/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hdfs.server.namenode;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.URI;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.EnumSet;
import java.util.List;

import org.apache.hadoop.util.Preconditions;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.crypto.CryptoProtocolVersion;
import org.apache.hadoop.fs.CreateFlag;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.DFSTestUtil;
import org.apache.hadoop.hdfs.DFSUtilClient;
import org.apache.hadoop.hdfs.DistributedFileSystem;
import org.apache.hadoop.hdfs.HdfsConfiguration;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.BlockListAsLongs;
import org.apache.hadoop.hdfs.protocol.BlockListAsLongs.BlockReportReplica;
import org.apache.hadoop.hdfs.protocol.ClientProtocol;
import org.apache.hadoop.hdfs.protocol.DatanodeID;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
import org.apache.hadoop.hdfs.protocol.HdfsConstants;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolClientSideTranslatorPB;
import org.apache.hadoop.hdfs.security.token.block.ExportedBlockKeys;
import org.apache.hadoop.hdfs.server.blockmanagement.BlockManagerTestUtil;
import org.apache.hadoop.hdfs.server.datanode.DataNode;
import org.apache.hadoop.hdfs.server.datanode.DataStorage;
import org.apache.hadoop.hdfs.server.protocol.BlockCommand;
import org.apache.hadoop.hdfs.server.protocol.BlockReportContext;
import org.apache.hadoop.hdfs.server.protocol.DatanodeCommand;
import org.apache.hadoop.hdfs.server.protocol.DatanodeProtocol;
import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
import org.apache.hadoop.hdfs.server.protocol.DatanodeStorage;
import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocol;
import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocols;
import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
import org.apache.hadoop.hdfs.server.protocol.ReceivedDeletedBlockInfo;
import org.apache.hadoop.hdfs.server.protocol.SlowDiskReports;
import org.apache.hadoop.hdfs.server.protocol.SlowPeerReports;
import org.apache.hadoop.hdfs.server.protocol.StorageBlockReport;
import org.apache.hadoop.hdfs.server.protocol.StorageReceivedDeletedBlocks;
import org.apache.hadoop.hdfs.server.protocol.StorageReport;
import org.apache.hadoop.io.EnumSetWritable;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.net.DNS;
import org.apache.hadoop.net.NetworkTopology;
import org.apache.hadoop.security.Groups;
import org.apache.hadoop.security.RefreshUserMappingsProtocol;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hadoop.test.GenericTestUtils;
import org.apache.hadoop.util.ExitUtil;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.StringUtils;
import org.apache.hadoop.util.Time;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.hadoop.util.VersionInfo;
import org.apache.hadoop.util.concurrent.SubjectInheritingThread;
import org.slf4j.event.Level;

/**
 * Main class for a series of name-node benchmarks.
 *
 * Each benchmark measures throughput and average execution time 
 * of a specific name-node operation, e.g. file creation or block reports.
 *
 * The benchmark does not involve any other hadoop components
 * except for the name-node. Each operation is executed
 * by calling directly the respective name-node method.
 * The name-node here is real all other components are simulated.
 *
 * For usage, please see <a href="http://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-common/Benchmarking.html#NNThroughputBenchmark">the documentation</a>.
 * Meanwhile, if you change the usage of this program, please also update the
 * documentation accordingly.
 */
public class NNThroughputBenchmark implements Tool {
  private static final Logger LOG =
      LoggerFactory.getLogger(NNThroughputBenchmark.class);
  private static final int BLOCK_SIZE = 16;
  private static final String GENERAL_OPTIONS_USAGE =
      "[-keepResults] | [-logLevel L] | [-UGCacheRefreshCount G] [-nonSuperUser]";

  static Configuration config;
  static NameNode nameNode;
  static NamenodeProtocol nameNodeProto;
  static ClientProtocol clientProto;
  static DatanodeProtocol dataNodeProto;
  static RefreshUserMappingsProtocol refreshUserMappingsProto;
  static String bpid = null;

  NNThroughputBenchmark(Configuration conf) throws IOException {
    config = conf;
    // We do not need many handlers, since each thread simulates a handler
    // by calling name-node methods directly
    config.setInt(DFSConfigKeys.DFS_DATANODE_HANDLER_COUNT_KEY, 1);
    // Turn off minimum block size verification
    config.setInt(DFSConfigKeys.DFS_NAMENODE_MIN_BLOCK_SIZE_KEY, 0);
    // set exclude file
    config.set(DFSConfigKeys.DFS_HOSTS_EXCLUDE,
      "${hadoop.tmp.dir}/dfs/hosts/exclude");
    File excludeFile = new File(config.get(DFSConfigKeys.DFS_HOSTS_EXCLUDE,
      "exclude"));
    if(!excludeFile.exists()) {
      if(!excludeFile.getParentFile().exists() && !excludeFile.getParentFile().mkdirs())
        throw new IOException("NNThroughputBenchmark: cannot mkdir " + excludeFile);
    }
    new FileOutputStream(excludeFile).close();
    // set include file
    config.set(DFSConfigKeys.DFS_HOSTS, "${hadoop.tmp.dir}/dfs/hosts/include");
    File includeFile = new File(config.get(DFSConfigKeys.DFS_HOSTS, "include"));
    new FileOutputStream(includeFile).close();
  }

  void close() {
    if(nameNode != null)
      nameNode.stop();
  }

  static void setNameNodeLoggingLevel(Level logLevel) {
    LOG.info("Log level = " + logLevel.toString());
    // change log level to NameNode logs
    DFSTestUtil.setNameNodeLogLevel(logLevel);
    GenericTestUtils.setLogLevel(LoggerFactory.getLogger(
            NetworkTopology.class.getName()), logLevel);
    GenericTestUtils.setLogLevel(LoggerFactory.getLogger(
            Groups.class.getName()), logLevel);
  }

  /**
   * Base class for collecting operation statistics.
   *
   * Overload this class in order to run statistics for a 
   * specific name-node operation.
   */
  abstract class OperationStatsBase {
    private String baseDirName = "/nnThroughputBenchmark";
    protected static final String OP_ALL_NAME = "all";
    protected static final String OP_ALL_USAGE = "-op all <other ops options>";

    private String baseDir;
    protected short replication;
    protected long blockSize;
    protected int  numThreads = 0;        // number of threads
    protected int  numOpsRequired = 0;    // number of operations requested
    protected int  numOpsExecuted = 0;    // number of operations executed
    protected long cumulativeTime = 0;    // sum of times for each op
    protected long elapsedTime = 0;       // time from start to finish
    protected boolean keepResults = false;// don't clean base directory on exit
    protected boolean nonSuperUser = false; // enter/exit safe mode
    protected Level logLevel;             // logging level, ERROR by default
    protected int ugcRefreshCount = 0;    // user group cache refresh count

    protected List<StatsDaemon> daemons;

    /**
     * Operation name.
     */
    abstract String getOpName();

    /**
     * Parse command line arguments.
     *
     * @param args arguments
     * @throws IOException
     */
    abstract void parseArguments(List<String> args) throws IOException;

    /**
     * Generate inputs for each daemon thread.
     *
     * @param opsPerThread number of inputs for each thread.
     * @throws IOException
     */
    abstract void generateInputs(int[] opsPerThread) throws IOException;

    /**
     * This corresponds to the arg1 argument of 
     * {@link #executeOp(int, int, String)}, which can have different meanings
     * depending on the operation performed.
     *
     * @param daemonId id of the daemon calling this method
     * @return the argument
     */
    abstract String getExecutionArgument(int daemonId);

    /**
     * Execute name-node operation.
     *
     * @param daemonId id of the daemon calling this method.
     * @param inputIdx serial index of the operation called by the deamon.
     * @param arg1 operation specific argument.
     * @return time of the individual name-node call.
     * @throws IOException
     */
    abstract long executeOp(int daemonId, int inputIdx, String arg1) throws IOException;

