Md. Sumon Islam sumonst21

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

How to create an HTTPS certificate for localhost domains

This focuses on generating the certificates for loading local virtual hosts hosted on your computer, for development only.

Do not use self-signed certificates in production ! For online certificates, use Let's Encrypt instead (tutorial).

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

CentOS-6 Redis PHP Session Handler

This guide is for installing redis as a replacement for the memcached php session store when using php71u IUS packages on a CentOS-6 environment.

	<?php
	/**
	* Timing Class for benchmarking in PHP
	* @ref: http://www.if-not-true-then-false.com/2010/php-timing-class-class-for-measure-php-scripts-execution-time-and-php-web-page-load-time/
	*/
	class Timing {
	private $break;
	private $start_time;
	private $stop_time;

	<?php

	/**
	* Find the starting Monday for the given week (or for the current week if no date is passed)
	*
	* This is required as strtotime considers Sunday the first day of a week,
	* making strtotime('Monday this week') on a Sunday return the adjacent Monday
	* instead of the previous one.
	*
	* @param string\|\DateTime\|null $date

	#
	# Monitor file $1 for changes
	# Send an alert emai to $2 if file $1 changes
	# usage: inotify_email_watcher.sh /var/log/messages [email protected]
	if [ -z "$2" ]; then
	echo "Usage: inotify_email_watcher.sh"
	exit 1
	fi
	# if the file exists
	if [ -f $1 ] \|\| [ -d $1 ]; then

	#/bin/sh
	# Usage instructions: sh find.sh php\|tr '\n' '; '
	# Then copy and paste the output and execute it
	ext=$1
	C="\u200E \u200F \u202A \u202B \u202C \u202D \u202E \u2066 \u2067 \u2068 \u2069 \u202C"
	for a in $C; do echo find . -type f -name \"*.$ext\" -exec grep -H \$\'$a\' {} \\\; ; done

	server {
	listen 80 default_server;
	listen [::]:80 default_server;
	location / {
	return 301 https://www.domain.com$request_uri;
	}
	}

	server {
	listen 443 ssl http2;