boost.threads [was RE: [boost] Re: sockets /network programming Requirements]

From: williamkempf_at_[hidden]
Date: 2001-08-01 09:27:10

--- In boost_at_y..., "Alexander Terekhov" <terekhov_at_d...> wrote:
> 
> > class foo
> > {
> > public:
> >    foo() : owner() { }
> >    bool current_thread_is_owner() { return thread() == owner; }
> > private:
> >    thread owner;
> > };
> >
> > foo * instance;
> >
> > void thrd1()
> > {
> >    instance = new foo;
> > }
> >
> > void thrd2()
> > {
> >    if (foo->current_thread_is_owner())
> >       do_something();
> > }
> >
> > Ignoring all synchronization problems intentionally left out and 
the
> > fact that this is a very contrived example you should get the 
idea.
> 
> ignoring all synchronization problems you could also do it
> via "static thread& thread::current()" which is much more
> clear, IMHO:
> 
> class foo
> {
> public:
>    foo() : owner( thread::current() ) { }
>    bool current_thread_is_owner() { return thread::current() == 
owner; }
> private:
>    thread& owner;
> };
> 
> foo * instance;
> 
> void thrd1()
> {
>    instance = new foo;
> }
> 
> void thrd2()
> {
>    if (foo->current_thread_is_owner())
>       do_something();
> }

No, you can't do it this way, because thrd1 may terminate long before 
the call to current_thread_is_owner() in thrd2 is ever invoked.  This 
would leave you with a reference to an object that no longer exists.

Bill Kempf