Design problem, how to call other structs method ?

[rain2307]

The demo:

I made a simple demo https://github.com/divflex/demo-rpc

stackoverflow

https://stackoverflow.com/questions/76097231/tarpc-how-to-call-outer-structs-method

Question:

The HelloServer is basiclly a proxy for the SingletonInstance, so the say_hi method need to call the same method on SingletonInstance.
What's the proper way to call SingletonInstance::say_hi ?

My idea:

Through messaging
https://github.com/divflex/demo-rpc/blob/ffe9dd49c0d2bcdf65771b00397e64473d7debfd/server/src/server.rs#L24

I created a tx(tokio::sync::mpsc) property on HelloServer, so the instance can use self.tx.send() to communicate with SingletonInstance.But HelloServer also need a receiver to get results. This seems too complicated.

The second question

Is this part of code ok?
https://github.com/divflex/demo-rpc/blob/ffe9dd49c0d2bcdf65771b00397e64473d7debfd/server/src/server.rs#L33