    /**
     * Print the results of the benchmarking.
     */
    abstract void printResults();

    OperationStatsBase() {
      baseDir = baseDirName + "/" + getOpName();
      replication = (short) config.getInt(DFSConfigKeys.DFS_REPLICATION_KEY, 3);
      blockSize = config.getLongBytes(DFSConfigKeys.DFS_BLOCK_SIZE_KEY, BLOCK_SIZE);
      numOpsRequired = 10;
      numThreads = 3;
      logLevel = Level.ERROR;
      ugcRefreshCount = Integer.MAX_VALUE;
    }

    void benchmark() throws IOException {
      daemons = new ArrayList<StatsDaemon>();
      long start = 0;
      try {
        numOpsExecuted = 0;
        cumulativeTime = 0;
        if(numThreads < 1)
          return;
        int tIdx = 0; // thread index < nrThreads
        int opsPerThread[] = new int[numThreads];
        for(int opsScheduled = 0; opsScheduled < numOpsRequired;
                                  opsScheduled += opsPerThread[tIdx++]) {
          // execute  in a separate thread
          opsPerThread[tIdx] = (numOpsRequired-opsScheduled)/(numThreads-tIdx);
          if(opsPerThread[tIdx] == 0)
            opsPerThread[tIdx] = 1;
        }
        // if numThreads > numOpsRequired then the remaining threads will do nothing
        for(; tIdx < numThreads; tIdx++)
          opsPerThread[tIdx] = 0;
        generateInputs(opsPerThread);
        setNameNodeLoggingLevel(logLevel);
        for(tIdx=0; tIdx < numThreads; tIdx++)
          daemons.add(new StatsDaemon(tIdx, opsPerThread[tIdx], this));
        start = Time.now();
        LOG.info("Starting " + numOpsRequired + " " + getOpName() + "(s).");
        for(StatsDaemon d : daemons)
          d.start();
      } finally {
        while(isInProgress()) {
          // try {Thread.sleep(500);} catch (InterruptedException e) {}
        }
        elapsedTime = Time.now() - start;
        for(StatsDaemon d : daemons) {
          incrementStats(d.localNumOpsExecuted, d.localCumulativeTime);
          // System.out.println(d.toString() + ": ops Exec = " + d.localNumOpsExecuted);
        }
      }
    }

    private boolean isInProgress() {
      for(StatsDaemon d : daemons)
        if(d.isInProgress())
          return true;
      return false;
    }

    void cleanUp() throws IOException {
      if (!nonSuperUser) {
        try {
          clientProto.setSafeMode(HdfsConstants.SafeModeAction.SAFEMODE_LEAVE,
                  false);
        } catch (Exception e){
          LOG.error("Potentially insufficient permission: try running the tool" +
                    "with -nonSuperUser argument or login as super user");
          throw e;
        }
      }
      if(!keepResults)
        clientProto.delete(getBaseDir(), true);
      else {
        if (!nonSuperUser) {
          try {
            clientProto.setSafeMode(HdfsConstants.SafeModeAction.SAFEMODE_ENTER,
                    true);
            clientProto.saveNamespace(0, 0);
          } catch (Exception e){
            LOG.error("Potentially insufficient permission: try running the tool" +
                      " with -nonSuperUser argument or login as super user");
            throw e;
          }
        }
      }
    }
    public String getBaseDirName() {
      return baseDirName;
    }
    public void setBaseDirName(String baseDirName) {
      this.baseDirName = baseDirName;
    }
    int getNumOpsExecuted() {
      return numOpsExecuted;
    }

    long getCumulativeTime() {
      return cumulativeTime;
    }

    long getElapsedTime() {
      return elapsedTime;
    }

    long getAverageTime() {
      return numOpsExecuted == 0 ? 0 : cumulativeTime / numOpsExecuted;
    }

    double getOpsPerSecond() {
      return elapsedTime == 0 ? 0 : 1000*(double)numOpsExecuted / elapsedTime;
    }

    public String getBaseDir() {
      setBaseDir(baseDirName + "/" + getOpName());
      return baseDir;
    }

    public void setBaseDir(String baseDir) {
      this.baseDir = baseDir;
    }

    String getClientName(int idx) {
      return getOpName() + "-client-" + idx;
    }

    void incrementStats(int ops, long time) {
      numOpsExecuted += ops;
      cumulativeTime += time;
    }

    /**
     * Parse first 2 arguments, corresponding to the "-op" option.
     *
     * @param args argument list
     * @return true if operation is all, which means that options not related
     * to this operation should be ignored, or false otherwise, meaning
     * that usage should be printed when an unrelated option is encountered.
     */
    protected boolean verifyOpArgument(List<String> args) {
      if(args.size() < 2 || ! args.get(0).startsWith("-op"))
        printUsage();

      // process common options
      int krIndex = args.indexOf("-keepResults");
      keepResults = (krIndex >= 0);
      if(keepResults) {
        args.remove(krIndex);
      }

      int nonSuperUserIndex = args.indexOf("-nonSuperUser");
      nonSuperUser = (nonSuperUserIndex >= 0);
      if(nonSuperUser) {
        args.remove(nonSuperUserIndex);
      }

      int llIndex = args.indexOf("-logLevel");
      if(llIndex >= 0) {
        if(args.size() <= llIndex + 1)
          printUsage();
        logLevel = Level.valueOf(args.get(llIndex+1));
        args.remove(llIndex+1);
        args.remove(llIndex);
      }

      int ugrcIndex = args.indexOf("-UGCacheRefreshCount");
      if(ugrcIndex >= 0) {
        if(args.size() <= ugrcIndex + 1)
          printUsage();
        int g = Integer.parseInt(args.get(ugrcIndex+1));
        if(g > 0) ugcRefreshCount = g;
        args.remove(ugrcIndex+1);
        args.remove(ugrcIndex);
      }

      String type = args.get(1);
      if(OP_ALL_NAME.equals(type)) {
        type = getOpName();
        return true;
      }
      if(!getOpName().equals(type))
        printUsage();
      return false;
    }

    void printStats() {
      LOG.info("--- " + getOpName() + " stats  ---");
      LOG.info("# operations: " + getNumOpsExecuted());
      LOG.info("Elapsed Time: " + getElapsedTime());
      LOG.info(" Ops per sec: " + getOpsPerSecond());
      LOG.info("Average Time: " + getAverageTime());
    }
  }

  /**
   * One of the threads that perform stats operations.
   */
  private class StatsDaemon extends SubjectInheritingThread {
    private final int daemonId;
    private int opsPerThread;
    private String arg1;      // argument passed to executeOp()
    private volatile int  localNumOpsExecuted = 0;
    private volatile long localCumulativeTime = 0;
    private final OperationStatsBase statsOp;

    StatsDaemon(int daemonId, int nrOps, OperationStatsBase op) {
      this.daemonId = daemonId;
      this.opsPerThread = nrOps;
      this.statsOp = op;
      setName(toString());
    }

    @Override
    public void work() {
      localNumOpsExecuted = 0;
      localCumulativeTime = 0;
      arg1 = statsOp.getExecutionArgument(daemonId);
      try {
        benchmarkOne();
      } catch(IOException ex) {
        LOG.error("StatsDaemon " + daemonId + " failed: \n"
            + StringUtils.stringifyException(ex));
      }
    }

    @Override
    public String toString() {
      return "StatsDaemon-" + daemonId;
    }

    void benchmarkOne() throws IOException {
      for(int idx = 0; idx < opsPerThread; idx++) {
        if((localNumOpsExecuted+1) % statsOp.ugcRefreshCount == 0)
          refreshUserMappingsProto.refreshUserToGroupsMappings();
        long stat = statsOp.executeOp(daemonId, idx, arg1);
        localNumOpsExecuted++;
        localCumulativeTime += stat;
      }
    }

    boolean isInProgress() {
      return localNumOpsExecuted < opsPerThread;
    }

    /**
     * Schedule to stop this daemon.
     */
    void terminate() {
      opsPerThread = localNumOpsExecuted;
    }
  }

