Rnjai Lamba rnjailamba

##References

ActiveRecord Associations

##Create Models

Create tables:

rails g model Location

rails g model User

rails g model Checkin

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

Note: I'm currently taking a break from this course to focus on my studies so I can finally graduate

Frontend Development

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#How to Construct Yourself UI in KeystoneJS

KeystoneJS provide Admin UI with one set of route controllers and view templates(list&item) for all of the models.But usually,you will need some custome views other than Admin UI to display models. Although the KeystoneJS documention don't tell us much about how to contruct custome view,we can learn this from the source code in skeleton project generated by yo keystone,or you can just check out the keystone demo project's source code.We will walk through the blog feature's implementation in this demo application to demonstrate how to construct custome UI in KeystoneJS application.

As KeystoneJS documention described in Routes & Views section,there is a routes/index.js file, where we bind application's URL patterns to the controllers that load and process data, and render the appropriate template.You can find following code in it:

app.get('/blog/:catego

	# app/controllers/users/password_controller.rb

	class Users::PasswordsController < Devise::PasswordsController
	def resource_params
	params.require(:user).permit(:email, :password, :password_confirmation)
	end
	private :resource_params
	end

	== PostgreSQL

	Braintree
	* https://www.braintreepayments.com/braintrust/scaling-postgresql-at-braintree-four-years-of-evolution

	Instagram
	* http://www.databasesoup.com/2012/04/sharding-postgres-with-instagram.html
	* http://media.postgresql.org/sfpug/instagram_sfpug.pdf
	* http://instagram-engineering.tumblr.com/post/10853187575/sharding-ids-at-instagram#_=_
	* http://instagram-engineering.tumblr.com/post/40781627982/handling-growth-with-postgres-5-tips-from-instagram

	Producer

	Setup
	bin/kafka-topics.sh --zookeeper esv4-hcl197.grid.linkedin.com:2181 --create --topic test-rep-one --partitions 6 --replication-factor 1
	bin/kafka-topics.sh --zookeeper esv4-hcl197.grid.linkedin.com:2181 --create --topic test --partitions 6 --replication-factor 3

	Single thread, no replication

	bin/kafka-run-class.sh org.apache.kafka.clients.tools.ProducerPerformance test7 50000000 100 -1 acks=1 bootstrap.servers=esv4-hcl198.grid.linkedin.com:9092 buffer.memory=67108864 batch.size=8196

	class ApiController < ApplicationController
	# define which model will act as token authenticatable
	acts_as_token_authentication_handler_for Login

	# Prevent CSRF attacks by raising an exception.
	# For APIs, you may want to use :null_session instead.
	protect_from_forgery with: :null_session

	respond_to :json
	skip_before_filter :verify_authenticity_token, if: :json_request?

	var i = 0;

	setInterval(function() {
	if (i++ % 2) {
	console.log('I\'m the child!');
	} else {
	console.error('I\'m the child!');
	}
	}, 1500);

Rnjai Lamba rnjailamba

Latency numbers every programmer should know

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Frontend Development