Class: Ganglia::GMetric

Inherits:
Object
  • Object
show all
Defined in:
lib/gmetric.rb

Constant Summary collapse

SLOPE = 
{
  'zero'        => 0,
  'positive'    => 1,
  'negative'    => 2,
  'both'        => 3,
  'unspecified' => 4
}

Class Method Summary collapse

Class Method Details

.pack(metric) ⇒ Object 



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# File 'lib/gmetric.rb', line 36

def self.pack(metric)
  metric = {
    :hostname => '',
    :group    => '',
    :spoof    => 0,
    :units    => '',
    :slope    => 'both',
    :tmax     => 60,
    :dmax     => 0
  }.merge(metric)

  # convert bools to ints
  metric[:spoof] = 1 if metric[:spoof].is_a? TrueClass
  metric[:spoof] = 0 if metric[:spoof].is_a? FalseClass

  raise "Missing key, value, type" if not metric.key? :name or not metric.key? :value or not metric.key? :type
  raise "Invalid metric type" if not %w(string int8 uint8 int16 uint16 int32 uint32 float double).include? metric[:type]

  meta = XDRPacket.new
  data = XDRPacket.new

  # METADATA payload
  meta.pack_int(128)                            # gmetadata_full
  meta.pack_string(metric[:hostname])           # hostname
  meta.pack_string(metric[:name].to_s)          # name of the metric
  meta.pack_int(metric[:spoof].to_i)            # spoof hostname flag

  meta.pack_string(metric[:type].to_s)          # one of: string, int8, uint8, int16, uint16, int32, uint32, float, double
  meta.pack_string(metric[:name].to_s)          # name of the metric
  meta.pack_string(metric[:units].to_s)         # units for the value, e.g. 'kb/sec'
  meta.pack_int(SLOPE[metric[:slope]])          # sign of the derivative of the value over time, one of zero, positive, negative, both, default both
  meta.pack_uint(metric[:tmax].to_i)            # maximum time in seconds between gmetric calls, default 60
  meta.pack_uint(metric[:dmax].to_i)            # lifetime in seconds of this metric, default=0, meaning unlimited

  ## MAGIC NUMBER: equals the elements of extra data, here it's 1 because I added Group.
  meta.pack_int(1)

  ## METADATA EXTRA DATA: functionally key/value
  meta.pack_string("GROUP")
  meta.pack_string(metric[:group].to_s)

  # DATA payload
  data.pack_int(128+5)                          # string message
  data.pack_string(metric[:hostname].to_s)      # hostname
  data.pack_string(metric[:name].to_s)          # name of the metric
  data.pack_int(metric[:spoof].to_i)            # spoof hostname flag
  data.pack_string("%s")                        #
  data.pack_string(metric[:value].to_s)         # value of the metric

  [meta.data, data.data]
end

.send(host, port, metric) ⇒ Object 



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# File 'lib/gmetric.rb', line 15

def self.send(host, port, metric)
  gmetric = self.pack(metric)

  if defined?(EventMachine) and EventMachine.reactor_running?
    # open an ephemereal UDP socket since
    # we do not plan on recieving any data
    conn = EM.open_datagram_socket('', 0)

    conn.send_datagram gmetric[0], host, port
    conn.send_datagram gmetric[1], host, port
    conn.close_connection_after_writing
  else
    conn = UDPSocket.new
    conn.connect(host, port)

    conn.send gmetric[0], 0
    conn.send gmetric[1], 0
    conn.close
  end
end