  /**
   * Clean all benchmark result directories.
   */
  class CleanAllStats extends OperationStatsBase {
    // Operation types
    static final String OP_CLEAN_NAME = "clean";
    static final String OP_CLEAN_USAGE = "-op clean";

    CleanAllStats(List<String> args) {
      super();
      parseArguments(args);
      numOpsRequired = 1;
      numThreads = 1;
      keepResults = true;
    }

    @Override
    String getOpName() {
      return OP_CLEAN_NAME;
    }

    @Override
    void parseArguments(List<String> args) {
      boolean ignoreUnrelatedOptions = verifyOpArgument(args);
      if(args.size() > 2 && !ignoreUnrelatedOptions)
        printUsage();
    }

    @Override
    void generateInputs(int[] opsPerThread) throws IOException {
      // do nothing
    }

    /**
     * Does not require the argument
     */
    @Override
    String getExecutionArgument(int daemonId) {
      return null;
    }

    /**
     * Remove entire benchmark directory.
     */
    @Override
    long executeOp(int daemonId, int inputIdx, String ignore)
    throws IOException {
      if (!nonSuperUser) {
        try{
          clientProto.setSafeMode(HdfsConstants.SafeModeAction.SAFEMODE_LEAVE,
                  false);
        } catch (Exception e){
          LOG.error("Potentially insufficient permission: try running the tool" +
                    " with -nonSuperUser argument or login as super user");
          throw e;
        }
      }
      long start = Time.now();
      clientProto.delete(getBaseDirName(), true);
      long end = Time.now();
      return end-start;
    }

    @Override
    void printResults() {
      LOG.info("--- " + getOpName() + " inputs ---");
      LOG.info("Remove directory " + getBaseDirName());
      printStats();
    }
  }

  /**
   * File creation statistics.
   *
   * Each thread creates the same (+ or -1) number of files.
   * File names are pre-generated during initialization.
   * The created files do not have blocks.
   */
  class CreateFileStats extends OperationStatsBase {
    // Operation types
    static final String OP_CREATE_NAME = "create";
    static final String OP_CREATE_USAGE =
        "-op create [-threads T] [-files N] [-blockSize S] [-filesPerDir P]"
        + " [-baseDirName D] [-close]";

    protected FileNameGenerator nameGenerator;
    protected String[][] fileNames;
    private boolean closeUponCreate;

    CreateFileStats(List<String> args) {
      super();
      parseArguments(args);
    }

    @Override
    String getOpName() {
      return OP_CREATE_NAME;
    }

    @Override
    void parseArguments(List<String> args) {
      boolean ignoreUnrelatedOptions = verifyOpArgument(args);
      int nrFilesPerDir = 4;
      closeUponCreate = false;
      for (int i = 2; i < args.size(); i++) {       // parse command line
        if(args.get(i).equals("-files")) {
          if(i+1 == args.size())  printUsage();
          numOpsRequired = Integer.parseInt(args.get(++i));
        } else if (args.get(i).equals("-blockSize")) {
          if(i+1 == args.size())  printUsage();
          blockSize = StringUtils.TraditionalBinaryPrefix.string2long(args.get(++i));
        } else if(args.get(i).equals("-threads")) {
          if(i+1 == args.size())  printUsage();
          numThreads = Integer.parseInt(args.get(++i));
        } else if(args.get(i).equals("-filesPerDir")) {
          if(i+1 == args.size())  printUsage();
          nrFilesPerDir = Integer.parseInt(args.get(++i));
        } else if(args.get(i).equals("-baseDirName")) {
          if (i + 1 == args.size()) {
            printUsage();
          }
          setBaseDirName(args.get(++i));
        } else if(args.get(i).equals("-close")) {
          closeUponCreate = true;
        } else if(!ignoreUnrelatedOptions)
          printUsage();
      }
      nameGenerator = new FileNameGenerator(getBaseDir(), nrFilesPerDir);
    }

    @Override
    void generateInputs(int[] opsPerThread) throws IOException {
      assert opsPerThread.length == numThreads : "Error opsPerThread.length";
      if (!nonSuperUser) {
        try{
          clientProto.setSafeMode(HdfsConstants.SafeModeAction.SAFEMODE_LEAVE,
              false);
        } catch (Exception e){
          LOG.error("Potentially insufficient permission: try running the tool" +
                    "with -nonSuperUser argument or login as super user");
          throw e;
        }
      }
      // int generatedFileIdx = 0;
      LOG.info("Generate " + numOpsRequired + " intputs for " + getOpName());
      LOG.info("basedir: " + getBaseDir());
      fileNames = new String[numThreads][];
      try {
        for(int idx=0; idx < numThreads; idx++) {
          int threadOps = opsPerThread[idx];
          fileNames[idx] = new String[threadOps];
          for(int jdx=0; jdx < threadOps; jdx++) {
            fileNames[idx][jdx] = nameGenerator.
                    getNextFileName("ThroughputBench");
          }
        }
      } catch (ArrayIndexOutOfBoundsException e) {
        LOG.error("The current environment allows {} files to be created. " +
            "If you want to test more files, please update the -filesPerDir parameter.",
                nameGenerator.getFileCount());
        throw e;
      }
    }

    /**
     * returns client name
     */
    @Override
    String getExecutionArgument(int daemonId) {
      return getClientName(daemonId);
    }

    /**
     * Do file create.
     */
    @Override
    long executeOp(int daemonId, int inputIdx, String clientName)
    throws IOException {
      long start = Time.now();
      clientProto.create(fileNames[daemonId][inputIdx],
          FsPermission.getDefault(), clientName,
          new EnumSetWritable<CreateFlag>(EnumSet
              .of(CreateFlag.CREATE, CreateFlag.OVERWRITE)), true,
          replication, blockSize, CryptoProtocolVersion.supported(), null,
          null);
      long end = Time.now();
      for (boolean written = !closeUponCreate; !written;
        written = clientProto.complete(fileNames[daemonId][inputIdx],
            clientName, null, HdfsConstants.GRANDFATHER_INODE_ID)) {
      };
      return end-start;
    }

    @Override
    void printResults() {
      LOG.info("--- " + getOpName() + " inputs ---");
      LOG.info("baseDir = " + getBaseDir());
      LOG.info("nrFiles = " + numOpsRequired);
      LOG.info("nrThreads = " + numThreads);
      LOG.info("nrFilesPerDir = " + nameGenerator.getFilesPerDirectory());
      printStats();
    }
  }

  /**
   * Directory creation statistics.
   *
   * Each thread creates the same (+ or -1) number of directories.
   * Directory names are pre-generated during initialization.
   */
  class MkdirsStats extends OperationStatsBase {
    // Operation types
    static final String OP_MKDIRS_NAME = "mkdirs";
    static final String OP_MKDIRS_USAGE = "-op mkdirs [-threads T] [-dirs N] " +
        "[-dirsPerDir P] [-baseDirName D]";

    protected FileNameGenerator nameGenerator;
    protected String[][] dirPaths;

    MkdirsStats(List<String> args) {
      super();
      parseArguments(args);
    }

