Subject: Re: RFC: getting a unique integer value
From: Patrick Lam (plam@plam.lcs.mit.edu)
Date: Sat Oct 13 2001 - 12:47:53 CDT
On Sun, 14 Oct 2001, Martin Sevior wrote:
> On Fri, 12 Oct 2001, Matti Picus wrote:
>
> > Generating a unique int ID seems to be faulty in many places in AbiWord.
> > The general method is to use the result from UT_rand() and hope that it is
> > unique.
>
> Thanks to Pat Lam we have a great XP random number generator. This will on
> average give you an identical random number one in 2^32 attempts. That's
> approximately 1 in 4,000,000,000 attempts so we're pretty safe :-)
Yes, I used the random number generator from some library.
If you get a collision with two numbers returned from UT_rand in a 32-bit
address space, you've got other things to worry about; it's far more
likely that you'll get hit by a truck, or your roof will spontaneously
cave in.
Keeping a counter introduces other problems too. You need to lock your
counter (to prevent problems with concurrency), etc. And it won't make
you do better.
pat
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