Re: detail::atomic_counter

From: williamkempf_at_[hidden]
Date: 2001-11-29 10:33:40

--- In boost_at_y..., "Peter Dimov" <pdimov_at_m...> wrote:
> From: <williamkempf_at_h...>
> > --- In boost_at_y..., "Greg Colvin" <gcolvin_at_u...> wrote:
> > > The advantage of using ++ and -- is that raw integer types 
support 
> > them.
> > 
> > And are rarely (if ever) thread safe.  So you're not helping 
anybody 
> > by duplicating the interface of raw integer types here, IMHO.
> 
> Raw integers are completely thread safe when there is only one 
thread. ;-)

No, they're not.  The program is safe from race conditions by the 
fact that there's only one thread, but that doesn't make the integer 
thread safe.  I realize you know this (that's why you've got the 
smiley), but I think it's important to state this.  It's very 
important to not do ANYTHING that gives the niave programmer the idea 
that integral types are thread safe.  They turn out to be enough of 
the time to likely lead such a niave user into thinking they always 
are.  That's one reason I don't like the integer arithmetic operators 
being used for increment and decrement of a thread safe counter.  The 
other is that the operations suggest functionality that doesn't exist 
(such as post-fix versions, other integer operations or even just an 
assumption on the return type).

Bill Kempf