Outbox framework improvements: builder, interceptors, fair queue, graceful shutdown, dialect schemas

[leonlee]

Summary

• Builder pattern on OutboxDispatcher with required connectionProvider, eventStore, listenerRegistry
• Single-listener registry keyed by (aggregateType, eventType) with AggregateType.GLOBAL default
• EventInterceptor for cross-cutting before/after dispatch hooks (audit, logging, metrics)
• Fair queue draining: 2:1 weighted round-robin (hot 2/3, cold 1/3) between hot and cold queues
• Graceful shutdown with accepting flag, shutdown() + awaitTermination with configurable drain timeout
• AbstractJdbcEventStore hierarchy: H2 (subquery claim), MySQL (UPDATE...ORDER BY...LIMIT), PostgreSQL (FOR UPDATE SKIP LOCKED + RETURNING)
• JdbcEventStores ServiceLoader registry with detect(DataSource) auto-detection
• Dialect-specific schema files (H2, MySQL, PostgreSQL) shipped in the JAR under schema/
• Schema-diff CI workflow using sqldef to generate migration DDL on PRs
• Refactored package structure (JDBI-inspired), renamed to EventStore/OutboxEvent/EventStatus
• Added outbox-demo (H2, no Spring) and outbox-spring-demo (Spring Boot REST)
• Comprehensive test coverage (~141 tests)

Test plan

• mvn test — all 141 tests pass
• mvn -pl outbox-jdbc package -DskipTests — schema files present in JAR
• Verify schema-diff workflow triggers on PR with schema changes
• Run outbox-demo and outbox-spring-demo end-to-end

🤖 Generated with Claude Code

[github-actions]

Schema Diff

H2

New file (no baseline on main).

MySQL

-- dry run --
BEGIN;
CREATE TABLE outbox_event (
  event_id VARCHAR(36) PRIMARY KEY,
  event_type VARCHAR(128) NOT NULL,
  aggregate_type VARCHAR(64),
  aggregate_id VARCHAR(128),
  tenant_id VARCHAR(64),
  payload JSON NOT NULL,
  headers JSON,
  status TINYINT NOT NULL,
  attempts INT NOT NULL DEFAULT 0,
  available_at DATETIME(6) NOT NULL,
  created_at DATETIME(6) NOT NULL,
  done_at DATETIME(6),
  last_error TEXT,
  locked_by VARCHAR(128),
  locked_at DATETIME(6)
);
CREATE INDEX idx_status_available ON outbox_event(status, available_at, created_at);
COMMIT;

PostgreSQL

-- dry run --
BEGIN;
CREATE TABLE outbox_event (
  event_id VARCHAR(36) PRIMARY KEY,
  event_type VARCHAR(128) NOT NULL,
  aggregate_type VARCHAR(64),
  aggregate_id VARCHAR(128),
  tenant_id VARCHAR(64),
  payload JSONB NOT NULL,
  headers JSONB,
  status SMALLINT NOT NULL,
  attempts INT NOT NULL DEFAULT 0,
  available_at TIMESTAMPTZ NOT NULL,
  created_at TIMESTAMPTZ NOT NULL,
  done_at TIMESTAMPTZ,
  last_error TEXT,
  locked_by VARCHAR(128),
  locked_at TIMESTAMPTZ
);
CREATE INDEX idx_status_available ON outbox_event(status, available_at, created_at);
COMMIT;