vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

evansiroky

var fs = require('fs'),
    async = require('async'),
    csv = require('csv');
 
var input = fs.createReadStream(filename);
var parser = csv.parse({
  columns: true,
  relax: true
});
 

PurpleBooth

Contributing

When contributing to this repository, please first discuss the change you wish to make via issue, email, or any other method with the owners of this repository before making a change.

Please note we have a code of conduct, please follow it in all your interactions with the project.

Pull Request Process

1. Ensure any install or build dependencies are removed before the end of the layer when doing a

chris-rock

// Part of https://github.com/chris-rock/node-crypto-examples

var crypto = require('crypto'),
    algorithm = 'aes-256-ctr',
    password = 'd6F3Efeq';

function encrypt(buffer){
  var cipher = crypto.createCipher(algorithm,password)
  var crypted = Buffer.concat([cipher.update(buffer),cipher.final()]);
  return crypted;

manjeshpv

// config/passport.js
				
// load all the things we need
var LocalStrategy   = require('passport-local').Strategy;

var mysql = require('mysql');

var connection = mysql.createConnection({
				  host     : 'localhost',
				  user     : 'root',

branneman

Better local require() paths for Node.js

Problem

When the directory structure of your Node.js application (not library!) has some depth, you end up with a lot of annoying relative paths in your require calls like:

const Article = require('../../../../app/models/article');

Those suck for maintenance and they're ugly.

Possible solutions

crtr0

// set-up a connection between the client and the server
var socket = io.connect();

// let's assume that the client page, once rendered, knows what room it wants to join
var room = "abc123";

socket.on('connect', function() {
   // Connected, let's sign-up for to receive messages for this room
   socket.emit('room', room);
});

dideler

Inspired by this article. Neat tricks for speeding up integer computations.

Note: cin.sync_with_stdio(false); disables synchronous IO and gives you a performance boost. If used, you should only use cin for reading input (don't use both cin and scanf when sync is disabled, for example) or you will get unexpected results.

Multiply by a power of 2

x = x << 1; // x = x * 2

paolorossi

/*
 * Inspired by: http://stackoverflow.com/questions/4360060/video-streaming-with-html-5-via-node-js
 */

var http = require('http'),
    fs = require('fs'),
    util = require('util');

http.createServer(function (req, res) {
  var path = 'video.mp4';

jacobian

from django.db import models

class Person(models.Model):
    name = models.CharField(max_length=200)
    groups = models.ManyToManyField('Group', through='GroupMember', related_name='people')
    
    class Meta:
        ordering = ['name']
    
    def __unicode__(self):