Md Eftakhairul Islam eftakhairul

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

User cases (description of sequences of events that, taken together, lead to a system doing something useful)
- Who is going to use it?
- How are they going to use it?

A running example of the code from:

This gist creates a working example from blog post, and a alternate example using simple worker pool.

TLDR: if you want simple and controlled concurrency use a worker pool.

	SHELL := /bin/bash

	REV := $(shell git rev-parse HEAD)
	CHANGES := $(shell test -n "$$(git status --porcelain)" && echo '+CHANGES' \|\| true)

	TARGET := packer-provisioner-itamae-local
	VERSION := $(shell cat VERSION)

	OS := darwin freebsd linux openbsd
	ARCH := 386 amd64

	#!/bin/bash

	if [ ! $1 ]; then
	echo " Example of use: $0 database_name dir_to_store"
	exit 1
	fi
	db=$1
	out_dir=$2
	if [ ! $out_dir ]; then
	out_dir="./"

	#!/bin/bash

	# Kill process on requested port
	# Author: Md Eftakhairul Islam

	if [[ $# -eq 0 ]]; then
	echo "Port is not specified"
	exit 1
	fi

	#!/bin/bash
	iatest=$(expr index "$-" i)

	#######################################################
	# SOURCED ALIAS'S AND SCRIPTS BY zachbrowne.me
	#######################################################

	# Source global definitions
	if [ -f /etc/bashrc ]; then
	. /etc/bashrc

	'use strict';

	/**
	* Person class.
	*
	* @constructor
	* @param {String} name - name of a person.
	* @param {Number} age - age of a person.
	* @param {String} gender - gender of a person.
	*/

	package main

	import (
	"fmt"

	"github.com/spf13/viper"
	)

	// Create private data struct to hold config options.
	type config struct {

	let regex;

	/* matching a specific string */
	regex = /hello/; // looks for the string between the forward slashes (case-sensitive)... matches "hello", "hello123", "123hello123", "123hello"; doesn't match for "hell0", "Hello"
	regex = /hello/i; // looks for the string between the forward slashes (case-insensitive)... matches "hello", "HelLo", "123HelLO"
	regex = /hello/g; // looks for multiple occurrences of string between the forward slashes...

	/* wildcards */
	regex = /h.llo/; // the "." matches any one character other than a new line character... matches "hello", "hallo" but not "h\nllo"
	regex = /h.llo/; // the "" matches any character(s) zero or more times... matches "hello", "heeeeeello", "hllo", "hwarwareallo"

	const fileDownload = (req, res, next) => {
	const requestedFileName = `${req.params.id}:${req.params.filename}`;
	const filePath = path.join([req.app.get('basedir'), 'storage'].join('/') , requestedFileName);

	if (!fileSystem.existsSync(filePath)) {
	return res.status(403).send({error: 'FileNotExists'}).end();
	}

	const stat = fileSystem.statSync(filePath);
	const filename = path.basename(filePath);