LOKE cache-kit

Examples

Basic usage

For the most common cases use a simple 2 layer LRU + Redis cache is sufficient.

import { Cache, LruMemoryCacheStore, RedisCacheStore } from "@loke/cache-kit";
import Redis from "ioredis";
import { create as createLogger } from "@loke/logger";

const logger = createLogger();
const redisClient = new Redis();

const cache = new Cache(
  // Keys should be prefixed with the project name to make them unique across
  // all of LOKE
  "foo-service:users:fetch:{userId}",
  // Cache stores will be checked in order, and the first cache to return a
  // value will be used
  [new LruMemoryCacheStore({ max: 1000 }), new RedisCacheStore(redisClient)],
  logger,
);

const userId = 123;

const user = cache.apply({ userId }, async () => {
  // This function will only be called if the cache is empty
  const value = await fetch(`http://example.com/user/${userId}`);

  // the ttl is returned as part of the result so it can vary per request
  return {
    value,
    ttl: 60 * 60 * 1000, // 1 hour in milliseconds
  };
});

Single flight cache

In cases where you don't want the overhead of storing the value in a cache, you can use the cache for single flighting requests. Concurrent requests will piggyback on the result of the first request.

import { Cache } from "@loke/cache-kit";
import { create as createLogger } from "@loke/logger";

const logger = createLogger();

const cache = new Cache(
  "users:{userId}",
  // An empty list of caches will result in a single flight only cache, where
  // the value is only cached for the duration of the request
  [],
  logger,
);

CompressedRedisCacheStore

CompressedRedisCacheStore acts as a drop in replacement for RedisCacheStore. It supports reading uncompressed content created by RedisCacheStore, and will compress the stored data if appropriate.

Applications should be using at least v1.0.4 of RedisCacheStore before switching to CompressedRedisCacheStore, to avoid errors if the uncompressed store tries to read compressed content during deployment.

const cache = new Cache(
  "foo-service:users:fetch:{userId}",
  [
    new LruMemoryCacheStore({ max: 1000 }),
    new CompressedRedisCacheStore(redisClient),
  ],
  logger,
);

TODO

• [ ] JSON reviver support