destination.py

from .candidate import Candidate
from .meta import MetaObject


class Destination(MetaObject):

    class Implementation(MetaObject.Implementation):
        pass

    def setup(self, message):
        """
        Setup is called after the meta message is initially created.
        """
        from .message import Message
        assert isinstance(message, Message)

    def __str__(self):
        return "<%s>" % (self.__class__.__name__,)


class CandidateDestination(Destination):

    """
    A destination policy where the message is sent to one or more specified candidates.
    """
    class Implementation(Destination.Implementation):

        def __init__(self, meta, *candidates):
            """
            Construct a CandidateDestination.Implementation object.

            META the associated CandidateDestination object.

            CANDIDATES is a tuple containing zero or more Candidate objects.  These will contain the
            destination addresses when the associated message is sent.
            """
            assert isinstance(candidates, tuple), type(candidates)
            assert len(candidates) >= 0, len(candidates)
            assert all(isinstance(candidate, Candidate) for candidate in candidates), [type(candidate) for candidate in candidates]
            super(CandidateDestination.Implementation, self).__init__(meta)
            self._candidates = candidates

        @property
        def candidates(self):
            return self._candidates


class CommunityDestination(Destination):

    """
    A destination policy where the message is sent to one or more community members selected from
    the current candidate list.

    At the time of sending at most NODE_COUNT addresses are obtained using
    community.yield_random_candidates(...) to receive the message.
    """
    class Implementation(Destination.Implementation):

        def __init__(self, meta, *candidates):
            """
            Construct a CandidateDestination.Implementation object.

            META the associated CandidateDestination object.

            CANDIDATES is a tuple containing zero or more Candidate objects.  These will contain the
            destination addresses when the associated message is sent.
            """
            assert isinstance(candidates, tuple), type(candidates)
            assert len(candidates) >= 0, len(candidates)
            assert all(isinstance(candidate, Candidate) for candidate in candidates), [type(candidate) for candidate in candidates]
            super(CommunityDestination.Implementation, self).__init__(meta)
            self._candidates = candidates

        @property
        def node_count(self):
            return self._meta._node_count

        @property
        def candidates(self):
            return self._candidates

    def __init__(self, node_count):
        """
        Construct a CommunityDestination object.

        NODE_COUNT is an integer giving the number of nodes where, when the message is created, the
        message must be sent to.  These nodes are selected using the
        community.yield_random_candidates(...) method.  NODE_COUNT must be zero or higher.
        """
        assert isinstance(node_count, int)
        assert node_count >= 0
        self._node_count = node_count

    @property
    def node_count(self):
        return self._node_count

    def __str__(self):
        return "<%s node_count:%d>" % (self.__class__.__name__, self._node_count)