Force threads to leave object before destruction

When using multithreading I often run into the following problem:

I’ve got an object, say a network receiver(but could be anything). And a function that gets the data. Now sometimes there simply is no data, and you want to let the thread wait to get it’s data. A blocking call, very much like being used by Berkeley sockets and it’s derived implementations.

The principle is simple:

Forgive my mediocre illustrational skills. I'm a programmer after all:)

Well now of course there is other ways of implementing this. But my usual implementation with C++11 is as follows:

  • Object A Calls the function in object B on a separate thread, that is dedicated to this task.
  • Object B Uses an std::condition_variable construction to block the thread until the data is actually acquired.
  • Object A Places the data in a queue, which is read out by the main thread.

Now my actual problem arises on the destruction of object B, if it has to be destructed before object A(returning a nullptr, or something similar on the blocking call). I really wouldn’t know how to efficiently wrap up object B.

The main problem is that object B isn’t aware of the thread, and a thread can only have one handle, which is inside object A.

Now I could cook something up using atomic counters, more std::condition_variables. But I have a feeling there has to be a more elegant and reliable solution to this problem:).

Note: I’m using C++11, so I’ve used that to illustrate everything. And I’m hoping to solve it using that. Although this of course this is a more of a general concurrency problem.


Source: c++

Leave a Reply