异步 singleflight

文档：async_singleflight.

lib.rs:

tokio 的 singleflight 实现。

灵感来自 singleflight.

示例

use futures::future::join_all;
use std::sync::Arc;
use std::time::Duration;

use async_singleflight::Group;

const RES: usize = 7;

async fn expensive_fn() -> Result<usize, ()> {
    tokio::time::sleep(Duration::new(1, 500)).await;
    Ok(RES)
}

#[tokio::main]
async fn main() {
    let g = Arc::new(Group::<_, ()>::new());
    let mut handlers = Vec::new();
    for _ in 0..10 {
        let g = g.clone();
        handlers.push(tokio::spawn(async move {
            let res = g.work("key", expensive_fn()).await.0;
            let r = res.unwrap();
            println!("{}", r);
        }));
    }

    join_all(handlers).await;
}