Tonic mutable state

Hello, fellow rustaceans. I very recently started using tonic (part of the tokio project) and I am trying to create a simple server. My problem is thus:

use entity_service_server::*;
use nvcore::ecs::EntityManager;
use tonic::{transport::Server, Request, Response, Status};

pub struct EntityManagerService {
    entity_manager: EntityManager,
impl EntityManagerService {
    fn new() -> EntityManagerService {
        EntityManagerService {
            entity_manager: EntityManager::new(),
impl EntityService for EntityManagerService {
    async fn create(&self, request: Request<Name>) -> Result<Response<EntityId>, Status> {
        let res = EntityId {
            id: self

In the create message, I need to modify the state of the EntityManagerService, but when tonic generates the stubs, the borrow is should I get around this? Full disclosure, I am very new to rust in general, and very very new to tonic specifically (I started yesterday, as a matter of fact).
I am experimenting with writing a backend+ui application where the backend manages all of the data, and any number of light weight, ephemeral ui clients can make queries about the current state/ask the backend to change some state and display this data as they see fit. Ideally, I want to be able to implement these frontends in any language/framework (rust's current UI situation is still quite infantile) I am not sure if using something like tonic is the best route, so any input towards a better solution would be appreciated.

You will need to wrap it the fields you wish to modify in a mutex or similar.

Ah...I suppose that makes sense. But from my understanding tokio (upon which tonic runs ) is single-threaded and used 'green threads', so there shouldn't be the possibility of locking...
I'll try it, though.

Tokio will, by default, use a number of threads equal to your number of CPU cores, though it can be configured to be single threaded.

Okay. That makes sense.

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