Yilong Li dragonly

Multiple SSH Keys settings for different github account

create different public key

create different ssh key according the article Mac Set-Up Git

$ ssh-keygen -t rsa -C "[email protected]"

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

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

Better local require() paths for Node.js

Problem

When the directory structure of your Node.js application (not library!) has some depth, you end up with a lot of annoying relative paths in your require calls like:

const Article = require('../../../../app/models/article');

Those suck for maintenance and they're ugly.

Possible solutions

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

SSH keypair setup for GitHub (or GitHub/GitLab/BitBucket, etc, etc)

Create a repo.

Make sure there is at least one file in it (even just the README.md)

Generate a SSH key pair (private/public):

ssh-keygen -t rsa -C "[email protected]"

	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

	// adapted from http://www.youtube.com/watch?v=qNM0k522R7o

	extern vec2 size;
	extern int samples = 5; // pixels per axis; higher = bigger glow, worse performance
	extern float quality = 2.5; // lower = smaller glow, better quality

	vec4 effect(vec4 colour, Image tex, vec2 tc, vec2 sc)
	{
	vec4 source = Texel(tex, tc);
	vec4 sum = vec4(0);

	# Remove anything linked to nvidia
	sudo apt-get remove --purge nvidia*
	sudo apt-get autoremove

	# Search for your driver
	apt search nvidia

	# Select one driver (the last one is a decent choice)
	sudo apt install nvidia-370

	# put this in your ~/.gitconfig, then issue `git lg` will get you a pretty git branch topology view
	#
	# this is just a start point, customizations can be done by further fine tuning referencing
	# https://git-scm.com/docs/git-log & https://git-scm.com/docs/pretty-formats
	#
	# --graph draws the git commits tree
	# --date=local is used in the following --format
	#
	# format explanation:
	# %C(colorname)xxx%C(reset) encloses text `xxx` with color `colorname`