Synnefo » snf-ganeti » ganeti-local

def ReadLockedPidFile(path):

  """Reads a locked PID file.

  This can be used together with L{StartDaemon}.

  @type path: string

  @param path: Path to PID file

  @return: PID as integer or, if file was unlocked or couldn't be opened, None

  """

  try:

    fd = os.open(path, os.O_RDONLY)

  except EnvironmentError, err:

    if err.errno == errno.ENOENT:

      # PID file doesn't exist

      return None

    raise

  try:

    try:

      # Try to acquire lock

      LockFile(fd)

    except errors.LockError:

      # Couldn't lock, daemon is running

      return int(os.read(fd, 100))

  finally:

    os.close(fd)

  return None