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From Brian Pane <bp...@pacbell.net>
Subject Re: Removing C-L filter when C-L is known was Re: conserving file descriptors vs. ap_save_brigade()
Date Sat, 06 Jul 2002 20:16:26 GMT
Justin Erenkrantz wrote:

>On Sat, Jul 06, 2002 at 12:09:40PM -0700, Ryan Bloom wrote:
>  
>
>>Pay attention to what that message says please.  It says "The filter
>>should always be in the stack, and it should always collect
>>information."  It doesn't say "The filter should always be touching the
>>C-L for the response."  We use the data collected by the c-L filter in
>>other places, so we should always try to compute the C-L in the filter.
>>However, we should NEVER buffer unless we absolutely have to.
>>    
>>
>
>What data is it collecting?  r->bytes_sent?  We already know what
>that value will be as it will be identical to the C-L.
>
>To make it concrete as to what I have been suggesting in
>ap_content_length_filter:
>
>if (!ctx) { /* first time through */
>    char *c;
>    c = apr_table_get(r->headers_out, "Content-Length");
>

This won't help us much: in all the cases where the ap_save_brigade()
in the C-L filter is a performance problem (e.g., the pipe and SSI
examples), we're not going to have a C-L in r->headers_out.

And this change will slow down the server, by adding another call to
apr_table_get(), which we already know is a performance problem.

--Brian



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