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From Dean Gaudet <dgau...@arctic.org>
Subject mod_include heuristic
Date Tue, 22 Jul 1997 08:46:22 GMT
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.  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.  (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. 

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?

Dean


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