Rafael Sliveira Cordeiro rafaelsc

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

CSS units

Recommendations of unit types per media type:

Media	Recommended	Occasional use	Infrequent use	Not recommended
Screen	em, rem, %	px	ch, ex, vw, vh, vmin, vmax	cm, mm, in, pt, pc
Print	em, rem, %	cm, mm, in, pt, pc	ch, ex	px, vw, vh, vmin, vmax

Relative units

$/
  artifacts/
  build/
  docs/
  lib/
  packages/
  samples/
  src/
 tests/

System Design Cheatsheet

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

Basic Steps

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?

General

Repos

Create Root CA (Done once)

Create Root Key

Attention: this is the key used to sign the certificate requests, anyone holding this can sign certificates on your behalf. So keep it in a safe place!

openssl genrsa -des3 -out rootCA.key 4096

	//
	// Regular Expression for URL validation
	//
	// Author: Diego Perini
	// Created: 2010/12/05
	// Updated: 2018/09/12
	// License: MIT
	//
	// Copyright (c) 2010-2018 Diego Perini (http://www.iport.it)
	//

	internal static IEnumerable<T> MyIntersect<T>(this IEnumerable<T> first, IEnumerable<T> second) {
	Debug.Assert(first != null);
	Debug.Assert(second != null);
	var firstHashset = first as HashSet<T>;
	var secondHashset = second as HashSet<T>;
	if (firstHashset != null && secondHashset != null) {
	return (firstHashset.Count > secondHashset.Count)
	? firstHashset.Intersect(second)
	: secondHashset.Intersect(first);
	}

	#!/bin/bash

	# generate new personal ed25519 ssh keys
	ssh-keygen -o -a 100 -t ed25519 -f ~/.ssh/id_ed25519 -C "rob thijssen <[email protected]>"
	ssh-keygen -o -a 100 -t ed25519 -f ~/.ssh/id_robtn -C "rob thijssen <[email protected]>"

	# generate new host cert authority (host_ca) ed25519 ssh key
	# used for signing host keys and creating host certs
	ssh-keygen -t ed25519 -f manta_host_ca -C manta.network

	// Browser-Sync support for Cordova projects
	// To use this, add the following snippet as a after_run hook using something like
	// <hook type="after_prepare" src="hooks/browser-sync.js" />
	// Also add ws: 'unsafe-inline' to the CSP in index.html
	// The do Cordova run, and changing anything in www/ will live-reload the cordova app on emulator/device

	module.exports = function(context) {
	if (context.opts.options[0] === '--browser-sync-mode') {
	// Prepare was called by this script, so don't run the script again
	return;