#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8

import abc
from typing import Dict, Any, Optional

from message import Message


class MessageQueueBackend(abc.ABC):
    @abc.abstractmethod
    def consume(self) -> Optional[Message]:
        pass

    @abc.abstractmethod
    def produce(self, message: Message) -> None:
        pass

class MemoryQueueBackend(MessageQueueBackend):
    """内存消息队列实现"""
    def __init__(self):
        self._queue = []

    def consume(self) -> Optional[Message]:
        return self._queue.pop(0) if self._queue else None

    def produce(self, message: Message):
        self._queue.append(message)