Re: [boost] detail::atomic_counter

From: Greg Colvin (gcolvin_at_[hidden])
Date: 2001-11-19 09:51:30

From: Itay Maman <gtpaw_at_[hidden]>
> --- In boost_at_y..., Jesse Jones <jesjones_at_h...> wrote:
>  > At 5:18 PM +0200 11/17/01, Peter Dimov wrote:
>  > >In order to make shared_ptr thread safe (w.r.t. reference counting) we need
>  > >an atomic_counter type, with the following operations defined:
>  > >
>  > >atomic_counter a(n); // n is the initial value, convertible to 'long'
>  > >++a; // atomic increment, returns the new value (by value, type 'long')
>  > >--a; // atomic decrement, returns the new value (by value, type 'long')
>  > >a; // convertible to long, atomic read (to support use_count() and 
> unique())
>  >
>  > The copy semantics need to be ironed out. In the code that was posted
>  > the Windows version can be copied with no problems. The pthreads
>  > version can also be copied, but I think bad things will happen
>  > because the mutex is bit-wise copied. Simply disabling copying may be
>  > OK.
>  >
>  >    -- Jesse
> 
> 
> I don't agree with you. I think that atomic_counter's underlying philosophy 
> is: "it's just like the good old long type, except you need not protect it 
> when multiple threads are involved". 

I'll let Peter speak to what the philosophy is, but I believe
atomic_counter should be as simple and fast as possible, doing
one thing and doing it well.  If you also want an atomic_integer
then go for it.