Class: DaemonKit::PidFile

Inherits:
Object show all
Defined in:
lib/daemon_kit/pid_file.rb

Overview

Simple pidfile handling for daemon processes

Instance Method Summary collapse

Constructor Details

#initialize(path) ⇒ PidFile

Returns a new instance of PidFile.



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# File 'lib/daemon_kit/pid_file.rb', line 6

def initialize( path )
  @path = path.to_absolute_path
end

Instance Method Details

#cleanup ⇒ Object Also known as: zap 



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# File 'lib/daemon_kit/pid_file.rb', line 50

def cleanup
  File.delete( @path ) rescue Errno::ENOENT
end

#ensure_stopped! ⇒ Object 



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# File 'lib/daemon_kit/pid_file.rb', line 43

def ensure_stopped!
  if self.running?
    puts "Process already running with id #{self.pid}"
    exit 1
  end
end

#exists? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/daemon_kit/pid_file.rb', line 10

def exists?
  File.exists?( @path )
end

#pid ⇒ Object

Return the pid contained in the pidfile, or nil



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# File 'lib/daemon_kit/pid_file.rb', line 35

def pid
  return nil unless self.exists?

  File.open( @path ) { |f|
    return f.gets.to_i
  }
end

#running? ⇒ Boolean

Returns true if the process is running

Returns:

  • (Boolean) 


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# File 'lib/daemon_kit/pid_file.rb', line 15

def running?
  return false unless self.exists?

  # Check if process is in existence
  # The simplest way to do this is to send signal '0'
  # (which is a single system call) that doesn't actually
  # send a signal
  begin
    Process.kill(0, self.pid)
    return true
  rescue Errno::ESRCH
    return false
  rescue ::Exception   # for example on EPERM (process exists but does not belong to us)
    return true
  #rescue Errno::EPERM
  #  return false
  end
end

#write! ⇒ Object 



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# File 'lib/daemon_kit/pid_file.rb', line 55

def write!
  File.open( @path, 'w' ) { |f|
    f.puts Process.pid
  }
end