node-multicache

MultiCache

MultiCache is an Multiple Object caching module for node.js. Objects are cached via a backing store.

(Inspired by obcache)

Currently 2 stores are supported.

• Memory
• Redis

Multicache First check for each item in cache parallely, Than do only one singlr call to fetch data from underlying datastore for which no data is present in cache. Respond with data from both Cache and Main data store merged.

Usage

const Cache = require('./lib/cache');

// Create a Redis cache
const cache = new Cache('redis', {port: 6379, host: '127.0.0.1'});

To cache response of a function:

1. Wrap original function like below

var wrapper = cache.wrap(original);

1. Now call the wrapped function

wrapper(arg1,arg2...argn,function(err,res) {
  if (!err) {
     // do something with res
  }
});

API

### cache.wrap Wraps a given function and returns a cached version of it. Functions to be wrapped must have a callback function as the last argument. The callback function is expected to recieve 2 arguments - err and data. data gets stored in the cache.

The first n-1 arguments are used to create the key. Subsequently, when the wrapped function is called with the same n arguments, it would lookup the key in cache, and if found, call the callback with the associated data.

Notes: In case of memory store, It is expected that the callback will never modified the returned data, as any modifications of the original will change the object in cache.

Lets Say input ids are : [123, 143];

Response of orignal function should always be:

{
  123: {},
  143: {}
}

Memory Store:

Key	Type	Description
max	Integer	Maximum no of keys in LRU store
maxAge	Integer	TTL in miliseconds

Redis Store:

Key	Type	Description	Default
maxAge	Integer	TTL in miliseconds	60 Seconds
db	Integer	Redis Server DB	0
prefix	String	Prefix to be used for redis key	mbc:
twemproxy	Boolean	Redis server is behind twemproxy or not	false
host	String	Redis Host	127.0.0.1
port	Integer	Redis Port	6379