Re: store module abstractions

On Sun, Feb 18, 2001, Kevin Littlejohn wrote:
>
> >>> Henrik Nordstrom wrote
> > The responsibility for managing the indes of what files are in the cache
> > is being moved down to the FS/store layer, and support of retreival of
> > this index will be optional (today only required for cache digests).
> > This is move part of "modio round 2".
>
> Ok, that makes sense. Does that mean an incoming request for a file on a box
> with 5 different fs'es mounted would potentially have to query every fs to see
> if it has the file?

Yup, but this isn't as exensive as you may think - especially if you
keep a "unified" index for all the ufs-based filesystems.

> What happens in the case of collisions - say someone's mounted an fs
> previously used in another cache?

Good question? :)

Ok, here's my take on the current thread.

The initial squidfs work done by duane was more splitting
off the IO rather than the FS calls. modio 1 confused this.
So now I have a little more clue about things. :)

modio 2 is looking to split up the FS code even more to
support pretty much any type of backing store. However,
its not as hard as you all think. How about someone
spends the time ..

* .. cleaning up the storeUfsCheckEvent() code so that
  one event doing this exists per FS rather than it being
  wrapped up in a seperate list like this. Go look at
  the code, you'll see what I mean .. :)

* modifying diskd, aufs and ufs to provide the IO hooks which
  you all have spoken about.

* Make sure that you don't force people to use this IO layer
  for custom non-ufs-type FSes (like reiserfs_raw.)

Its not as hard as you think. And it won't interfere with my work
at all (basically I'm ignoring ufs/aufs/diskd/coss entirely for
the time being) and it'll help out in leaps and bounds later
one - remember that to make the ufs based fses work with the modio 2
ideas it'll need to keep its own inmemory index rathr than relying
on squid to do it .. and one FS codebase will be easier to maintain
than 3 or more.

Kevin/Robert - feel free to shoot at this. Please. :-)

Adrian

-- 
Adrian Chadd			"Romance novel?"
<adrian@creative.net.au>	 "Girl Porn."
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