Daemonizer: Simple framework for creating daemons with Ruby

$ gem install daemonizer

workers 2
poll_period 5

pool :daemonizer do
  workers 4
  log_file "log/daemonizer.log" #relative to Demfile

  prepare do |block|
    block.call
  end

  start do |worker_id, workers_count|
    logger.info "Started #{worker_id} from #{workers_count}"

    exit = false

    stop = proc {
      exit = true
    }

    trap('TERM', stop)
    trap('INT', stop)
    trap('EXIT', stop)

    loop do
      break if exit
      logger.info "Ping #{worker_id}"
      sleep 10
    end

    true
  end
end

settings_group do
  before_start do |worker_id, workers_count|
    #reconnect to db, etc.
  end

  #simple string option
  set_option :author, "Gleb Pomykalov"

  pool :new_daemonizer do
    on_poll do |pool|
      pool.stats.where(:private_dirty_rss).last_probes_by_count(8).mean.is_higher_then(150_000) do |stat|
        Daemonizer.logger.info "Memory limit exceeded for #{stat}. Gracefully stopping"
        worker = pool.find_worker_by_name(stat)
        worker.stop if worker
      end
    end
    workers 4
    log_file "log/daemonizer.log" #relative to Demfile

    handler MyBackgroundSolution::DaemonizerHandler

    not_cow_friendly #disable Copy-On-Write friendly (enabled by default)

    #automatically-parsed option by daemonizer
    set_option :queue do |worker_id, worker_count|
      "queue_#{worker_id}"
    end

    #lambda-option (transparent for daemonizer, fully processed by handler)
    set_option :on_error, lambda { |object| object.logger.fatal "epic fail"}
  end


  pool :new_daemonizer2 do
    workers 4
    log_file "log/daemonizer2.log" #relative to Demfile

    handler MyBackgroundSolution::DaemonizerHandler

    not_cow_friendly #disable Copy-On-Write friendly (enabled by default)

    #automatically-parsed option by daemonizer
    set_option :queue do |worker_id, worker_count|
      "another_queue_#{worker_id}"
    end

    after_prepare do |logger|
      require 'something'
    end

    #lambda-option (transparent for daemonizer, fully processed by handler)
    set_option :on_error, lambda { |object| object.logger.fatal "epic fail"}
  end
end

module MyBackgroundSolution
  class DaemonizerHandler < Daemonizer::Handler
    def preparee(starter, &block)
      require File.join(Daemonizer.root, '/config/environment') #Require rails
      require 'my_background_solution/worker' #Require our code
      super #now we are ready to fork
    end

    def start
      #we are in worker process
      logger.info "Starting cycle. We are number #{worker_id} from #{workers_count}"
      logger.info "Options - #{option(:queue)}" #We can get option :queue, which is set with set_option in pool configuration
      worker = Worker.new
      worker.run
      logger.info "Ending cycle"
    end
  end
end