HDDS-10345. Sorting isn't needed when excluding Datanodes during Ratis Pipeline Creation

[siddhantsangwan]

What changes were proposed in this pull request?

RatisPipelineProvider is used to create a new Ratis pipeline when SCM is asked to provide one and existing pipelines can't be used. Both WritableRatisContainerProvider and BackgroundPipelineCreator create pipelines this way, dynamically and in the background, respectively.

As part of new pipeline creation, Datanodes are excluded if they're already engaged in "ozone.scm.datanode.pipeline.limit" number of pipelines:

  private List<DatanodeDetails> filterPipelineEngagement() {
    List<DatanodeDetails> healthyNodes =
        getNodeManager().getNodes(NodeStatus.inServiceHealthy());
    List<DatanodeDetails> excluded = healthyNodes.stream()
        .map(d ->
            new DnWithPipelines(d,
                PipelinePlacementPolicy
                    .currentRatisThreePipelineCount(getNodeManager(),
                    getPipelineStateManager(), d)))
        .filter(d ->
            (d.getPipelines() >= getNodeManager().pipelineLimit(d.getDn())))
        .sorted(Comparator.comparingInt(DnWithPipelines::getPipelines))
        .map(d -> d.getDn())
        .collect(Collectors.toList());
    return excluded;
  }

As you can see, this list is sorted before returning. I don't think sorting here is required since those Datanodes will just get excluded and we don't really need ordering.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-10345

How was this patch tested?

Existing tests.

Successful CI in my fork: https://github.com/siddhantsangwan/ozone/actions/runs/7916689597

[nandakumar131]

LGTM. Pending CI.

[adoroszlai]

Thanks @siddhantsangwan for the patch, @nandakumar131 for the review.