Lib.rs

没有 AsyncDrop，等待正在被丢弃的项目是非平凡的。

此包装器允许等待，并可以在其中用于在不再使用时对 Arc 或类似内容的异步清理。

use dropbear::DropBear;
let (bearer, notify) = DropBear::new(x.clone());
drop(bearer);
assert_eq!(notify.await.unwrap(), x); // => true

use dropbear::DropBear;
let (bearer, notify) = DropBear::new(item);
let arc = Arc::new(bearer);
// Pass the arc elsewhere, handing ownership over
// Or clone it elsewhere, do some work here, then drop your copy
{
    // ...
}
// Receive the original item once the last Arc instance is dropped
let original_item = notify.await.unwrap();
// ... and perform async cleanup on the contents
perform_cleanup(original_item).await;