Broken Rust Thing

broken.rs

extern crate iron;
extern crate rustc_serialize;
extern crate router;

use iron::prelude::*;
use iron::status;
use router::Router;
use std::sync::{Arc, Mutex};
use rustc_serialize::json;
use std::io::Read;

#[derive(RustcEncodable, RustcDecodable)]
pub struct HelloStruct {
    hello: String,
}


fn main() {

    let mut router = Router::new();

    let mut data: HelloStruct = HelloStruct { hello: "world".to_string() };
    let data_arc = Arc::new(Mutex::new(data));

    let hello_data = data_arc.clone();
    let hello = move |_: &mut Request| -> IronResult<Response> {
        let d = hello_data.lock().unwrap();

        let payload = json::encode(&*d).unwrap();
        Ok(Response::with((status::Ok, payload)))
    };
    router.get("/", hello);

    let set_data = data_arc.clone();
    let set_who = move |req: &mut Request| -> IronResult<Response> {
        let mut payload = String::new();
        req.body.read_to_string(&mut payload).unwrap();
        let request: HelloStruct = json::decode(&payload).unwrap();

        let d = set_data.lock().unwrap();

        *d = request;

        let payload_out = json::encode(&*d).unwrap();
        Ok(Response::with((status::Ok, payload_out)))
    };
    router.post("/set", set_who);

    Iron::new(router).http("0.0.0.0:8080").unwrap();
}