Re: [squid-users] purging variants

thanks for the clarification. looks like i have some hacking to do.
so, are these squid object headers documented, like at what offset i
should look to see if an object is a variant, or should i just dive
into the code?

On 3/18/06, Henrik Nordstrom <henrik@henriknordstrom.net> wrote:
> lör 2006-03-18 klockan 08:41 -0500 skrev lawrence wang:
> > I see. But maybe I've phrased this wrong... It seems like when the
> > purge tool runs, it does find all the different variants for a given
> > URL and runs requests against each of them; of course the variants
> > which require specific headers return 404's when those are not found
> > in the request. Perhaps there's a way to relax this check without
> > breaking anything else?
>
> The PURGE tool must send the correct headers, or Squid won't know what
> to do. It's not a check, it's how things work. Squid-2.5 does not know
> what variants there is for a given URL, no more than it knows what URLs
> there is in the cache. All it knows to do is "OK, I now have these
> request headers and URL given to me from the client, is there a matching
> object". Without the headers it can not find or know the variant.
> Without the headers all Squid-2.5 find is that the object varies, but
> have no means of finding the variants. Note of warning: If you PURGE
> without the variant headers then Squid-2.5 forgets that the object
> varies and the remaining cached variants of the object can not be
> reached until Squid has again learned that the object varies by seeing a
> Vary header response from the server. This means that if you purge
> without the headers then there is no longer any way to purge the
> variants without first making a request (which will be a cache miss) for
> the URL.
>
> The PURGE tool could be modified to do this I suppose. Only needs to be
> taught the vary algorithm used by 2.5 and decode this into suitable
> request headers as part of the purge request sent to Squid. The required
> information for reconstructing the required headers is found in a meta
> TLV header of the object and is read by the purge tool. Only that it
> does not know the meaning of this information and consequently does not
> make use of it today.
>
>
> Regards
> Henrik
>
>
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Received on Mon Mar 27 2006 - 08:31:17 MST