How to use

pickupReplicaSet

method

in

org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault

@Override
protected Collection<DatanodeStorageInfo> pickupReplicaSet(
  Collection<DatanodeStorageInfo> moreThanOne,
  Collection<DatanodeStorageInfo> exactlyOne,
  Map<String, List<DatanodeStorageInfo>> rackMap) {
 // shareUDSet includes DatanodeStorageInfo that share same upgrade
 // domain with another DatanodeStorageInfo.
 Collection<DatanodeStorageInfo> all = combine(moreThanOne, exactlyOne);
 List<DatanodeStorageInfo> shareUDSet = getShareUDSet(
   getUpgradeDomainMap(all));
 // shareRackAndUDSet contains those DatanodeStorageInfo that
 // share rack and upgrade domain with another DatanodeStorageInfo.
 List<DatanodeStorageInfo> shareRackAndUDSet = new ArrayList<>();
 if (shareUDSet.size() == 0) {
  // All upgrade domains are unique, use the parent set.
  return super.pickupReplicaSet(moreThanOne, exactlyOne, rackMap);
 } else if (moreThanOne != null) {
  for (DatanodeStorageInfo storage : shareUDSet) {
   if (moreThanOne.contains(storage)) {
    shareRackAndUDSet.add(storage);
   }
  }
 }
 return (shareRackAndUDSet.size() > 0) ? shareRackAndUDSet : shareUDSet;
}

for(DatanodeStorageInfo storage : pickupReplicaSet(moreThanOne,
  exactlyOne, rackMap)) {
 if (!excessTypes.contains(storage.getStorageType())) {

for(DatanodeStorageInfo storage : pickupReplicaSet(moreThanOne,
  exactlyOne, rackMap)) {
 if (!excessTypes.contains(storage.getStorageType())) {

for(DatanodeStorageInfo storage : pickupReplicaSet(moreThanOne,
  exactlyOne, rackMap)) {
 if (!excessTypes.contains(storage.getStorageType())) {