Re: [Boost-users] How to call destructor on thread object?

Subject: Re: [Boost-users] How to call destructor on thread object?
From: Gavin Lambert (gavinl_at_[hidden])
Date: 2015-05-20 20:23:42

On 21/05/2015 12:12, Lane wrote:
> Here's a bit more detail of my current problem.
>
> I have implemented destructors within ClassA and ClassB. When adding
> this thread to the thread_group, the thread objects destructors are
> being called as soon as they're added to the thread_group.
>
>      struct MyStruct : ... {
>          boost::thread_group threads;
>      };
>
>      template <class Event, class FSM>
>      void psm_::MyEvent::on_entry(Event const& ev, FSM& sm)
>      {
>          auto bb = std::make_shared<bounded_buffer<MyData>>(100);
>
>          ClassA<bounded_buffer<MyData>> c_a(bb);
>          ClassB<bounded_buffer<MyData>> c_b(bb);
>
>          threads.add_thread(new boost::thread(c_a); // destructors
> called here
>          threads.add_thread(new boost::thread(c_b);
>      }

No, what's happening there is that the c_a and c_b temporary objects are 
being *copied* to the thread, and then the *originals* are being 
destroyed.  The copies owned by the thread remain undestroyed.

> I've wrapped the thread_group within unique_ptr so that I can call
> reset, but I don't even make it to this point because the thread objects
> have already been destroyed when being added to the thread (and program
> exits).
>
>      template <class Event, class FSM>
>      void psm_::MyEvent::on_exit(Event const& ev, FSM& sm)
>      {
>          std::unique_ptr<boost::thread_group> tg(&threads);
>          tg.reset();
>
>          threads.interrupt_all();
>          threads.join_all();
>      }

I'm sorry, but you clearly need to go back to school and learn how 
pointers work.

(And then go back and re-read my earlier post.  It's the one in MyStruct 
that has to be a unique_ptr and you're doing it in the wrong order.)