Thumbnailer specification: Move, Delete, Copy hints (Was: Re: GSD should not housekeep the thumbnails)

[Alexander Larsson]

On Tue, 2008-09-16 at 14:42 +0200, Philip Van Hoof wrote:
> On Tue, 2008-09-16 at 13:30 +0100, Rob Taylor wrote:

> > I guess when Philip's thumbnailer daemon is starting to get widely used,
> > It could do the job of cleaning the cache. This would mean that you
> > would no longer have thumbnails lying around for deleted files and it
> > could also clean out thumbnails that haven't been *accessed* after a
> > certain time period, which should give better performance.
> 
> Related to this discussion ... adding Andrew den Exter in CC, as I had
> an interesting conversation with Andrew about this.
> 
> So although the current Draft specification mentions a Move, Delete and
> Copy, according to Andrew (and I agree) this ain't necessary at all.
> 
> http://live.gnome.org/ThumbnailerSpec
> 
> A properly written thumbnailer, in modern days, would have a file
> monitor on each thumbnailed original and/or would initially scan all the
> thumbnails, read the exif info to get the original's location, and would
> do housekeeping fully automatically this way.

This sounds like an extremely bad idea. Monitoring is very costly (in
terms of e.g. inotify watches), not always availible (e.g. on non-local
files), and the filesystem might not be mounted (e.g. an external usb
disk that you still like to keep the thumbnails for). Furthermore,
scanning thousands of thumbnails on startup sounds like a performance
horror.