simdjson, Node.js and Napi::ObjectWrap

A Napi::ObjectWrap that allows to use C++ simdjson library with Node.js

This is a project wrapping the simdjson library for un use in Node. Note : This is a master projet and is still in developement. I am still woriking on some approaches to omptimze performances, but results so far seems interesting.

Requirements

When upgraded to simdjson 0.3.1 (coming soon!), any computer shoud be able to run projet. Performances are a lot more interesting on computers with an SIMD architecture.

Getting started

git clone https://github.com/croteaucarine/simdjson_node_objectwrap
cd simdjson_node_objectwrap
npm install

Constructor

• new simdjson() : Creates an empty object. load and parse must be called in order to manipulate the object.
• new simdjson(string document) : Creates a fully manipulable object.
• new simdjson(object path) : Key path must me used to send defined path as string (example : {path : 'mydoc.json'}). Creates a fully manipulable object.
• new simdjson(object doc) : Key path must me used to send document as string (example : {doc : docVariable}). Creates a fully manipulable object.

Static Methods

simdjson.isValid will be implemented soon!

Code usage and example

The library implements JSON parsing and basic JSON methods length, keys and iterator. The library also implements navigation through JSON pointer defined by the RFC6901 standard.

Basic usage example

Example below is also available in repo under the folder examples and can be run with node examples/basic_usage.js

'use strict';

const fs = require('fs');
const { simdjson } = require('bindings')('addon');

const simdjsonOBJ = new simdjson({path : 'jsonexamples/github_events.json'});

// Display object content
console.log(simdjsonOBJ);

// Display Object Keys
console.log(simdjsonOBJ.keys());

// Display Object length
console.log(simdjsonOBJ.length);

// Display strignified Object
console.log(JSON.stringify(simdjsonOBJ));

// Loop through JSON Array 
// try-catch intercepts error if object is not an array
try {
    var i  = 1;
    for (let item of simdjsonOBJ) {
        console.log(item);
        i++;
    }
} catch(error) {
    console.error(error);
}

// Display nested elements
try {
    var i  = 1;
    for (let item of simdjsonOBJ) {
        console.log(item.actor.login);
        i++;
    }
} catch(error) {
    console.error(error);
}

JSON Pointer example (JavaScript Object Notation (JSON) Pointer (RFC 6901))

Example below and more JSON Pointer uses are also available in repo under the file jsonPointer.js and can be run with node examples/jsonPointer.js

var simdjsonOBJ = new simdjson({ path : 'jsonexamples/small/cars.json' });
console.log(simdjsonOBJ.getValue('0/tire_pressure/1'));   // outputs 39.9

var simdjsonOBJ = new simdjson({ path : 'jsonexamples/small/demo.json' });
console.log(simdjsonOBJ.getValue('Image/IDs/2'));  // outputs 234
console.log(simdjsonOBJ.getValue('Image/Width'));  // outputs 800
console.log(simdjsonOBJ.getValue('Image/Height')); // outputs 600
console.log(simdjsonOBJ.getValue('Image/Width') * simdjsonOBJ.getValue('/Image/Height')); // outputs 480000

simdjsonOBJ = new simdjson({ path : 'jsonexamples/twitter.json'});
console.log(simdjsonOBJ.getValue('statuses/0/id')); // outputs 505874924095815700

Benchmarks

The script benchmarks contains multiple comparaisons between the native JavaScript JSON methods and equivalent simdjson methods (parse, length, keys, iterator and JSON Pointer). The benchmarks run with multiple JSON file formats that are located in the jsonexamples folder and results output in respective files in the benchmarks folder. To run benchmarks : npm run benchmarks

Benchmarks results in GB/s

Fichier	simdjson#parse (GB/s)	JSON#parse (GB/s)
apache_builds.json	0.6582093176	0.3197537729
canada.json	0.5285019113	0.1369665620
citm_catalog.json	1.3283484553	0.3857911551
github_events.json	0.4011839264	0.3163136989
gsoc-2018.json	1.5753144939	0.5841688036
instruments.json	0.9355347016	0.3719788183
marine_ik.json	0.5655987608	0.1880935363
mesh.json	0.5523368471	0.2016259385
mesh.pretty.json	0.7585213936	0.3226030418
numbers.json	0.4698898210	0.2040313806
random.json	0.8534592398	0.2135693655
twitter.json	1.1542076927	0.2716755377
twitterescaped.json	0.7656334327	0.2160604291
update-center.json	0.9921201220	0.1903520690

Performance results

Docker

docker build -t docker build -t simdjson_node_objectwrap . 

License

This code is made available under the Apache License 2.0.