关闭/修改来自 FASTAPI 端点的现有 aio_pika 连接

Question

I am using aio_pika as a robust interface for rabbitmq. FASTAPI startup event creates an aio_pika channel and starts consuming a queue as seen below. What I need to do is have an endpoint that closes/modifies this connection that is already running. This allows another remote application close/modify this consumer.

I want this endpoint, but I don't know how to pass an endpoint the swarm_connection which is already instantiated by the FASTAPI startup event.

#The endpoint I need, but how to pass in swarm_connection?
@app.get("/close")
async def close_pika():
    swarm_connection.close()

Code I have so far that is working to start things up

@app.on_event("startup")
def startup():
    loop = asyncio.get_event_loop()
    asyncio.ensure_future(main(loop))

async def main(loop):
    #RabbitMQ
    swarm_connection = await aio_pika.connect_robust(host=host,
                                               port=5672,
                                               login=login,
                                               password=pass,
                                               loop=loop
                                               )
    # Creating channel
    swarm_channel = await swarm_connection.channel()
    # Maximum message count which will be processing at the same time.
    await swarm_channel.set_qos(prefetch_count = 1)

    org1_queue = await swarm_channel.declare_queue('org1', auto_delete=False, durable=True, arguments={'x-max-priority':1})
    await org1_queue.consume(solve_problem_test)

Answer 1

The asyncio.wait method can wait for the first of several async tasks to complete (if run with the argument return_when=asyncio.FIRST_COMPLETED ). So one idea would be use an asyncio.Event as a signal. Modify the last line in your main method to wait for either your queue or the event being set, and set the event in your /close endpoint. Something along the lines of:

closing_connection = asyncio.Event()

@app.get("/close")
async def close_pika():
    closing_connection.set()

# ...
async def main(loop):
    # ...
    _, pending = await asyncio.wait(
        [org1_queue.consume(solve_problem_test), closing_connection.wait()],
        return_when=asyncio.FIRST_COMPLETED
    )
    for task in pending:
        task.cancel()

    # Here you can call swarm_connection.close() or whatever you need to do

The last part is to cancel whichever task was not awaited.