On Wed, Aug 1, 2018 at 8:25 PM Jody Garnett <[email protected]> wrote:
> Can you tell me more above it the direct access to the coordinate array?
>
Ok. Basically we have bits of code that love to work against arrays of
ordinates, direct access to the ordinate array avoids
having to build a new copy of the internal array in the consumer code
(e.g., reprojection is significantly faster when working directly
against an array of ordinates, than when reprojecting point by point).
Check the getXYArray and getOrdinateArray(dimension) here:
https://github.com/geotools/geotools/blob/9fbd02a320fa19d563972808d226a0a0445a5b13/modules/library/main/src/main/java/org/geotools/geometry/jts/LiteCoordinateSequence.java#L278
and their usage in these two places:
https://github.com/geotools/geotools/blob/9fbd02a320fa19d563972808d226a0a0445a5b13/modules/library/main/src/main/java/org/geotools/geometry/jts/Decimator.java#L463
https://github.com/geotools/geotools/blob/9fbd02a320fa19d563972808d226a0a0445a5b13/modules/library/main/src/main/java/org/geotools/geometry/jts/LineIterator2.java#L76
and then also direct access on the write side here:
https://github.com/geotools/geotools/blob/9fbd02a320fa19d563972808d226a0a0445a5b13/modules/library/main/src/main/java/org/geotools/geometry/jts/Decimator.java#L540
Now, ideally on the last bit of code it would be nice to avoid having that
second array allocation for the packed, final size version of the array,
and instead just tell the sequence to keep its array, but consider only the
first N elements. Back when this was coded (over 10 years ago) we did not
have yet
PNGJ and Marlin, so I'm guessing doing that did not give much benefit, but
today it might, given the different weight of the various map serving steps.
Something to try out on a rainy day, or if/when we participate again in a
performance contest [1], along with Laurent's suggestion to
pool the arrays instead of re-allocating them over and over for each new
geometry read (that would require a StreamingRenderer specific
coordinate sequence factory that has a "dispose" method which will give
back the ordinate arrays to the pool).
Cheers
Andrea
[1] Reminder, while we haven't had a FOSS4G performance shootout in a long
while, the performance is still being checked regularly,
e.g.
http://www.agrotic.org/blog/wp-content/uploads/2016/12/02_performance_qgis_server.pdf
and
https://github.com/camptocamp/ms_perfs
https://github.com/camptocamp/docker-geoserver/
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