Broadcast receiver can't be cloned, why?

[IamFake]

Hi. Previously I've use crossbeam channels like a signal to stop between threads (MPMC). Explanation:

I have thread#1 and tokio_task#1, in tokio_task#1 I have a loop with function call. After creating crossbeam_channel I send Sender to thread#1 and receiver in tokio_task#1. Because of loop in tokio_task#1 I need be able to clone receiver, which crossbeam let's me to do. So when thread#1 is exits - tokio_task#1 see that and exits too and vise versa.

But as I found, this might make troubles when using crossbeam receiver in tokio task, so I choose to use tokio broadcast channel and now I've stuck, because I can't clone receiver directly. Instead I must send Sender to tokio_task#1 and on every iteration of loop call to sender.subscribe(). The problem here is when thread#1 is exits - there is still alive 1 receiver and 1 sender in tokio_task#1, so tokio task can't determine that he needs to exit. Crossbeam let's me to just call .clone() on receiver and that's it, and when thread#1 is exits - I've no Senders alive.

I've feeling that this is not best aproach to bind thread and task together, or different threads, or even two long tasks, can u suggest me for more correct approach to bind threads/tasks together, so that when one exits, all exits too? Or how to deal here with channels in tokio?

[Darksonn]

Question in title: There was a PR to add that feature, but there was some issue with it so it was closed. Somebody could make a new PR if they wanted.

Question in body: Graceful shutdown is covered in this chapter. A watch channel can be used instead of broadcast as well.

Note regarding crossbeam: Crossbeam is a blocking channel, so you can't use it in async code. Read more here.