Struct Response 

pub struct Response<A: Application> {
    pub journal_persisted_wire_seq: DurableWireSeqCursor,
    pub ack_policy: Arc<AtomicU8>,
    pub replication_metrics: Option<Arc<ReplicationMetrics>>,
    pub replica_active: Option<[Arc<AtomicBool>; 2]>,
    pub heartbeat_interval: Option<Duration>,
    pub wait: WaitStrategy,
    pub utilization: Arc<StageUtilization>,
    pub encoder: ResponseEncoderArc<A>,
    pub fence_state: Arc<FenceState>,
    pub active_connections: Arc<AtomicU64>,
}

Configuration and shared state for the response stage.

Fields

journal_persisted_wire_seq: DurableWireSeqCursor

Highest wire seq durably persisted on this node’s journal. In the same sequence space as OutputSlot.wire_seq and the replica metrics (metrics.in_memory_sequence / metrics.acked_sequence), so the durability gate can compare these values numerically and the comparison is meaningful regardless of starting_sequence (fresh vs recovered primary). Typed DurableWireSeqCursor so the gate cannot be wired to a ring-space counter — the pre-v14 bug class. Updated by the journal stage after every fsync batch via set_last_seq_publisher.

ack_policy: Arc<AtomicU8>

Operator-selected ack policy, published through a shared AtomicU8 so the admin ACK-POLICY command can swap it at runtime without restarting the node. The response stage reads this once per gate iteration with a relaxed load (cheaper than a Mutex or refcounted Arc<Policy> snapshot) and rebuilds its local Policy when the byte changes. See crate::ack_policy::AckPolicy::as_u8 for the encoding.

replication_metrics: Option<Arc<ReplicationMetrics>>

Per-slot replica cursors. None for standalone deployments (no replication wiring) — the policy then evaluates against the primary alone.

replica_active: Option<[Arc<AtomicBool>; 2]>

Per-slot replica active flags. Only “true” slots are included in the cursor view fed to Policy::evaluate, so disconnected slots don’t pollute the view with stale zero cursors. When the resulting view is too small to satisfy a clause, the policy reports degraded and the gate stalls. Mirrors replication_metrics — None in standalone.

heartbeat_interval: Option<Duration>

wait: WaitStrategy

How this thread waits — on an empty output ring, and inside the durability gate on the journal-disk and replication threads.

utilization: Arc<StageUtilization>

encoder: ResponseEncoderArc<A>

Wire encoder for application-shaped payloads. Constructed once at boot (Arc::new(ExchangeResponseEncoder)) and shared with the DPDK response stage.

fence_state: Arc<FenceState>

Node fencing state. When latched (a higher epoch was observed), the stage exits without the best-effort flush — in-flight responses for orders on a superseded epoch must not be acknowledged. Fencing co-sets shutdown, so the latch is only consulted on the shutdown path (zero steady-state cost). See crate::fence.

active_connections: Arc<AtomicU64>

Live-connection count shared with the accept loop’s max_connections gate. Incremented there after auth; decremented here — the response stage owns the connection map, so “an entry left the map” is the one place a connection verifiably dies exactly once, whichever side (reader disconnect or a drop decision here) initiated it.