Michael Fairchild fairchild

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

I'm a fan of MiniTest::Spec. It strikes a nice balance between the simplicity of TestUnit and the readable syntax of RSpec. When I first switched from RSpec to MiniTest::Spec, one thing I was worried I would miss was the ability to add matchers. (A note in terminology: "matchers" in MiniTest::Spec refer to something completely different than "matchers" in RSpec. I won't get into it, but from now on, let's use the proper term: "expectations").

Understanding MiniTest::Expectations

Let's take a look in the code (I'm specifically referring to the gem, not the standard library that's built into Ruby 1.9):

# minitest/spec.rb

module MiniTest::Expectations

OpenTransact

Get started with AT&T's opentransact API, a sample app can be found at:

http://pure-sunset-8157.herokuapp.com/

In order to get started:

Register your application with AT&T's Developer Portal
Obtain a client_id and client_secret from AT&T's Developer Portal
Set up settlement options with AT&T in order to enable payments

	Latency Comparison Numbers (~2012)
	----------------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD

	<!doctype html>
	<html>
	<head>
	<meta charset="utf-8">
	<title>App Redirection</title>
	</head>
	<body>
	<!--
	NOTE: This was a great hack in days gone by, but now both Apple and Google have improved their support for custom
	protocol handlers.

	#!/usr/bin/env ruby

	require 'rubygems'
	require 'eventmachine'
	require 'em-mqtt'
	require 'sinatra/base'
	require 'thin'


	class WebApp < Sinatra::Base

	#!/usr/bin/env sh

	##
	# This is script with usefull tips taken from:
	# https://github.com/mathiasbynens/dotfiles/blob/master/.osx
	#
	# install it:
	# curl -sL https://raw.github.com/gist/2108403/hack.sh \| sh
	#

	def icon(name, size=1)
	#icon("camera-retro")
	#<i class="icon-camera-retro"></i>

	html = "<i class='icon-#{name}' "
	html += "style='font-size:#{size}em' "
	html += "></i>"
	html.html_safe
	end

	require 'fnordmetric'
	require 'fnordmetric/logger'
	# This is a quickie ruby script to set up some base data for the dashboard

	income_billing_keys = [:weekly_billing_external, :weekly_income_quickbooks, :weekly_break_even]
	bank_account_keys = [:bank_account_checking, :bank_account_money_market, :bank_account_bonus_employee, :bank_account_bonus_boardmembers, :quickbooks_receivables, :quickbooks_payables]
	website_traffic_keys = [:visitors_daily]
	jenkins_keys = [:jenkins_build_success_daily, :jenkins_build_failure_daily]

	demo_data = {

	// Lefalet shortcuts for common tile providers - is it worth adding such 1.5kb to Leaflet core?

	L.TileLayer.Common = L.TileLayer.extend({
	initialize: function (options) {
	L.TileLayer.prototype.initialize.call(this, this.url, options);
	}
	});

	(function () {