[boost] [uuid] uuid::create() function

From: Andy (atompkins_at_[hidden])
Date: 2007-06-04 13:18:16

Other than the current approach (which I agree is not acceptable), I see 
6 alternatives to the uuid::create() function.  I believe all of them 
have been mentioned before.

1.  Make the random number generator a static object.  Document the 
function as not thread safe.  This will be fast, but easy to use 
incorrectly (e.g. in a multi-threaded program).

2.  Make the random number generator a static object and protect calls to 
it with a mutex.  This is a thread safe solution, but it will be slow 
because of the mutex.

3.  Make the random number generator live in thread local storage.  This 
will be a thread safe solution, but requires Boost.Thread.

4.  Use the current seed as the random numbers directly.  Will this 
solution provide 'good' uuids?  That is, is this source of random numbers 
good enough?

5.  Create a function object (that has the random number generator as a 
member) that produces uuids. Is this too complicated?
i.e.:
class uuid_generator {
public:
  uuid_generator() {
    engine.seed(get_seed());
  }
  uuid operator() const;
private:
  Engine& engine;
};

6.  Create a CAS/lock-free random number generator.  This is hard to 
implement.

I am favoring number 4, unless it will not produce good uuids.  Then I 
favor number 5.

I guess I am looking for direction as to how to proceed.

Andy.