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Date: Thu, 1 Mar 2001 10:59:45 -0800 (PST)
From: <rbb@covalent.net>
To: <new-httpd@apache.org>
Subject: Re: [VOTE]  ap_r* model.
In-Reply-To: <3A9E9295.ACD750C8@algroup.co.uk>
Message-ID: <Pine.LNX.4.30.0103011034160.14132-100000@koj>
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On Thu, 1 Mar 2001, Ben Laurie wrote:

> rbb@covalent.net wrote:
> >
> > I have asked for people to vote on this subject informally, and it never
> > gets anywhere, because nobody responds.  To that end, and because I want
> > closure on this, I am calling for a formal vote now.
> >
> > How do we implement ap_r?
> >
> >         [ ]  As a macro wrapper around ap_f* and the r->bb brigade
> >         [ ]  Using the OLD_WRITE filter
> >
> > The advantages and disadvantages of each of these models has been
> > discussed on this list for weeks.  I can give a brief synopsis, or people
> > can check the archives.  People on this list should be able to answer any
> > questions about the two models, so that there is no confusion when people
> > vote.
>
> I'd like to request the brief synopsis. Although I did read the mails at
> the time, I ran out of storage capacity to keep them in my head. Sorry!

Not a problem.  People, keep me honest.  If I miss something important,
let me know.

ap_r* macros:

advantages:
	The problem with ap_r* is that they don't buffer data.  We have
already solved this problem for ap_f*, so this takes advantage of that by
using the ap_f* calls in ap_r*.

disadvantage:
	People need to use r->bb in their handler, or the data may get out
of synch.  This is only an issue for people who want to use both ap_r*
functions and make their own buckets and their own brigade.  So, if they
want to create their own buckets, and add them to r->bb, that will work
fine, but if they want to use ap_r*, and they have their own brigade, bb,
they will have ordering issues.

OLD_WRITE:

advantages:
	The order is always correct.  This is a filter that sits just
under the handler, so as long as the filter is there, the order is
correct.

disadvantages:
	This is a special filter, that solves the buffering problem in a
way completely unrelated to ap_f*.  This means that we have to maintain
two independant solutions.

	If a filter is added in between the handler and the OLD_WRITE
filter, then the performance improvement disappears.

Both solutions have documentation issues, one we have to document r->bb,
one requires documenting the filter ordering issue.

If this isn't enough detail let me know, and I can go into it a lot more.

Ryan

_______________________________________________________________________________
Ryan Bloom                        	rbb@apache.org
406 29th St.
San Francisco, CA 94131
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