On Thu, Feb 09, 2006 at 03:24:58PM -0000, John Hall wrote:
> "Ronan" <[EMAIL PROTECTED]> wrote in message
> >
> > Anyone have any input on this? What would be the implications? Should it
> > just be a straight translation perl -> c , or are there other factors?
>
> Ronan,
>
> Why would using pcre be quicker? Perl's regex engine is written in C as
> well. Besides, there is more to SA than just matching regexes.
The most important Difference between 'grep-ing' by pcre versus perl
in my opinion is the 'Startup-Time'. Starting/dynamically-linking a
whole 'perl-interpreter' is a lot more Work than just starting a pcre
Pattern-Engine.
So if you 'just grep for Text' with a script, pcre(grep) is your
friend. BUT if you need lots of dynamic libraries, use loadable
Modules, and connect to networks, like spamassassin does,
'pcre' simply has nothing to compare with that.
And in the case of 'spamd' the startup-phase loads only once,
then there only fork children, so there should be no large
startup-penalty.
ONLY you should not use 'dangerous/slow perl-patterns'
(avoid ambiguities, avoid remembering brackets without (?: ),
limit pattern-match-lengths by not using '.*' but .{min,max},
construct easily decidable left-factored searches)
As far as I remember perl does 'allow' a few more complicated
(not to say convoluted) cases than pcre does, but you'll better
not use them anyway in spamassassin patterns.
Stucki
--
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