Re: performance patch

[Curtis Villamizar <]

In message <Pine.GSO.3.96.980317212825.9361D-100000@localhost>, Robert Martin-L
egene writes:
> I don't run the code myself, but.....
> 
> On Tue, 17 Mar 1998, Curtis Villamizar wrote:
> 
> > Index: src/syntax.pl
> > ===================================================================
> > RCS file: /usr/local/CVS-routing-dev/irr-source/dbase/src/syntax.pl,v
> > retrieving revision 2.4
> > diff -c -r2.4 syntax.pl
> > *** syntax.pl	1997/11/14 20:49:12	2.4
> > --- syntax.pl	1998/03/17 19:59:25
> > ***************
> > *** 490,501 ****
> >   #
> >   # Now check the actual keywords
> >   #
> > ! 	while($tmppol =~ s/(\S+)//) {
> > ! 	    if (!&isaskeyword($1)) {
> > ! 		return $O_ERROR, 
> > ! 		"syntax error in \"$ATTL{$key}: peer $as cost $pref\"\n\t$1 ".
> > ! 
> > ! 		    "is not a routing policy KEYWORD";
> >   	    }
> >   	}
> >   	return $O_OK;
> > --- 490,501 ----
> >   #
> >   # Now check the actual keywords
> >   #
> > !        local($tmpword);
> > !        foreach $tmpword ( split("\\s+", "$tmppol") ) {
> > ! 	   if (!&isaskeyword($tmpword)) {
> > ! 	       return $O_ERROR, 
> > ! 	       "syntax error in \"$ATTL{$key}: peer $as cost $pref\"\n".
> > ! 		   \t$tmpword is not a routing policy KEYWORD";
> 
> Aren't you missing a " in the beginning here?

Yes.  I debugged, edited the original change one more time, mailed,
tried it and fixed it.  Already mailed.  Oops.

> >   	    }
> >   	}
> >   	return $O_OK;
> > 
> 
> Also, wouldn't this use of split by ever so slightly faster? :
> 
> split(/\s+/, $tmppol)

This was a serious performance problem, not just an inconsequential
tweak.

It went from over an hour to a few minutes for the very long string
that is the as-in statement for AS1673.  The difference is changing
the length of the string $tmppol a few thousand times vs a single
string split operation.  Whether avoiding the double quotes around
$tmppol or avoiding the local variable $tmpword would cut off another
few seconds doesn't really matter much.

Curtis