Re: conflict of interest

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> >> 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.
> >
> > Why not do that when verifying object and do purge silently?
>
> It is possible that I could accrue many hits on some object without
> needing to verify it. The draft states that when we purge and object
> we are supposed to report the hits.
>
> > We also can keep hash->url translations in a dbm file.
>
> How well does that perform?
 awfully (for squid). They guarantee to find a dbm key in 1 or max 2 disk
 accesses with "unlimited" db size. Thats something. Good for scripts that
 might want to translate hash to url, but slow to be a hot-spot.

> How many non-blocking reads/writes per second can Squid do on a dbm file?

 perhaps none ;) dbm lookups are blocking. updates even more. Task for
 separate processes/threads. If only needed for LRU and purge tasks, this
 may be acceptable.

 Or put URL in front of disk object, we'd wish to check for hash colls anyway.
 Also, allows to rebuild index from files on disks.
 
> >> 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?
> >
> > remembering neighbors is bad. By the time we want to report, neighbor
> > might be well dead for a while.
>
> I agree, but those are the rules....

  better stick with common sense and document a bug ;)

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  Andres Kroonmaa mail: andre@online.ee
  Network Manager
  Organization: MicroLink Online Tel: 6308 909
  Tallinn, Sakala 19 Pho: +372 6308 909
  Estonia, EE0001 http://www.online.ee Fax: +372 6308 901
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Received on Tue Jul 29 2003 - 13:15:44 MDT