Russ Hammett Kritner

System Design Cheatsheet

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

Basic Steps

Clarify and agree on the scope of the system

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?

Virtual Hosts on nginx (CSC309)

When hosting our web applications, we often have one public IP address (i.e., an IP address visible to the outside world) using which we want to host multiple web apps. For example, one may wants to host three different web apps respectively for example1.com, example2.com, and example1.com/images on the same machine using a single IP address.

How can we do that? Well, the good news is Internet browsers

	/****** ANSWERS ******/

	// ⭐: 1
	const addThemAllUp = frequencyChanges => frequencyChanges.reduce((a, b) => a + b)

	// ⭐: 2
	const findFirstRepeatedFrequency = frequencyChanges => {
	let index = 0
	let currentFrequency = 0
	const frequencies = new Set()

	# full diff
	git diff <SHA1> <SHA1> -- `find . -name '<pattern>'`

	# only file names
	git diff <SHA1> <SHA1> --name-status -- `find . -name '<pattern>'`

	#!/bin/bash
	#
	# git-mv-with-history -- move/rename file or folder, with history.
	#
	# Moving a file in git doesn't track history, so the purpose of this
	# utility is best explained from the kernel wiki:
	#
	# Git has a rename command git mv, but that is just for convenience.
	# The effect is indistinguishable from removing the file and adding another
	# with different name and the same content.

	1) Create a branch with the tag
	git branch {tagname}-branch {tagname}
	git checkout {tagname}-branch

	2) Include the fix manually if it's just a change ....
	git add .
	git ci -m "Fix included"
	or cherry-pick the commit, whatever is easier
	git cherry-pick {num_commit}

	-- Removes all objects (in the correct order) added to
	-- SQL Server by the stock ASP.NET membership provider
	drop table aspnet_PersonalizationAllUsers
	drop table aspnet_PersonalizationPerUser
	drop table aspnet_Profile
	drop table aspnet_SchemaVersions
	drop table aspnet_UsersInRoles
	drop table aspnet_WebEvent_Events
	drop table aspnet_Paths
	drop table aspnet_Membership