Micro cache

cache.js

const LRU = require('lru-cache')

// Micro-caching
exports.cache = function (resolver, keyFactory, { max = 500, maxAge = 3000, perUser = true } = {}) {
  const microCache = new LRU({
    max,
    maxAge,
  })
  return async (holder, args, context) => {
    let key = typeof keyFactory === 'function' ? keyFactory(holder, args, context) : keyFactory
    if (perUser) key = `${context.userId}:${key}`
    let result = microCache.get(key)
    if (!result) {
      result = await resolver(holder, args, context)
      microCache.set(key, result)
    }
    return result
  }
}