struct ServiceA{
    field_a: String,
}

struct ServiceB{
    field_b: i32,
}

impl ServiceA {
    pub async fn init(self: Arc<Self>){
        tokio::spawn(async move { self.daemon_task().await});
    }

    async fn daemon_task(&self){
        //do loop task
    }
}

enum Service {
    A(ServiceA),
    B(ServiceB)
}

I have arc_obj: Arc<Service>. How can I downgrade it to an Arc<ServiceA> when arc_obj is Service::A?

I use enum dispatch and tokio, so I wrap a Service object in Arc to use it in multiple threads. ServiceA needs init to start a daemon task, which wants an Arc<ServiceA>. How can I get it?