feat(backend): complete modular monolith with ledger, fastapi and websocket

app/ws/manager.py

@@ -0,0 +1,38 @@
+import logging
+from typing import Dict, Set
+from fastapi import WebSocket, WebSocketDisconnect
+
+logger = logging.getLogger(__name__)
+
+class ConnectionManager:
+    """WebSocket 实时连接与订阅频道管理器"""
+
+    def __init__(self):
+        # 活跃连接池: market_address -> Set[WebSocket]
+        self.active_connections: Dict[str, Set[WebSocket]] = {}
+
+    async def connect(self, websocket: WebSocket, channel: str):
+        await websocket.accept()
+        if channel not in self.active_connections:
+            self.active_connections[channel] = set()
+        self.active_connections[channel].add(websocket)
+        logger.info(f"Client connected to channel {channel}. Total: {len(self.active_connections[channel])}")
+
+    def disconnect(self, websocket: WebSocket, channel: str):
+        if channel in self.active_connections:
+            self.active_connections[channel].discard(websocket)
+            if not self.active_connections[channel]:
+                del self.active_connections[channel]
+        logger.info(f"Client disconnected from channel {channel}")
+
+    async def broadcast_to_channel(self, channel: str, message: dict):
+        """向特定频道所有订阅者推送 JSON 消息"""
+        if channel in self.active_connections:
+            for connection in list(self.active_connections[channel]):
+                try:
+                    await connection.send_json(message)
+                except Exception as e:
+                    logger.error(f"Error broadcasting message: {e}")
+                    self.disconnect(connection, channel)
+
+ws_manager = ConnectionManager()