delay.rs

use failure::Error;
use futures::{Async, Future, Poll};
use std::time::{Duration, Instant};
use tokio::runtime::Runtime;
use tokio::timer::Delay;

#[macro_use]
extern crate futures;

struct Node {
    pub value: u32,
    pub delay: Delay,
}

impl Node {
    fn new() -> Node {
        Node {
            value: 0,
            delay: Delay::new(Instant::now() + Duration::from_secs(1)),
        }
    }

    fn inc(&mut self) {
        self.value += 1;
        println!("{}", self.value);
    }
}

impl Future for Node {
    type Item = ();
    type Error = Error;

    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
        self.inc();
        self.delay = Delay::new(Instant::now() + Duration::from_secs(1));
        let _ = try_ready!(self.delay.poll());

        Ok(Async::NotReady)
    }
}

fn main() {
    let mut rt = Runtime::new().unwrap();
    let node = Node::new();

    rt.block_on(node).expect("Something went terribly wrong");
}