Scott Yu scootcho

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

Tutorial: Designing a GraphQL API

This tutorial was created by Shopify for internal purposes. We've created a public version of it since we think it's useful to anyone creating a GraphQL API.

It's based on lessons learned from creating and evolving production schemas at Shopify over almost 3 years. The tutorial has evolved and will continue to change in the future so nothing is set in stone.

How to get on Rinkeby Testnet in less than 10 minutes

Following instructions from the excellent https://www.rinkeby.io/

Synchronizing a Full Node

A full node lets you access all state. There is a light node (state-on-demand) and wallet-only (no state) instructions as well,

	/* HOC fundamentally is just a function that accepts a Component and returns a Component:
	(component) => {return componentOnSteroids; } or just component => componentOnSteroids;
	Let's assume we want to wrap our components in another component that is used for debugging purposes,
	it just wraps them in a DIV with "debug class on it".
	Below ComponentToDebug is a React component.
	*/

	//HOC using Class
	//it's a function that accepts ComponentToDebug and implicitly returns a Class
	let DebugComponent = ComponentToDebug => class extends Component {

	import { Component } from "React";

	export var Enhance = ComposedComponent => class extends Component {
	constructor() {
	this.state = { data: null };
	}
	componentDidMount() {
	this.setState({ data: 'Hello' });
	}
	render() {

	#!/bin/sh

	# Make sure to:
	# 1) Name this file `backup.sh` and place it in /home/ubuntu
	# 2) Run sudo apt-get install awscli to install the AWSCLI
	# 3) Run aws configure (enter s3-authorized IAM user and specify region)
	# 4) Fill in DB host + name
	# 5) Create S3 bucket for the backups and fill it in below (set a lifecycle rule to expire files older than X days in the bucket)
	# 6) Run chmod +x backup.sh
	# 7) Test it out via ./backup.sh

	upstream api_node_js {
	server 127.0.0.1:8080;
	}

	server {
	listen 80 default_server;
	listen [::]:80 default_server ipv6only=on;

	root /var/www/my-kickass-domain/public_html;
	index index.html index.htm;

	# Create a container from the mongo image,
	# run is as a daemon (-d), expose the port 27017 (-p),
	# set it to auto start (--restart)
	# and with mongo authentication (--auth)
	# Image used is https://hub.docker.com/_/mongo/
	docker pull mongo
	docker run --name YOURCONTAINERNAME --restart=always -d -p 27017:27017 mongo mongod --auth

	# Using the mongo "localhost exception" (https://docs.mongodb.org/v3.0/core/security-users/#localhost-exception)
	# add a root user

	# to generate your dhparam.pem file, run in the terminal
	openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048

	var express = require('express');
	var path = require('path');
	var favicon = require('serve-favicon');
	var logger = require('morgan');
	var cookieParser = require('cookie-parser');
	var bodyParser = require('body-parser');
	var forceSSL = require('express-force-ssl');

	var routes = require('./routes/index');
	var users = require('./routes/users');