Function _cancel_and_wait

Lib/asyncio/tasks.py:537–551

Cancel the *fut* future or task and wait until it completes.

(fut)

async def _cancel_and_wait(fut):
    """Cancel the *fut* future or task and wait until it completes."""

    loop = events.get_running_loop()
    waiter = loop.create_future()
    cb = functools.partial(_release_waiter, waiter)
    fut.add_done_callback(cb)

    try:
        fut.cancel()
        # We cannot wait on *fut* directly to make
        # sure _cancel_and_wait itself is reliably cancellable.
        await waiter
    finally:
        fut.remove_done_callback(cb)


class _AsCompletedIterator: