How to use

chooseRandom

method

in

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

private DatanodeStorageInfo chooseFromNextRack(Node next,
  Set<Node> excludedNodes,
  long blocksize,
  int maxNodesPerRack,
  List<DatanodeStorageInfo> results,
  boolean avoidStaleNodes,
  EnumMap<StorageType, Integer> storageTypes) throws NotEnoughReplicasException {
 final String nextRack = next.getNetworkLocation();
 try {
  return chooseRandom(nextRack, excludedNodes, blocksize, maxNodesPerRack,
    results, avoidStaleNodes, storageTypes);
 } catch(NotEnoughReplicasException e) {
  if (LOG.isDebugEnabled()) {
   LOG.debug("Failed to choose from the next rack (location = " + nextRack
     + "), retry choosing randomly", e);
  }
  //otherwise randomly choose one from the network
  return chooseRandom(NodeBase.ROOT, excludedNodes, blocksize,
    maxNodesPerRack, results, avoidStaleNodes, storageTypes);
 }
}

chooseRandom(numOfReplicas, "~" + localMachine.getNetworkLocation(),
  excludedNodes, blocksize, maxReplicasPerRack, results,
  avoidStaleNodes, storageTypes);
   + localMachine.getNetworkLocation() + "), fallback to local rack", e);
chooseRandom(numOfReplicas-(results.size()-oldNumOfReplicas),
       localMachine.getNetworkLocation(), excludedNodes, blocksize, 
       maxReplicasPerRack, results, avoidStaleNodes, storageTypes);

 return chooseRandom(NodeBase.ROOT, excludedNodes, blocksize,
   maxNodesPerRack, results, avoidStaleNodes, storageTypes);
 return chooseRandom(localRack, excludedNodes,
   blocksize, maxNodesPerRack, results, avoidStaleNodes, storageTypes);
} catch (NotEnoughReplicasException e) {
 return chooseRandom(NodeBase.ROOT, excludedNodes, blocksize,
   maxNodesPerRack, results, avoidStaleNodes, storageTypes);

return chooseRandom(NodeBase.ROOT, excludedNodes, blocksize,
  maxNodesPerRack, results, avoidStaleNodes, storageTypes);

/**
 * Randomly choose <i>numOfReplicas</i> targets from the given <i>scope</i>.
 * @return the first chosen node, if there is any.
 */
protected DatanodeStorageInfo chooseRandom(int numOfReplicas,
             String scope,
             Set<Node> excludedNodes,
             long blocksize,
             int maxNodesPerRack,
             List<DatanodeStorageInfo> results,
             boolean avoidStaleNodes,
             EnumMap<StorageType, Integer> storageTypes)
             throws NotEnoughReplicasException {
 StringBuilder builder = null;
 if (LOG.isDebugEnabled()) {
  builder = debugLoggingBuilder.get();
  builder.setLength(0);
  builder.append("[");
 }
 CHOOSE_RANDOM_REASONS.get().clear();
 boolean badTarget = false;
 DatanodeStorageInfo firstChosen = null;
 while (numOfReplicas > 0) {
  // the storage type that current node has
  StorageType includeType = null;
  DatanodeDescriptor chosenNode = null;
  if (clusterMap instanceof DFSNetworkTopology) {
   for (StorageType type : storageTypes.keySet()) {
    chosenNode = chooseDataNode(scope, excludedNodes, type);

chooseRandom(numOfReplicas, NodeBase.ROOT, excludedNodes, blocksize,
  maxNodesPerRack, results, avoidStaleNodes, storageTypes);
return writer;

private DatanodeStorageInfo chooseFromNextRack(Node next,
  Set<Node> excludedNodes,
  long blocksize,
  int maxNodesPerRack,
  List<DatanodeStorageInfo> results,
  boolean avoidStaleNodes,
  EnumMap<StorageType, Integer> storageTypes) throws NotEnoughReplicasException {
 final String nextRack = next.getNetworkLocation();
 try {
  return chooseRandom(nextRack, excludedNodes, blocksize, maxNodesPerRack,
    results, avoidStaleNodes, storageTypes);
 } catch(NotEnoughReplicasException e) {
  if (LOG.isDebugEnabled()) {
   LOG.debug("Failed to choose from the next rack (location = " + nextRack
     + "), retry choosing ramdomly", e);
  }
  //otherwise randomly choose one from the network
  return chooseRandom(NodeBase.ROOT, excludedNodes, blocksize,
    maxNodesPerRack, results, avoidStaleNodes, storageTypes);
 }
}

chooseRandom(numOfReplicas, "~" + localMachine.getNetworkLocation(),
  excludedNodes, blocksize, maxReplicasPerRack, results,
  avoidStaleNodes, storageTypes);
   + localMachine.getNetworkLocation() + "), fallback to local rack", e);
chooseRandom(numOfReplicas-(results.size()-oldNumOfReplicas),
       localMachine.getNetworkLocation(), excludedNodes, blocksize, 
       maxReplicasPerRack, results, avoidStaleNodes, storageTypes);

