processing
to get what you need.  With the minimal API facilities of mhonarc,
you can determine which messages are new.

You will need to maintain your own thread IDs.  A simple map can
be used to maintain the message to thread ID association.  Thread ID
generation can be a simple counter.

You can check out the mha-preview program in the examples/ directory
of the mhonarc distribution for an example of how to develop a
wrapper program.  Your wrapper will require some more knowledge of
the internals of mhonarc that is not documented in the API appendix
of the docs.

You can examine the library for a list of the internal
data structures used by mhonarc.  The ones under "Message information
variables" will probably be of the most interest to you.  You can
even examine the .mhonarc.db file of an archive to get a clearer
picture of how the various hashes are structured.

Side Note: I like the idea of having thread IDs.  Something to consider
if/when mhonarc is rewritten, and maybe something possible with the
existing code base.  Mhonarc is an old program and various users are
definitely hitting up against its limitations.  Motivation is my main
enemy in doing a complete re-implementation.


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