    @Override
    String getOpName() {
      return OP_MKDIRS_NAME;
    }

    @Override
    void parseArguments(List<String> args) {
      boolean ignoreUnrelatedOptions = verifyOpArgument(args);
      int nrDirsPerDir = 2;
      for (int i = 2; i < args.size(); i++) {       // parse command line
        if(args.get(i).equals("-dirs")) {
          if(i+1 == args.size())  printUsage();
          numOpsRequired = Integer.parseInt(args.get(++i));
        } else if(args.get(i).equals("-threads")) {
          if(i+1 == args.size())  printUsage();
          numThreads = Integer.parseInt(args.get(++i));
        } else if(args.get(i).equals("-dirsPerDir")) {
          if(i+1 == args.size())  printUsage();
          nrDirsPerDir = Integer.parseInt(args.get(++i));
        } else if(args.get(i).equals("-baseDirName")) {
          if (i + 1 == args.size()) {
            printUsage();
          }
          setBaseDirName(args.get(++i));
        } else if(!ignoreUnrelatedOptions)
          printUsage();
      }
      nameGenerator = new FileNameGenerator(getBaseDir(), nrDirsPerDir);
    }

    @Override
    void generateInputs(int[] opsPerThread) throws IOException {
      assert opsPerThread.length == numThreads : "Error opsPerThread.length";
      if (!nonSuperUser) {
        try {
          clientProto.setSafeMode(HdfsConstants.SafeModeAction.SAFEMODE_LEAVE,
                  false);
        } catch (Exception e){
          LOG.error("Potentially insufficient permission: try running the tool" +
                    " with -nonSuperUser argument or login as super user");
          throw e;
        }
      }
      LOG.info("Generate " + numOpsRequired + " inputs for " + getOpName());
      dirPaths = new String[numThreads][];
      try {
        for(int idx=0; idx < numThreads; idx++) {
          int threadOps = opsPerThread[idx];
          dirPaths[idx] = new String[threadOps];
          for(int jdx=0; jdx < threadOps; jdx++) {
            dirPaths[idx][jdx] = nameGenerator.
                    getNextFileName("ThroughputBench");
          }
        }
      } catch (ArrayIndexOutOfBoundsException e) {
        LOG.error("The current environment allows {} directories to be created. " +
            "If you want to test more directories, please update the -dirsPerDir parameter.",
                nameGenerator.getFileCount());
        throw e;
      }
    }

    /**
     * returns client name
     */
    @Override
    String getExecutionArgument(int daemonId) {
      return getClientName(daemonId);
    }

    /**
     * Do mkdirs operation.
     */
    @Override
    long executeOp(int daemonId, int inputIdx, String clientName)
        throws IOException {
      long start = Time.now();
      clientProto.mkdirs(dirPaths[daemonId][inputIdx],
          FsPermission.getDefault(), true);
      long end = Time.now();
      return end-start;
    }

    @Override
    void printResults() {
      LOG.info("--- " + getOpName() + " inputs ---");
      LOG.info("baseDir = " + getBaseDir());
      LOG.info("nrDirs = " + numOpsRequired);
      LOG.info("nrThreads = " + numThreads);
      LOG.info("nrDirsPerDir = " + nameGenerator.getFilesPerDirectory());
      printStats();
    }
  }

  /**
   * Open file statistics.
   *
   * Measure how many open calls (getBlockLocations())
   * the name-node can handle per second.
   */
  class OpenFileStats extends CreateFileStats {
    // Operation types
    static final String OP_OPEN_NAME = "open";
    static final String OP_USAGE_ARGS =
        " [-threads T] [-files N] [-blockSize S] [-filesPerDir P]"
        + " [-useExisting] [-baseDirName D]";
    static final String OP_OPEN_USAGE = 
      "-op " + OP_OPEN_NAME + OP_USAGE_ARGS;

    private boolean useExisting;  // do not generate files, use existing ones

    OpenFileStats(List<String> args) {
      super(args);
    }

    @Override
    String getOpName() {
      return OP_OPEN_NAME;
    }

    @Override
    void parseArguments(List<String> args) {
      int ueIndex = args.indexOf("-useExisting");
      useExisting = (ueIndex >= 0);
      if(useExisting) {
        args.remove(ueIndex);
      }
      super.parseArguments(args);
    }

    @Override
    void generateInputs(int[] opsPerThread) throws IOException {
      // create files using opsPerThread
      String[] createArgs = new String[] {
          "-op", "create",
          "-threads", String.valueOf(this.numThreads),
          "-files", String.valueOf(numOpsRequired),
          "-blockSize", String.valueOf(blockSize),
          "-filesPerDir",
          String.valueOf(nameGenerator.getFilesPerDirectory()),
          "-baseDirName", getBaseDirName(),
          "-close"};
      List<String> createArgsList = new ArrayList<String>(Arrays.asList(createArgs));
      if (this.nonSuperUser){
        createArgsList.add("-nonSuperUser");
      }
      CreateFileStats opCreate =  new CreateFileStats(createArgsList);
      if(!useExisting) {  // create files if they were not created before
        opCreate.benchmark();
        LOG.info("Created " + numOpsRequired + " files.");
      } else {
        LOG.info("useExisting = true. Assuming "
            + numOpsRequired + " files have been created before.");
      }
      // use the same files for open
      super.generateInputs(opsPerThread);
      if(clientProto.getFileInfo(opCreate.getBaseDir()) != null
          && clientProto.getFileInfo(getBaseDir()) == null) {
        clientProto.rename(opCreate.getBaseDir(), getBaseDir());
      }
      if(clientProto.getFileInfo(getBaseDir()) == null) {
        throw new IOException(getBaseDir() + " does not exist.");
      }
    }

    /**
     * Do file open.
     */
    @Override
    long executeOp(int daemonId, int inputIdx, String ignore)
    throws IOException {
      long start = Time.now();
      clientProto.getBlockLocations(fileNames[daemonId][inputIdx], 0L,
          blockSize);
      long end = Time.now();
      return end-start;
    }
  }

  /**
   * Delete file statistics.
   *
   * Measure how many delete calls the name-node can handle per second.
   */
  class DeleteFileStats extends OpenFileStats {
    // Operation types
    static final String OP_DELETE_NAME = "delete";
    static final String OP_DELETE_USAGE =
      "-op " + OP_DELETE_NAME + OP_USAGE_ARGS;

    DeleteFileStats(List<String> args) {
      super(args);
    }

    @Override
    String getOpName() {
      return OP_DELETE_NAME;
    }

    @Override
    long executeOp(int daemonId, int inputIdx, String ignore)
    throws IOException {
      long start = Time.now();
      clientProto.delete(fileNames[daemonId][inputIdx], false);
      long end = Time.now();
      return end-start;
    }
  }

  /**
   * Append file statistics.
   * Measure how many append calls the name-node can handle per second.
   */
  class AppendFileStats extends OpenFileStats {
    // Operation types
    static final String OP_APPEND_NAME = "append";
    public static final String APPEND_NEW_BLK = "-appendNewBlk";
    static final String OP_APPEND_USAGE =
        "-op " + OP_APPEND_NAME + OP_USAGE_ARGS + " [" + APPEND_NEW_BLK + ']';
    private boolean appendNewBlk = false;

    AppendFileStats(List<String> args) {
      super(args);
    }

    @Override
    String getOpName() {
      return OP_APPEND_NAME;
    }

    @Override
    void parseArguments(List<String> args) {
      appendNewBlk = args.contains(APPEND_NEW_BLK);
      if (this.appendNewBlk) {
        args.remove(APPEND_NEW_BLK);
      }
      super.parseArguments(args);
    }

    @Override
    long executeOp(int daemonId, int inputIdx, String ignore)
        throws IOException {
      long start = Time.now();
      String src = fileNames[daemonId][inputIdx];
      EnumSetWritable<CreateFlag> enumSet = null;
      if (appendNewBlk) {
        enumSet = new EnumSetWritable<>(EnumSet.of(CreateFlag.NEW_BLOCK));
      } else {
        enumSet = new EnumSetWritable<>(EnumSet.of(CreateFlag.APPEND));
      }
      clientProto.append(src, "TestClient", enumSet);
      long end = Time.now();
      return end - start;
    }
  }

