Junchen Xia jcxia43

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

常用的 HTML 头部标签

详细介绍参见原文：yisibl/blog#1

<!DOCTYPE html> <!-- 使用 HTML5 doctype，不区分大小写 -->
<html lang="zh-cmn-Hans"> <!-- 更加标准的 lang 属性写法 http://zhi.hu/XyIa -->
<head>
    <meta charset='utf-8'> <!-- 声明文档使用的字符编码 -->
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" /> <!-- 优先使用 IE 最新版本和 Chrome -->

2015-01-29 Unofficial Relay FAQ

Compilation of questions and answers about Relay from React.js Conf.

Disclaimer: I work on Relay at Facebook. Relay is a complex system on which we're iterating aggressively. I'll do my best here to provide accurate, useful answers, but the details are subject to change. I may also be wrong. Feedback and additional questions are welcome.

What is Relay?

Relay is a new framework from Facebook that provides data-fetching functionality for React applications. It was announced at React.js Conf (January 2015).

This document has moved!

It's now here, in The Programmer's Compendium. The content is the same as before, but being part of the compendium means that it's actively maintained.

FWIW: I (@rondy) am not the creator of the content shared here, which is an excerpt from Edmond Lau's book. I simply copied and pasted it from another location and saved it as a personal note, before it gained popularity on news.ycombinator.com. Unfortunately, I cannot recall the exact origin of the original source, nor was I able to find the author's name, so I am can't provide the appropriate credits.

Effective Engineer - Notes

By Edmond Lau
Highly Recommended 👍
http://www.theeffectiveengineer.com/

	module Jekyll
	# Sass plugin to convert .scss to .css
	#
	# Note: This is configured to use the new css like syntax available in sass.
	require 'sass'
	class SassConverter < Converter
	safe true
	priority :low

	def matches(ext)

	require "open-uri"
	require "nokogiri"
	require "pp"

	base_url = "http://dribbble.com"
	@file = File.open('dribbble_profile_urls.txt','w')

	def get_web_link(url)
	doc = Nokogiri::HTML(open(url))
	doc.css('.profile-details .url').each do \|link\|

	module DefaultValues

	def has_default_values(default_values = {})

	class_attribute :default_values
	self.default_values = default_values

	after_initialize :assign_default_values

	include InstanceMethods

	module ConcernName
	extend ActiveSupport::Concern

	included do
	# Object methods go here
	end

	module ClassMethods
	# Class methods go here
	end

	[General]
	loglevel = notify
	skip-proxy = 127.0.0.1, 192.168.0.0/16, 10.0.0.0/8, 172.16.0.0/12, 100.64.0.0/10, localhost, *.local, ::ffff:0:0:0:0/1, ::ffff:128:0:0:0/1
	bypass-tun = 192.168.0.0/16, 10.0.0.0/8, 172.16.0.0/12

	# dns-server = 119.29.29.29,223.5.5.5,114.114.115.115
	# external-controller-access = PASSWORD@0.0.0.0:6155
	# ipv6 = true

	// REMEMBER TO CHANGE THE external-controller-access' PASSWORD