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Latency Comparison Numbers
--------------------------
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

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package main

/*
URL: https://github.com/mccoyst/myip/blob/master/myip.go
URL: http://changsijay.com/2013/07/28/golang-get-ip-address/
*/

import (
	"net"
	"os"

sanae10001

Find the commit history of the desired software and version in github. e.g. "https://github.com/Homebrew/homebrew-core/commits/master/Formula/git.rb"
Click `raw` button, get raw url e.g. "https://raw.githubusercontent.com/Homebrew/homebrew-core/6f85b5c82436b2f8beb3c0fd64f36d6f466cf0f7/Formula/git.rb"
brew unlink `formula` e.g. "brew unlink git"
brew install `url`
You can use `brew switch` switch version

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package main

import (
	"fmt"
	"labix.org/v2/mgo"
	"labix.org/v2/mgo/bson"
	"time"
)

type Person struct {

sanae10001

How to setup your own CA with OpenSSL

For educational reasons I've decided to create my own CA. Here is what I learned.

First things first

Lets get some context first.

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func readLine(path string) {
  inFile, _ := os.Open(path)
  defer inFile.Close()
  scanner := bufio.NewScanner(inFile)
	scanner.Split(bufio.ScanLines) 
  
  for scanner.Scan() {
    fmt.Println(scanner.Text())
  }
}

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import (
	"bufio"
	"io"
)

type FileLineFunc func(line []byte) (isExit bool, err error)

func ReadLines(file io.Reader, bufLen int, f FileLineFunc) error {
	buffer := make([]byte, 0, bufLen)
	scanner := bufio.NewScanner(file)

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// Convert string to bytes array, don't allocate extra memory
// General: []byte(string), this may allocate memory more than len(string)
func StringToBytes(s string) []byte {
	b := make([]byte, len(s))
	copy(b[:], s)
	return b
}

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package main

import (
	"crypto"
	"crypto/rsa"
	"crypto/sha1"
	"crypto/x509"
	"encoding/base64"
	"fmt"
)

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macos: 
1. networksetup -getcomputername
2. scutil --get ComputerName

windows:
1. echo %ComputerName%