vasanthk

System Design Cheatsheet

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

Basic Steps

1. 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?

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

paulirish

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

MohamedAlaa

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

aparrish

isaacs

# Hello, and welcome to makefile basics.
#
# You will learn why `make` is so great, and why, despite its "weird" syntax,
# it is actually a highly expressive, efficient, and powerful way to build
# programs.
#
# Once you're done here, go to
# http://www.gnu.org/software/make/manual/make.html
# to learn SOOOO much more.

piscisaureus

Locate the section for your github remote in the .git/config file. It looks like this:

[remote "origin"]
	fetch = +refs/heads/*:refs/remotes/origin/*
	url = git@github.com:joyent/node.git

Now add the line fetch = +refs/pull/*/head:refs/remotes/origin/pr/* to this section. Obviously, change the github url to match your project's URL. It ends up looking like this:

Starefossen

Sessions

New Session

• tmux new [-s name] [cmd] (:new) - new session

Switch Session

• tmux ls (:ls) - list sessions
• tmux switch [-t name] (:switch) - switches to an existing session

elfassy

#=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_on('Button Value')

chenglou

Interesting part (unmounting & API) is at the end if you're not interested in the rest =).

Stress Tests

This animation proposal is just an attempt. In case it doesn't work out, I've gathered a few examples that can test the power of a future animation system.

1. Parent is an infinitely spinning ball, and has a child ball that is also spinning. Clicking on the parent causes child to reverse spinning direction. This tests the ability of the animation system to compose animation, not in the sense of applying multiple interpolations to one or more variables passed onto the child (this should be trivial), but in the sense that the parent's constantly updating at the same time as the child, and has to ensure that it passes the animation commands correctly to it. This also tests that we can still intercept these animations (the clicking) and immediately change their configuration instead of queueing them.

2. Typing letters and let them fly in concurrently. This tests concurrency, coordination of an array of ch