[c++-pthreads] Re: pthread_cancel and EH: let's try this again

[Peter Dimov]

Alexander Terekhov wrote:
> Peter Dimov wrote:
> [...]
>> Keeping the cancellation request active doesn't need to be done by
>> reasserting in the destructor. It can simply be left active. Since
>> cancellation is implicitly disabled during stack unwinding,
> 
> No. Intelligent cancel delivery aside for a moment, it's explicitly
> disabled only after delivery (and pthread_exit()). Consider:
> 
>  some_dtor() throw() {
>    if (active_exception<thread_cancel_request>(0)) {
>      pthread_cancel(pthread_self());
>      pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &errno);
>      try {
>        fclose(temp_dataset); // no need to flush
>      }
>      catch(...) { }
>    }
>    else {
>      try {
>        fclose(temp_dataset); // no need to flush if we hit cancel
>      }
>      catch(...) { // canceled
>        pthread_cancel(pthread_self());
>      }
>    }
>  }

I don't get it. What is this code supposed to achieve?