in hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/container/placement/algorithms/SCMContainerPlacementRackAware.java [275:418]
protected List<DatanodeDetails> chooseDatanodesInternalLegacy(
List<DatanodeDetails> excludedNodes,
List<DatanodeDetails> favoredNodes, int nodesRequired,
Map<String, Long> mapSizeRequired)
throws SCMException {
Preconditions.checkArgument(nodesRequired > 0);
metrics.incrDatanodeRequestCount(nodesRequired);
int datanodeCount = networkTopology.getNumOfLeafNode(NetConstants.ROOT);
int excludedNodesCount = excludedNodes == null ? 0 : excludedNodes.size();
if (datanodeCount < nodesRequired + excludedNodesCount) {
throw new SCMException("No enough datanodes to choose. " +
"TotalNode = " + datanodeCount +
" RequiredNode = " + nodesRequired +
" ExcludedNode = " + excludedNodesCount, null);
}
long metadataSizeRequired = mapSizeRequired.get(META_DATA_SIZE_REQUIRED);
long dataSizeRequired = mapSizeRequired.get(DATA_SIZE_REQUIRED);
List<DatanodeDetails> mutableFavoredNodes = favoredNodes;
List<DatanodeDetails> mutableUsedNodes = new ArrayList<>();
// sanity check of favoredNodes
if (mutableFavoredNodes != null && excludedNodes != null) {
mutableFavoredNodes = new ArrayList<>();
mutableFavoredNodes.addAll(favoredNodes);
mutableFavoredNodes.removeAll(excludedNodes);
}
int favoredNodeNum = mutableFavoredNodes == null ? 0 :
mutableFavoredNodes.size();
List<DatanodeDetails> chosenNodes = new ArrayList<>();
int favorIndex = 0;
if (excludedNodes == null || excludedNodes.isEmpty()) {
// choose all nodes for a new pipeline case
// choose first datanode from scope ROOT or from favoredNodes if not null
DatanodeDetails favoredNode = favoredNodeNum > favorIndex ?
mutableFavoredNodes.get(favorIndex) : null;
DatanodeDetails firstNode;
if (favoredNode != null) {
firstNode = favoredNode;
favorIndex++;
} else {
firstNode = chooseNode(null, null, null, metadataSizeRequired,
dataSizeRequired);
}
chosenNodes.add(firstNode);
nodesRequired--;
if (nodesRequired == 0) {
return Arrays.asList(chosenNodes.toArray(new DatanodeDetails[0]));
}
// choose second datanode on the same rack as first one
favoredNode = favoredNodeNum > favorIndex ?
mutableFavoredNodes.get(favorIndex) : null;
DatanodeDetails secondNode;
if (favoredNode != null &&
networkTopology.isSameParent(firstNode, favoredNode)) {
secondNode = favoredNode;
favorIndex++;
} else {
secondNode = chooseNode(chosenNodes, Arrays.asList(firstNode),
Arrays.asList(firstNode), metadataSizeRequired, dataSizeRequired);
}
chosenNodes.add(secondNode);
nodesRequired--;
if (nodesRequired == 0) {
return Arrays.asList(chosenNodes.toArray(new DatanodeDetails[0]));
}
mutableUsedNodes.addAll(chosenNodes);
// choose remaining datanodes on different rack as first and second
return chooseNodes(null, chosenNodes, mutableFavoredNodes,
mutableUsedNodes, favorIndex, nodesRequired, mapSizeRequired);
} else {
List<DatanodeDetails> mutableExcludedNodes = new ArrayList<>(excludedNodes);
// choose node to meet replication requirement
// case 1: one excluded node, choose one on the same rack as the excluded
// node, choose others on different racks.
DatanodeDetails favoredNode;
if (excludedNodes.size() == 1) {
favoredNode = favoredNodeNum > favorIndex ?
mutableFavoredNodes.get(favorIndex) : null;
DatanodeDetails firstNode;
if (favoredNode != null &&
networkTopology.isSameParent(excludedNodes.get(0), favoredNode)) {
firstNode = favoredNode;
favorIndex++;
} else {
firstNode = chooseNode(mutableExcludedNodes, excludedNodes,
excludedNodes, metadataSizeRequired, dataSizeRequired);
}
chosenNodes.add(firstNode);
nodesRequired--;
if (nodesRequired == 0) {
return Arrays.asList(chosenNodes.toArray(new DatanodeDetails[0]));
}
// choose remaining nodes on different racks
mutableUsedNodes.addAll(chosenNodes);
mutableUsedNodes.addAll(mutableExcludedNodes);
return chooseNodes(null, chosenNodes, mutableFavoredNodes,
mutableUsedNodes, favorIndex, nodesRequired, mapSizeRequired);
}
// case 2: two or more excluded nodes, if these two nodes are
// in the same rack, then choose nodes on different racks, otherwise,
// choose one on the same rack as one of excluded nodes, remaining chosen
// are on different racks.
for (int i = 0; i < excludedNodesCount; i++) {
for (int j = i + 1; j < excludedNodesCount; j++) {
if (networkTopology.isSameParent(
excludedNodes.get(i), excludedNodes.get(j))) {
// choose remaining nodes on different racks
mutableUsedNodes.addAll(chosenNodes);
mutableUsedNodes.addAll(mutableExcludedNodes);
return chooseNodes(mutableExcludedNodes, chosenNodes,
mutableFavoredNodes, mutableUsedNodes, favorIndex,
nodesRequired, mapSizeRequired);
}
}
}
// choose one data on the same rack with one excluded node
favoredNode = favoredNodeNum > favorIndex ?
mutableFavoredNodes.get(favorIndex) : null;
DatanodeDetails secondNode;
if (favoredNode != null && networkTopology.isSameParent(
mutableExcludedNodes.get(0), favoredNode)) {
secondNode = favoredNode;
favorIndex++;
} else {
secondNode =
chooseNode(chosenNodes, mutableExcludedNodes, mutableExcludedNodes,
metadataSizeRequired, dataSizeRequired);
}
chosenNodes.add(secondNode);
mutableExcludedNodes.add(secondNode);
nodesRequired--;
if (nodesRequired == 0) {
return Arrays.asList(chosenNodes.toArray(new DatanodeDetails[0]));
}
// choose remaining nodes on different racks
mutableUsedNodes.addAll(chosenNodes);
mutableUsedNodes.addAll(mutableExcludedNodes);
return chooseNodes(mutableExcludedNodes, chosenNodes, mutableFavoredNodes,
mutableUsedNodes,
favorIndex, nodesRequired, mapSizeRequired);
}
}