Re: [boost] Bug in sp_counted_base and atomic_count?

From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-04-18 07:20:29

Дмитрий Вьюков wrote:

>    sp_counted_base(): use_count_( 1 ), weak_count_( 1 ) // <---------
> ordinal store

There's also a hidden ordinary store to the vtable pointer. In general, when 
passing an object X from thread A to thread B, you are expected to ensure 
the necessary visibility (and not the author of X). Usually the queue that 
you're using for message passing will contain the acquire/release pair in 
pop/push. Otherwise you wouldn't be able to pass ordinary objects between 
threads. Or to take a simple example:

X * px;

thread_A()
{
    store_release( &px, new X );
}

thread_B()
{
    X * p = load_acquire( &px );
    // use *p
}

The store/load part ensures the visibility of X in thread B and not X 
itself.