Pavel Kalvoda PJK

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?

Each of these commands will run an ad hoc http static server in your current (or specified) directory, available at http://localhost:8000. Use this power wisely.

Discussion on reddit.

Python 2.x

$ python -m SimpleHTTPServer 8000

Step 0:

Get Homebrew installed on your mac if you don't already have it

Step 1:

Install highlight. "brew install highlight". (This brings down Lua and Boost as well)

	#define _GNU_SOURCE
	#include <errno.h>
	#include <sched.h>
	#include <signal.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <sys/mount.h>
	#include <sys/stat.h>
	#include <sys/syscall.h>
	#include <sys/types.h>

	# Use https (public access) instead of git for git-submodules. This modifies only Travis-CI behavior!

	# disable the default submodule logic
	git:
	submodules: false

	# use sed to replace the SSH URL with the public URL, then init and update submodules
	before_install:
	- sed -i 's/[email protected]:/https:\/\/github.com\//' .gitmodules
	- git submodule update --init --recursive

	$stack, $draws = [], {}

	def method_missing *args
	return if args[0][/^to_/]
	$stack << args.map { \|a\| a or $stack.pop }
	$draws[$stack.pop(2)[0][0]] = args[1] if args[0] == :<
	end

	class Array
	def +@

	#!/usr/bin/env ruby

	rss = '.+?Rss:\s+(\d+)'
	share = '.+?Shared_Clean:\s+(\d+)'
	share << '.+?Shared_Dirty:\s+(\d+)'
	priv = '.+?Private_Clean:\s+(\d+)'
	priv << '.+?Private_Dirty:\s+(\d+)'
	MEM_REGEXP = /\[heap\]#{rss}#{share}#{priv}/m

	def mem_usage_linux

	Get the Heroku db as detailed here:
	http://devcenter.heroku.com/articles/pgbackups#exporting_via_a_backup

	1. heroku pgbackups:capture
	2. heroku pgbackups:url <backup_num> #=>backup_url
	- get backup_num with cmd "heroku pgbackups"
	3. curl -o latest.dump <backup_url>

	Then locally do:
	$ pg_restore --verbose --clean --no-acl --no-owner -h localhost -U myuser -d mydb latest.dump