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CircleCI

Introduction

NPM

this package is a very light (no dependencies) module to drastically optimise the usage of memory in data-driven application. Using basic objects/arrays in JS is very sub-optimal, and typed array often fail to fit people's needs. Also, using JSON to serialise your data leads to major bottleneck in disk / memory / network usage. This library cater for this problem by providing an implementation of an array with bit-per-bit optimisation of your memory usage.

alt text

Exemple spawning 65536 arrays of 128 int of variable size in JS.

tests are available :

npm run test

Usage

npm install memory-efficient-object

Example of usage :

const {schemaEngine, MEObject} = require('memory-efficient-object');

const schema = {
    "id" : "uint(2)",
    "letter" : "char",
    "isBlue" : "bool",
    "size" : "uint(32)",
    "x" : "int(32)",
    "name" : "string(4)",
    "coords" : "uint(8)[3]",
    "lights" : "bool[3]"
};

let testSchema = schemaEngine.add(schema);

// 2nd argument optional values

let test = new MEObject(testSchema, { 
    id: 3,
    letter: 'A',
    isBlue: true,
    size: 4294967295,
    x: -5000,
    name: 'Yann',
    coords: [ 1, 2, 3 ],
    lights: [ true, false, true ]
});

// ...set some values
// ....

console.log(test.toJson());

/*
Will display :
{ id: 3,
  letter: 'A',
  isBlue: true,
  size: 4294967295,
  x: -5000,
  name: 'Yann',
  coords: [ 1, 2, 3 ],
  lights: [ true, false, true ] }
*/

console.log(test.serialize());

/*
    Will display: ǿ��↓硙慮渁ȃԀ
    As you can appreciate, this is a much smaller string (10 char vs. 150).
*/

// serialize then unserialize
let testUnSerialised = new MEObject(testSchema, test.serialize());
console.log(testUnSerialised.toJson());

// will re-display the same JSON object again after unserialization 

More details :

const {schemaEngine, MEObject} = require('memory-efficient-object');

// Define your schema

const schema = {
    "id" : "uint(2)"
};

// This add it to the schema engine which compiles it and keeps it

let testSchema = schemaEngine.add(schema);

// Create an Object using this schema

let test = new MEObject(testSchema);

// set a value

test.set("id", 1)

// get a value

test.get("id")

Schema Definition

Available datatypes

Name description length
bit simply a bit 1
bool Same than bit, but will accept / return true/false instead of 0/1 automatically 1
char Same than uint(8), but will accept / return a character automatically 8
uint(n) Unsigned Int of size n n
int(n) signed Int of size n n
string(n) string of size n n * 8

use arrays

const {schemaEngine, MEObject} = require('../index');

const schema = {
    "coords" : "uint(8)[3]",
};

let testSchema = schemaEngine.add(schema);
let test = new MEObject(testSchema);

test.set("coords", [1,2,3]);
test.get("coords"); // [1,2,3]
test.get("coords", 1); // 2

Note on usage

Choose your datatypes very carefully, using as few bytes as you can, this is the key to optimising your app !

The serialised output of this library is compression friendly, bare in mind that until defragmentation is implemented, only dataset with bigger datatypes will benefit from it.

ToDo

  • fill gaps between values dynamically

About

Memory efficient implementation of objects / arrays for bits and bytes mainpulation (int, char, uint, ...) in JS, using schema for serialisation

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