[Boost-users] [random] Problems generating pseudorandom 64-bit ints across multiple computers

Subject: [Boost-users] [random] Problems generating pseudorandom 64-bit ints across multiple computers
From: James Madison (jmadisondev_at_[hidden])
Date: 2009-02-24 21:46:24

I am currently developing a distributed application where many clients need
to generate unique 64-bit random numbers which will be used as keys.  I am
having problems getting boost to do this.  For my first attempt, I tried
something like the following:

        boost::mt19937 RandomNumberGenerator::s_algorithm;

        boost::uniform_int<unsigned long long>
RandomNumberGenerator::s_range(
            std::numeric_limits<unsigned long long>::min(),
std::numeric_limits<unsigned long long>::max());

        boost::variate_generator<boost::mt19937&,
boost::uniform_int<unsigned long long> >
            RandomNumberGenerator::s_rng(RandomNumberGenerator::s_algorithm,
RandomNumberGenerator::s_range);

I had two issues though:

1.  Is this really giving me random 64 bit numbers, or is it just generating
32-bit numbers and then doing bit expansion?

2.  The values always started with the same number.

Trying to find a fix for #2, I though of using a hashed GUID as a seed.  The
problem is I noticed the seed value takes a 32 bit int, which essentially
means a 1/2^32 chance of the first value colliding even if chosen completely
randomly, which is unacceptable for my application.

I am back where I started.  Is there any clean way to use boost to generate
random 64-bit intergers, when the same application is going to be run across
multiple computers?