https://gitlab.com/snippets/1961910

jacinto.rb

# frozen_string_literal: true

require "net-telnet"

class Jacinto
  include Enumerable

  # Array(slab_id, items_count)
  SLABS = /^STAT items:(\d+):number (\d+)$/

  # Array(cache_key, data_bytesize, expires_in)
  ITEMS = /^ITEM (.+) \[(\d+) b; (\d+) s\]$/

  # @param client [Dalli::Client]
  def initialize(client, timeout: 3)
    @client  = client
    @timeout = Integer(timeout)
  end

  def each(&block)
    return to_enum __method__ unless block_given?

    each_connection do |telnet|
      each_slab(telnet) do |(slab_id, items_count)|
        each_item(telnet, slab_id, items_count, &block)
      end
    end

    self
  end

  def inspect
    "#<#{self.class}>"
  end

  alias to_s inspect

  private

  def each_slab(telnet, &block)
    telnet.cmd("stats items").scan(SLABS, &block)
  end

  def each_item(telnet, slab_id, items_count)
    telnet.cmd("stats cachedump #{slab_id} #{items_count}")
      .scan(ITEMS) do |(cache_key, data_bytesize, expires_in)|
        yield(cache_key, data_bytesize.to_i, expires_in.to_i)
      end
  end

  # yields telnet connection to each server in the ring
  def each_connection
    @client.__send__(:ring).servers.each do |server|
      begin
        telnet = Net::Telnet.new({
          "Host"    => server.hostname,
          "Port"    => server.port,
          "Prompt"  => /(^END$)/,
          "Timeout" => @timeout
        })

        yield telnet
      rescue Errno::ECONNREFUSED => e
        warn e
      ensure
        telnet&.close
      end
    end
  end
end