Created
September 12, 2016 09:25
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#![allow(dead_code)] | |
use std::f32::INFINITY; | |
use std::sync::{Arc}; | |
use std::thread; | |
use std::sync::mpsc::channel; | |
struct Store { | |
name: String, | |
items: Vec<Item>, | |
} | |
#[derive(Debug)] | |
struct Item { | |
name: &'static str, | |
price: f32, | |
} | |
impl Store { | |
fn new(name: String) -> Store { | |
Store { | |
name: name, | |
items: vec![], | |
} | |
} | |
fn add_item(&mut self, item: Item) { | |
self.items.push(item); | |
} | |
fn price(&self, item_name: &str) -> f32 { | |
for item in &self.items { | |
if item.name == item_name { | |
return item.price; | |
} | |
} | |
panic!("no such item {:?}", item_name); | |
} | |
fn total_price(&self, shopping_list: &[&str]) -> f32 { | |
shopping_list.iter() | |
.map(|name| self.price(name)) | |
.fold(0.0, |a, b| a + b) | |
} | |
} | |
fn build_stores() -> Vec<Store> { | |
let mut stores = vec![]; | |
let mut store = Store::new(format!("Rustmart")); | |
store.add_item(Item { name: "chocolate", price: 5.0 }); | |
store.add_item(Item { name: "socks", price: 23.0 }); | |
store.add_item(Item { name: "plush Mozilla dinosaur", price: 13.0 }); | |
stores.push(store); | |
let mut store = Store::new(format!("Rarget")); | |
store.add_item(Item { name: "chocolate", price: 2.5 }); | |
store.add_item(Item { name: "socks", price: 20.0 }); | |
store.add_item(Item { name: "plush Mozilla dinosaur", price: 20.0 }); | |
stores.push(store); | |
stores | |
} | |
fn main() { | |
let stores = build_stores(); | |
let shopping_list = vec!["chocolate", "plush Mozilla dinosaur"]; | |
//let shopping_list = Arc::new(shopping_list); | |
let mut best = None; | |
let mut best_price = INFINITY; | |
// using Threads! | |
let mut handles = vec![]; | |
for store in stores { | |
let shopping_list = shopping_list.clone(); | |
handles.push(thread::spawn(move || { | |
let sum = store.total_price(&shopping_list); | |
(store.name, sum) | |
})); | |
} | |
for handle in handles { | |
let (name, sum) = handle.join().unwrap(); | |
if sum < best_price { | |
best_price = sum; | |
best = Some(name); | |
} | |
} | |
println!("--> Go to {}!", best.unwrap()); | |
// Goal: join the threads here! | |
// Extra credit: rewrite to use channels or mutexes. | |
// using Channels! | |
for store in stores { | |
let shopping_list = shopping_list.clone(); | |
let (tx, rx) = channel(); | |
thread::spawn(move || { | |
let sum = store.total_price(&shopping_list); | |
tx.send((store.name, sum)).unwrap(); | |
}); | |
let (name, sum) = rx.recv().unwrap(); | |
if sum < best_price { | |
best_price = sum; | |
best = Some(name); | |
} | |
} | |
println!("--> Go to {}!", best.unwrap()); | |
} |
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