atomic enum in rust

atomic_enum.rs

use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;

pub enum RunFlagState {
    Running = 0,
    Paused = 1,
    Cancelled = 2,
}

// TODO: is there some mechanism to automate this (nightly)?
impl From<usize> for RunFlagState {
    fn from(val: usize) -> Self {
        use self::RunFlagState::*;
        match val {
            0 => Running,
            1 => Paused,
            2 => Cancelled,
            _ => unreachable!(),
        }
    }
}

#[derive(Clone)]
pub struct RunFlag {
    flag: Arc<AtomicUsize>,
}

impl RunFlag {
    pub fn new(state: RunFlagState) -> Self {
        RunFlag {
            flag: Arc::new(AtomicUsize::new(state as usize)),
        }
    }

    pub fn cancel(&self) {
        self.set_state(RunFlagState::Cancelled)
    }
    pub fn pause(&self) {
        self.set_state(RunFlagState::Paused)
    }
    pub fn run(&self) {
        self.set_state(RunFlagState::Running)
    }

    #[inline]
    pub fn get_state(&self) -> RunFlagState {
        self.flag.load(Ordering::SeqCst).into()
    }
    fn set_state(&self, state: RunFlagState) {
        self.flag.store(state as usize, Ordering::SeqCst)
    }
}