class RRDRepo

Attributes

filename[R]

Public Class Methods

create(filename, datasources, start = Time.now) click to toggle source

# File lib/rrd_repo.rb, line 6
def self.create(filename, datasources, start = Time.now)
  one_day = 60 * 60 * 24

  rrd = RRD::Base.new(filename)
  rrd.create(:start => start, :step => 60) do
    datasources.each do |name|
      datasource name, :type => :gauge, :heartbeat => 120, :min => 0, :max => :unlimited
    end
    archive :average, :every => 60, :during => one_day
    archive :average, :every => 300, :during => one_day
  end
  RRDRepo.new(filename)
end

new(filename) click to toggle source

# File lib/rrd_repo.rb, line 20
def initialize(filename)
  @filename = filename
end

Public Instance Methods

_rrd() click to toggle source

# File lib/rrd_repo.rb, line 61
def _rrd
  raise("Unable to open RRD, because it doesn't exist: #{@filename}") unless File.exist?(@filename)
  @rrd ||= RRD::Base.new(@filename)
end

info() click to toggle source

# File lib/rrd_repo.rb, line 28
def info
  info = _rrd.info
  archives = unflatten_archives(info)
  {
    :step => info["step"],
    :archives => archives.map do |archive|
      {
        :consolidation_function => archive["cf"],
        :resolution_sec => info["step"] * archive["pdp_per_row"],
        :duration_sec => info["step"] * archive["pdp_per_row"] * archive["rows"]
      }
    end
  }
end

latest_value(datasource) click to toggle source

# File lib/rrd_repo.rb, line 24
def latest_value(datasource)
  _rrd.info["ds[#{datasource}].last_ds"].to_f
end

read(resolution, start_ts, end_ts, function = :average) click to toggle source

# File lib/rrd_repo.rb, line 43
def read(resolution, start_ts, end_ts, function = :average)
  start_time = (start_ts.to_i / resolution) * resolution
  end_time = (end_ts.to_i / resolution) * resolution
  data = _rrd.fetch(
    function,
    :resolution => resolution,
    :start => start_time,
    :end => end_time
  )
  header, values = data.first, data[1..-1]
  nan_filtered = values.reject { |v| v[1..-1].any?(&:nan?) }
  nan_filtered.map { |v| Hash[header.zip(v)] }
end

write(time, values = []) click to toggle source

# File lib/rrd_repo.rb, line 57
def write(time, values = [])
  _rrd.update(time, *values)
end

Private Instance Methods

unflatten_archives(info) click to toggle source

Takes a flat hash output from an rrd “info” call and unflattens it by each archive.

Input: {

"rra[0].pdp_per_row"=>1,
"rra[0].xff"=>0.5,
"rra[1].pdp_per_row"=>168,
"rra[1].xff"=>0.5,
 ...

}

Output: [

{
  "pdp_per_row"=>1,
  "xff" => 0.5,
},
{
  "pdp_per_row" => 168,
  "xff" => 0.5
}

]

# File lib/rrd_repo.rb, line 91
def unflatten_archives(info)
  info.select { |key, value| key.index("rra") == 0 }
    .group_by { |elem| elem[0].split('.')[0] }
    .sort_by { |rra, _| rra }
    .map { |rra, values| Hash[values.map { |key, val| [key.split('.')[1], val] }] }
end