Class: Solanum::Source::Cpu

Inherits:
Solanum::Source show all
Defined in:
lib/solanum/source/cpu.rb

Constant Summary collapse

STAT_FILE = 
'/proc/stat'
STATES = 
%w{user nice system idle iowait irqhard irqsoft}

Instance Attribute Summary collapse

Attributes inherited from Solanum::Source

#attributes, #period, #type

Instance Method Summary collapse

Methods inherited from Solanum::Source

#next_run

Constructor Details

#initialize(opts) ⇒ Cpu

Returns a new instance of Cpu.



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# File 'lib/solanum/source/cpu.rb', line 11

def initialize(opts)
  super(opts)
  @last = nil
  @detailed = opts['detailed'] || false
  @per_core = opts['per_core'] || false
  @usage_states = opts['usage_states'] || {}
end

Instance Attribute Details

#detailed ⇒ Object (readonly)

Returns the value of attribute detailed.



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# File 'lib/solanum/source/cpu.rb', line 5

def detailed
  @detailed
end

#per_core ⇒ Object (readonly)

Returns the value of attribute per_core.



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# File 'lib/solanum/source/cpu.rb', line 5

def per_core
  @per_core
end

#usage_states ⇒ Object (readonly)

Returns the value of attribute usage_states.



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# File 'lib/solanum/source/cpu.rb', line 5

def usage_states
  @usage_states
end

Instance Method Details

#collect! ⇒ Object

Collect metric events.



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# File 'lib/solanum/source/cpu.rb', line 34

def collect!
  # Parse lines from usage stats.
  lines = File.readlines(STAT_FILE).take_while {|l| l.start_with? 'cpu' }
  totals = {}
  lines.each do |line|
    name, data = parse_info(line)
    totals[name] = data
  end

  # Need at least one run to start reporting accurate metrics.
  unless @last
    @last = totals
    return []
  end

  # Calculate diffs from previous measurements.
  diffs = {}
  totals.each do |name, data|
    diffs[name] = Hash.new(0)
    data.each do |state, jiffies|
      last = @last[name] && @last[name][state]
      diffs[name][state] = jiffies - last if last
    end
  end
  @last = totals

  # Convert diffs to relative percentages.
  diffs.each do |name, diff|
    elapsed = diff.values.reduce(&:+)
    diff.keys.each do |state|
      diff[state] = diff[state].to_f/elapsed
    end
  end

  # Generate metric events.
  events = []

  # aggregate cpu usage
  usage = 1.0 - diffs['cpu']['idle']
  events << {
    service: 'cpu usage',
    metric: usage,
    state: state_over(@usage_states, usage),
  }

  # detailed aggregate cpu state metrics
  if @detailed
    diffs['cpu'].each do |state, usage|
      events << {
        service: 'cpu state',
        metric: usage,
        cpu_state: state,
      }
    end
  end

  # even more detailed per-core usage
  if @per_core
    diffs.each do |name, diff|
      next if name == 'cpu'

      usage = 1.0 - diff['idle']
      events << {
        service: 'cpu core usage',
        metric: usage,
        state: state_over(@usage_states, usage),
        cpu_core: name,
      }

      if @detailed
        diff.each do |state, usage|
          events << {
            service: 'cpu core state',
            metric: usage,
            cpu_core: name,
            cpu_state: state,
          }
        end
      end
    end
  end

  events
end

#parse_info(line) ⇒ Object

Calculate cpu utilization from the cumulative time spent in ‘jiffies’ (1/100 sec) since system boot.



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# File 'lib/solanum/source/cpu.rb', line 22

def parse_info(line)
  fields = line.chomp.split(' ')
  name = fields.shift
  data = Hash.new(0)
  STATES.each_with_index do |state, i|
    data[state] = fields[i].to_i
  end
  return name, data
end