[ka-Map-dev] modification to tile cache structure

[Paul Spencer]

This comes with absolutely no warranty at all ... if it erases  
everything on your root drive, and emails itself to everyone you  
know ... you've been warned ;)

Seriously though, use with caution ... we wrote this up to fix up  
some of our caches and it may not be exactly right for a stock ka-Map.

You would run it using:

./update_cache_dirs.sh /tmp/kacache

Also note that I have not yet updated tile.php in cvs, but the change  
is trivial if you want to try it:

135c135
< $szMetaTileId = "t".$metaTop."l".$metaLeft;
---
 > $szMetaTileId = "t".$metaTop."/l".$metaLeft;


Cheers

Paul

#! /bin/sh
# save as update_cache_dirs.sh

## This function echos its argument and exits
fatal_error ()
{
     echo >&2
     [ -n "$1" ] && echo "! $1" >&2
     echo >&2
     exit 1
}

## Perform update operation on a directory
update_dir()
{
     DIRNAME=`dirname $1`
     BASENAME=`basename $1`

     TOP=`echo "$BASENAME" | cut -dl -f1`
     LEFT=l`echo "$BASENAME" | cut -dl -f2`

     #echo "dir=$DIRNAME   metatile=$BASENAME   TOP=$TOP  LEFT=$LEFT"

     [ -d $DIRNAME/$TOP ] || mkdir -p $DIRNAME/$TOP

     echo "mv $DIRNAME/$BASENAME $DIRNAME/$TOP/$LEFT"
     mv $DIRNAME/$BASENAME $DIRNAME/$TOP/$LEFT
}

CACHEDIR=$1

[ -z "$CACHEDIR" ] && fatal_error "cachedir arg missing. Usage: $0  
<cachedir>"

##
## If called with 1st arg = processdir then call update_dir() with arg2
##
if [ $CACHEDIR = processdir ] && [ -n $2 ]; then
     update_dir $2
     exit 0
fi


##
## Otherwise default behavior is to look for all metatile dirs and  
process them
##
find $CACHEDIR -name "t*l*" -mindepth 5 -maxdepth 5 -type d -exec $0  
processdir {} \;



On 23-Oct-06, at 10:19 PM, Morgan Pyne wrote:

> Hi Paul (and others!)
>
> I would definitely welcome the change, as we have already reached  
> the limits of an ext3 filesystem (~32768 subdirs) on a number of  
> occasions. While we could solve this by moving to some other  
> filesystem, I think that adding the extra depth is a good thing  
> anyway -  ext3 is a common default filesystem for many Linux distros.
>
> I was wondering however if it might be possible to migrate a cache  
> to the new structure rather than completely invalidate it?  I'm  
> sure I'm not the only one who would prefer to be able to keep my  
> cache if possible - precaching again would take considerable time.  
> If the change only involves adding a slash between the top and left  
> values in the path then I'm guessing the cache migration could be a  
> one-liner for a good Perl monger.
>
> Another thing to consider might be to make this new cache structure  
> optional, and default to the old one.
>
> Thanks (for _all_ the good work on ka-map!),
> Morgan
>
>
> On 24/10/2006, at 1:33 PM, Paul Spencer wrote:
>
>> Devs (and others)
>>
>> Before we release 1.0, I'd like to change the tile caching  
>> structure to include an extra level of directories by inserting  
>> a / between the top and left values in the meta-tile directory.
>>
>> The change is trivial and safe, but it invalidates an existing  
>> cache (well, makes it useless)
>>
>> What do you think of this change?
>>
>> Cheers
>>
>> Paul
>> +-----------------------------------------------------------------+
>> |Paul Spencer                          pspencer at dmsolutions.ca    |
>> +-----------------------------------------------------------------+
>> |Chief Technology Officer                                         |
>> |DM Solutions Group Inc                http://www.dmsolutions.ca/ |
>> +-----------------------------------------------------------------+
>>
>>
>>
>>
>> _______________________________________________
>> ka-Map-dev mailing list
>> ka-Map-dev at lists.maptools.org
>> http://lists.maptools.org/mailman/listinfo/ka-map-dev
>
> _______________________________________________
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> ka-Map-dev at lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/ka-map-dev

+-----------------------------------------------------------------+
|Paul Spencer                          pspencer at dmsolutions.ca    |
+-----------------------------------------------------------------+
|Chief Technology Officer                                         |
|DM Solutions Group Inc                http://www.dmsolutions.ca/ |
+-----------------------------------------------------------------+