Joseph Dung kod3r

The introduction to Reactive Programming you've been missing

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.

In reply to "@Vlad_Roberto: No, not a programmer. I just know there's better ways to doing anything without massive energy consumption & Banks."

The problem of blockchain synchronization is the following:

Imagine you are sitting in a bunker. You have no idea what people are out there and what are their intentions. You only receive some incoming messages from strangers that may contain anything. They can be just random garbage or deliberately crafted messages to confuse you or lie to you. You never know. You cannot trust anyone.e

The problem of "money" or any other "social contract" is that everyone should be able to know what the majority agrees to without trusting some intermediaries (otherwise they can easily obuse their special position). If everyone votes for "X", then you sitting in a bunker must somehow independently figure out that all those other people indeed voted for "X" and not for "Y" or "Z". But remember: you cannot trust anyone's message and messages are the only thing you get from the outsi

ANNOUNCEMENT

I have moved this over to the Tech Interview Cheat Sheet Repo and has been expanded and even has code challenges you can run and practice against!

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All updates now moved over to https://github.com/dconnolly/Chromecast-Backgrounds

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

Installing CartoDB on Ubuntu Server 12.04

Get CartoDB Rails application source

sudo apt-get update

sudo apt-get install git

cd ~

git clone --recursive https://github.com/CartoDB/cartodb20.git

	/* Getopt for GNU.
	NOTE: getopt is now part of the C library, so if you don't know what
	"Keep this file name-space clean" means, talk to drepper@gnu.org
	before changing it!
	Copyright (C) 1987,88,89,90,91,92,93,94,95,96,98,99,2000,2001
	Free Software Foundation, Inc.
	This file is part of the GNU C Library.

	The GNU C Library is free software; you can redistribute it and/or
	modify it under the terms of the GNU Lesser General Public

	//*****************************************************************************
	/// @file
	/// @brief
	/// Arduino SmartThings Shield LED Example
	//*****************************************************************************
	#include <SoftwareSerial.h> //TODO need to set due to some weird wire language linker, should we absorb this whole library into smartthings
	#include <SmartThings.h>


	#define PIN_THING_RX 3

	import sys
	import cv

	class FaceDetect():
	def __init__(self):
	cv.NamedWindow ("CamShiftDemo", 1)
	device = 0
	self.capture = cv.CaptureFromCAM(device)
	capture_size = (320,200)
	cv.SetCaptureProperty(self.capture, cv.CV_CAP_PROP_FRAME_WIDTH, capture_size[0])

	import java.util.Arrays;

	class Solution {
	public int solution(int K, int[] A) {
	Arrays.sort(A);
	return getKC(K, A);
	}

	public int getKC(int K, int[] A) {