Enum Waiter 

pub enum Waiter<P: Protocol> {
    Unary(Sender<Result<Frame<P::Response>>>),
    Streaming {
        binding: u64,
        tx: Sender<Result<Frame<P::Response>>>,
    },
    Abandoned,
}

What is waiting on a tag.

r[impl jetstream.subscription.definition] A unary call’s tag is freed by its one response. A subscription’s is held for as long as the producer may still emit, and freed by the terminator — which is why the two cannot share a representation.

Variants

Unary(Sender<Result<Frame<P::Response>>>)

One response, then the tag is free.

Streaming

Many responses under one tag, until the terminator.

r[impl jetstream.subscription.identity] The binding is which subscription this slot belongs to, and it is what makes abandoning one safe: a tag is reused once its terminator frees it, so a stream dropped after that would otherwise find a different subscription’s waiter under its old number and silence it. Identifiers start at one and are never reused, so a stale holder simply fails to match.

Fields

binding: u64

tx: Sender<Result<Frame<P::Response>>>

Abandoned

The caller dropped its stream. Frames are discarded, and the tag stays held until the terminator arrives.

r[impl jetstream.subscription.identity] Releasing it at drop instead would let the tag be rebound while the producer is still emitting under it, and an in-lane item carries no binding identifier to tell the two apart.