redis-cache-fn

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<Object>)

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

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

fn = Cache.wrap(function<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)