Synnefo » snf-ganeti

class ConfdCountingCallback:

  """Callback that calls another callback, and counts the answers

  """

  def __init__(self, callback, logger=None):

    """Constructor for ConfdCountingCallback

    @type callback: f(L{ConfdUpcallPayload})

    @param callback: function to call when getting answers

    @type logger: logging.Logger

    @param logger: optional logger for internal conditions

    """

    if not callable(callback):

      raise errors.ProgrammerError("callback must be callable")

    self._callback = callback

    self._logger = logger

    # answers contains a dict of salt -> count

    self._answers = {}

  def RegisterQuery(self, salt):

    if salt in self._answers:

      raise errors.ProgrammerError("query already registered")

    self._answers[salt] = 0

  def AllAnswered(self):

    """Have all the registered queries received at least an answer?

    """

    return utils.all(self._answers.values())

  def _HandleExpire(self, up):

    # if we have no answer we have received none, before the expiration.

    if up.salt in self._answers:

      del self._answers[up.salt]

  def _HandleReply(self, up):

    """Handle a single confd reply, and decide whether to filter it.

    @rtype: boolean

    @return: True if the reply should be filtered, False if it should be passed

             on to the up-callback

    """

    if up.salt in self._answers:

      self._answers[up.salt] += 1

  def __call__(self, up):

    """Filtering callback

    @type up: L{ConfdUpcallPayload}

    @param up: upper callback

    """

    if up.type == UPCALL_REPLY:

      self._HandleReply(up)

    elif up.type == UPCALL_EXPIRE:

      self._HandleExpire(up)

    self._callback(up)