Class: PidFile

Inherits:
Object
  • Object
show all
Defined in:
lib/pidfile.rb

Defined Under Namespace

Classes: DuplicateProcessError

Constant Summary collapse

VERSION = 
'0.3.0'
DEFAULT_OPTIONS = 
{
  :pidfile => File.basename($0, File.extname($0)) + ".pid",
  :piddir => '/tmp',
}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ PidFile

Returns a new instance of PidFile.



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# File 'lib/pidfile.rb', line 13

def initialize(*args)
  opts = {}

  #----- set options -----#
  case
  when args.length == 0 then
  when args.length == 1 && args[0].class == Hash then
    arg = args.shift

    if arg.class == Hash
      opts = arg
    end
  else
    raise ArgumentError, "new() expects hash or hashref as argument"
  end

  opts = DEFAULT_OPTIONS.merge opts

  @piddir     = opts[:piddir]
  @pidfile    = opts[:pidfile]
  @pidpath    = File.join(@piddir, @pidfile)
  @fh         = nil

  #----- Does the pidfile or pid exist? -----#
  if self.pidfile_exists?
    if self.class.running?(@pidpath)
      raise DuplicateProcessError, "Process (#{$0} - #{self.class.pid(@pidpath)}) is already running."
      
      exit! # exit without removing the existing pidfile
    end

    self.release
  end

  #----- create the pidfile -----#
  create_pidfile

  at_exit { release }
end

Instance Attribute Details

#piddir ⇒ Object (readonly)

Returns the value of attribute piddir.



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# File 'lib/pidfile.rb', line 2

def piddir
  @piddir
end

#pidfile ⇒ Object (readonly)

Returns the value of attribute pidfile.



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# File 'lib/pidfile.rb', line 2

def pidfile
  @pidfile
end

#pidpath ⇒ Object (readonly)

Returns the value of attribute pidpath.



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# File 'lib/pidfile.rb', line 2

def pidpath
  @pidpath
end

Class Method Details

.pid(path = nil) ⇒ Object

Returns the PID, if any, of the instantiating process



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# File 'lib/pidfile.rb', line 99

def self.pid(path=nil)
  if pidfile_exists?(path)
    open(path, 'r').read.to_i
  end
end

.pidfile_exists?(path = nil) ⇒ Boolean

class method for determining the existence of pidfile

Returns:

  • (Boolean) 


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# File 'lib/pidfile.rb', line 106

def self.pidfile_exists?(path=nil)
  path ||= File.join(DEFAULT_OPTIONS[:piddir], DEFAULT_OPTIONS[:pidfile])

  File.exists?(path)
end

.running?(path = nil) ⇒ Boolean

boolean stating whether the calling program is already running

Returns:

  • (Boolean) 


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# File 'lib/pidfile.rb', line 113

def self.running?(path=nil)
  calling_pid = nil
  path ||= File.join(DEFAULT_OPTIONS[:piddir], DEFAULT_OPTIONS[:pidfile])

  if pidfile_exists?(path)
    calling_pid = pid(path)
  end

  process_exists?(calling_pid)
end

Instance Method Details

#alive? ⇒ Boolean

Boolean stating whether this process is alive and running

Returns:

  • (Boolean) 


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# File 'lib/pidfile.rb', line 69

def alive?
  return false unless self.pid && (self.pid == Process.pid)

  self.class.process_exists?(self.pid)
end

#locktime ⇒ Object

returns the modification time of the pidfile



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# File 'lib/pidfile.rb', line 90

def locktime
  File.mtime(self.pidpath)
end

#pid ⇒ Object

Returns the PID, if any, of the instantiating process



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# File 'lib/pidfile.rb', line 58

def pid
  return @pid unless @pid.nil?

  if self.pidfile_exists?
    @pid = open(self.pidpath, 'r').read.to_i
  else
    @pid = nil
  end
end

#pidfile_exists? ⇒ Boolean

does the pidfile exist?

Returns:

  • (Boolean) 


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# File 'lib/pidfile.rb', line 76

def pidfile_exists?
  self.class.pidfile_exists?(pidpath)
end

#release ⇒ Object

unlock and remove the pidfile. Sets pid to nil



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# File 'lib/pidfile.rb', line 81

def release
  unless @fh.nil?
    @fh.flock(File::LOCK_UN)
    remove_pidfile
  end
  @pid = nil
end