Need exit mechanism for sample: Threadpool task queue

[poor1017]

Hi @cameron314

I read all the samples in concurrentqueue/samples.md, they are great, except:

For sample: Threadpool task queue I think we should replace wait_dequeue() with wait_dequeue_timed(). Because there is a while (true), so we need a break to exit this while, but wait_dequeue() may cause the break never be achieved.

Thank you!

[cameron314]

Ah, the assumption was that one of the tasks would cause the processing code to break out of the loop. I could probably make that more clear (at the expense of a longer example).

[poor1017]

If using wait_dequeue() and the queue may be empty all the time, the loop may hang all the time, at this time, how to break out of the loop?

And now, if some one destroy the queue, an undefined error occurs?

[cameron314]

It's the responsibility of whoever owns the thread (and queue) to tell it to clean itself up. There's multiple ways to do this, but a common one is to set a flag and enqueue dummy data to wake up the thread, then join it.

[poor1017]

Got it, thank you!