Re: Boost.Threads - thread_desc concept

From: williamkempf_at_[hidden]
Date: 2001-07-02 08:39:07

--- In boost_at_y..., "Alexander Terekhov" <terekhov_at_d...> wrote:
> 
> >    namespace thread {
> >
> >       namespace detail {
> >          void __cdecl thread::fun(void* arg) {
> >             try {
> >                (*(boost::function0<void>*)arg)();
> >             } catch(...) {
> >             terminate();
> >             }
> >          }
> >       }
> >
> >       ref create(boost::function0<void> f) {
> >          return ref(_beginthread(detail::fun,(void*)&f));
> >       }
> >
> >       class ref {
> >          HANDLE id;
> >          ref(HANDLE id) : id(id) {}
> >          ...
> >       };
> >    }
> 
> you are passing the address of creator's _local_
> variable to another (new) thread. you can not do
> it without extra synchronization. in the code above
> the local variable "f" could be reclaimed
> (create() returns) even before new thread would
> have a chance to use it in thread::fun. the code
> above is incorrect.
> 
> correct solution (w/o extra synch) could be to "copy"
> "f" into C++ thread _OBJECT_ and let him manage it.

Ahem.  That's only one correct solution.  Beyond using extra synch 
code you can also just copy f onto the heap and let the 
detail::thread::fun() delete it.

Bill Kempf