Struct ChannelDelivery 

pub struct ChannelDelivery { /* private fields */ }

Genuine delivery ack returned by ChannelHandle::publish_with_delivery.

Distinct from backpressure: it reports whether a published message was actually received by a subscriber, not whether it was admitted to the bus.

Copy is preserved from published liminal-rs 0.9.1. A1 added two fields; the one that briefly cost Copy was signal: PressureSignal, which is four usizes and now derives Copy itself (durable_position: Option<u64> and pressure_config: ChannelPressureConfig were already Copy). Nothing about this type wants move semantics, and taking Copy away from a published type breaks callers silently — let a = delivery; use(delivery); simply stops compiling.

Implementations

impl ChannelDelivery

pub const fn delivery_id(&self) -> Option<DeliveredId>

The exact live identity supplied by the publication’s transport.

pub const fn delivered_count(&self) -> usize

Number of local subscribers the message was genuinely delivered to.

pub const fn matched_count(&self) -> usize

Number of local subscribers whose predicate matched the message, whether or not their inbox took it. With Self::delivered_count it tells “nobody was subscribed” (0 matched) from “subscribers were there and none took it” (matched, 0 delivered). Zero when the publish was refused before any fan-out (a durable watermark Reject).

pub const fn is_delivered(&self) -> bool

Whether the message was accepted by at least one subscriber.

pub const fn durable_position(&self) -> Option<u64>

The store-assigned append sequence of this publish on a durable channel, None on a memory channel.

This is the durable position G1 of docs/design/wire-durability-gaps-20260831.md names: haematite’s append assigns it, and before this field the caller discarded it, so no client of a durable channel could ever learn where its publish landed. Any resume/ack protocol needs exactly this value.

Assigned is not flushed: the position is real the moment the append returns, but the store flushes on graceful shutdown only (G4’s flush half), so a crash can still lose the tail. The position tells you WHERE the publish sits, not that it survives every failure mode.

pub const fn pressure(&self) -> &PressureSignal

The A1 backpressure signal for this publish (docs/design/A1-DEFER-SEMANTICS.md §6: “ChannelDelivery gains a pressure() accessor (additive)”).

Orthogonal to Self::is_delivered. Delivery answers “did a subscriber receive it”; pressure answers “should you slow down”. A publish to a channel with no subscribers is Accept and delivered to nobody; a publish every consumer buffered is Defer and delivered to everybody.

pub const fn is_admitted(&self) -> bool

Whether the bus took custody of the message (A1 §7): Accept or Defer.

The accessor an aion worker’s fire-and-forget completion policy reads, deliberately distinct from Self::is_delivered (“a subscriber genuinely received it”). A Deferred message is admitted — the bus holds it and the consumer’s next pop is its redelivery — so a producer that re-publishes it with a fresh key double-delivers. false means Reject: shed, delivered to nobody, and the producer owns the retry.

pub fn defer_delay(&self) -> Option<Duration>

The producer’s advisory pacing hint (A1 §3): base + (max − base) × buffer_fill_fraction, from this channel’s configured delay policy. None on Accept — an accepted publish is not paced.

The bus never blocks a producer on this and never lies about it: ignoring the hint leads to Reject on an ephemeral channel, and to growing hints and eventually the pre-append watermark Reject on a durable one.

Trait Implementations

impl Clone for ChannelDelivery

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for ChannelDelivery

impl Debug for ChannelDelivery

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for ChannelDelivery

impl PartialEq for ChannelDelivery

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for ChannelDelivery