How can i create a simultaneous routine if a request isn't finished after X milliseconds-CodePudding

I have a program that has to unconditionally respond after X seconds, that response can either be the actual response i need if under X seconds or some sort of "Gathering resources, please wait" message if the time has passed.

How can i do something along the lines of

make request
start timer
if request.responded:
  return request
if timer.hasPassed(X):
  return False

While still having the request active, ready to respond as soon as it is finished?

CodePudding user response：

You seem to be looking for asyncio.wait_for. It accepts a coroutine and a timeout parameter, awaits the coroutine and raises asyncio.TimeoutError (as well as cancelling the coroutine) if the timeout period is exceeded. More here.

async def eternity():
    # Sleep for one hour
    await asyncio.sleep(3600)
    print('yay!')

async def main():
    # Wait for at most 1 second
    try:
        await asyncio.wait_for(eternity(), timeout=1.0)
    except asyncio.TimeoutError:
        print('timeout!')

If you want to keep the coroutine running after the timeout and eventually get its result you need to create a task and shield it from cancellation:

async def long_running_task():
    await asyncio.sleep(5)
    return True

async def main():
    task = asyncio.create_task(long_running_task())
    try:
        return await asyncio.wait_for(asyncio.shield(task), timeout=1)
    except asyncio.TimeoutError:
        print('Time out')
    return await task