refactor(store): extract shared AbstractEventStore and registry utilities

[devin-ai-integration]

Description

The seven broker backed EventStore implementations each re-implemented the same boilerplate: nullable nodeId/eventStoreMode/prefix defaulting, SINGLE_CHANNEL channel-name resolution, mode validation, self-message filtering, the EventType -> Queue<registrationId> + registrationId -> handle bookkeeping with its identical unsubscribe loop, the Arrays.stream(EventType.values()).forEach(this::unsubscribe) shutdown, and the unchecked ListenerRegistration dispatch loop. This PR moves all of it into three shared types under store.event, so the concrete stores only contain broker-specific code. Net −540/+353 lines with no behavior change.

AbstractEventStore (base class for all remote stores):

protected AbstractEventStore(nodeId, eventStoreMode, defaultEventStoreMode, channelPrefix, defaultChannelPrefix)
protected EventType resolveType(EventType)   // ALL_SINGLE_CHANNEL in SINGLE_CHANNEL mode
protected String   channelName(EventType)    // channelPrefix + resolveType(type).name()
protected void     stampNodeId(EventMessage)
protected boolean  isRemote(EventMessage)    // !nodeId.equals(msg.getNodeId())
protected void     unsubscribeAll()
protected void     validateSubscribe(EventType)

SubscriptionRegistry<I, S> replaces the two ad-hoc maps in the pub/sub stores, so e.g. Redis pub/sub becomes:

subscriptions.add(type, regId, topic);
// unsubscribe0:
subscriptions.remove(type, (id, topic) -> topic.removeListener(id));

ListenerRegistry holds the local ListenerRegistration queues for the poll based stores (Kafka, Redis Stream) and owns the single remaining unchecked cast used to dispatch a message to typed listeners.

Per-store defaults are preserved by passing them to super(...): Redis pub/sub and NATS keep an empty prefix, Hazelcast (both) and Redis reliable/stream keep "SOCKETIO4J:", Kafka keeps "SOCKETIO4J-", and Redis Stream keeps SINGLE_CHANNEL as its default mode while everything else keeps MULTI_CHANNEL.

Type of Change

• Code refactoring

Related Issue

N/A

Changes Made

• Added store/event/AbstractEventStore.java, store/event/SubscriptionRegistry.java, store/event/ListenerRegistry.java
• Reworked RedisPubSubEventStore, RedisPubSubReliableEventStore, RedisStreamEventStore, NatsEventStore, HazelcastPubSubEventStore, HazelcastPubSubRingBufferEventStore and KafkaEventStore to extend AbstractEventStore and use the shared registries
• Removed the per-store duplicates of getStreamName/getSubjectName/getTopicName/topic, resolve, validateSubscribe, getEventStoreMode and the duplicated unsubscribe/shutdown/dispatch loops

Testing

• Tests pass locally with mvn test — mvn -pl netty-socketio-core verify (compile + checkstyle + license) passes; the store integration tests are Testcontainers based and are exercised by CI
• New tests added for new functionality (pure refactor, no behavior change)

Checklist

• Code follows project coding standards (checkstyle clean)
• Self-review completed
• Commit messages follow conventional format
• No merge conflicts

Additional Notes

No public API changed: constructors, builders and the EventStore SPI keep their existing signatures.

Link to Devin session: https://app.devin.ai/sessions/78bf7322d0ff4d139f1f0c157954bfad
Requested by: @sanjomo

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[devin-ai-integration]

Test run: store integration tests (Devin)

Full netty-socketio-core suite on this branch with Docker/Testcontainers (Redis, Kafka, Hazelcast, NATS):

Tests run: 709, Failures: 0, Errors: 0, Skipped: 0, Flakes: 14

Channel-name / default-mode invariants (all 7 backends unchanged)

Temporary reflection test over AbstractEventStore#channelName with mocked clients:

RedisPubSubEventStore              MULTI_CHANNEL   CONNECT
NatsEventStore                     MULTI_CHANNEL   CONNECT
RedisPubSubReliableEventStore      MULTI_CHANNEL   SOCKETIO4J:CONNECT
RedisStreamEventStore              SINGLE_CHANNEL  SOCKETIO4J:ALL_SINGLE_CHANNEL
HazelcastPubSubEventStore          MULTI_CHANNEL   SOCKETIO4J:CONNECT
HazelcastPubSubRingBufferEventStore MULTI_CHANNEL  SOCKETIO4J:CONNECT
KafkaEventStore                    MULTI_CHANNEL   SOCKETIO4J-CONNECT
validateSubscribe rules OK

Matches pre-refactor naming/modes exactly. validateSubscribe still throws UnsupportedOperationException for the two illegal mode/type combinations.

Flakes (14) — likely environmental

All were "clients failed to join room within timeout" in Hazelcast/Kafka/NATS distributed tests and passed on retry. DistributedKafkaMultiChannelMemoryTest run in isolation: main 12/12 in 17.53s, branch 12/12 in 17.43s — identical, so contention during the 18-min full run is the likely cause. A full-suite run on main was not done for a like-for-like flake comparison.

Session: https://app.devin.ai/sessions/78bf7322d0ff4d139f1f0c157954bfad

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.