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From Greg Stein <gst...@lyra.org>
Subject Re: [PATCH] mod_proxy Keepalives
Date Mon, 02 Apr 2001 07:57:21 GMT
On Mon, Apr 02, 2001 at 02:55:11AM -0400, Chuck Murcko wrote:
> Graham Leggett wrote:
> > Greg Stein wrote:
>...
> > > Further, using a conn_rec for an *outbound* connection is just wrong. Yes,
> > > there is a tiny bit of similarity. But things like base_server,
> > > vhost_lookup_data, remote_logname, double_reverse, local_ip, local_host, etc
> > > ... none of those apply whatsoever to outbound connections.
> > 
> > Using a conn_rec for an outbound connection has allowed us to use
> > filters - which has cut down the proxy code by an enormous amount.
> > Outbound connections are almost identical to inbound ones - once the
> > status or request lines have been removed both outbound and inbound
> > requests are virtually the same.
> 
> Greg, are you suggesting we need to reimplement filters for outbound
> connects (in general) to gain their benefits? That just sounds like too
> big a bit of reusability to toss. I mean, it sure looks to me like
> there's at least as much stuff in a conn_rec that an outbound connect
> can use as there is that it can't. And what's not used is a matter of
> bytes per connection, not a large amount of wastage.

The filters should not be tied to request_rec or conn_rec. Unfortunately,
they are.

I'd be most interested in understanding how the proxy-outbound filters you
are using (I forgot the list) are tied to the conn_rec. If we can discover
how they are tied, then we can get them fixed.

Filters are arranged as a simple chain. Somewhere, you record the head of
that chain, and you organize how items are inserted into a current/active
chain. I don't believe that conn_rec.output_filters is any benefit to you;
the filter system itself: yes. I believe you can use the filters, and that
you can use them without needing a conn_rec.

Summary: for expediency, I can see how you may want to use a conn_rec. But
please recognize and (I hope) make it a long-term goal to remove them. As a
precondition, that means the (builtin) filters that you want to use need to
fixed. I'd totally agree to those fixes on two reasons: make the filters
more isolated/independent/less-coupled, and enable mod_proxy to stop using
conn_rec for outbound connections.

[ consider: any filter referencing a conn_rec or a request_rec becomes
  tightly coupled with the Apache system. And ideal filter is just massaging
  data that flows through it. ]

Cheers,
-g

-- 
Greg Stein, http://www.lyra.org/

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