Example for accessing and mutating server state in RPC calls?

[mystal]

All the examples I've found so far don't have any real state on the server that is accessed or mutated in RPC calls. I went digging and found the emerald project which seems to do some of that here:
https://github.com/ethereumproject/emerald-rs/blob/master/src/rpc

That seems like a reasonable approach to take, using Arc<Mutex> to access and mutate server state. Does that sound right?

[tomusdrw]

Yes, the state needs to be wrapped in a Mutex (Arc is not necessary afair, unless you want to have access to that state outside of the RPC server implementation).

[tomusdrw]

Actually it's a fair point that we should add some more real-life examples.