[c++-pthreads] Re: thread-safety definition

[Alexander Terekhov]

Ted Baker wrote:
> 
> > The problem is that cleanup -- e.g. execution of C++ destructors on
> > stack unwinding -- may involve calls to I/O routines that are themselves
> > cancellation points.  If these routines fail, then the cleanup functions
> > will not achieve their intended purpose; they will not be able to release
> > the resources that the thread holds.  Nathan's model implies that they
> > will fail.
> 
> This cannot happen if cancellation is automagically disabled during
> execution of (all) destructors, along with the stack unwinding code
> that is performed during exception processing.

Except that it would pretty much preclude SAFE exploitation of 
cancellation in the destructors (stuff ala "~temp_dataset()" which 
can simply catch cancel request exception and "re-enable/re-inject"). 
Burning processing cycles on cancel enable/disable is another issue 
here, BTW. Intelligent cancellation that would check the dynamic 
context (2-pase ES with exception specs acting like "fences" NOT 
causing unnecessary unwinding) would work much better, I guess.

regards,
alexander.