[OSM-dev] Renderd + expire_list

Lennard ldp at xs4all.nl
Thu Oct 21 00:27:04 BST 2010

On 20-10-2010 15:51, Samir Faci (Dev) wrote:

> I was going to submit a patch... but I wanted to understand the
> intended purpose of these changes.

The intended purpose was to remove the need to setup rendering threads 
with renderd, when they wouldn't be used anyway.

> it seems like the program flow now is to only render in combination
> with touchFrom or deleteFrom.

That's a bug. The default behaviour is to rerender tiles, and only when 
a suitable combination of min-zoom and touch-from/delete-from is given, 
to switch to those exclusively. I just committed a fix that does more 
explicit checking of these combinations.

So, for example:

Expire tiles z9 and up by setting their timestamp to the past. This 
causes mod_tile to issue a rerender the next time the expired tile is 
--min-zoom=9 --touch-from=9

Rerender tiles z8-11 and touch z12+. The lower zooms take much longer to 
render, so this rerenders those right away, while delaying rendering the 
higher zooms until someone actually looks at them.
--min-zoom=8 --touch-from=12

If you give no min-zoom/max-zoom (default is 0 and 18 respectively), and 
no touch-from/delete-from, it will go through all zooms and rerender 
them, based on the input file.


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