Memoize functions results using an lru-cache.

Installation

npm i lru-memoizer --save

Intro

This module uses an lru-cache internally to cache the results of an async function.

The load function can have N parameters and the last one must be a callback. The callback should be an errback (first parameter is err).

The hash function purpose is generate a custom hash for storing results. It has all the arguments applied to it minus the callback, and must return an string synchronous.

The disable function allows you to conditionally disable the use of the cache. Useful for test environments.

The freeze option (defaults to false) allows you to deep-freeze the result of the async function.

The clone option (defaults to false) allows you to deep-clone the result every time is returned from the cache.

Usage

var memoizer = require('lru-memoizer');

var memoizedGet = memoizer({
  //defines how to load the resource when
  //it is not in the cache.
  load: function (options, callback) {
    request.get(options, callback);
  },

  //defines how to create a cache key from the params.
  hash: function (options) {
    return options.url + qs.stringify(options.qs);
  },

  //don't cache in test environment
  disable: isTestEnv(),

  //all other params for the LRU cache.
  max: 100,
  maxAge: 1000 * 60
});

memoizedGet({
  url: 'https://google.com',
  qs: { foo: 123 }
}, function (err, result, body) {
 //console.log(body);
})

Sync lru-memoizer

Use memoizer.sync to cache things that are slow to calculate or methods returning promises.

var memoizer = require('lru-memoizer');
var memoizedGet = memoizer.sync({
  //defines how to load the resource when
  //it is not in the cache.
  load: function (params) {
    //return something_hard_to_compute;s
  },

  //defines how to create a cache key from the params.
  hash: function (params) {
    return params.foo;
  },

  //all other params for the LRU cache.
  max: 100,
  maxAge: 1000 * 60
});

Similar modules

This module is very similar to async-cache, the main difference is the hash function.

License

MIT 2016 - José F. Romaniello