from fastapi import FastAPI
import asyncio

app = FastAPI()
user_sched = {}

async def my_async_task():
    # 这里是异步任务的代码
    # 倒计时3秒
    await asyncio.sleep(10)
    print("close")

async def task_start(username, device):
    task = asyncio.create_task(my_async_task())
    user_sched[username] = task
@app.get("/video/{username}/{device}")
async def startup(username, device):
    if username not in user_sched:
        await task_start(username, device)
    else:
        t = user_sched['1']
        t.cancel()
        await task_start()

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8004)