Re: [boost] singleton and thread safety

From: Jonathan Turkanis (technews_at_[hidden])
Date: 2005-08-02 14:05:33

Jason Hise wrote:
> Jonathan Turkanis wrote:

>> You might want to look at this thread:
>>
>> http://tinyurl.com/9xe83
>>
>> Jonathan
>>
> That does indeed confirm that function-local statics are not
> initialized
> in a thread-safe manner on some current popular C++ compilers.  So to
> avoid the whole mess regarding the DCLP, the best approach would
> probably be eager initialization, before the program enters a
> multi-threaded context.  Is initializing from the constructor of a
> namespace-scope global enough to ensure this?

I don't think so, since you might want to access singletons from static
initializers in other translation units.

Have you considered using call_once:
http://www.boost.org/doc/html/call_once.html?  It might look like this:

  boost::once_flag  foo_once = BOOST_ONCE_INIT;
  Thing*            t = 0;

  void foo_init()
  {
    t = new Thing;
  }

  void foo()
  {
     boost::call_once(&foo_init, foo_once);
     // Use *t
  }

I'm not sure this will work, so check it with someone else.

> -Jason

Jonathan