module Takwimu

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A note on GAUGE_COUNTERS.

The sample_rate argument allows for the parameterization of instruments that decide to report data as gauges, that would typically be reported as counters.

Aggregating counters is typically done simply with the `+` operator, which doesn't preserve the number of unique reporters that contributed to the count, or allow for one to learn the average of the counts posted.

A gauge is typically aggregated by simply replacing the previous value, however, some systems do more with gauges when aggregating across multiple sources of that gauge, like, average, or compute stdev.

This is problematic, however, when a gauge is being used as a counter, to preserve the average / stdev computational properties from above, because the interval that the gauge is being read it, affects the derivative of the increasing count. Instead of the derivative over 60s, the derivative is taken every 10s, giving us a derivative value that's approximately 1/6th of the actual derivative over 60s.

We compensate for this by allowing Instruments to correct for this, and ensure that, even though it's an estimate, the data is scaled appropriately to the target aggregation interval, not just the collection interval.

CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Constants

TIMERS
VERSION

Attributes

config[RW]

Public Class Methods

configure() { |config| ... } click to toggle source

# File lib/takwimu.rb, line 46
def self.configure
  yield(config)
end

reset() click to toggle source

# File lib/takwimu.rb, line 42
def self.reset
  @config = Takwimu::Configuration.new
end

start() click to toggle source

Starts the reporting client

Arguments:

- interval: How often, in seconds, to instrument and report
- aggregation_period: The minimal aggregation period in use, in seconds.
- statsd: The statsd reporter. This should be an instance of statsd-ruby
- panels: The instrumentation "panels" in use. See `resource_usage.rb` for
  an example panel, which is the default if none are provided.

# File lib/takwimu.rb, line 59
def self.start() #interval: Takwimu.config.interval, aggregation_period: Takwimu.config.aggregation_period, statsd: Takwimu.config.statsd, panels: Takwimu.config.panels, hostname: Takwimu.config.hostname)
  require 'statsd'
  statsd_client = Takwimu.config.statsd
  panels        = Takwimu.config.panels
  sample_rate   = Takwimu.config.interval.to_f / Takwimu.config.aggregation_period.to_f
  hostname = Takwimu.config.hostname

  if statsd_client == :default && ENV["PORT"]
    statsd_client = Statsd.new('127.0.0.1', ENV["PORT"])
  end

  if statsd_client && statsd_client != :default
    reporter = Takwimu::Reporter.new(statsd: statsd_client, sample_rate: sample_rate, hostname: hostname)

    unless panels.length > 0
      panels << Takwimu::ResourceUsage.new(sample_rate)
    end

    #Rails.logger.info "#{panels.inspect}"

    Periodic.new reporter: reporter, sample_rate: sample_rate, panels: panels
  end
end