no async in sync::watch::reciever::borrow_and_update()

[MagnumTrader]

Hi,

i have a question about the best implementation.
I have a scenario where a struct updates its state frequently, notifying over a broadcasting channel which the waiters are awaiting in a loop, in turn watchers hold a Arc<RwLock> to access the data and do their thing.

now i stumbled upon the watch channel in the sync module which seems to be what im looking for here! i only care about the latest update since this are financial markets in realtime.

now to my question.

the borrow_and_update() method on reciever is not async.
And according to the docs i should prefer using it over
rx.changed().await; let x = rx.borrow() // do stuff with x
according to this

but since borrow_and_update() is not async. will this cause problems?
is there any reason for this to not be async since most functions and methods in tokio are.

best regards
M

[Darksonn]

What the docs suggest is using

rx.changed().await;
let x = rx.borrow_and_update();

instead of

rx.changed().await;
let x = rx.borrow();

So both versions have an .await.

[MagnumTrader]

oh i think i misunderstood the concept. in my head borrow_and_update() would do both the checking for an update, borrowing and update last seen value but that isnt the intended behavior?

rx.changed().await;
// additional changes can happen here
let x = rx.borrow();

rx.changed().await;
// additional changes can happen here aswell
let x = rx.borrow_and_update();

[Darksonn]

The borrow_and_update method will never sleep, so it does not need to be async.