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From Albert Lash <>
Subject Re: notes on filters in 2.2.x
Date Fri, 27 Feb 2009 10:09:37 GMT
On Tue, Feb 24, 2009 at 10:27 PM, Roy T. Fielding <> wrote:

> I spent a while looking at mod_deflate and various filter related
> issues in 2.2.x/trunk, but I had to context switch away before
> I could create such a large fix.  This message is to write
> down my conclusions so that I can remember them and maybe fix
> the silly thing when I get a chance, or maybe encourage someone
> else to do it in the meantime.
> The current state is broken.  There is no other way to describe it.
> mod_deflate is adding -gzip to the end of etags in order to be
> correct in regard to variants, but ap_meets_conditions() is not
> aware of the -gzip addition; in fact, etags are compared before
> the output filter is even initialized for a given response, so
> there is no way for ap_meets_conditions() to work without resorting
> to stupid hacks like always checking for "foo" and "foo-gzip" in
> the core (even the hack is difficult without completely rewriting
> how etags are compared).

For what its worth (maybe to confirm your observations?), while trying to
track down a memory leak with mod_perl, I noted that Apache started using a
little more memory for every request only when mod_deflate was enabled.

And to sing the praise of filters, I believe them to be a very good thing
for dynamic content generation. And, even if its not the most efficient,
mod_ext_filter is a sweet one.

- Albert

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