From: bill_kempf (williamkempf_at_[hidden])
Date: 2002-01-16 12:28:54
--- In boost_at_y..., "Peter Dimov" <pdimov_at_m...> wrote:
> From: "bill_kempf" <williamkempf_at_h...>
> > --- In boost_at_y..., "Peter Dimov" <pdimov_at_m...> wrote:
> > > A programmer that wants to catch the cancellation exception may
> > have good
> > > reasons to do so. In particular, letting an exception escape
from a
> > > destructor during stack unwinding terminates the process, no
> > questions
> > > asked. ;-)
> >
> > That's not a reason to catch the request, it's a reason to
DISABLE
> > requests. A cancellation "exception" can be uncatchable and
still be
> > safe in cases such as this.
>
> So, code that currently has
>
> try
> {
> // ...
> }
> catch(...)
> {
> // eat exceptions, we're in a destructor
> }
>
> will need to be fixed to disable cancellation as well.
Only if it makes calls to any "cancellation points".
>
> > > Making this exception non-catchable by catch(...) may also
break
> > correct
> > > code (in the sense that it may silently become exception
unsafe.)
> >
> > Care to explain in detail?
>
> systemWideMutex.lock();
>
> try
> {
> // ...
> }
> catch(...)
> {
> systemWideMutex.unlock();
> throw;
> }
>
> systemWideMutex.unlock();
>
> Not very good style but correct and working.
Not conforming to the current Boost.Threads interface, however.
There's no access to lock()/unlock() methods on a mutex.
I do see the point, however. RAII isn't used universally to insure
proper resource cleanup is performed. Good point.
Bill Kempf