Re: [boost] [atomic] comments

Subject: Re: [boost] [atomic] comments
From: Tim Blechmann (tim_at_[hidden])
Date: 2011-11-01 14:00:25

> > the standard says "should" not "must" -- the gcc guys have not made this
> > decision without good reasons, and I agree with these reasons
> 
> It says "should" but only for the lock-free case:
> 
> [ Note: Operations that are lock-free should also be address-free. That is,
> atomic operations on the same memory location via two different addresses
> will communicate atomically. The implementation should not depend on any
> per-process state. This restriction enables communication by memory that is
> mapped into a process more than once and by memory that is shared between
> two processes. —end note ]

i am neither a native speaker nor a language lawyer. but to me sentence 3 does 
not seem to be limited to the lock-free state.

> [ Note: the representation of an atomic specialization need not have the
> same size as its corresponding argument type. Specializations should have
> the same size whenever possible, as this reduces the effort required to port
> existing code. —end note ]
> 
> The two recommendations are contradictory, so it's a quality of
> implementation issue.

tim