#[trait_variant::make(HttpService: Send)]
pub trait DatabaseClient: Clone   Sized   Send   Sync   'static {
// some async fn defined
}

pub struct AppState<DB: DatabaseClient> {
    db: DB,
}

async fn restart_engine<DB: DatabaseClient>(Path(id): Path<EngineId>, State(state): State<AppState<DB>>) -> Result<()> {...}

fn get_engine_router<DB: DatabaseClient>() -> Router<AppState<DB>> {
    Router::new()
        .route("/:id/restart", post(restart_engine::<DB>))
}