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justanotherdot/task-local-with-timeouts.rs

Created March 13, 2021 10:11
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task-local-with-timeouts.rs
use rand::Rng;
use std::default::Default;
use std::{cell::RefCell, collections::HashMap, time::Duration};
use tokio::{self, select, task, task_local, time::timeout};
fn rand_gen_millis() -> (u64, u64) {
let mut rng = rand::thread_rng();
let t1 = rng.gen_range(0..10);
let t2 = rng.gen_range(0..10);
(t1, t2)
}
fn main() {
let (t1, t2) = rand_gen_millis();
let rt = tokio::runtime::Runtime::new().expect("failed to start async runtime");
let produce_ten_or_one = async move {
let handler = task::spawn(async move {
task_local! {
pub static WRITER: RefCell<HashMap<String, i64>>;
}
let request_handler = || {
WRITER.with(|writer| {
*writer.borrow_mut().entry("value".to_string()).or_default() += 3;
writer.borrow().get("value").cloned()
})
};
WRITER
.scope(Default::default(), async move {
let a1 = timeout(Duration::from_millis(t1), async {
WRITER.with(|writer| {
writer.borrow_mut().insert("value".to_string(), 1);
writer.borrow().get("value").cloned()
})
});
let a2 = timeout(Duration::from_millis(t2), async {
WRITER.with(|writer| {
writer.borrow_mut().insert("value".to_string(), 7);
});
WRITER.with(|writer| {
let v = writer.borrow().get("value").cloned();
assert_eq!(v, Some(7));
});
request_handler()
});
select! {
v1 = a1 => {
v1.ok().flatten()
}
v2 = a2 => {
v2.ok().flatten()
}
}
})
.await
});
let result = handler.await.expect("failed to execute handler");
dbg!(result);
assert!(result == Some(10) || result == Some(1));
};
rt.block_on(produce_ten_or_one);
}
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