# File lib/svengali/plugins/eucalyptus.rb, line 176
  def self.Cloud(default_user,default_pass)
    @@default_user = default_user
    @@default_pass = default_pass
  end

# File lib/svengali/plugins/eucalyptus.rb, line 310
  def self.dump_machine_cache_info(machine_cache_hash)
    file = open(CACHE_FILE_NAME,"w")
    YAML.dump(machine_cache_hash,file)
    file.close()
  end

# File lib/svengali/plugins/eucalyptus.rb, line 196
  def self.get_a_machine(params_hash)

    # if @@do_cache true, Cloud class tries to reuse guest instance on Eucalyptus
    # whether exist appropriate instace is checked in terms of IP address
    if Cloud.is_exist_requested_machine(params_hash[:ipaddr]) && @@do_cache
      debug_p "reused a guset instance which has address #{params_hash[:ipaddr]}"
      # load instance ID corresponding to requested IP address from cache file
      machine_cache_hash = Cloud.load_machine_cache_info()
      instance_id = machine_cache_hash[params_hash[:ipaddr]]
    else
      # calling of this method isn't needed under normal conditions
      get_ipaddr_of_instance_pre()
      
      debug_p "executing euca-run-instance...."
      # ** Attention ** below is draft code
      instance_id = run_image(params_hash[:imageid])
      debug_p "euca-run-instance finished."

      #get a CLibIPAddr insance
      ipaddr = get_ipaddr_of_instance(instance_id)
      debug_p "IP address of the kicked instance: " + ipaddr.to_s

      debug_p "configure network setting to the kicked instance."
      vanilla_machine = Machine.new(ipaddr)
      vanilla_machine.set_auth_info(DEFAULT_USER,DEFAULT_PASS)
      vanilla_machine.establish_session()

      vanilla_machine.config_nw_interface(:ipaddr => params_hash[:ipaddr], :interface => params_hash[:interface], :netmask => params_hash[:netmask], :gateway => params_hash[:gateway], :onboot => "yes")
      vanilla_machine.set_resolver(:primary_ip => params_hash[:dns],:interface => params_hash[:interface])

      #reloads network configuration
      #10 seconds after, this will return with nil value
      # TODO: should eliminate assumption for platform
      debug_p "reload network configuration...."
      puts vanilla_machine.exec!("/sbin/service network restart", 10)
      debug_p "reloading of network configuration may have finished."

      # write machine info to cache file
      if @@do_cache
        machine_cache_hash = Cloud.load_machine_cache_info()
        debug_p "----------------loaded_hash------------------"
        debug_p machine_cache_hash.inspect()
        debug_p "class name of machine_cache_hash is #{machine_cache_hash.class}"
        debug_p "---------------------------------------------"
        machine_cache_hash[params_hash[:ipaddr]] = instance_id
        Cloud.dump_machine_cache_info(machine_cache_hash)
      end
      
    end
    
    configured_machine = Machine.new(params_hash[:ipaddr])
    configured_machine.set_auth_info(DEFAULT_USER,DEFAULT_PASS)
    configured_machine.establish_session()
    configured_machine.set_instance_info(instance_id)

    if @@do_cache
      configured_machine.set_whether_do_cache(true)
    end
    
    return configured_machine
  end

# File lib/svengali/plugins/eucalyptus.rb, line 182
  def self.get_a_machine_with_imageup(params_hash)
    check_has_keys(params_hash,[:imagepath])
    
    unless params_hash[:imageid] = upload_and_register_image(params_hash[image_path_str],120)
      puts "uploading and registration of image failed"
      err_message_and_exit("I wll exit")
    end

    not_tested()
    return self.get_a_machine(params_hash)
  end

# File lib/svengali/plugins/eucalyptus.rb, line 268
  def self.get_ipaddr_of_instance(instance_id)
    unless @@pre_alived_hash
      err_message_and_exit("get_ipaddr_of_instance_pre() should be called on the eve of run_image(...)")
    end

    debug_p @@pre_alived_hash.inspect()
    
    while(true)
      alived_hash = find_machines_on_range_by_ping(DHCP_LEASE_RANGE)
      
      # find difference
      alived_hash.delete_if{ |key,value| @@pre_alived_hash.has_key?(key)}

      if alived_hash.size == 1
        debug_p alived_hash.inspect()
        ret = alived_hash.shift()[0]
        debug_p "found #{ret}"
        return CLibIPAddr.new(ret)
      elsif alived_hash.size > 1
        err_message_and_exit("There may be other booting machine!")
      end
      sleep 1 #leave a space
    end

  end

# File lib/svengali/plugins/eucalyptus.rb, line 296
  def self.get_ipaddr_of_instance_pre()
    @@pre_alived_hash = find_machines_on_range_by_ping(DHCP_LEASE_RANGE)
  end

# File lib/svengali/plugins/eucalyptus.rb, line 260
  def self.is_exist_requested_machine(ipaddr)
    return is_exist_by_ping(ipaddr)
  end

# File lib/svengali/plugins/eucalyptus.rb, line 318
  def self.load_machine_cache_info()
    if File.exist?(CACHE_FILE_NAME)
      ret_hash = nil
      open(CACHE_FILE_NAME){ |file|
        ret_hash = YAML.load(file)
      }

      return ret_hash
    else
      return Hash.new()
    end
  end

# File lib/svengali/plugins/eucalyptus.rb, line 305
  def self.set_whether_do_cache(true_or_false)
    @@do_cache = true_or_false
  end