private DatanodeStorageInfo chooseFromNextRack(Node next,
  Set<Node> excludedNodes,
  long blocksize,
  int maxNodesPerRack,
  List<DatanodeStorageInfo> results,
  boolean avoidStaleNodes,
  EnumMap<StorageType, Integer> storageTypes) throws NotEnoughReplicasException {
 final String nextRack = next.getNetworkLocation();
 try {
  return chooseRandom(nextRack, excludedNodes, blocksize, maxNodesPerRack,
    results, avoidStaleNodes, storageTypes);
 } catch(NotEnoughReplicasException e) {
  if (LOG.isDebugEnabled()) {
   LOG.debug("Failed to choose from the next rack (location = " + nextRack
     + "), retry choosing ramdomly", e);
  }
  //otherwise randomly choose one from the network
  return chooseRandom(NodeBase.ROOT, excludedNodes, blocksize,
    maxNodesPerRack, results, avoidStaleNodes, storageTypes);
 }
}

 return chooseRandom(NodeBase.ROOT, excludedNodes, blocksize,
   maxNodesPerRack, results, avoidStaleNodes, storageTypes);
 return chooseRandom(localRack, excludedNodes,
   blocksize, maxNodesPerRack, results, avoidStaleNodes, storageTypes);
} catch (NotEnoughReplicasException e) {
 return chooseRandom(NodeBase.ROOT, excludedNodes, blocksize,
   maxNodesPerRack, results, avoidStaleNodes, storageTypes);

return chooseRandom(NodeBase.ROOT, excludedNodes, blocksize,
  maxNodesPerRack, results, avoidStaleNodes, storageTypes);

return chooseRandom(NodeBase.ROOT, excludedNodes, blocksize,
  maxNodesPerRack, results, avoidStaleNodes, storageTypes);

chooseRandom(numOfReplicas, "~" + localMachine.getNetworkLocation(),
  excludedNodes, blocksize, maxReplicasPerRack, results,
  avoidStaleNodes, storageTypes);
   + localMachine.getNetworkLocation() + "), fallback to local rack", e);
chooseRandom(numOfReplicas-(results.size()-oldNumOfReplicas),
       localMachine.getNetworkLocation(), excludedNodes, blocksize, 
       maxReplicasPerRack, results, avoidStaleNodes, storageTypes);

/**
 * Randomly choose <i>numOfReplicas</i> targets from the given <i>scope</i>.
 * @return the first chosen node, if there is any.
 */
protected DatanodeStorageInfo chooseRandom(int numOfReplicas,
             String scope,
             Set<Node> excludedNodes,
             long blocksize,
             int maxNodesPerRack,
             List<DatanodeStorageInfo> results,
             boolean avoidStaleNodes,
             EnumMap<StorageType, Integer> storageTypes)
             throws NotEnoughReplicasException {
  
 int numOfAvailableNodes = clusterMap.countNumOfAvailableNodes(
   scope, excludedNodes);
 int refreshCounter = numOfAvailableNodes;
 StringBuilder builder = null;
 if (LOG.isDebugEnabled()) {
  builder = debugLoggingBuilder.get();
  builder.setLength(0);
  builder.append("[");
 }
 boolean badTarget = false;
 DatanodeStorageInfo firstChosen = null;
 while(numOfReplicas > 0 && numOfAvailableNodes > 0) {
  DatanodeDescriptor chosenNode = chooseDataNode(scope);
  if (excludedNodes.add(chosenNode)) { //was not in the excluded list
   if (LOG.isDebugEnabled() && builder != null) {
    builder.append("\nNode ").append(NodeBase.getPath(chosenNode)).append(" [");

/**
 * Randomly choose <i>numOfReplicas</i> targets from the given <i>scope</i>.
 * @return the first chosen node, if there is any.
 */
protected DatanodeStorageInfo chooseRandom(int numOfReplicas,
             String scope,
             Set<Node> excludedNodes,
             long blocksize,
             int maxNodesPerRack,
             List<DatanodeStorageInfo> results,
             boolean avoidStaleNodes,
             EnumMap<StorageType, Integer> storageTypes)
             throws NotEnoughReplicasException {
  
 int numOfAvailableNodes = clusterMap.countNumOfAvailableNodes(
   scope, excludedNodes);
 int refreshCounter = numOfAvailableNodes;
 StringBuilder builder = null;
 if (LOG.isDebugEnabled()) {
  builder = debugLoggingBuilder.get();
  builder.setLength(0);
  builder.append("[");
 }
 boolean badTarget = false;
 DatanodeStorageInfo firstChosen = null;
 while(numOfReplicas > 0 && numOfAvailableNodes > 0) {
  DatanodeDescriptor chosenNode = chooseDataNode(scope);
  if (excludedNodes.add(chosenNode)) { //was not in the excluded list
   if (LOG.isDebugEnabled() && builder != null) {
    builder.append("\nNode ").append(NodeBase.getPath(chosenNode)).append(" [");

 return chooseRandom(NodeBase.ROOT, excludedNodes, blocksize,
   maxNodesPerRack, results, avoidStaleNodes, storageTypes);
 return chooseRandom(localRack, excludedNodes,
   blocksize, maxNodesPerRack, results, avoidStaleNodes, storageTypes);
} catch (NotEnoughReplicasException e) {
 return chooseRandom(NodeBase.ROOT, excludedNodes, blocksize,
   maxNodesPerRack, results, avoidStaleNodes, storageTypes);

 chooseRandom(numOfReplicas, NodeBase.ROOT, excludedNodes, blocksize,
   maxNodesPerRack, results, avoidStaleNodes, storageTypes);
} catch (NotEnoughReplicasException e) {

 chooseRandom(numOfReplicas, NodeBase.ROOT, excludedNodes, blocksize,
   maxNodesPerRack, results, avoidStaleNodes, storageTypes);
} catch (NotEnoughReplicasException e) {