  /**
   * List file status statistics.
   *
   * Measure how many get-file-status calls the name-node can handle per second.
   */
  class FileStatusStats extends OpenFileStats {
    // Operation types
    static final String OP_FILE_STATUS_NAME = "fileStatus";
    static final String OP_FILE_STATUS_USAGE =
      "-op " + OP_FILE_STATUS_NAME + OP_USAGE_ARGS;

    FileStatusStats(List<String> args) {
      super(args);
    }

    @Override
    String getOpName() {
      return OP_FILE_STATUS_NAME;
    }

    @Override
    long executeOp(int daemonId, int inputIdx, String ignore)
    throws IOException {
      long start = Time.now();
      clientProto.getFileInfo(fileNames[daemonId][inputIdx]);
      long end = Time.now();
      return end-start;
    }
  }

  /**
   * Rename file statistics.
   *
   * Measure how many rename calls the name-node can handle per second.
   */
  class RenameFileStats extends OpenFileStats {
    // Operation types
    static final String OP_RENAME_NAME = "rename";
    static final String OP_RENAME_USAGE =
      "-op " + OP_RENAME_NAME + OP_USAGE_ARGS;

    protected String[][] destNames;

    RenameFileStats(List<String> args) {
      super(args);
    }

    @Override
    String getOpName() {
      return OP_RENAME_NAME;
    }

    @Override
    void generateInputs(int[] opsPerThread) throws IOException {
      super.generateInputs(opsPerThread);
      destNames = new String[fileNames.length][];
      for(int idx=0; idx < numThreads; idx++) {
        int nrNames = fileNames[idx].length;
        destNames[idx] = new String[nrNames];
        for(int jdx=0; jdx < nrNames; jdx++)
          destNames[idx][jdx] = fileNames[idx][jdx] + ".r";
      }
    }

    @Override
    long executeOp(int daemonId, int inputIdx, String ignore)
    throws IOException {
      long start = Time.now();
      clientProto.rename(fileNames[daemonId][inputIdx],
                      destNames[daemonId][inputIdx]);
      long end = Time.now();
      return end-start;
    }
  }

  /**
   * Minimal data-node simulator.
   */
  private static class TinyDatanode implements Comparable<String> {
    private static final long DF_CAPACITY = 100*1024*1024;
    private static final long DF_USED = 0;

    NamespaceInfo nsInfo;
    DatanodeRegistration dnRegistration;
    DatanodeStorage storage; //only one storage
    final List<BlockReportReplica> blocks;
    int nrBlocks; // actual number of blocks
    BlockListAsLongs blockReportList;
    final int dnIdx;

    private static int getNodePort(int num) throws IOException {
      int port = 1 + num;
      Preconditions.checkState(port < Short.MAX_VALUE);
      return port;
    }

    TinyDatanode(int dnIdx, int blockCapacity) throws IOException {
      this.dnIdx = dnIdx;
      this.blocks = Arrays.asList(new BlockReportReplica[blockCapacity]);
      this.nrBlocks = 0;
    }

    @Override
    public String toString() {
      return dnRegistration.toString();
    }

    String getXferAddr() {
      return dnRegistration.getXferAddr();
    }

    void register() throws IOException {
      // get versions from the namenode
      nsInfo = nameNodeProto.versionRequest();
      dnRegistration = new DatanodeRegistration(
          new DatanodeID(DNS.getDefaultIP("default"),
              DNS.getDefaultHost("default", "default"),
              DataNode.generateUuid(), getNodePort(dnIdx),
              DFSConfigKeys.DFS_DATANODE_HTTP_DEFAULT_PORT,
              DFSConfigKeys.DFS_DATANODE_HTTPS_DEFAULT_PORT,
              DFSConfigKeys.DFS_DATANODE_IPC_DEFAULT_PORT),
          new DataStorage(nsInfo),
          new ExportedBlockKeys(), VersionInfo.getVersion());
      // register datanode
      dnRegistration = dataNodeProto.registerDatanode(dnRegistration);
      dnRegistration.setNamespaceInfo(nsInfo);
      //first block reports
      storage = new DatanodeStorage(DatanodeStorage.generateUuid());
      final StorageBlockReport[] reports = {
          new StorageBlockReport(storage, BlockListAsLongs.EMPTY)
      };
      dataNodeProto.blockReport(dnRegistration, bpid, reports,
              new BlockReportContext(1, 0, System.nanoTime(), 0L));
    }

    /**
     * Send a heartbeat to the name-node.
     * Ignore reply commands.
     */
    void sendHeartbeat() throws IOException {
      // register datanode
      // TODO:FEDERATION currently a single block pool is supported
      StorageReport[] rep = { new StorageReport(storage, false,
          DF_CAPACITY, DF_USED, DF_CAPACITY - DF_USED, DF_USED, 0L) };
      DatanodeCommand[] cmds = dataNodeProto.sendHeartbeat(dnRegistration, rep,
          0L, 0L, 0, 0, 0, null, true,
          SlowPeerReports.EMPTY_REPORT, SlowDiskReports.EMPTY_REPORT)
          .getCommands();
      if(cmds != null) {
        for (DatanodeCommand cmd : cmds ) {
          if(LOG.isDebugEnabled()) {
            LOG.debug("sendHeartbeat Name-node reply: " + cmd.getAction());
          }
        }
      }
    }

    boolean addBlock(Block blk) {
      if(nrBlocks == blocks.size()) {
        if(LOG.isDebugEnabled()) {
          LOG.debug("Cannot add block: datanode capacity = " + blocks.size());
        }
        return false;
      }
      blocks.set(nrBlocks, new BlockReportReplica(blk));
      nrBlocks++;
      return true;
    }

    void formBlockReport() {
      // fill remaining slots with blocks that do not exist
      for (int idx = blocks.size()-1; idx >= nrBlocks; idx--) {
        Block block = new Block(blocks.size() - idx, 0, 0);
        blocks.set(idx, new BlockReportReplica(block));
      }
      blockReportList = BlockListAsLongs.encode(blocks);
    }

    BlockListAsLongs getBlockReportList() {
      return blockReportList;
    }

    @Override
    public int compareTo(String xferAddr) {
      return getXferAddr().compareTo(xferAddr);
    }

    /**
     * Send a heartbeat to the name-node and replicate blocks if requested.
     */
    @SuppressWarnings("unused") // keep it for future blockReceived benchmark
    int replicateBlocks() throws IOException {
      // register datanode
      StorageReport[] rep = { new StorageReport(storage,
          false, DF_CAPACITY, DF_USED, DF_CAPACITY - DF_USED, DF_USED, 0) };
      DatanodeCommand[] cmds = dataNodeProto.sendHeartbeat(dnRegistration,
          rep, 0L, 0L, 0, 0, 0, null, true,
          SlowPeerReports.EMPTY_REPORT, SlowDiskReports.EMPTY_REPORT)
          .getCommands();
      if (cmds != null) {
        for (DatanodeCommand cmd : cmds) {
          if (cmd.getAction() == DatanodeProtocol.DNA_TRANSFER) {
            // Send a copy of a block to another datanode
            BlockCommand bcmd = (BlockCommand)cmd;
            return transferBlocks(bcmd.getBlocks(), bcmd.getTargets(),
                                  bcmd.getTargetStorageIDs());
          }
        }
      }
      return 0;
    }

