Re: msg-id

[Thorfinn <thorfinn@xxxxxxxxxxxxxx>]

On Mon 13 Dec 2004 at 10:49:55AM -0800, in <Pine.LNX.4.53.0412131028230.17897@xxxxxxxxxxxxxxxx>,
John Stanley <stanley@xxxxxxxx> wrote:
> Seth Breidbart <sethb@xxxxxxxxx>:
[snippage]
> >You might read my example more carefully.  
> I read your example. Since the pid is part of the id, the only way that my 
> algorithm could duplicate message ids is for TWO processes to have the 
> same message id at the same epochtime AND for the locking mechanism that 
> prevents duplicate sequences to fail. I know of NO operating system that 
> assigns the same pid to two different processes, so even if the sequence 
> number fails, the pids will be different.

Go back and read again.  Particularly regarding field order in the two
algorithms.

> >Because the new owner used a _different_ algorithm,
> What new owner? What so what if he uses an algorithm that will duplicate 
> message ids? We are talking about THIS algorithm, which does not.

He doesn't use an algorithm which duplicates message ids.  However, when
compared to *your* algorithm, at some point, it is possible that your
"no duplicates" algorithm will have generated IDs which happen to be
identical to his "no duplicates" algorithm.

Both, considered on their own, will generate unique IDs. Taken together,
they don't.  So, where is your uniqueness?  Non existent, unless you can
guarantee that you will own that domain name forever and never give it
up.

> >I'm saying that I'm not worried about sufficiently-low failure
> >probabilities. 
> Yep. Got that. Unfortunately, "MUST" and "unique" combine to zero. Either 
> you don't mean "unique" or you don't mean "MUST". Which is it?

We mean MUST, and we also accept that MUST applies in the universe of
practicalities, where nothing is actually of zero probability, so "close
enough" is good enough.

You don't accept that, that's fine.  Everyone else, AFAICT, does accept
that.  If anyone else doesn't, speak up now.

[snippage]
> "Charles Lindsey" <chl@xxxxxxxxxxxxxxxx>:
> >Consider the two message-ids:
> >   <12345678@xxxxxxxxxxxxxxx>
> >   <12345678@xxxxxxxxxxxxxxx>
> >They are DIFFERENT message-ids. Yes?
> Not as far as I can tell.

Well, now that you've actually changed what Charles wrote, they look the
same.  

<12345678@xxxxxxxxxxxxxxx>
<12345678@XXXXXXXXXXXXXXX>

are different Message-IDs, though.

Later,

  Thorf

-- 
<a href="http://tertius.net.au/~thorfinn/";>thorfinn@xxxxxxxxxxxxxx</a>
"I miss the box full of gaffer tape that Neef used to have."
    -- Hobbes#vurt.net