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From Sander Striker <>
Subject Re: mod_cache
Date Mon, 07 Mar 2005 06:47:30 GMT
>Justin Erenkrantz wrote:
>> Sander Striker wrote:

>> Luckily for us, there is more work left even in mod_cache.  Right now,
>> whenever we hit a Cache-Control: no-cache in the request, the cache 
>> declines to handle the request, while it could be handling it (be it
>> with a required validation request to the backend).  That would be a
>> lot more efficient.  And within bounds of the spec.
> I'm not sure what you mean.  Do you mean that if we get a Cache-Control: 
> no-cache, that we should attempt to treat it as mandatory revalidation 
> of the content?


> Interesting.  Right now, we just get out of the way.

Right.  We don't have to AFAUI, as long as we revalidate.
> One approach would be to remove the no-cache check and move it down into 
> ap_cache_check_freshness() and make our response always be stale in this 
> case.


>> Furthermore, Cache-Control: max-age=0 or even max-age=X seems to be
>> completely ignored.  A response is given back with an Age header with
>> a larger value then what max-age was set to in the request.
> This *should* be handled by ap_cache_check_freshness().  I'll admit that 
> I haven't spent a lot of time in there.  On a cursory look, it seems 
> that it should be handling this correctly.

That's what I initially thought when I glanced over it.  Then I started
wondering why headers are retrieved from h->req_hdrs, instead of
r->headers_in.  I noticed we save the request headers of the request
that got a resource into the cache.  Are we maybe mistakenly using
those stored headers instead of the ones from the current request?
I need to go over the code, but this is what popped into my head on
first glance.


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