[geos-devel] RE: LineSegment copy removal, ABI protection 2

[Martin Davis]

> Martin, should LineSegment store REAL coordinates or can it 
> safely store references to them ?

References should be safe - LineSegment never changes its coordinates.
It may reorder them, however (but this should work with references,
right)?

I didn't get the attachment - is this a fix that might be good for JTS
too?

Martin Davis, Senior Technical Architect
Vivid Solutions Inc.      www.vividsolutions.com
Suite #1A-2328 Government Street Victoria, B.C. V8T 5G5
Phone: (250) 385 6040 - Local 308 Fax: (250) 385 6046


> -----Original Message-----
> From: strk at refractions.net [mailto:strk at refractions.net] 
> Sent: June 27, 2005 11:41 AM
> To: geos-devel at geos.refractions.net; Martin Davis
> Subject: LineSegment copy removal, ABI protection 2
> 
> 
> I've found that many of the Coordinate copies are
> done within LineSegment. LineSegment contains two
> points and ops on them.
> 
> Fiddling with SubgraphDepthLocater I've handled
> to reduce run time of the attached test from
> 279.71 to 17.17 seconds !
> 
> I obtained this avoiding to construct a LineSegment
> until really needed.
> 
>   %   cumulative   self              self     total           
>                    time   seconds   seconds    calls   s/call 
>   s/call  name                       84.82    237.26   237.26 
>  7645820     0.00     0.00  geos::LineSegment::reverse()
>  
> Martin, should LineSegment store REAL coordinates or can it 
> safely store references to them ?
> 
> ... this change would break both ABI and API, probably unused 
> parts but still ... maybe we should add a new class like 
> LightLineSegment to avoid it in this case.
> 
> --strk;
>