kafecho

# This playbook installs and configure corosync and pacemaker on a set of nodes part of a given group.
---

# See the file /etc/ansible/hosts where the group is actually defined. There might be a way to define groups in a file 'closer' to this playbook.
- hosts: clusternodes
  vars:
    mcastport : 5405
  tasks:
  
  # It would be better to use Ansible to change the IP tables config to allow corosync/pacemaker on the nodes part of the cluster.

kafecho

---
- name: Downloading and enable the EPEL repository definitions.
  action: command rpm -Uvh --replacepkgs http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

kafecho

val n = 40
// Measure in milliseconds how long it takes to compute a Fibonacci sequence.
timeThis(msecs){
  println ("Naive recursion fib of " + n + ": " + fib(n))
}

// Measure in nanoseconds how long it takes to compute a Fibonacci sequence.
timeThis(nanosecs){
 println ("Tail recursion fib of " + n + ": " + fib2(n))
}

kafecho

Naive recursion fib of 40: 102334155
It took 9911 msecs to execute the operation.
Tail recursion fib of 40: 102334155
It took 151000 nanosecs to execute the operation.
I am going to sleep...
Nice to wake up
It took 1000 msecs to execute the operation.

kafecho

trait TimeUnit
case object msecs extends TimeUnit
case object nanosecs extends TimeUnit
object Watch{
  /* A hashmap to map a time unit to a tuple containing:
  * - a description of the time unit in english.
  * - a function invoked to measure the time in the given unit
  */
  val timeUnits = Map[TimeUnit,Tuple2[String,() => Long]] (
    msecs -> ("msecs",System.currentTimeMillis _),

kafecho

package org.kafecho.learning.akka

import java.net.InetSocketAddress
import akka.actor.Actor
import akka.actor.ActorLogging
import akka.actor.ActorSystem
import akka.actor.Props
import akka.actor.actorRef2Scala
import akka.io.IO
import akka.io.UdpFF

kafecho

package org.kafecho.learning.akka

import akka.util.ByteString
import org.slf4j.LoggerFactory

object Timer{
  def timeThis[T](fn : => T) : T = {
    val start = System.currentTimeMillis()
    val t = fn
    val stop = System.currentTimeMillis()

kafecho

package org.kafecho.learning.midi
import javax.sound.midi.MidiSystem
import javax.sound.midi.ShortMessage
import scala.util.Random

object MidiTest extends App {
  val rcvr = MidiSystem.getReceiver
  while (true) {
    val myMsg = new ShortMessage
    myMsg.setMessage(ShortMessage.NOTE_ON, 8, Random.nextInt.abs % 127, 93)

kafecho

package org.kafecho.learning.monad

import java.util.UUID

/** My attempt at implementing the Reader Monad concept.
  * The Reader Monad encapsulates a computation which:
  * - requires a dependency of type D
  * - produces values of type A.
  */
case class Reader[D, A](computation: D => A) {

kafecho

---
- hosts: cd-servers
  gather_facts: no
  sudo: true
  user: deploy
  tasks:
  - name: Install Couchdb dependencies
    yum: name={{ item }} state=installed
    with_items:
    - autoconf