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From Rob Hartill <>
Subject Re: mod_include heuristic
Date Tue, 22 Jul 1997 16:53:10 GMT
On Tue, 22 Jul 1997, Dean Gaudet wrote:

> Ok, here is something that I think I would be happy with:  use boyer-moore
> and mmap() in mod_include to speed it up.  Then use a quick and dirty
> two-pass heuristic to calculate Last-Modified (and ETag) provided that all
> of the directives are truly static.

what do you mean by "directives are truly static" here ?

Do you mean <!--#include virtual="/foo.html" -->  is considered "static" ?.

What's to say that /foo.html isn't being updated by an external program -
a setup I make use of.

> The first pass aborts as soon as it
> encounters something non-static. 
> The end result will probably be about the same performance as the existing
> mod_include.  With the added benefit of Last-Modifieds for caches to chew
> on.

mod_expires does work well with caches.

> (Plus even Content-Lengths.)  This eliminates much of the need for
> XBitHack, certainly enough that we don't have to consider other extensions
> to it. 

There are practical ways to work around XBitHack and be cache-friendly.

> The directive "IncludesTwoPassThresh NNN" would indicate that two-pass
> should be aborted whenever NNN bytes have been read from the inputs...
> which lets it be disable, and prevents it from being a problem on large
> inputs. 
> Oh yeah, another implementation detail, it has to generate clever ETags. 
> I suggest "inode-mtime" pairs for each file, in the order of inclusion. 
> Abort the two pass if the length of the ETag goes over 128 bytes. 
> What think you?

I like the bit about disabling it  :-)

Rob Hartill                              Internet Movie Database (Ltd)   .. a site for sore eyes.

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