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From "Bill Stoddard" <b...@wstoddard.com>
Subject Re: [VOTE] ap_r* model.
Date Fri, 02 Mar 2001 22:55:40 GMT
Sorry Ryan, I am changing my vote too.   Based entirely on the discussion
unfortunately...  The fewer opportunities we open for module authors to
muck-up the better off we'll be.  Pragmatic wins over Philosophy.

Add my vote to the OLD_WRITE filter tally.

Bill

----- Original Message -----
From: Greg Stein <gstein@lyra.org>
To: <new-httpd@apache.org>
Sent: Friday, March 02, 2001 4:21 PM
Subject: Re: [VOTE] ap_r* model.


> On Fri, Mar 02, 2001 at 09:19:15AM -0600, William A. Rowe, Jr. wrote:
> > From: <rbb@covalent.net>
> > Sent: Friday, March 02, 2001 9:04 AM
> >
> >
> > > I think I remember gstein writing...
> > >
> > > > happen", but can only happen by a deliberate action of a module
author. They
> > > > have to take special measures to get themselves in front of OLD_WRITE.
We
> > > > don't have to take precautions against deliberate troublemakers; there
are
> > > > too many other ways that a module author can screw things up.
> > >
> > > The problem isn't me as a module author, it is the other guy.  My module
> > > may be fine, but what if there is another module that isn't.
> >
> > Here's the upshot.
> >
> > OLD_WRITE filter can be blown away not paying attention to filter
ordering.
>
> OLD_WRITE just stops optimizing. It doesn't break.
>
> > r->bb can be blown away by anyone not paying attention to the request's
own brigade.
> >
> > Which of these is harder to debug ?!?  Harder to document ?!?  That's the
key!
> >
> > [We aren't talking about buckets here guys... the -brigade- is that stream
that
> > is sent down the filter stack.  I have yet to be convinced we need more
than one
> > per request.  As FirstBill and rbb point out, you just keep adding to it.]
> >
> > I see ordering problems as the hardest headache to debug.  r->bb
misordering is
> > fairly straightforward - if you start misordering, the module _author_
messed up.
> > If you have a filtering problem, the user will have some impact on filter
ordering.
> > That means they can create a problem.  If it's a choice between the module
author
> > and the end user creating bugs, I'll take the author's bugs any day.
>
> The OLD_WRITE scheme *never* has ordering problems. Ever.
>
> The only possible problem is that it won't be used. But that only happens if
> the module author deliberately inserts their filter ahead of OLD_WRITE.
> Explicit code to do it. The user can't make it happen.
>
> Harder to debug? OLD_WRITE won't cause ordering problems. Document?
> OLD_WRITE would be classified as AP_FTYPE_INTERNAL. The doc on the filter
> types states that module authors should never use that, or insert in front
> of it. When a module author goes to figure out which type they want, it is
> immediately obvious to steer clear.
>
> r->bb can cause ordering bugs. There is no point in the documentation to
> describe the gotchas of synchronization and misordering.
>
> Cheers,
> -g
>
> --
> Greg Stein, http://www.lyra.org/
>


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