ruben1

System Design Cheatsheet

Step One: Framing The Problem

• Identify the use cases that are in scope
• Determine constraints based on scoped use cases

use case : the things your system needs to be do.

constraints : the things your system will have to consider to be able to do stuff

ruben1

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

ruben1

// Example 1
mediator.name = 'Doug';
mediator.subscribe('nameChange', function(arg){
     console.log(this.name);
     this.name = arg;
     console.log(this.name);
});

mediator.publish('nameChange', 'Jorn');

ruben1

Sublime Text 2 – Useful Shortcuts (PC)

Loosely ordered with the commands I use most towards the top. Sublime also offer full documentation.

Editing

Ctrl+C	copy current line (if no selection)
Ctrl+X	cut current line (if no selection)
Ctrl+⇧+K	delete line
Ctrl+↩	insert line after

ruben1

=Navigating=
    visit('/projects')
    visit(post_comments_path(post))

=Clicking links and buttons=
    click_link('id-of-link')
    click_link('Link Text')
    click_button('Save')
    click('Link Text') # Click either a link or a button
    click('Button Value')

ruben1

// Import node modules
var Q = require('q');
var Promise = require('bluebird');
var GitHubApi = require('github');

// Instantiate github API.
// NOTE: This is just used for async demonstration purposes, you can imagine any other async functions through this example
var github = new GitHubApi({
    version: '3.0.0'
});