Daemonizing rake tasks using dtach

dtachdaemon.rb

namespace :myapp do
  namespace :mynamespace do

    class MyProcessRunner
      def self.basename
        "task_name"
      end
      
      def self.socket
        Rails.root.join("tmp", "sockets", "#{basename}.dtach")
        # or write in tmp/pids, as its presence can be assumed?
      end
      
      def self.pid_file
        Rails.root.join("tmp", "pids", "#{basename}.pid")      
      end
      
      def self.write_pid
        raise 'pid file exists!' if File.exists? pid_file
        File.open(pid_file, 'w+') { |f| f.puts Process.pid }
      end
      
      def self.pid
        File.read(pid_file)
      end
      
      def self.delete_pid
        File.delete pid_file
      end
      
      def self.kill_process
        exec "kill -s TERM #{pid}"
        File.delete(pid_file)
      end
    end
    
    desc 'run the task in the console as regular rake task'
    task :run => :environment do
      begin
        MyProcessRunner.write_pid
        tp = Some::Task::With::Loop.new #and sleep
        tp.start
      rescue
        Rails.logger.error $!.backtrace.join("\n")
      ensure
        MyProcessRunner.delete_pid
      end
    end
    
    desc "run the task as a daemon using dtach"
    task :start => :environment do
      begin
        sh "dtach -n #{MyProcessRunner.socket} rake myapp:mynamespace:run"
      rescue 
        puts $!.backtrace.join("\n")
      end
    end
    
    desc "stop the dtached daemon"
    task :stop => :environment do
      MyProcessRunner.kill_process
    end
    
    desc 'attach the dtached daemon to the console'
    task :attach => :environment do
      exec "dtach -a #{MyProcessRunner.socket}"
    end
    
    desc 'restart the dtached daemon'
    task :restart => [:environment, :stop, :start]
  end
end