Struct CapacityTracker 

pub struct CapacityTracker { /* private fields */ }

Per-consumer tracker for current in-flight and buffered message counts.

Implementations

impl CapacityTracker

pub const fn new(capacity: ConsumerCapacity) -> Self

Creates a tracker for an explicitly declared consumer capacity.

pub const fn derived(capacity: ConsumerCapacity, queued: usize) -> Self

Builds a tracker whose two bands are DERIVED from queued — the authoritative depth of the queue the messages actually sit in — rather than accumulated by independent record_* mutations (A1 §0.1/§2, docs/design/A1-DEFER-SEMANTICS.md).

The in-flight band is min(queued, max_in_flight) and the buffered band is queued.saturating_sub(max_in_flight), so the occupancy invariant queued == current_in_flight + current_buffer_depth holds for EVERY queued, and neither band can be decremented below zero because neither band is ever decremented at all. That is what retires the CapacityError::InFlightUnderflow / CapacityError::BufferUnderflow drift class by construction: the hot path calls this constructor and reads Self::pressure_signal, and never touches a record_* mutator.

The mutators stay for the explicit-credit (v2) accounting the design specifies but does not ship, and for the standalone unit tests already written against them.

pub const fn capacity(&self) -> &ConsumerCapacity

Returns the consumer capacity declaration this tracker follows.

pub const fn current_in_flight(&self) -> usize

Returns the number of messages currently being processed by the consumer.

pub const fn current_buffer_depth(&self) -> usize

Returns the number of messages currently buffered for the consumer.

pub const fn record_delivery(&mut self)

Records that a message was delivered and processing began.

pub const fn record_completion(&mut self) -> Result<(), CapacityError>

Records that processing completed for one in-flight message.

Errors

Returns CapacityError::InFlightUnderflow if no message is currently in flight.

pub const fn record_buffered(&mut self)

Records that a message was buffered pending consumer capacity.

pub const fn record_buffer_drained(&mut self) -> Result<(), CapacityError>

Records that one buffered message left the buffer.

Errors

Returns CapacityError::BufferUnderflow if no message is currently buffered.

pub const fn pressure_signal(&self) -> PressureSignal

Determines the pressure signal for the next message without mutating counters.

Trait Implementations

impl Clone for CapacityTracker

fn clone(&self) -> CapacityTracker

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CapacityTracker

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

Formats the value using the given formatter.

impl Eq for CapacityTracker

impl PartialEq for CapacityTracker

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for CapacityTracker