Rust - 与 Arc 一起使用时无法读取互斥锁内的文件

Question

I am unable to get this code to work, it always return an empty string and no bytes are read

let mut contents = String::new();
let file_ref = Arc::new(Mutex::new(my_file));
let mut guard = file_ref.lock().unwrap();
let bytes = guard
    .read_to_string(&mut contents)
    .expect("File to be read");
dbg!(bytes);

Answer 1

It seems a file can be read only once, I was reading the my_file in previous lines, looks like that seems to be the issue and I need to clone the file pointer itself too...