cache-point

Simple, filesystem-backed memoisation cache. Use to cache the output of expensive operations speeding up future invocations with the same input.

Synopsis

import Cache from 'cache-point'
import { setTimeout as sleep } from 'node:timers/promises'

/* mock function to simulate a slow, remote request */
async function fetchUser (id) {
  await sleep(1000)
  return { id, name: 'Layla' }
}

class Users {
  constructor () {
    this.cache = new Cache({ dir: 'tmp/example' })
  }

  async getUser (id) {
    let user
    try {
      /* cache.read() will resolve on hit, reject on miss */
      user = await this.cache.read(id)
    } catch (err) {
      if (err.code === 'ENOENT') {
        /* cache miss, fetch remote user */
        user = await fetchUser(id)
        this.cache.write(id, user)
      }
    }
    return user
  }
}

console.time('getUser')
const users = new Users()
const user = await users.getUser(10)
console.timeEnd('getUser')
console.log(user)

The first invocation will take 1 second while the remote user is fetched.

$ node example/simple.js
getUser: 1.025s
{ id: 10, name: 'Layla' }

Since the cache is now warm, future invocations will be fast.

$ node example/simple.js
getUser: 17.07ms
{ id: 10, name: 'Layla' }

API Reference

cache-point

cache-point
- Cache ⏏
  - new Cache([options])
  - .dir : string
  - .read(keys) ⇒ Promise
  - .readSync(keys) ⇒ string
  - .write(keys, content) ⇒ Promise
  - .writeSync(keys, content)
  - .getChecksum(keys) ⇒ string
  - .clear() ⇒ Promise
  - .remove() ⇒ Promise

Cache ⏏

Kind: Exported class

new Cache([options])

Param	Type
[options]	`object`
[options.dir]	`string`

cache.dir : `string`

Current cache directory. Can be changed at any time.

Kind: instance property of Cache

cache.read(keys) ⇒ `Promise`

A cache hit resolves with the stored value, a miss rejects with an ENOENT error code.

Kind: instance method of Cache
Throws:

ENOENT

Param	Type	Description
keys	`*`	One or more values to uniquely identify the data. Can be any value, or an array of values of any type.