Redis Cache for Node.js

cache.js

// cache/baseCache.js
// This is our abstract base class defining the contract for our cache implementations.
class BaseCache {
  async get(key) {
    throw new Error('Method "get" must be implemented');
  }
  
  async set(key, value, ttl) {
    throw new Error('Method "set" must be implemented');
  }
  
  async del(key) {
    throw new Error('Method "del" must be implemented');
  }
}

module.exports = BaseCache;

// cache/in_memory_cache.js
require('dotenv').config();
const BaseCache = require('./baseCache');

const DEFAULT_TTL = process.env.CACHE_DEFAULT_TTL
  ? parseInt(process.env.CACHE_DEFAULT_TTL, 10)
  : 60;

class InMemoryCache extends BaseCache {
  constructor(defaultTTL = DEFAULT_TTL) {
    super();
    this.store = new Map();
    this.defaultTTL = defaultTTL;
  }

  async get(key) {
    const record = this.store.get(key);
    if (!record) return null;
    // Check if expired
    if (record.expireAt && record.expireAt < Date.now()) {
      this.store.delete(key);
      return null;
    }
    return record.value;
  }

  async set(key, value, ttl) {
    ttl = ttl || this.defaultTTL;
    const expireAt = ttl ? Date.now() + ttl * 1000 : null;
    this.store.set(key, { value, expireAt });
  }

  async del(key) {
    return this.store.delete(key);
  }
}

module.exports = InMemoryCache;

// cache/redis_cache.js
require('dotenv').config();
const Redis = require('ioredis');
const BaseCache = require('./baseCache');

const DEFAULT_TTL = process.env.CACHE_DEFAULT_TTL
  ? parseInt(process.env.CACHE_DEFAULT_TTL, 10)
  : 60;

class RedisCache extends BaseCache {
  constructor(defaultTTL = DEFAULT_TTL) {
    super();
    this.defaultTTL = defaultTTL;
    this.client = new Redis(process.env.REDIS_URL);
    this.client.on('error', (err) => {
      console.error('Redis error:', err);
    });
  }

  async get(key) {
    return await this.client.get(key);
  }

  async set(key, value, ttl) {
    ttl = ttl || this.defaultTTL;
    if (ttl) {
      await this.client.set(key, value, 'EX', ttl);
    } else {
      await this.client.set(key, value);
    }
  }

  async del(key) {
    await this.client.del(key);
  }
}

module.exports = RedisCache;

// cache/index.js
require('dotenv').config();
const InMemoryCache = require('./inMemoryCache');
const RedisCache = require('./redisCache');

// Choose Redis in production; otherwise use in-memory cache.
const cache = process.env.NODE_ENV === 'production'
  ? new RedisCache()
  : new InMemoryCache();

module.exports = cache;