src/dubbo/cluster/_interfaces.py

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import abc
from typing import Optional

from dubbo.node import Node
from dubbo.protocol import Invocation, Invoker

__all__ = ["Directory", "LoadBalance", "Cluster"]


class Directory(Node, abc.ABC):
    """
    Directory interface.
    """

    @abc.abstractmethod
    def get_list(self, invocation: Invocation) -> list[Invoker]:
        """
        List the directory.
        :param invocation: The invocation.
        :type invocation: Invocation
        :return: The list of invokers.
        :rtype: List
        """
        raise NotImplementedError()


class LoadBalance(abc.ABC):
    """
    The load balance interface.
    """

    @abc.abstractmethod
    def select(self, invokers: list[Invoker], invocation: Invocation) -> Optional[Invoker]:
        """
        Select an invoker from the list.
        :param invokers: The invokers.
        :type invokers: List[Invoker]
        :param invocation: The invocation.
        :type invocation: Invocation
        :return: The selected invoker. If no invoker is selected, return None.
        :rtype: Optional[Invoker]
        """
        raise NotImplementedError()


class Cluster(abc.ABC):
    """
    Cluster interface.
    """

    @abc.abstractmethod
    def join(self, directory: Directory) -> Invoker:
        """
        Join the cluster.
        :param directory: The directory.
        :type directory: Directory
        :return: The cluster invoker.
        :rtype: Invoker
        """
        raise NotImplementedError()