Created
April 3, 2020 10:03
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Service handler using Rust async
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use async_std::sync::{channel, Receiver}; | |
use futures::future::FutureExt; | |
use rand::rngs::SmallRng; | |
use rand::FromEntropy; | |
use rand::Rng; | |
use std::thread; | |
use std::time; | |
use tokio::time::delay_for; | |
#[derive(PartialEq, Clone, Debug)] | |
enum HaveToWait { | |
Complete(String), | |
NewRequest(usize), | |
} | |
async fn do_something2(x: usize) -> String { | |
let mut rng = SmallRng::from_entropy(); | |
delay_for(time::Duration::from_millis(rng.gen_range(10, 50))).await; | |
if x == 999 { | |
"".to_owned() | |
} else { | |
format!("Wow, I consumed {}", x) | |
} | |
} | |
fn smart_consume(recv: Receiver<usize>) { | |
let mut pool = Vec::new(); | |
let mut rt = tokio::runtime::Runtime::new().unwrap(); | |
let mut popped = true; | |
loop { | |
if popped || pool.is_empty() { | |
pool.push( | |
recv.recv() | |
.map(|x| HaveToWait::NewRequest(x.unwrap())) | |
.boxed(), | |
); | |
popped = false; | |
} | |
let (r, _, mut new_pool) = rt.block_on(futures::future::select_all(pool)); | |
match r { | |
HaveToWait::Complete(msg) => { | |
println!("{:?}", msg); | |
if msg.is_empty() { | |
return; | |
} | |
} | |
HaveToWait::NewRequest(arg) => { | |
// new request | |
new_pool.push(do_something2(arg).map(|x| HaveToWait::Complete(x)).boxed()); | |
popped = true; | |
} | |
} | |
pool = new_pool; | |
} | |
} | |
pub fn complex() { | |
let mut rt = tokio::runtime::Runtime::new().unwrap(); | |
let (send, recv) = channel(1000); | |
let t = thread::spawn(move || smart_consume(recv)); | |
let mut rng = SmallRng::from_entropy(); | |
for i in 0..1000 { | |
rt.block_on(send.send(i)); | |
thread::sleep(time::Duration::from_millis(rng.gen_range(1, 10))); | |
} | |
t.join().unwrap(); | |
} |
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