Struct Backpressure 

pub struct Backpressure { /* private fields */ }

Keyed backpressure over the outbox claim: resolves per-namespace ceilings and plans a round-robin, headroom-capped, fair-shared claim per sweep.

Holds only read-side state (the quota cache + this node’s shard fraction); the claim itself goes through the unchanged OutboxStore the dispatcher already owns. Cheap to clone (the cache shares its inner handle).

Implementations

impl Backpressure

pub fn new(quota: QuotaCache, fraction: OwnedShardFraction) -> Self

Build keyed backpressure from a quota cache and this node’s owned-shard fraction.

pub async fn claim_round_robin( &self, store: &Arc<dyn OutboxStore>, batch_size: u32, held: &HashSet<WorkflowId>, ) -> Result<Vec<OutboxRow>, StoreError>

Claim up to batch_size rows across all namespaces-with-pending-work, with the batch budget allocated PER NAMESPACE first (a guaranteed fair slice each), then distributed round-robin across each namespace’s routes. Returns every claimed row, in claim order.

Rows not claimed (a tenant at its ceiling, or the batch budget exhausted) stay durably Pending and are reconsidered next sweep — the keyed backpressure: nothing is dropped, no RESOURCE_EXHAUSTED is surfaced.

Errors

Propagates a store error from the route probe or any scoped claim; the dispatcher logs it and retries next tick (a transient backend failure must not tear the loop down).

Trait Implementations

impl Clone for Backpressure

fn clone(&self) -> Backpressure

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Backpressure

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

Formats the value using the given formatter.