Re: nnmail-split-it

[David Moore <dmoore@UCSD.EDU>]

Lars Magne Ingebrigtsen <larsi@ifi.uio.no> writes:

> Paul Franklin <paul@cs.washington.edu> writes:
> 
> > Hmm.  I wrote some elisp code to do splitting like this.  I didn't
> > distribute it because:
> > 
> > * I realized that the bottleneck was disk access time (over NFS).
> 
> The box I'm sitting with now is a 486/slow without NFS, and splitting
> is kinda slow here as well.

	Two different costs.  There is a per message cost (like NFS and
file stating).  There is also a per split cost (which is roughly O(n*m)
where n is the number of splits, and m is the number of headers in the
message).

> > It generates a alist of headers, unwrapping lines within headers and
> > separating values from duplicate headers with "\n".  You then match
> > with a header or multiple ones concatenated (very useful, for me at
> > least).  I never compared them with the default split rules, but I'm
> > fairly sure that this code is tight enough that it's very unlikely to
> > be a bottleneck.

	This is similar to what I suggested, but I wasn't going to
bother to put the headers into concatenated strings, since that is quite
slow itself.  But tracking the start/end position of those strings makes
doing a buffer regexp search much much faster since it limits the scope
of the search.

	As far as why it's a reverse search.  Well, I added the \1 sub
ability, and didn't think about the double .* affects with that,
probably because I wasn't using it with 'sender', and I think I used
`\\w' instead of `.'.  I recommend that people try [^ :]* or \\w*
instead of .* and see if that helps.  I'm not totally sure why Per used
a reverse search in the first place, but I left it because most of the
"uninteresting" headers are at the beginning (received, etc), and it'll
hit the lowest of any multiply matching lines.


-- 
David Moore <dmoore@ucsd.edu>       | Computer Systems Lab      __o
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