def get_hub():
    """
    Checks whether poll is available and falls back
    on select if it isn't.

    Note about epoll:

    Review: https://review.openstack.org/#/c/18806/

    There was a problem where once out of every 30 quadrillion
    connections, a coroutine wouldn't wake up when the client
    closed its end. Epoll was not reporting the event or it was
    getting swallowed somewhere. Then when that file descriptor
    was re-used, eventlet would freak right out because it still
    thought it was waiting for activity from it in some other coro.
    """
    try:
        import select
        if hasattr(select, "poll"):
            return "poll"
        return "selects"
    except __HOLE__:
        return None
dataset/ETHPy150Open openstack/swift/swift/common/utils.py/get_hub