288 lines
7.9 KiB
Python
288 lines
7.9 KiB
Python
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"""
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消息总线核心模块
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支持发布-订阅模式，异步消息处理
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"""
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import asyncio
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import json
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import threading
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import uuid
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from typing import Callable, Dict, List, Any, Optional
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from dataclasses import dataclass, field, asdict
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from datetime import datetime
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from enum import Enum
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import logging
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logger = logging.getLogger(__name__)
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message_bus_lock = threading.RLock()
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class MessageType(Enum):
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"""消息类型枚举"""
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EVENT = "event"
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COMMAND = "command"
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QUERY = "query"
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@dataclass
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class Message:
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"""消息数据类"""
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id: str = field(default_factory=lambda: str(uuid.uuid4()))
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message_type: MessageType = MessageType.EVENT
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topic: str = ""
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payload: Dict[str, Any] = field(default_factory=dict)
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source: str = "unknown"
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timestamp: str = field(default_factory=lambda: datetime.utcnow().isoformat())
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correlation_id: Optional[str] = None
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def to_dict(self) -> Dict[str, Any]:
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"""转换为字典"""
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data = asdict(self)
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data['message_type'] = self.message_type.value
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return data
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def to_json(self) -> str:
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"""转换为JSON字符串"""
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return json.dumps(self.to_dict())
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@classmethod
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def from_dict(cls, data: Dict[str, Any]) -> 'Message':
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"""从字典创建消息"""
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data['message_type'] = MessageType(data.get('message_type', 'event'))
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return cls(**data)
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class MessageBus:
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"""消息总线 - 核心组件"""
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def __init__(self):
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"""初始化消息总线"""
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# 话题订阅者映射: {topic: [handler1, handler2, ...]}
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self._subscribers: Dict[str, List[Callable]] = {}
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# 中间件列表
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self._middlewares: List[Callable] = []
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# 消息历史（可选）
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self._message_history: List[Message] = []
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# 最大历史消息数
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self._max_history = 1000
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# 死信队列
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self._dead_letter_queue: List[Message] = []
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logger.info("消息总线已初始化")
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def subscribe(self, topic: str, handler: Callable) -> str:
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"""
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订阅主题
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Args:
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topic: 主题名称
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handler: 消息处理函数 (async or sync)
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Returns:
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订阅ID
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"""
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with message_bus_lock:
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if topic not in self._subscribers:
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self._subscribers[topic] = []
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self._subscribers[topic].append(handler)
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subscription_id = f"{topic}_{id(handler)}"
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logger.info(f"订阅者已注册: {subscription_id}")
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return subscription_id
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def unsubscribe(self, topic: str, handler: Callable) -> bool:
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"""
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取消订阅
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Args:
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topic: 主题名称
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handler: 处理函数
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Returns:
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是否成功取消
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"""
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with message_bus_lock:
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if topic in self._subscribers:
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try:
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self._subscribers[topic].remove(handler)
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logger.info(f"订阅者已移除: {topic}")
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return True
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except ValueError:
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return False
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return False
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def add_middleware(self, middleware: Callable) -> None:
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"""
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添加中间件
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Args:
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middleware: 中间件函数
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"""
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with message_bus_lock:
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self._middlewares.append(middleware)
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logger.info(f"中间件已添加: {middleware.__name__}")
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def publish(self,
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topic: str,
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payload: Dict[str, Any],
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message_type: MessageType = MessageType.EVENT,
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source: str = "system",
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correlation_id: Optional[str] = None) -> Message:
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"""
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发布消息
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Args:
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topic: 主题名称
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payload: 消息内容
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message_type: 消息类型
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source: 消息源
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correlation_id: 关联ID
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Returns:
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发布的消息对象
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"""
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with message_bus_lock:
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# 创建消息
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message = Message(
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message_type=message_type,
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topic=topic,
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payload=payload,
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source=source,
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correlation_id=correlation_id or str(uuid.uuid4())
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)
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# 记录消息历史
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self._record_message(message)
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# 执行中间件
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for middleware in self._middlewares:
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middleware(message)
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logger.info(f"消息已发布到主题 '{topic}': {message.id}")
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# 分发消息给订阅者
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self._dispatch(message)
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return message
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def _dispatch(self, message: Message) -> None:
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"""
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分发消息给订阅者
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Args:
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message: 消息对象
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"""
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handlers = self._subscribers.get(message.topic, [])
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if not handlers:
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logger.warning(f"主题 '{message.topic}' 没有订阅者")
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return
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tasks = []
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for handler in handlers:
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try:
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handler(message)
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except Exception as e:
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logger.error(f"处理程序出错: {e}")
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self._dead_letter_queue.append(message)
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def _record_message(self, message: Message) -> None:
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"""
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记录消息到历史
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Args:
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message: 消息对象
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"""
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self._message_history.append(message)
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# 保持历史大小
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if len(self._message_history) > self._max_history:
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self._message_history.pop(0)
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def get_message_history(self, topic: Optional[str] = None, limit: int = 100) -> List[Message]:
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"""
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获取消息历史
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Args:
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topic: 可选的主题过滤
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limit: 返回消息数量限制
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Returns:
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消息列表
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"""
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with message_bus_lock:
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history = self._message_history
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if topic:
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history = [msg for msg in history if msg.topic == topic]
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return history[-limit:]
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def get_dead_letter_queue(self) -> List[Message]:
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"""
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获取死信队列
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Returns:
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失败消息列表
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"""
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with message_bus_lock:
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return self._dead_letter_queue.copy()
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def clear_dead_letter_queue(self) -> None:
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"""清空死信队列"""
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with message_bus_lock:
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self._dead_letter_queue.clear()
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logger.info("死信队列已清空")
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def get_topics(self) -> List[str]:
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"""
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获取所有主题
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Returns:
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主题列表
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"""
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with message_bus_lock:
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return list(self._subscribers.keys())
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def get_subscriber_count(self, topic: str) -> int:
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"""
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获取主题订阅者数量
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Args:
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topic: 主题名称
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Returns:
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订阅者数量
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"""
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with message_bus_lock:
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return len(self._subscribers.get(topic, []))
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async def shutdown(self) -> None:
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"""优雅关闭消息总线"""
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logger.info("消息总线正在关闭...")
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self._subscribers.clear()
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self._middlewares.clear()
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logger.info("消息总线已关闭")
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# 全局消息总线实例
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_message_bus: Optional[MessageBus] = None
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def get_message_bus() -> MessageBus:
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"""
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获取或创建全局消息总线实例
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Returns:
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消息总线实例
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"""
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global _message_bus
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with message_bus_lock:
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if _message_bus is None:
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_message_bus = MessageBus()
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return _message_bus
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def reset_message_bus() -> None:
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"""重置全局消息总线实例（用于测试）"""
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global _message_bus
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_message_bus = None
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