examples/src/shared_completion.rs

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//! Share one immutable job result with current and late observers.
//!
//! A oneshot channel has one receiver. Serving these independent consumers with oneshot would
//! require one channel per consumer and manual fan-out, and a late consumer would need separate
//! result storage. Completion retains the result and exposes it to every observer.

use asyncband::completion;

#[tokio::main(flavor = "current_thread")]
async fn main() {
    let (completer, completion) = completion::new();
    let dashboard = completion.clone();
    let audit_log = completion.clone();

    let worker = tokio::spawn(async move {
        tokio::task::yield_now().await;
        completer
            .complete(String::from("build 42 succeeded"))
            .unwrap();
    });

    let (dashboard_result, audit_result) = tokio::join!(dashboard.wait(), audit_log.wait());
    let dashboard_result = dashboard_result.unwrap();
    let audit_result = audit_result.unwrap();
    worker.await.unwrap();

    let late_observer = completion.clone();
    let late_result = late_observer.wait().await.unwrap();

    assert!(std::ptr::eq(dashboard_result, audit_result));
    assert!(std::ptr::eq(dashboard_result, late_result));
    println!("{late_result}");
}