>>Nick Allen <nick.allen...@gmail.com> writes:
>> Sorry, most of the technical stuff referred to is above my head, but I
>> may be able to help with an explanation of why the technical people
>> put a loop in.
>>
>> At one point, when the age limit for a tile was reached, and the
>> programme was started, it immediately deleted the old tile(s) before
>> it tried to download the new. No issue most of the time, but if for
>> instance you downloaded tiles before going on a holiday so you could
>> use viking whilst away but without internet, you could find after a
>> week or so that all of your map tiles had deleted!
Note the map cache crashing issue is only related to the in *memory* cache, not
the disk cache.
>That's a good point. So I think there needs to be two rules:
>
> if a tile is a wanted, and it's old enough (create data at the server)
> to be unfresh (30 days or at least 7, to be polite), fetch new, and
> **if successfull** replace
The download at the moment already does this in case the download fails.
> if a tile has not been **read** (or written) in some long lifetime,
> then remove, and perhaps only if the tile cache is using too much
> space. This lifetime should be more like 6m.
Unfortunately it's hard to track when anything is read, since these days
a lot of filesystems don't record the atime anymore since otherwise
every file read results in file write.
> perhaps have something that prunes the cache to no more than X MB,
> deleting the least-recently read/downloaded.
There was some thoughts on cache management were made here:
https://josm.openstreetmap.de/wiki/SharedTileCache
But progress seems to have stalled.
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