    /**
     * Transfer blocks to another data-node.
     * Just report on behalf of the other data-node
     * that the blocks have been received.
     */
    private int transferBlocks( Block blocks[],
                                DatanodeInfo xferTargets[][],
                                String targetStorageIDs[][]
                              ) throws IOException {
      for(int i = 0; i < blocks.length; i++) {
        DatanodeInfo blockTargets[] = xferTargets[i];
        for(int t = 0; t < blockTargets.length; t++) {
          DatanodeInfo dnInfo = blockTargets[t];
          String targetStorageID = targetStorageIDs[i][t];
          DatanodeRegistration receivedDNReg;
          receivedDNReg = new DatanodeRegistration(dnInfo,
            new DataStorage(nsInfo),
            new ExportedBlockKeys(), VersionInfo.getVersion());
          ReceivedDeletedBlockInfo[] rdBlocks = {
            new ReceivedDeletedBlockInfo(
                  blocks[i], ReceivedDeletedBlockInfo.BlockStatus.RECEIVED_BLOCK,
                  null) };
          StorageReceivedDeletedBlocks[] report = { new StorageReceivedDeletedBlocks(
              new DatanodeStorage(targetStorageID), rdBlocks) };
          dataNodeProto.blockReceivedAndDeleted(receivedDNReg, bpid, report);
        }
      }
      return blocks.length;
    }
  }

  /**
   * Block report statistics.
   *
   * Each thread here represents its own data-node.
   * Data-nodes send the same block report each time.
   * The block report may contain missing or non-existing blocks.
   */
  class BlockReportStats extends OperationStatsBase {
    static final String OP_BLOCK_REPORT_NAME = "blockReport";
    static final String OP_BLOCK_REPORT_USAGE =
        "-op blockReport [-datanodes T] [-reports N] " +
        "[-blocksPerReport B] [-blocksPerFile F] [-blockSize S] [-baseDirName D]";

    private int blocksPerReport;
    private int blocksPerFile;
    private TinyDatanode[] datanodes; // array of data-nodes sorted by name

    BlockReportStats(List<String> args) {
      super();
      numThreads = 10;
      numOpsRequired = 30;
      this.blocksPerReport = 100;
      this.blocksPerFile = 10;
      // set heartbeat interval to 3 min, so that expiration were 40 min
      config.setLong(DFSConfigKeys.DFS_HEARTBEAT_INTERVAL_KEY, 3 * 60);
      parseArguments(args);
      // adjust replication to the number of data-nodes
      this.replication = (short)Math.min(replication, getNumDatanodes());
    }

    /**
     * Each thread pretends its a data-node here.
     */
    private int getNumDatanodes() {
      return numThreads;
    }

    @Override
    String getOpName() {
      return OP_BLOCK_REPORT_NAME;
    }

    @Override
    void parseArguments(List<String> args) {
      boolean ignoreUnrelatedOptions = verifyOpArgument(args);
      for (int i = 2; i < args.size(); i++) {       // parse command line
        if(args.get(i).equals("-reports")) {
          if(i+1 == args.size())  printUsage();
          numOpsRequired = Integer.parseInt(args.get(++i));
        } else if(args.get(i).equals("-datanodes")) {
          if(i+1 == args.size())  printUsage();
          numThreads = Integer.parseInt(args.get(++i));
        } else if(args.get(i).equals("-blocksPerReport")) {
          if(i+1 == args.size())  printUsage();
          blocksPerReport = Integer.parseInt(args.get(++i));
        } else if(args.get(i).equals("-blocksPerFile")) {
          if(i+1 == args.size())  printUsage();
          blocksPerFile = Integer.parseInt(args.get(++i));
        } else if (args.get(i).equals("-blockSize")) {
          if(i+1 == args.size())  printUsage();
          blockSize = StringUtils.TraditionalBinaryPrefix.string2long(args.get(++i));
        } else if(args.get(i).equals("-baseDirName")) {
          if (i + 1 == args.size()) {
            printUsage();
          }
          setBaseDirName(args.get(++i));
        } else if(!ignoreUnrelatedOptions)
          printUsage();
      }
    }

    @Override
    void generateInputs(int[] ignore) throws IOException {
      int nrDatanodes = getNumDatanodes();
      int nrBlocks = (int)Math.ceil((double)blocksPerReport * nrDatanodes
                                    / replication);
      int nrFiles = (int)Math.ceil((double)nrBlocks / blocksPerFile);
      datanodes = new TinyDatanode[nrDatanodes];
      // create data-nodes
      for(int idx=0; idx < nrDatanodes; idx++) {
        datanodes[idx] = new TinyDatanode(idx, blocksPerReport);
        datanodes[idx].register();
        datanodes[idx].sendHeartbeat();
      }

      // create files
      LOG.info("Creating " + nrFiles + " files with " + blocksPerFile + " blocks each.");
      FileNameGenerator nameGenerator;
      nameGenerator = new FileNameGenerator(getBaseDir(), 100);
      String clientName = getClientName(007);
      if (!nonSuperUser) {
        try {
          clientProto.setSafeMode(HdfsConstants.SafeModeAction.SAFEMODE_LEAVE,
                  false);
        } catch (Exception e){
          LOG.error("Potentially insufficient permission: try running the tool" +
                    " with -nonSuperUser argument or login as super user");
          throw e;
        }
      }
      for(int idx=0; idx < nrFiles; idx++) {
        String fileName = nameGenerator.getNextFileName("ThroughputBench");
        clientProto.create(fileName, FsPermission.getDefault(), clientName,
            new EnumSetWritable<CreateFlag>(EnumSet.of(CreateFlag.CREATE, CreateFlag.OVERWRITE)), true, replication,
            blockSize, CryptoProtocolVersion.supported(), null, null);
        ExtendedBlock lastBlock = addBlocks(fileName, clientName);
        clientProto.complete(fileName, clientName, lastBlock, HdfsConstants.GRANDFATHER_INODE_ID);
      }
      // prepare block reports
      for(int idx=0; idx < nrDatanodes; idx++) {
        datanodes[idx].formBlockReport();
      }
    }

    private ExtendedBlock addBlocks(String fileName, String clientName)
    throws IOException {
      DatanodeInfo[] excludeNodes = null;
      DatanodeInfo[] dnInfos = clientProto.getDatanodeReport(
          HdfsConstants.DatanodeReportType.LIVE);
      if (dnInfos != null && dnInfos.length > 0) {
        List<DatanodeInfo> tmpNodes = new ArrayList<>();
        String localHost = DNS.getDefaultHost("default", "default");
        for (DatanodeInfo dnInfo : dnInfos) {
          if (!localHost.equals(dnInfo.getHostName()) ||
              (dnInfo.getXferPort() > datanodes.length)) {
            tmpNodes.add(dnInfo);
          }
        }

        if (tmpNodes.size() > 0) {
          excludeNodes = tmpNodes.toArray(new DatanodeInfo[tmpNodes.size()]);
        }
      }

      ExtendedBlock prevBlock = null;
      for(int jdx = 0; jdx < blocksPerFile; jdx++) {
        LocatedBlock loc = addBlock(fileName, clientName,
            prevBlock, excludeNodes, HdfsConstants.GRANDFATHER_INODE_ID, null);
        prevBlock = loc.getBlock();
        for(DatanodeInfo dnInfo : loc.getLocations()) {
          int dnIdx = dnInfo.getXferPort() - 1;
          datanodes[dnIdx].addBlock(loc.getBlock().getLocalBlock());
          ReceivedDeletedBlockInfo[] rdBlocks = { new ReceivedDeletedBlockInfo(
              loc.getBlock().getLocalBlock(),
              ReceivedDeletedBlockInfo.BlockStatus.RECEIVED_BLOCK, null) };
          StorageReceivedDeletedBlocks[] report = { new StorageReceivedDeletedBlocks(
              new DatanodeStorage(datanodes[dnIdx].storage.getStorageID()),
              rdBlocks) };
          dataNodeProto.blockReceivedAndDeleted(datanodes[dnIdx].dnRegistration,
              bpid, report);
        }
        // IBRs are asynchronously processed by NameNode. The next
        // ClientProtocol#addBlock() may throw NotReplicatedYetException.
      }
      return prevBlock;
    }

