memoize-fs

memoize-fs

memoize/cache in file system solution for Node.js

Motivation

This project is inspired by the memoize project by Mariusz Nowak aka medikoo. The motivation behind this module is that sometimes you have to persist cached function calls but you do not want to deal with an extra process (ie. managing a Redis store). Memoization is best technique to save on memory or CPU cycles when we deal with repeated operations. For detailed insight see: http://en.wikipedia.org/wiki/Memoization

Features

• Works with any type and length of function arguments – no serialization is needed
• Support for promisified functions
• Cache can be invalidated manually

Installation

In your project path:

$ npm install memoize-fs

Usage

var memoize = require('memoize-fs')({ cachePath: require('path').join(__dirname, '../../build/cache' }),
    fun = function (a, b) { return a + b; };

memoize.fn(fun).then(function (memFn) {
    memFn(1, 2).then(function (result) {
        assert.strictEqual(result, 3);
        memFn(1, 2).then(function (result) { // cache hit
            assert.strictEqual(result, 3);
        }, function (err) { /* handle error */ });
    }, function (err) { /* handle error */ });
}, function (err) { /* handle error */ });

Note that a result of a momoised function is always a Promise instance!

Memoizing promisified functions

In order to memoize an async function it must be first promisified in the following manner:

Before:

var funAsync = function (a, b, cb) { setTimeout(function () { cb(null, a + b); }, 100); };

// later
funAsync(1, 2, function (err, result) {
    if (err) throw err;
    console.log(result);
});

After:

var funPromisified = function (a, b) {
    return new require('es6-promise').Promise(function (resolve, reject) {
        setTimeout(function () { resolve(a + b); }, 100);
    });
};

// later
funPromisified(1, 2).then(function (result) {
    console.log(result);
}, function (err) {
    throw err;
});

// now we can memoize it
memoize.fn(funPromisified).then(...

Configuration

####TODO: continue with docs here