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From "Vadim Gritsenko" <>
Subject RE: Caching and key collision?
Date Thu, 31 Jan 2002 01:36:29 GMT
> From: Michael Hartle []
> giacomo wrote:
> >On Wed, 30 Jan 2002, Gerhard Froehlich wrote:
> >
> >>>Thanks for the answers. JispFileSystemStore will do with the long
> >>>names. But what about accidental key collision? This still can
> >>>
> >But chances are very low as IIRC from a developers point of view a
> >must be unique only withing a Component (FileGenerator,
> >XSLTTransformer, etc.) and not over the hole system. The cache itself
> >pre- or appends other values to form a system wide unique key for the
> >cache entry.
> >
> I ocasionally have a problem that might have its origins in these very
> rare but possible accidental key collisions:
> I am using an regexp-based pipeline which breaks down URI space into a
> set of parameters. These are passed to an XSP which generates dynamic
> SVG content which is solely based on these parameters. In order to
> minimize regeneration and utilize the cache, I added a generateKey()
> function to the XSP which, as already described, creates a key of type
> long on those parameters via hashing them. Now, in very rare
> in an sample web page showing many generated images (imgA, imgB,
> each located at another point in URI space (uriA, uriB, uriC), thus
> one based on its set of parameters (prmA, prmB, prmC,...), one image,
> (imgB, loaded from uriB, thus based on prmB) suddenly looks like
> one (shows imgA, loaded from uriB, should be based on prmB); when
> forcefully reloading the image from its URL, I seem to get a

How you are doing this? Cocoon's cache (IIRC) can not be invalidated
from outside of Cocoon.


> regeneration and the correct result.
> It may be due to an unrelated mistake of mine that I haven't been able
> to detect yet, but accidental key collisions might explain such a
> sporadic behaviour.
> Best regards,
> Michael Hartle,
> Hartle & Klug GbR

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