Структура OwnedPermit

use tokio::sync::mpsc;

let (tx, mut rx) = mpsc::channel(1);

// Reserve capacity
let permit = tx.reserve_owned().await.unwrap();

// Send a message on the permit, returning the sender.
let tx = permit.send(456);

// The value sent on the permit is received
assert_eq!(rx.recv().await.unwrap(), 456);

// We may now reuse `tx` to send another message.
tx.send(789).await.unwrap();

use tokio::sync::mpsc;

let (tx, rx) = mpsc::channel(1);

// Clone the sender and reserve capacity
let permit = tx.clone().reserve_owned().await.unwrap();

// Trying to send on the original `tx` will fail, since the `permit`
// has reserved all the available capacity.
assert!(tx.try_send(123).is_err());

// Release the permit without sending a message, returning the clone
// of the sender.
let tx2 = permit.release();

// We may now reuse `tx` to send another message.
tx.send(789).await.unwrap();

use tokio::sync::mpsc;

let (tx, rx) = mpsc::channel::<()>(2);

let permit1 = tx.clone().reserve_owned().await.unwrap();
let permit2 = tx.clone().reserve_owned().await.unwrap();
assert!(permit1.same_channel(&permit2));

let (tx2, rx2) = mpsc::channel::<()>(1);

let permit3 = tx2.clone().reserve_owned().await.unwrap();
assert!(!permit3.same_channel(&permit2));

use tokio::sync::mpsc;

let (tx, rx) = mpsc::channel::<()>(1);

let permit = tx.clone().reserve_owned().await.unwrap();
assert!(permit.same_channel_as_sender(&tx));

let (tx2, rx2) = mpsc::channel::<()>(1);
assert!(!permit.same_channel_as_sender(&tx2));