[boost] Re: Threads: Atomic Counter (sig_atomic_t)

From: Valentin Bonnard (Bonnard.V_at_[hidden])
Date: 2000-09-01 18:38:48

On Fri, Sep 01, 2000 at 09:39:34AM +0100, Kevlin Henney wrote:
> In message <024b01c013ac$27171260$37781990_at_[hidden]>, Greg Colvin
> <gcolvin_at_[hidden]> writes
> >From: Daryle Walker <darylew_at_[hidden]>
> >> 
> >> Doesn't C ,and therefore C++, have a "sig_atomic_t" type that works like
> >> this?  (I mentioned this type during the thread discussions.)  Could we use
> >> it somehow, without (always) resorting to platform-specific extensions?
> >
> >In a word, no.  The C and C++ standards promise very little
> >(some would argue nothing) of any real use about sig_atomic_t.
> 
> And the only things they do "promise" are related to signals, not to
> threading.

That's the same thing !

> Introducing a dependency on <csignal> would be misleading
> (threads and signals interact _badly_) and incorrect :-}

(signals interact badly with almost everything)

Why do you think that a shared unprotected (ie w/o locks) variable 
of type volatile sig_atomic_t can't be used for inter-thread 
communication ?

(BTW, I haven't been able to find specific guaranties about 
sig_atomic_t in the C++ standard; are they hidden in the C 
standard ? In particular, is sig_atomic_t()++ guarantied 
to be atomic ?)

-- 
Valentin Bonnard