KAK kuntoaji

2023 update

ℹ️ Please note this research is from 2016 when Opera has first added their browser "VPN", even before the "Chinese deal" was closed. They have since introduced some real VPN apps but this below is not about them.

🕵️ Some folks also like to use this article to show a proof that the Opera browser is a spyware or that Opera sells all your data to 3rd parties or something like that. This article here doesn't say anything like that.

When setting up (that's immediately when user enables it in settings) Opera VPN sends few API requests to https://api.surfeasy.com to obtain credentials and proxy IPs, see below, also see The Oprah Proxy.

The browser then talks to a proxy de0.opera-proxy.net (when VPN location is set to Germany), it's IP address can only be resolved from within Opera when VPN is on, it's 185.108.219.42 (or similar, see below). It's an HTTP/S proxy which requires auth.

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

Turning PostgreSQL into a queue serving 10,000 jobs per second

RDBMS-based job queues have been criticized recently for being unable to handle heavy loads. And they deserve it, to some extent, because the queries used to safely lock a job have been pretty hairy. SELECT FOR UPDATE followed by an UPDATE works fine at first, but then you add more workers, and each is trying to SELECT FOR UPDATE the same row (and maybe throwing NOWAIT in there, then catching the errors and retrying), and things slow down.

On top of that, they have to actually update the row to mark it as locked, so the rest of your workers are sitting there waiting while one of them propagates its lock to disk (and the disks of however many servers you're replicating to). QueueClassic got some mileage out of the novel idea of randomly picking a row near the front of the queue to lock, but I can't still seem to get more than an an extra few hundred jobs per second out of it under heavy load.

So, many developers have started going straight t

This all applies to Ruby 2.1. In some cases a setting is not available in 2.0, this is noted. There is also a different with 1.9, 1.8, and REE --- these are not noted.

All the relevant code is in https://github.com/ruby/ruby/blob/master/gc.c

RUBY_HEAP_MIN_SLOTS

default: 10000

The number of heap slots to start out with. This should be set high enough so that your app has enough or almost enough memory after loading so that it doesn't have to allocate more memory on the first request (althogh this probably isn't such a big deal for most apps).

(todo: figure out how big a slot is. i think the answer can be infered from this code.)

In August 2007 a hacker found a way to expose the PHP source code on facebook.com. He retrieved two files and then emailed them to me, and I wrote about the issue:

http://techcrunch.com/2007/08/11/facebook-source-code-leaked/

It became a big deal:

http://www.techmeme.com/070812/p1#a070812p1

The two files are index.php (the homepage) and search.php (the search page)

	require "active_record"

	ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
	ActiveRecord::Migration.class_eval do
	create_table(:records) do \|t\|
	t.string :column
	end
	end

	data = 50_000.times.map { \|i\| Hash[column: "Column #{i}"] }

	require 'rubygems'
	require 'openssl'
	require 'digest/md5'
	key = OpenSSL::PKey::RSA.new(2048)
	cipher = OpenSSL::Cipher::AES.new(256, :CBC)
	ctx = OpenSSL::SSL::SSLContext.new
	puts "Spoof must be in DER format and saved as root.cer"
	raw = File.read "root.cer"
	cert = OpenSSL::X509::Certificate.new raw
	cert.version = 2

	require 'open-uri'
	require 'json'

	language = 'en'

	print 'What do you need to know? : '
	article = URI::encode gets.chomp

	request_url = "http://#{language}.wikipedia.org/w/api.php?action=parse&page=#{article}&format=json&prop=text&section=0"

	require 'ap'
	require 'mail'

	# String monkeypatch
	# This is one of many possible "encoding problem" solutions. It's actually an intractable problem
	# but you'd have to read "Gödel, Escher, Bach" to understand why...
	class String
	def clean_utf8
	# self.force_encoding("UTF-8").encode("UTF-16BE", :invalid=>:replace, :replace=>"?").encode("UTF-8")
	unpack('C').pack('U') if !valid_encoding?

	def select_date(date, options = {})
	field = options[:from]
	base_id = find(:xpath, ".//label[contains(.,'#{field}')]")[:for]
	year, month, day = date.split(',')
	select year, :from => "#{base_id}_1i"
	select month, :from => "#{base_id}_2i"
	select day, :from => "#{base_id}_3i"
	end

	def select_time(hour, minute, options = {})