RedisCache

RedisCache is a Cache implementation backed by Redis. It supports distributed cache invalidation via Redis pub/sub, making it suitable for multi-host deployments.

import { RedisCache } from "@farbenmeer/tag-based-cache/redis-cache";

Requires the @redis/client package as a peer dependency.

Constructor

new RedisCache(redis: RedisClientType)

• Parameters:
  • redis: A connected RedisClientType instance from @redis/client.

Usage

import { createClient } from "@redis/client";
import { RedisCache } from "@farbenmeer/tag-based-cache/redis-cache";

const redis = createClient();
await redis.connect();

const cache = new RedisCache(redis);

await cache.set({
  key: "book:1",
  data: { title: "Dune" },
  ttl: 300,
  tags: ["books", "book:1"],
});

const entry = await cache.get("book:1");
// { data: { title: "Dune" }, attachment: null }

How It Works

Storage

Entries are stored as separate Redis keys:

• data:{key} — JSON-serialized data, with Redis TTL expiration.
• attachment:{key} — Binary data, with Redis TTL expiration.
• tag:{tag} — A Redis set containing all keys associated with that tag.

Invalidation

When delete(tags) is called:

1. All keys associated with the given tags are looked up via the tag:{tag} sets.
2. The corresponding data:*, attachment:*, and tag:* keys are deleted.
3. An invalidation message is published to the invalidate Redis channel so other connected instances are notified.

Subscriptions

subscribe uses a dedicated Redis connection (created via redis.duplicate()) to listen on the invalidate pub/sub channel. The subscription is set up lazily on the first subscribe call and torn down when the last subscriber unsubscribes.

const unsubscribe = cache.subscribe((tags, meta) => {
  console.log("Invalidated:", tags);
});

// Later:
unsubscribe();

When to Use

• Multi-host deployments where cache invalidation needs to propagate across processes.
• When you need the TApi Caching Strategies pub/sub system to work across multiple servers.