Module queue 

Queue / Deque Storage Module

FIFO/LIFO message queue with:

• Push/Pop from both ends (deque)
• Consumer groups with acknowledgment
• Dead-letter queue support
• Priority queue mode
• Per-message TTL

Modules

consumer_group

Consumer Groups for Queue

deque

Core Queue / Deque implementation

mode

presence

Queue consumer presence — issue #742.

Structs

ConsumerGroup

A consumer group manages message delivery and acknowledgment for a set of consumers reading from the same queue.

ConsumerPresence

One row of presence state, returned by snapshot.

ConsumerPresenceRegistry

Process-local registry of consumer presence. Cheap mutex + small hashmap is the right shape: writes are O(1), reads are a single snapshot copy, and the cardinality is bounded by the operator’s worker fleet (typically dozens, not thousands).

PendingEntry

A pending message awaiting acknowledgment

QueueStore

Core queue data structure supporting FIFO, LIFO, and priority modes.

Enums

PresenceState

Lifecycle bucket derived from last_seen_age_ms vs the configured ttl_ms. Snapshot consumers (Red UI, virtual tables) read this flag and never re-derive the rule.

QueueMode

QueueSide

Which end of the queue to push/pop from

Constants

DEFAULT_PRESENCE_TTL_MS

Default heartbeat budget — a consumer is considered active for this long after its last beat. Operators can override per server via the runtime config; the registry itself is agnostic and takes the budget as an argument on every read path.