On Tuesday 20 July 2004 15:12, Sven Neumann wrote:
> Bryan Ford <[EMAIL PROTECTED]> writes:
> > I'm soliciting feedback, discussion, and hopefully ultimately
> > support for a very simple proposal that I've written up in
> > preliminary form at this page:
> >
> >     http://www.brynosaurus.com/cachedir/
> I don't think the .thumbnails directory can be considered ephemeral or
> otherwise regenerable content. Regenerating all thumbnails can be very
> difficult and time-consuming. The original data might be on removable
> media and even if all the images are on disk you certainly don't want
> to go through the hassle of regenerating them all since you will most
> probably need a number of different applications to do that. I suggest
> that you change your proposal so that it explicitely states that the
> .thumbnails directory should _not_ be tagged as a cache directory.

I fully agree with your opinion that thumbnails shouldn't be considered 
particularly _ephemeral_.  But then I'm not proposing that the presence of a 
cache directory tag should indicate that the directory be considered 
ephemeral, or should be"fair game" for systemwide cron jobs or whatever to 
clear out on a regular basis.  In fact, the full proposal on my web site 
already specifically disallows such an interpretation of cache directory 
tags.  With or without a cache directory tag, it should be entirely up to the 
application to determine the _longevity_ of the data in its cache(s) for all 
normal operational purposes.  The cache directory tag merely makes the 
statement that, in the event of an emergency (e.g., the hard drive dies and 
has to be restored from a backup), nothing critical is lost - the contents of 
the cache _can_ be regenerated automatically.

While thumbnails aren't necessarily ephemeral, they certainly are 
automatically regenerable - it is the standard behavior for all applications 
I know of that use them to regenerate them automatically if they disappear 
for any reason.  Sure, the original source material may be on removable 
media, so some of the thumbnails won't actually be _regenerated_ until the 
user inserts that particular CD-ROM and browses it again.  But even if those 
thumbnails hadn't been lost, they wouldn't ever be used until that point 
anyway.  Since the thumbnails are effectively useless until and unless the 
original content re-appears, and they can be regenerated from the original 
content once it does re-appear, I can't see how their storage matters beyond 
the performance penalty of having to re-compute the thumbnails from scratch.  
And that's the definition of a cache: if you lose it, you wait longer for 
stuff to load next time, but it's not disaster.

Aside from all that, though, I'm not going to push for my particular opinion 
on what does or does not constitute a cache to be adopted by all 
applications.  My purpose at the moment is merely to establish a convention 
by which applications can tag cache directories as such, if and when the 
respective developers and/or users feel appropriate.

> Since GIMP doesn't put swap files into a dedicated directory your
> proposal will also not work for GIMP swap files (which are admittedly
> not worth to be archived).

I had thought that that was what the ~/.gimp-2.0/tmp directory was for, but on 
re-running the GIMP I see that I was mistaken.  So you're right - in order to 
adopt the proposed convention for its tile cache, the GIMP would have to make 
an additional subdirectory and move its swap file into there.

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