Re: [squid-users] Elapsed Time

On Jun 22, 2009, at 7:03 PM, Amos Jeffries wrote:

> On Mon, 22 Jun 2009 15:50:51 -0300, Alejandro Martinez
> <amartinez_at_equital.com.uy> wrote:
>> Amos, thanks for your reply.
>>
>> The last question, how do youy estimate that time ??
>
> Now there is a deep philosophical question. You would probably best
> look up
> research info to get an accurate answer. [...]

I realize that I'm jumping in late into this discussion, but I think
that the most productive route would be to look at the algorithms used
by website statistics programs which claim to report such things.

> Basically: requests are broken into 3 sets: unprocessed, selected,
> and
> finished.
>
> 1) take request X as a starting point.
> 2) Then select all requests that have X as a referrer made within 30
> seconds (user max attention span for page load time).
> 3) Repeat (2) until no more requests are added using referer info.
> 4) Then pick a timespan T and select all requests made from same IP
> as X
> within time T of the existing range.
> 5) shuffle the first request we started with in (1) into the finished
> pile.
> 5) for each request now selected (4) go back and repeat (1)->(4) for X
> being that selected request.
> 6) repeat steps (2)->(5) until there are no new requests to handle.
> 7) track the earliest and latest timestamp from all requests
> processed in
> the above. Your 'visitor time' for _one_ session is the difference
> between
> those two.

That seems plausible to me. Considering the wide spread use of NAT,
I'd recommend using User-agent along with IP in step 4.

> I highly recommend finding an existing tool that does all this for
> you.
> Writing it from scratch is complicated at best and I'm sure I missed
> some
> complex issue out of my quick description above.

Agreed. And I think that the place to look for existing tools is in
various webstats programs.

Cheers,

-j

-- 
Jeffrey Goldberg                        http://www.goldmark.org/jeff/