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From Dirk-Willem van Gulik <>
Subject Re: store_headers in memcache and diskcache
Date Sat, 09 Feb 2008 17:00:50 GMT

On Feb 9, 2008, at 5:36 AM, josh rotenberg wrote:

> Dirk, my comments inline ...
> On Feb 8, 2008 11:19 AM, Dirk-Willem van Gulik  
> <> wrote:
> .. snip snip ..
>> Ok - more or less merged a lot between both modules (2) --- al the
>> good bits are yours :) Does that make sense to you ?
> Hah! Then there is a lot of work to do!

Agreed - next step (I guess)  is to isolate all the good things in mod- 
disk-cache; such as the two level hash on Vary - move this into  
general mod_cache and cache_util.c (i.e. to make sure that when you  
get a store_headers/body -- the vary info is handed to you on a silver  
platter already -- the server knows best). So that all cache modules  
can benefit here.

>> -       create/open -- we could fetch it all already then.
>> -       Or defer to the actual header/body routines - as you and I  
>> do now.
>> -       Or just 'punt' and store the thing as one big wack - as  
>> generally
>> you are
>>        propably going to need both ?
> I struggled with this one a lot. In some ways an all or nothing
> approach seems better. Less setting and getting, its there or its not.

Ok - I'll run some tests on a real server; to see what % gets headers  
but not bodies.

> I guess I was mainly trying to follow the mod_disk_cache model, and in
> some ways conform to what the provider api for caching seems to
> assume, that the two are separate. I think I was also discussing with
> someone the possibility of having body data auto-populate in the cache
> (via something completely outside of apache) and it sounded cool to be
> able to dump content into the cache without having to worry about
> faking up a header entry. And/or the possibility of allowing headers

Right -- and/or having an external process (or even a near zero cost  
listener) be able to update or invalidate entries.

> and bodies to be stored in different servers/pools, so that perhaps
> header info is expiring or LRU'ing at a different rate. Just thoughts,
> really, though, not sure if it makes sense to overdesign for it.
> If you want to collaborate on the google project let me know and I can
> add you, or you can take over, or however.

Whichever is easiest. Happy to plop it in there at google. As it has a  
while to go before we should/could offer this for inclusion at httpd/ 


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