Datadog

middleware.rb

# frozen_string_literal: true

require "datadog/statsd"

class QueueTime
  def initialize(app)
    @app = app
  end

  def call(env)
    start   = env["HTTP_X_REQUEST_START"].to_f * 1000
    wait    = env["puma.request_body_wait"]
    current = Time.now.to_f * 1000

    DogStatsD.statsd.histogram("puma.queue_time", (current - wait - start).to_i, tags: ["environment:production"]) unless start == 0

    @status, @headers, @response = @app.call(env)
    [@status, @headers, self]
  end

  def each(&block)
    @response.each(&block)
  end
end

class DogStatsD
  def self.statsd
    @statsd ||= ::Datadog::Statsd.new("localhost", 8125)
  end

  def self.forked
    @statsd = nil
  end

  def self.close
    @statsd&.flush
    @statsd&.close
    @statsd = nil
  end
end