[ka-Map-users] Some thoughts/questions about tile.php

[Tim Schaub]

Just a reminder that there is a "tile_source" "cache" option for layer
metadata.  If you set this in your mapfile, the call to tile.php is
avoided completely (tile source is determined on the client side).  This
does speed things up a bit.  I agree that it would be good to optimize
tile.php - anything that you could do would be somewhere between the
speed of the cache option and the current tile.php speed.

Terse docs:
http://ka-map.ominiverdi.org/wiki/index.php/Mapfile_Metadata_Configurati
on#Mapfile_LAYER_Section

Tim

-----Original Message-----
From: ka-map-users-bounces at lists.maptools.org
[mailto:ka-map-users-bounces at lists.maptools.org] On Behalf Of Stephen
Woodbridge
Sent: Thursday, July 13, 2006 1:33 PM
To: ka-map-users at lists.maptools.org ML
Subject: [ka-Map-users] Some thoughts/questions about tile.php

Hello Paul, et al,

I have been looking at tile.php and had some thoughts/questions about
how it works and how it might be made faster.

1) currently the first thing it does is open lock file on the metatile
2) if the file exist, it gets a shared lock
3) serves the image
4) removes the lock

It seems like it would be faster to avoid this locking, ie: if the file
exists just serve it. If image creation were written to a tmp file name
and renamed to the actual tile name when the write was done and the file
closed, this would be atomic and should avoid the problem that the code
above is dealing with.

Since the whole concept of tiled mapping is to generate once and serve
many times it seems this would be a valuable performance improvement by
avoiding 3 file operations per tile requested.


Second issue is that directory structure is pretty flat as Paul has
mentioned in the past. I was thinking that a very trivial change would
be to split the directories tnnnnn-lnnnnnn into tnnnnn/lnnnnnn which
would significantly reduce the number of entries in any given directory.

Any thoughts or issues on these would be appreciated.

Best regards,
   -SteveW
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