conflict of interest

The past couple of days I have been munging squid 1.2 to support using
SHA digests as cache keys. This is of course a result of the
discussion some months ago about compressing URLs which then became
'why not just use MD5 hashes?' FWIW, I started with SHA instead of MD5
because some people hinted it might be better and has no use
restrictions. However, it will be easy to plug MD5 in (or any other
scheme) should any desire to do so.

Anyway, Kostas is working on adding hit metering into Squid and today
we realized that hit metering will become very difficult when the
cache key is one-way hash of the URL. When we need to purge
an object, we're supposed to make a HEAD request for the URL to
report the hits. But we won't have the URL any more.

In fact, hit metering will require quite a bit of additional overhead
for every object. In addition to some four integer counters, the draft
requires that hits be reported back to the source of the object, and
not necessarily the origin server. So we'd have to remember which
neighbor gave us each object. ick.

Thoughts?

SHA: http://csrc.nist.gov/fips/fip180-1.txt
Hit Metering: http://info.internet.isi.edu/7c/in-drafts/.cache?metering

Duane W.
Received on Tue Jul 29 2003 - 13:15:44 MDT