Go to Rust: controller with tokio

controller.rs

use std::error::Error;
use tokio::sync::RwLock;

#[derive(Default)]
struct ReqData {
    seq: i32,
    last_path: String,
}

#[derive(Default)]
pub struct Controller {
    req_data: RwLock<ReqData>,
}

impl Controller {
    pub fn new() -> Self {
        Default::default()
    }

    async fn request(&self, path: &str) -> Result<(), Box<dyn Error + Sync + Send>> {
        let mut ref_data = self.req_data.write().await;
        ref_data.seq += 1;
        // A real implementation would make a network call here. Call await to make this
        // non-trivially async.
        async {
            ref_data.last_path = format!("{path}&seq={}", ref_data.seq);
        }
        .await;
        Ok(())
    }
}