Notice callback drop timing in add_route

[Legend-Master]

I have tried to look up if I could listen to channel disconnects on a IpcReceiver when I'm using the ROUTER and only found out that the callback is dropped on receiver's channel disconnects so I could move a drop guard in to the handler after looking into the actual implementation, so I thought it might be good to document this

[glyn]

Thanks for documenting this behaviour. Could you also add a test?

[Legend-Master]

Could you also add a test?

They already exist:

ipc-channel/src/test.rs

Lines 419 to 473 in e5f8add

	#[test]
	fn router_drops_callbacks_on_sender_shutdown() {
	struct Dropper {
	sender: Sender<i32>,
	}
	impl Drop for Dropper {
	fn drop(&mut self) {
	self.sender.send(42).unwrap();
	}
	}
	let (tx0, rx0) = ipc::channel::<()>().unwrap();
	let (drop_tx, drop_rx) = crossbeam_channel::unbounded();
	let dropper = Dropper { sender: drop_tx };
	let router = RouterProxy::new();
	router.add_typed_route(
	rx0,
	Box::new(move |_| {
	let _ = &dropper;
	}),
	);
	drop(tx0);
	assert_eq!(drop_rx.recv(), Ok(42));
	}
	#[test]
	fn router_drops_callbacks_on_cloned_sender_shutdown() {
	struct Dropper {
	sender: Sender<i32>,
	}
	impl Drop for Dropper {
	fn drop(&mut self) {
	self.sender.send(42).unwrap()
	}
	}
	let (tx0, rx0) = ipc::channel::<()>().unwrap();
	let (drop_tx, drop_rx) = crossbeam_channel::unbounded();
	let dropper = Dropper { sender: drop_tx };
	let router = RouterProxy::new();
	router.add_typed_route(
	rx0,
	Box::new(move |_| {
	let _ = &dropper;
	}),
	);
	let txs = vec![tx0.clone(), tx0.clone(), tx0.clone()];
	drop(txs);
	drop(tx0);
	assert_eq!(drop_rx.recv(), Ok(42));
	}