@event-driven-platform/read-execution-coordinator-redis

Redis implementation of the technology-neutral @event-driven-platform/read-execution-coordinator contract.

Usage

import { createClient } from 'redis';
import { RedisReadExecutionCoordinator } from '@event-driven-platform/read-execution-coordinator-redis';

const client = createClient({ url: 'redis://localhost:6379' });
await client.connect();

const coordinator = new RedisReadExecutionCoordinator(client);
await coordinator.connect();

// Pass `coordinator` to DefaultReader as readExecutionCoordinator.

The command client is supplied and remains consumer-owned. The coordinator creates one duplicated subscriber connection internally. connect() connects that subscriber, wait() can connect it lazily, and close() closes only the internally owned subscriber.

Ownership model

Each ReadCacheKey maps to TTL-bounded lease state and a release notification channel. One global monotonic generation counter provides ownership fencing without creating immortal sequencing state per read key.

Claim, renew, and release use atomic Redis scripts. Renew/release compare the complete lease reference so a stale owner cannot mutate a later generation.

Follower waiting

Followers use Redis Pub/Sub rather than busy polling. Waiting checks lease existence before and after subscription to close the lost-wakeup race. Release publishes only after ownership-safe deletion succeeds.

Lease expiry itself does not publish. Bounded wait returns to Reader, which re-checks shared cache and re-contends according to the Reader protocol.

Redis/client/script failures become explicit coordinator unavailable outcomes. Reader owns the fail-closed distributed execution policy.

Integration verification

Real Redis verification is available through:

READ_COORDINATOR_REDIS_URL=redis://localhost:6379 \
  pnpm nx run @event-driven-platform/read-execution-coordinator-redis:test:integration

The ordinary unit-test target excludes integration specs. CI runs the real Redis target only when this adapter is affected directly or through the Nx project graph.

Related documentation

• docs/read-public-api.md
• docs/read-release-readiness.md