bdrb_start_stop.rb

# see http://refspecs.freestandards.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/iniscrptact.html
# for LSB-compliancy info
module BackgrounDRb
  class StartStop
    def start
      if running? # starting an already running process is considered a success
        puts "BackgrounDRb Already Running"
        exit(0)
      elsif dead? # dead, but pid exists
        remove_pidfile
      end
      
      # status == 3, not running.
      STDOUT.sync = true
      print("Starting BackgrounDRb .... ")
      start_bdrb
      puts "Success!"
    end
    
    def stop
      pid_files = Dir["#{RAILS_HOME}/tmp/pids/backgroundrb_*.pid"]
      puts "BackgrounDRb Not Running" if pid_files.empty?
      pid_files.each do |x|
        begin
          kill_process(x)
        rescue Errno::ESRCH
          # stopping an already stopped process is considered a success (exit status 0)
        end
      end
    end
    
    # returns the correct lsb code for the status:
    # 0 program is running or service is OK
    # 1 program is dead and /var/run pid file exists
    # 3 program is not running
    def status
      @status ||= begin
        if pidfile_exists? and process_running?
          0
        elsif pidfile_exists? # but not process_running
          1
        else
          3
        end
      end
      
      return @status
    end
    
    def pidfile_exists?; File.exists?(PID_FILE); end
    
    def process_running?
      begin
        Process.kill(0,self.pid)
        true
      rescue Errno::ESRCH
        false
      end
    end
    
    def running?;status == 0;end
    # pidfile exists but process isn't running
    
    def dead?;status == 1;end
    
    def pid
      File.read(PID_FILE).strip.to_i if pidfile_exists?
    end
    
    def remove_pidfile
      File.delete(PID_FILE)
    end

    def start_bdrb
      require "rubygems"
      require "yaml"
      require "erb"
      require "logger"
      require "packet"
      require "optparse"

      require "bdrb_config"
      require RAILS_HOME + "/config/boot"
      require "active_support"

      BackgrounDRb::Config.parse_cmd_options ARGV
    
      require RAILS_HOME + "/config/environment"
      require "bdrb_job_queue"
      require "backgroundrb_server"
      main_pid = fork do
        if BDRB_CONFIG[:backgroundrb][:log].nil? or BDRB_CONFIG[:backgroundrb][:log] != 'foreground'
          redirect_io(SERVER_LOGGER)
        end
        $0 = "backgroundrb master"
        BackgrounDRb::MasterProxy.new()
      end
      File.open(PID_FILE, "w") {|pidfile| pidfile.write(main_pid)}
    end

    def kill_process(pid_file)
      pid = File.open(pid_file, "r") { |pid_handle| pid_handle.gets.strip.to_i }
      pgid =  Process.getpgid(pid)
      Process.kill('-TERM', pgid)
      File.delete(pid_file) if File.exists?(pid_file)
      puts "Stopped BackgrounDRb worker with pid #{pid}"
    end
    
    
    # Free file descriptors and
    # point them somewhere sensible
    # STDOUT/STDERR should go to a logfile
    def redirect_io(logfile_name)
      begin; STDIN.reopen "/dev/null"; rescue ::Exception; end

      if logfile_name
        begin
          STDOUT.reopen logfile_name, "a"
          STDOUT.sync = true
        rescue ::Exception
          begin; STDOUT.reopen "/dev/null"; rescue ::Exception; end
        end
      else
        begin; STDOUT.reopen "/dev/null"; rescue ::Exception; end
      end

      begin; STDERR.reopen STDOUT; rescue ::Exception; end
      STDERR.sync = true
    end

  end
end