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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

Exporting (iCloud) Keychain and Safari credentials to a CSV file

Update (October 2021)

Exporting password + one-time code data from iCloud Keychain is now officially supported in macOS Monterey and Safari 15 (for Monterey, Big Sur, and Catalina). You can access it in the Password Manager’s “gear” icon (System Preferences > Passwords on Monterey, and Safari > Passwords everywhere else), or via the File > Export > Passwords... menu item). You shouldn't need to hack up your own exporter anymore.

Original, Obsolete Content (2014)

After my dad died, I wanted to be able to have access any of his online accounts going forward. My dad was a Safari user and used iCloud Keychain to sync his credentials across his devices. I don’t want to have to keep an OS X user account around just to access his accounts, so I wanted to export his credentials to a portable file.

Using OS X as a Syslog Server

This document describes how to set up an OS X to be a syslog server that logs messages from the local network. It was largely meant for my own purposes so that I don't forget what I did, but feel free to use it for your own purposes.

A problem with just "turning this on" is that you will not see the correct hostname in the syslog entries. What we will do is use

Atomic Types (Built-in and Scalar)

// Built-in types
$variable = null;             // null type

// Scalar types
$boolVar = true;              // bool type
$intVar = 42;                 // int type
$floatVar = 3.14;             // float type

	<!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>
	<!-- 声明文档使用的字符编码 -->
	<meta charset='utf-8'>
	<!-- 优先使用 IE 最新版本和 Chrome -->
	<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"/>
	<!-- 页面描述 -->
	<meta name="description" content="不超过150个字符"/>
	<!-- 页面关键词 -->

	version: '2'
	services:
	# The Application
	app:
	build:
	context: ./
	dockerfile: php-fpm.dockerfile
	working_dir: /var/www
	volumes:
	- ./:/var/www

	# Add to your .env.example and .env files
	CSP_ENABLED=true
	CSP_REPORT_ONLY=true