mathbot.rs

use std::{process::exit, sync::{Arc, RwLock}};
use std::sync::mpsc;
use std::thread;
use std::time::SystemTime;
use std::time::Duration;
use std::collections::HashMap;
use rand::prelude::*;

type DB = Arc<RwLock<HashMap<String, Arc<RwLock<usize>>>>>;

fn handle(sender: mpsc::Sender<(String, usize)>, db: DB) {
    let tasks = vec!["John Doe".to_owned(), "Haskell Curry".to_owned(), "Alan Turing".to_owned()];
    let mut count = 0;
    loop {
        if count >= tasks.len() {
            break;
        }
        {
            if let Some(rlock) = db.read().unwrap().get(&tasks[count]) {
                let ran = *rlock.read().unwrap();
                sender.send((tasks[count].to_owned(), ran)).unwrap();
                count += 1;
                continue;
            }
        }
        {
            let doc_lock = Arc::new(RwLock::new(0));
            let doc_lock_w = doc_lock.clone();
            let mut wlock = doc_lock_w.write().unwrap();
            {
                let mut wlock = db.write().unwrap();
                if wlock.contains_key(&tasks[count]) {
                    continue;
                }
                wlock.insert(tasks[count].clone(), doc_lock);
            }
            thread::sleep(Duration::from_secs(3));
            let value = rand::random();
            *wlock = value;
            count += 1;
        }
    }
}

fn main() {
    let db = Arc::new(RwLock::new(HashMap::new()));
    let (sender, reciever) = mpsc::channel();
    let sender1 = sender.clone();
    let sender2 = sender.clone();
    let sender3 = sender.clone();
    let db0 = db.clone();
    let db1 = db.clone();
    let db2 = db.clone();
    let db3 = db.clone();
    thread::spawn(|| {
        handle(sender, db0);
    });
    thread::spawn(|| {
        handle(sender1, db1);
    });
    thread::spawn(|| {
        handle(sender2, db2);
    });
    thread::spawn(|| {
        handle(sender3, db3);
    });
    let mut count = 0;
    loop {
        if count >= 9 {
            break;
        }
        if let Ok((name, value)) = reciever.recv() {
            count += 1;
            println!("{} : {}", name, value);
        }
    }
}