gistfile1.rb

require 'rubygems'
gem 'zookeeper'
require 'zookeeper'

REQUIRED_NUMBER_OF_PROCESSES = 2


class EventHandler
  import org.apache.zookeeper.Watcher
  
  def watches
    @registered_watches ||= {}
  end
  
  def register(path, &block)
    watches[path] = block
  end
  
  def process(event)
    path = nil
    path = event.get_path 
    msg = "#{event.class} received"
    msg += " path = #{path}" if path
    msg += " state = #{Zk::KEEPER_STATES[event.get_state]}"
    msg += " type = #{Zk::EVENT_TYPES[event.get_type]}"
    puts msg
    watches[path].call(event) if watches[path]
      
  end
end

zkWatcher = EventHandler.new
zk2Watcher = EventHandler.new

zk = ZooKeeper.new(:host => "localhost:2181", :watcher => zkWatcher)

zk2 = ZooKeeper.new(:host => "localhost:2181", :watcher => zk2Watcher)

begin
#this is demo code
  zk.delete("/barrier/ready")
rescue
end

zkWatcher.register("/barrier/ready") do |event|
    puts "oh yeah zk1 - we got quorum"  
end

zk.exists(:path => "/barrier/ready", :watch => true)


puts "zk1 joining process"
zk.create(:path => "/barrier/zk1", :data => "", :mode => :ephemeral)
if zk.children(:path => "/barrier").size >= REQUIRED_NUMBER_OF_PROCESSES
   zk.create(:path => "/barrier/ready", :data => "", :mode => :persistent)
end

zk2Watcher.register("/barrier/ready") do |event|
    puts "oh yeah zk2 - we got quorum"
    puts "removing ready node"
    zk2.delete(:path => "/barrier/ready")  
end
zk2.exists(:path => "/barrier/ready", :watch => true)


puts "zk2 joining process"
zk2.create(:path => "/barrier/zk2", :data => "", :mode => :ephemeral)
if zk2.children(:path => "/barrier").size >= REQUIRED_NUMBER_OF_PROCESSES
   zk2.create(:path => "/barrier/ready", :data => "", :mode => :persistent)
end