[mkgmap-dev] [Patch] Faster BoundaryGridFrom GerdP gpetermann_muenchen at hotmail.com on Fri May 4 11:23:28 BST 2012
Hi WanMil, attached is the reworked patch. Changes compared to r2724: - Performance improvement when a zip file is used to store precompiled boundaries and input file contains a large area of sea. Since we don't generate *.bnd files for sea-only tiles, the old algorithm did a costly sequential search for each *.bnd file that would cover such a sea-only tile. - Drawback: Boundaries in a zip file containing directories are only found if they are in the topmost level http://gis.19327.n5.nabble.com/file/n5685428/BoundaryGrid_v2.patch BoundaryGrid_v2.patch I had to change the logic a bit to avoid opening the zip file again and again. I fear this conflicts with your precompiled_sea.patch. Gerd WanMil wrote > > Hi Gerd, > > I also prefer solution 1. > > WanMil > >> Hi WanMil, >> >> you are right, the patched code is a bit slower for the normal case. >> I see two solutions: >> 1) We don't allow directories in the zip file. With this restriction we >> can >> simply stop searching if the wanted bnd file is not found instead of >> traveling through thousends of entries. >> We can alarm the user when we find a directory structure within the zip. >> 2) We save the list that is created in LocationHook.init() and use it as >> a >> parm for the BoundaryGrid >> constructor. >> >> I'd prefer option 1, what do you think? >> >> Gerd >> >> >> GerdP wrote >>> >>> Hi WanMil, >>> >>> attached is a small patch which drastically improves BoundaryGrid for >>> tiles that contain mostly sea. I found such a tile in south-america, and >>> the patched version is> 10 times faster. >>> It contais a large part of the pacific, and BoudaryGrid searches the >>> boundary zip file for >>>> 5000 different *.bnd files, most of them do not exist in your >>>> bounds_20120401.zip , so the >>> code in BoundaryUtil searches through all elements of the zip file to >>> find >>> out that it doesn't exist. >>> >>> The patch creates a HashSet first with the available files and calls >>> the >>> load routine only for >>> those that exist. >>> >>> Gerd >>> http://gis.19327.n5.nabble.com/file/n5680180/BoundaryGrid.java.patch >>> BoundaryGrid.java.patch >>> >> >> >> -- >> View this message in context: >> http://gis.19327.n5.nabble.com/Patch-Faster-BoundaryGrid-tp5680180p5682445.html >> Sent from the Mkgmap Development mailing list archive at Nabble.com. >> _______________________________________________ >> mkgmap-dev mailing list >> mkgmap-dev at .org >> http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev > > _______________________________________________ > mkgmap-dev mailing list > mkgmap-dev at .org > http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev > -- View this message in context: http://gis.19327.n5.nabble.com/Patch-Faster-BoundaryGrid-tp5680180p5685428.html Sent from the Mkgmap Development mailing list archive at Nabble.com.
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