    /**
     * Retry ClientProtocol.addBlock() if it throws NotReplicatedYetException.
     * Because addBlock() also commits the previous block,
     * it fails if enough IBRs are not processed by NameNode.
     */
    private LocatedBlock addBlock(String src, String clientName,
        ExtendedBlock previous, DatanodeInfo[] excludeNodes, long fileId,
        String[] favoredNodes) throws IOException {
      for (int i = 0; i < 30; i++) {
        try {
          return clientProto.addBlock(src, clientName,
              previous, excludeNodes, fileId, favoredNodes, null);
        } catch (NotReplicatedYetException|RemoteException e) {
          if (e instanceof RemoteException) {
            String className = ((RemoteException) e).getClassName();
            if (!className.equals(NotReplicatedYetException.class.getName())) {
              throw e;
            }
          }
          try {
            Thread.sleep(100);
          } catch (InterruptedException ie) {
            LOG.warn("interrupted while retrying addBlock.", ie);
          }
        }
      }
      throw new IOException("failed to add block.");
    }

    /**
     * Does not require the argument
     */
    @Override
    String getExecutionArgument(int daemonId) {
      return null;
    }

    @Override
    long executeOp(int daemonId, int inputIdx, String ignore) throws IOException {
      assert daemonId < numThreads : "Wrong daemonId.";
      TinyDatanode dn = datanodes[daemonId];
      long start = Time.now();
      StorageBlockReport[] report = { new StorageBlockReport(
          dn.storage, dn.getBlockReportList()) };
      dataNodeProto.blockReport(dn.dnRegistration, bpid, report,
          new BlockReportContext(1, 0, System.nanoTime(), 0L));
      long end = Time.now();
      return end-start;
    }

    @Override
    void printResults() {
      String blockDistribution = "";
      String delim = "(";
      for(int idx=0; idx < getNumDatanodes(); idx++) {
        blockDistribution += delim + datanodes[idx].nrBlocks;
        delim = ", ";
      }
      blockDistribution += ")";
      LOG.info("--- " + getOpName() + " inputs ---");
      LOG.info("baseDir = " + getBaseDir());
      LOG.info("reports = " + numOpsRequired);
      LOG.info("datanodes = " + numThreads + " " + blockDistribution);
      LOG.info("blocksPerReport = " + blocksPerReport);
      LOG.info("blocksPerFile = " + blocksPerFile);
      printStats();
    }
  }   // end BlockReportStats

  /**
   * Measures how fast redundancy monitor can compute data-node work.
   *
   * It runs only one thread until no more work can be scheduled.
   */
  class ReplicationStats extends OperationStatsBase {
    static final String OP_REPLICATION_NAME = "replication";
    static final String OP_REPLICATION_USAGE =
        "-op replication [-datanodes T] [-nodesToDecommission D] " +
        "[-nodeReplicationLimit C] [-totalBlocks B] [-blockSize S] "
        + "[-replication R] [-baseDirName D]";

    private final BlockReportStats blockReportObject;
    private int numDatanodes;
    private int nodesToDecommission;
    private int nodeReplicationLimit;
    private int totalBlocks;
    private int numDecommissionedBlocks;
    private int numPendingBlocks;

    ReplicationStats(List<String> args) {
      super();
      numThreads = 1;
      numDatanodes = 10;
      nodesToDecommission = 1;
      nodeReplicationLimit = 100;
      totalBlocks = 100;
      parseArguments(args);
      // number of operations is 4 times the number of decommissioned
      // blocks divided by the number of needed replications scanned 
      // by the redundancy monitor in one iteration
      numOpsRequired = (totalBlocks*replication*nodesToDecommission*2)
            / (numDatanodes*numDatanodes);

      String[] blkReportArgs = {
          "-op", "blockReport",
          "-datanodes", String.valueOf(numDatanodes),
          "-blocksPerReport", String.valueOf(totalBlocks*replication/numDatanodes),
          "-blocksPerFile", String.valueOf(numDatanodes),
          "-blockSize", String.valueOf(blockSize),
          "-baseDirName", getBaseDirName()};
      blockReportObject = new BlockReportStats(Arrays.asList(blkReportArgs));
      numDecommissionedBlocks = 0;
      numPendingBlocks = 0;
    }

    @Override
    String getOpName() {
      return OP_REPLICATION_NAME;
    }

    @Override
    void parseArguments(List<String> args) {
      boolean ignoreUnrelatedOptions = verifyOpArgument(args);
      for (int i = 2; i < args.size(); i++) {       // parse command line
        if(args.get(i).equals("-datanodes")) {
          if(i+1 == args.size())  printUsage();
          numDatanodes = Integer.parseInt(args.get(++i));
        } else if(args.get(i).equals("-nodesToDecommission")) {
          if(i+1 == args.size())  printUsage();
          nodesToDecommission = Integer.parseInt(args.get(++i));
        } else if(args.get(i).equals("-nodeReplicationLimit")) {
          if(i+1 == args.size())  printUsage();
          nodeReplicationLimit = Integer.parseInt(args.get(++i));
        } else if(args.get(i).equals("-totalBlocks")) {
          if(i+1 == args.size())  printUsage();
          totalBlocks = Integer.parseInt(args.get(++i));
        } else if(args.get(i).equals("-replication")) {
          if(i+1 == args.size())  printUsage();
          replication = Short.parseShort(args.get(++i));
        } else if (args.get(i).equals("-blockSize")) {
          if(i+1 == args.size())  printUsage();
          blockSize = StringUtils.TraditionalBinaryPrefix.string2long(args.get(++i));
        } else if(args.get(i).equals("-baseDirName")) {
          if (i + 1 == args.size()) {
            printUsage();
          }
          setBaseDirName(args.get(++i));
        } else if(!ignoreUnrelatedOptions)
          printUsage();
      }
    }

    @Override
    void generateInputs(int[] ignore) throws IOException {
      final FSNamesystem namesystem = nameNode.getNamesystem();

      // start data-nodes; create a bunch of files; generate block reports.
      blockReportObject.generateInputs(ignore);
      // stop redundancy monitor thread.
      BlockManagerTestUtil.stopRedundancyThread(namesystem.getBlockManager());

      // report blocks once
      int nrDatanodes = blockReportObject.getNumDatanodes();
      for(int idx=0; idx < nrDatanodes; idx++) {
        blockReportObject.executeOp(idx, 0, null);
      }
      // decommission data-nodes
      decommissionNodes();
      // set node replication limit
      BlockManagerTestUtil.setNodeReplicationLimit(namesystem.getBlockManager(),
          nodeReplicationLimit);
    }

    private void decommissionNodes() throws IOException {
      String excludeFN = config.get(DFSConfigKeys.DFS_HOSTS_EXCLUDE, "exclude");
      FileOutputStream excludeFile = new FileOutputStream(excludeFN);
      excludeFile.getChannel().truncate(0L);
      int nrDatanodes = blockReportObject.getNumDatanodes();
      numDecommissionedBlocks = 0;
      for(int i=0; i < nodesToDecommission; i++) {
        TinyDatanode dn = blockReportObject.datanodes[nrDatanodes-1-i];
        numDecommissionedBlocks += dn.nrBlocks;
        excludeFile.write(dn.getXferAddr().getBytes());
        excludeFile.write('\n');
        LOG.info("Datanode " + dn + " is decommissioned.");
      }
      excludeFile.close();
      clientProto.refreshNodes();
    }

    /**
     * Does not require the argument
     */
    @Override
    String getExecutionArgument(int daemonId) {
      return null;
    }

    @Override
    long executeOp(int daemonId, int inputIdx, String ignore) throws IOException {
      assert daemonId < numThreads : "Wrong daemonId.";
      long start = Time.now();
      // compute data-node work
      int work = BlockManagerTestUtil.getComputedDatanodeWork(
          nameNode.getNamesystem().getBlockManager());
      long end = Time.now();
      numPendingBlocks += work;
      if(work == 0)
        daemons.get(daemonId).terminate();
      return end-start;
    }

