Module: Daemonize

Defined in:
lib/feed_updater/vendor/daemons/daemonize.rb

Constant Summary collapse

VERSION = 
"0.1.1m"

Class Method Summary collapse

Class Method Details

.call_as_daemon(block, logfile_name = nil, oldmode = 0) ⇒ Object 



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# File 'lib/feed_updater/vendor/daemons/daemonize.rb', line 142

def call_as_daemon(block, logfile_name = nil, oldmode = 0)
  rd, wr = IO.pipe
  
  if tmppid = safefork
    # parent
    wr.close
    pid = rd.read.to_i
    rd.close
    
    Process.waitpid(tmppid)
    
    return pid
  else
    rd.close
    
    # Detach from the controlling terminal
    unless sess_id = Process.setsid
      raise Daemons.RuntimeException.new('cannot detach from controlling terminal')
    end

    # Prevent the possibility of acquiring a controlling terminal
    if oldmode.zero?
      trap 'SIGHUP', 'IGNORE'
      exit if pid = safefork
    end

    wr.write Process.pid
    wr.close
    
    Dir.chdir "/"   # Release old working directory
    File.umask 0000 # Insure sensible umask

    # Make sure all file descriptors are closed
    ObjectSpace.each_object(IO) do |io|
      unless [STDIN, STDOUT, STDERR].include?(io)
        begin
          unless io.closed?
            io.close
          end
        rescue ::Exception
        end
      end
    end

    # Free file descriptors and
    # point them somewhere sensible
    # STDOUT/STDERR should go to a logfile
    
    STDIN.reopen "/dev/null" rescue nil       
    
    if logfile_name
      begin
        STDOUT.reopen logfile_name, "a" 
      rescue ::Exception
        STDOUT.reopen "/dev/null" rescue nil
      end
    else
      STDOUT.reopen "/dev/null" rescue nil
    end
    
    STDERR.reopen STDOUT rescue nil    
  
    block.call
    
    exit
  end
end

.daemonize(logfile_name = nil, oldmode = 0) ⇒ Object

This method causes the current running process to become a daemon



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# File 'lib/feed_updater/vendor/daemons/daemonize.rb', line 213

def daemonize(logfile_name = nil, oldmode=0)
  srand # Split rand streams between spawning and daemonized process
  safefork and exit # Fork and exit from the parent

  # Detach from the controlling terminal
  unless sess_id = Process.setsid
    raise Daemons.RuntimeException.new('cannot detach from controlling terminal')
  end

  # Prevent the possibility of acquiring a controlling terminal
  if oldmode.zero?
    trap 'SIGHUP', 'IGNORE'
    exit if pid = safefork
  end

  Dir.chdir "/"   # Release old working directory
  File.umask 0000 # Insure sensible umask

  # Make sure all file descriptors are closed
  ObjectSpace.each_object(IO) do |io|
    unless [STDIN, STDOUT, STDERR].include?(io)
      begin
        unless io.closed?
          io.close
        end
      rescue ::Exception
      end
    end
  end

  # Free file descriptors and
  # point them somewhere sensible
  # STDOUT/STDERR should go to a logfile
  
  STDIN.reopen "/dev/null" rescue nil       
  
  if logfile_name
    begin
      STDOUT.reopen logfile_name, "a" 
    rescue ::Exception
      STDOUT.reopen "/dev/null" rescue nil
    end
  else
    STDOUT.reopen "/dev/null" rescue nil
  end
   
  STDERR.reopen STDOUT rescue nil           
  
  return oldmode ? sess_id : 0   # Return value is mostly irrelevant
end

.safefork ⇒ Object

Try to fork if at all possible retrying every 5 sec if the maximum process limit for the system has been reached



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# File 'lib/feed_updater/vendor/daemons/daemonize.rb', line 97

def safefork
  tryagain = true

  while tryagain
    tryagain = false
    begin
      if pid = fork
        return pid
      end
    rescue Errno::EWOULDBLOCK
      sleep 5
      tryagain = true
    end
  end
end

.simulate(logfile_name = nil) ⇒ Object 



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# File 'lib/feed_updater/vendor/daemons/daemonize.rb', line 115

def simulate(logfile_name = nil)
  # NOTE: STDOUT and STDERR will not be redirected to the logfile!
  
  Dir.chdir "/"   # Release old working directory
  File.umask 0000 # Insure sensible umask

  # Make sure all file descriptors are closed
  ObjectSpace.each_object(IO) do |io|
    unless [STDIN, STDOUT, STDERR].include?(io)
      begin
        unless io.closed?
          io.close
        end
      rescue ::Exception
      end
    end
  end

  # Free file descriptors and
  # point them somewhere sensible
  # STDOUT/STDERR should go to a logfile
  
  STDIN.reopen "/dev/null" rescue nil       
end