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redis-cache-fn

2.0.1 • Public • Published

redis-cache-fn

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Caches your functions via Redis. Features:

  • Uses Redis caching, expiration, and pub/sub.
  • Concurrency locking - if the function is being run elsewhere with the same arguments, it will wait for the result of that function instead of executing again.
  • Caching - caches results for as long as you want. If you set ttl=0, then you're just this library for concurrency locking, which is completely fine. However, please keep in mind that locking mechanism in this module is not robust - it is more suited towards caching.
  • Only tested with ioredis

Use Cases:

  • Race conditions
  • API calls with rate limits
  • Expensive database calls
  • Expensive function calls

Differences from redis-cache-decorator:

  • Uses a class system so that it's more maintainable
  • A slightly different API
  • Doesn't bother throwing when functions timeout. Use another library instead.
  • Removes stream support

API

const Cache = require('redis-cache-fn')(options)

  • client <required> - a ioredis client for GET/SET/PUBLISH, etc.
  • subscriber <required> - a ioredis client for PSUBSCRIBE
  • namespace = '' - a prefix for all the events
  • encoding = 'json' - how data is encoded between redis and node.js. Supported values are:
    • json - the default
    • string
    • buffer
  • ttl = '30s' - the TTL expiration in seconds.
  • timeout = 0 - how long to wait for the function to execute before executing the function again. By default, there is no timeout.
    • Ex. if it the current function has waited 30s for the function to complete elsewhere, it will say "F IT" and run the function itself.
  • pollInterval = '1s' - how often to poll for new values.
  • precache = 3/4 - when the age hits this threshold, execute the function again to so that the cache remains fresh.
  • onError = err => console.error(err.stack) - an error handler for redis network errors.

Cache = Cache.extend(options)

Subclasses the cache, extending its options. All options are overwritten except:

  • namespace - the namespace is simply concatenated with :s.

fn = Cache.wrap(function)

Decorates the function so that it hits the cache first.

{ Cache } = fn

The function's Cache constructor.

promise = fn()

Returns a promise.

promise.cache

The cache instance of this function call.

const hash = Cache.createHash(args)

const cache = new Cache(args)

value = await cache.set(value)

install

npm i redis-cache-fn

Downloadsweekly downloads

19

version

2.0.1

license

MIT

homepage

github.com

repository

Gitgithub

last publish

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