    @Override
    void printResults() {
      String blockDistribution = "";
      String delim = "(";
      for(int idx=0; idx < blockReportObject.getNumDatanodes(); idx++) {
        blockDistribution += delim + blockReportObject.datanodes[idx].nrBlocks;
        delim = ", ";
      }
      blockDistribution += ")";
      LOG.info("--- " + getOpName() + " inputs ---");
      LOG.info("baseDir = " + getBaseDir());
      LOG.info("numOpsRequired = " + numOpsRequired);
      LOG.info("datanodes = " + numDatanodes + " " + blockDistribution);
      LOG.info("decommissioned datanodes = " + nodesToDecommission);
      LOG.info("datanode replication limit = " + nodeReplicationLimit);
      LOG.info("total blocks = " + totalBlocks);
      printStats();
      LOG.info("decommissioned blocks = " + numDecommissionedBlocks);
      LOG.info("pending replications = " + numPendingBlocks);
      LOG.info("replications per sec: " + getBlocksPerSecond());
    }

    private double getBlocksPerSecond() {
      return elapsedTime == 0 ? 0 : 1000*(double)numPendingBlocks / elapsedTime;
    }

  }   // end ReplicationStats

  static void printUsage() {
    System.err.println("Usage: NNThroughputBenchmark"
        + "\n\t"    + OperationStatsBase.OP_ALL_USAGE
        + " | \n\t" + CreateFileStats.OP_CREATE_USAGE
        + " | \n\t" + MkdirsStats.OP_MKDIRS_USAGE
        + " | \n\t" + OpenFileStats.OP_OPEN_USAGE
        + " | \n\t" + DeleteFileStats.OP_DELETE_USAGE
        + " | \n\t" + AppendFileStats.OP_APPEND_USAGE
        + " | \n\t" + FileStatusStats.OP_FILE_STATUS_USAGE
        + " | \n\t" + RenameFileStats.OP_RENAME_USAGE
        + " | \n\t" + BlockReportStats.OP_BLOCK_REPORT_USAGE
        + " | \n\t" + ReplicationStats.OP_REPLICATION_USAGE
        + " | \n\t" + CleanAllStats.OP_CLEAN_USAGE
        + " | \n\t" + GENERAL_OPTIONS_USAGE
    );
    System.err.println();
    GenericOptionsParser.printGenericCommandUsage(System.err);
    System.err.println("If connecting to a remote NameNode with -fs option, " +
        "dfs.namenode.fs-limits.min-block-size should be set to 16.");
    ExitUtil.terminate(-1);
  }

  public static void runBenchmark(Configuration conf, String[] args)
      throws Exception {
    NNThroughputBenchmark bench = null;
    try {
      bench = new NNThroughputBenchmark(conf);
      ToolRunner.run(bench, args);
    } finally {
      if(bench != null)
        bench.close();
    }
  }

  /**
   * Main method of the benchmark.
   * @param aArgs command line parameters
   */
  @Override // Tool
  public int run(String[] aArgs) throws Exception {
    List<String> args = new ArrayList<String>(Arrays.asList(aArgs));
    if(args.size() < 2 || ! args.get(0).startsWith("-op"))
      printUsage();

    String type = args.get(1);
    boolean runAll = OperationStatsBase.OP_ALL_NAME.equals(type);

    final URI nnUri = FileSystem.getDefaultUri(config);
    // Start the NameNode
    String[] argv = new String[] {};

    List<OperationStatsBase> ops = new ArrayList<OperationStatsBase>();
    OperationStatsBase opStat = null;
    try {
      if(runAll || CreateFileStats.OP_CREATE_NAME.equals(type)) {
        opStat = new CreateFileStats(args);
        ops.add(opStat);
      }
      if(runAll || MkdirsStats.OP_MKDIRS_NAME.equals(type)) {
        opStat = new MkdirsStats(args);
        ops.add(opStat);
      }
      if(runAll || OpenFileStats.OP_OPEN_NAME.equals(type)) {
        opStat = new OpenFileStats(args);
        ops.add(opStat);
      }
      if(runAll || DeleteFileStats.OP_DELETE_NAME.equals(type)) {
        opStat = new DeleteFileStats(args);
        ops.add(opStat);
      }
      if (runAll || AppendFileStats.OP_APPEND_NAME.equals(type)) {
        opStat = new AppendFileStats(args);
        ops.add(opStat);
      }
      if(runAll || FileStatusStats.OP_FILE_STATUS_NAME.equals(type)) {
        opStat = new FileStatusStats(args);
        ops.add(opStat);
      }
      if(runAll || RenameFileStats.OP_RENAME_NAME.equals(type)) {
        opStat = new RenameFileStats(args);
        ops.add(opStat);
      }
      if(runAll || BlockReportStats.OP_BLOCK_REPORT_NAME.equals(type)) {
        opStat = new BlockReportStats(args);
        ops.add(opStat);
      }
      if(runAll || ReplicationStats.OP_REPLICATION_NAME.equals(type)) {
        if (nnUri.getScheme() != null && nnUri.getScheme().equals("hdfs")) {
          LOG.warn("The replication test is ignored as it does not support " +
              "standalone namenode in another process or on another host. ");
        } else {
          opStat = new ReplicationStats(args);
          ops.add(opStat);
        }
      }
      if(runAll || CleanAllStats.OP_CLEAN_NAME.equals(type)) {
        opStat = new CleanAllStats(args);
        ops.add(opStat);
      }
      if (ops.isEmpty()) {
        printUsage();
      }

      if (nnUri.getScheme() == null || nnUri.getScheme().equals("file")) {
        LOG.info("Remote NameNode is not specified. Creating one.");
        FileSystem.setDefaultUri(config, "hdfs://localhost:0");
        config.set(DFSConfigKeys.DFS_NAMENODE_HTTP_ADDRESS_KEY, "0.0.0.0:0");
        nameNode = NameNode.createNameNode(argv, config);
        NamenodeProtocols nnProtos = nameNode.getRpcServer();
        nameNodeProto = nnProtos;
        clientProto = nnProtos;
        dataNodeProto = nnProtos;
        refreshUserMappingsProto = nnProtos;
        bpid = nameNode.getNamesystem().getBlockPoolId();
      } else {
        DistributedFileSystem dfs = (DistributedFileSystem)
            FileSystem.get(getConf());
        nameNodeProto = DFSTestUtil.getNamenodeProtocolProxy(config, nnUri,
            UserGroupInformation.getCurrentUser());
        clientProto = dfs.getClient().getNamenode();
        InetSocketAddress nnAddr = DFSUtilClient.getNNAddress(nnUri);
        dataNodeProto = new DatanodeProtocolClientSideTranslatorPB(
            nnAddr, config);
        refreshUserMappingsProto =
            DFSTestUtil.getRefreshUserMappingsProtocolProxy(config, nnAddr);
        getBlockPoolId(dfs);
      }
      // run each benchmark
      for(OperationStatsBase op : ops) {
        LOG.info("Starting benchmark: " + op.getOpName() + ", baseDir: " + op.getBaseDir());
        op.benchmark();
        op.cleanUp();
      }
      // print statistics
      for(OperationStatsBase op : ops) {
        LOG.info("");
        op.printResults();
      }
    } catch(Exception e) {
      LOG.error(StringUtils.stringifyException(e));
      throw e;
    }
    return 0;
  }

  private void getBlockPoolId(DistributedFileSystem unused)
    throws IOException {
    final NamespaceInfo nsInfo = nameNodeProto.versionRequest();
    bpid = nsInfo.getBlockPoolID();
  }

  public static void main(String[] args) throws Exception {
    runBenchmark(new HdfsConfiguration(), args);
  }

  @Override // Configurable
  public void setConf(Configuration conf) {
    config = conf;
  }

  @Override // Configurable
  public Configuration getConf() {
    return config;
  }
}
