Performance concerns with cloning an AppState with a DB Pool

[matx64]

Hi, my application has some controllers to setup Routers. The only solution I found to share my "global" app state between them is by cloning.
I'm concerned about performance problems with that approach since the state has a database pool on it. Is there any? Also, is this the best approach to this problem?

Here's the snippet:

#[derive(Clone)]
pub struct AppState {
    pool: Pool<Postgres>,
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    
    // ...

    let pool = db::db_pool().await?;

    let app_state = AppState { pool };

    let app = Router::new()
        .nest("/users", user_routes(app_state.clone()))
        .nest("/dummies", dummy_routes(app_state.clone()));

    // ...
}

pub fn user_routes(state: AppState) -> Router {
    Router::new()
        .route("/", get(get_users))
        .with_state(state)
}

pub async fn get_users(state: State<AppState>) -> Result<Json<Vec<User>>, axum::http::StatusCode> {
    // ...
}

pub fn dummy_routes(state: AppState) -> Router {
    Router::new()
        .route("/dummy1", get(dummy))
        .with_state(state)
}

pub async fn dummy(state: State<AppState>) -> Result<Json<Vec<User>>, axum::http::StatusCode> {
    // ...
}

Thanks in advance!

[davidpdrsn]

You probably don’t need to worry. Cloning a connection pool is usually just bumping a reference count.

But I’d recommend you benchmark things if you wanna know more of what the impact is.

[matx64]

Alright, thanks a lot!