def find_next_host()

in cstar/strategy.py [0:0]


def find_next_host(strategy, topology, endpoint_mapping, progress, cluster_parallel, dc_parallel, max_concurrency,
                   stop_after, ignore_down_nodes):
    """Entry point for figuring out which host to do things on next."""

    if stop_after and ((len(progress.running) + len(progress.done) + len(progress.failed)) >= stop_after):
        return None

    remaining = topology.without_hosts(progress.done).without_hosts(progress.running).without_hosts(progress.failed)
    if progress.running and not cluster_parallel:
        remaining = remaining.with_cluster(next(iter(progress.running)).cluster)

    if progress.running and not dc_parallel:
        remaining = remaining.with_dc_or_distinct_cluster(progress.running)

    if not remaining:
        return None

    if max_concurrency and (len(progress.running) >= max_concurrency):
        return None

    if not ignore_down_nodes:
        for host in remaining:
            if not host.is_up:
                raise HostIsDown(host)

    return _strategy_mapping[strategy](remaining, endpoint_mapping, progress.running)