如何让Postgres使用FastAPI websocket异步(非阻塞)监听？

from fastapi import FastAPI, WebSocket
import asyncpg
import asyncio

app = FastAPI()

@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    while True:
        try:
            data = await websocket.receive_text()
            # 在这里处理接收到的消息
        except WebSocketDisconnect:
            break

@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    
    # 建立PostgreSQL数据库连接
    conn = await asyncpg.connect(user='your_username', password='your_password', database='your_database', host='your_host')
    
    # 创建异步监听器
    async with conn.transaction():
        await conn.execute("LISTEN your_channel")
        while True:
            try:
                # 等待异步通知
                await conn.notifies.get()
                # 在这里处理异步通知
            except WebSocketDisconnect:
                break
    
    # 关闭数据库连接
    await conn.close()

uvicorn main:app --host 0.0.0.0 --port 8000