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

[Alexander Terekhov]

Dave Butenhof wrote:
[...]
> than explicit API. I was thinking in terms of disabling cancel within a
> 'throw()' scope... but there might be other conditions. For example, we
> could disable inside either 'throw()' or any try with a catch(...) that
> doesn't rethrow... unless there's an INNER scope that allows throwing
> cancel AND with an explicit catch(cancel). So a nothrow destructor
> (regardless of whether all destructors were implicitly nothrow or not)
> could allow "local" cancellation by nesting a try{} catch(cancel) {}.

This will sort of "break" catch(...), I'm afraid.

> 
> (Sounds too complicated; but it's something to think about. ;-) )

The C++ incarnation of pthread_testcancel() will surely have a throw
spec "throw(std::thread_cancel_request)" or something like that. Now
imagine something along the lines of

void oper(/*...*/) throw(std::thread_cancel_request, std::bad_alloc);
/*...*/ oper_throw_handlers(/*...*/) throw();

void f1() throw() {
  /*...*/
  try { 
    oper(/*... "X" ...*/);
  }
  catch(...) { 
    /*...*/oper_throw_handlers(/*...*/);
  }
  /*...*/
}

void f2() throw() {
  /*...*/
  try { 
    oper(/*... "Y" ...*/);
  }
  catch(...) { 
    /*...*/oper_throw_handlers(/*...*/);
  }
  /*...*/
}

void f3() throw() {
  /*...*/
  try { 
    oper(/*... "Z" ...*/);
  }
  catch(...) { 
    /*...*/oper_throw_handlers(/*...*/);
  }
  /*...*/
}

/*...*/ oper_throw_handlers() throw() {
  try {
    throw;
  }
  catch(std::bad_alloc const &) {
    /*...*/
  }
  catch(std::thread_cancel_request const &) {
    /*...*/
  }
  /*...*/
}

regards,
alexander.

P.S. http://google.com/groups?selm=4007FC34.D5A1059%40web.de
     http://google.com/groups?selm=40095EC5.9FDB3513%40web.de
     http://google.com/groups?selm=400960FF.558DC7DB%40web.de
     (Subject: Re: is catch(...) safe)