/*
 * 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.hbase.rest;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.PrintStream;
import java.lang.reflect.Constructor;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.TreeMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.ArrayBackedTag;
import org.apache.hadoop.hbase.CompareOperator;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.Tag;
import org.apache.hadoop.hbase.client.BufferedMutator;
import org.apache.hadoop.hbase.client.ColumnFamilyDescriptorBuilder;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.Durability;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.client.Table;
import org.apache.hadoop.hbase.client.TableDescriptor;
import org.apache.hadoop.hbase.client.TableDescriptorBuilder;
import org.apache.hadoop.hbase.filter.BinaryComparator;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.PageFilter;
import org.apache.hadoop.hbase.filter.SingleColumnValueFilter;
import org.apache.hadoop.hbase.filter.WhileMatchFilter;
import org.apache.hadoop.hbase.io.compress.Compression;
import org.apache.hadoop.hbase.io.encoding.DataBlockEncoding;
import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
import org.apache.hadoop.hbase.rest.client.Client;
import org.apache.hadoop.hbase.rest.client.Cluster;
import org.apache.hadoop.hbase.rest.client.RemoteAdmin;
import org.apache.hadoop.hbase.util.ByteArrayHashKey;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
import org.apache.hadoop.hbase.util.Hash;
import org.apache.hadoop.hbase.util.MurmurHash;
import org.apache.hadoop.hbase.util.Pair;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.mapreduce.lib.reduce.LongSumReducer;
import org.apache.hadoop.util.LineReader;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Script used evaluating Stargate performance and scalability. Runs a SG client that steps through
 * one of a set of hardcoded tests or 'experiments' (e.g. a random reads test, a random writes test,
 * etc.). Pass on the command-line which test to run and how many clients are participating in this
 * experiment. Run <code>java PerformanceEvaluation --help</code> to obtain usage.
 * <p>
 * This class sets up and runs the evaluation programs described in Section 7, <i>Performance
 * Evaluation</i>, of the <a href="http://labs.google.com/papers/bigtable.html">Bigtable</a> paper,
 * pages 8-10.
 * <p>
 * If number of clients > 1, we start up a MapReduce job. Each map task runs an individual client.
 * Each client does about 1GB of data.
 */
public class PerformanceEvaluation extends Configured implements Tool {
  protected static final Logger LOG = LoggerFactory.getLogger(PerformanceEvaluation.class);

  private static final int DEFAULT_ROW_PREFIX_LENGTH = 16;
  private static final int ROW_LENGTH = 1000;
  private static final int TAG_LENGTH = 256;
  private static final int ONE_GB = 1024 * 1024 * 1000;
  private static final int ROWS_PER_GB = ONE_GB / ROW_LENGTH;

  public static final TableName TABLE_NAME = TableName.valueOf("TestTable");
  public static final byte[] FAMILY_NAME = Bytes.toBytes("info");
  public static final byte[] QUALIFIER_NAME = Bytes.toBytes("data");
  private TableName tableName = TABLE_NAME;

  protected TableDescriptor TABLE_DESCRIPTOR;
  protected Map<String, CmdDescriptor> commands = new TreeMap<>();
  protected static Cluster cluster = new Cluster();

  volatile Configuration conf;
  private boolean nomapred = false;
  private int N = 1;
  private int R = ROWS_PER_GB;
  private Compression.Algorithm compression = Compression.Algorithm.NONE;
  private DataBlockEncoding blockEncoding = DataBlockEncoding.NONE;
  private boolean flushCommits = true;
  private boolean writeToWAL = true;
  private boolean inMemoryCF = false;
  private int presplitRegions = 0;
  private boolean useTags = false;
  private int noOfTags = 1;
  private Connection connection;

  private static final Path PERF_EVAL_DIR = new Path("performance_evaluation");

  /**
   * Regex to parse lines in input file passed to mapreduce task.
   */
  public static final Pattern LINE_PATTERN = Pattern
    .compile("tableName=(\\w+),\\s+" + "startRow=(\\d+),\\s+" + "perClientRunRows=(\\d+),\\s+"
      + "totalRows=(\\d+),\\s+" + "clients=(\\d+),\\s+" + "flushCommits=(\\w+),\\s+"
      + "writeToWAL=(\\w+),\\s+" + "useTags=(\\w+),\\s+" + "noOfTags=(\\d+)");

  /**
   * Enum for map metrics. Keep it out here rather than inside in the Map inner-class so we can find
   * associated properties.
   */
  protected enum Counter {
    /** elapsed time */
    ELAPSED_TIME,
    /** number of rows */
    ROWS
  }

  /**
   * Constructor
   * @param c Configuration object
   */
  public PerformanceEvaluation(final Configuration c) {
    this.conf = c;

    addCommandDescriptor(RandomReadTest.class, "randomRead", "Run random read test");
    addCommandDescriptor(RandomSeekScanTest.class, "randomSeekScan",
      "Run random seek and scan 100 test");
    addCommandDescriptor(RandomScanWithRange10Test.class, "scanRange10",
      "Run random seek scan with both start and stop row (max 10 rows)");
    addCommandDescriptor(RandomScanWithRange100Test.class, "scanRange100",
      "Run random seek scan with both start and stop row (max 100 rows)");
    addCommandDescriptor(RandomScanWithRange1000Test.class, "scanRange1000",
      "Run random seek scan with both start and stop row (max 1000 rows)");
    addCommandDescriptor(RandomScanWithRange10000Test.class, "scanRange10000",
      "Run random seek scan with both start and stop row (max 10000 rows)");
    addCommandDescriptor(RandomWriteTest.class, "randomWrite", "Run random write test");
    addCommandDescriptor(SequentialReadTest.class, "sequentialRead", "Run sequential read test");
    addCommandDescriptor(SequentialWriteTest.class, "sequentialWrite", "Run sequential write test");
    addCommandDescriptor(ScanTest.class, "scan", "Run scan test (read every row)");
    addCommandDescriptor(FilteredScanTest.class, "filterScan",
      "Run scan test using a filter to find a specific row based "
        + "on it's value (make sure to use --rows=20)");
  }

  protected void addCommandDescriptor(Class<? extends Test> cmdClass, String name,
    String description) {
    CmdDescriptor cmdDescriptor = new CmdDescriptor(cmdClass, name, description);
    commands.put(name, cmdDescriptor);
  }

  /**
   * Implementations can have their status set.
   */
  interface Status {
    /**
     * Sets status
     * @param msg status message
     * @throws IOException if setting the status fails
     */
    void setStatus(final String msg) throws IOException;
  }

  /**
   * This class works as the InputSplit of Performance Evaluation MapReduce InputFormat, and the
   * Record Value of RecordReader. Each map task will only read one record from a PeInputSplit, the
   * record value is the PeInputSplit itself.
   */
  public static class PeInputSplit extends InputSplit implements Writable {
    private TableName tableName;
    private int startRow;
    private int rows;
    private int totalRows;
    private int clients;
    private boolean flushCommits;
    private boolean writeToWAL;
    private boolean useTags;
    private int noOfTags;

    public PeInputSplit(TableName tableName, int startRow, int rows, int totalRows, int clients,
      boolean flushCommits, boolean writeToWAL, boolean useTags, int noOfTags) {
      this.tableName = tableName;
      this.startRow = startRow;
      this.rows = rows;
      this.totalRows = totalRows;
      this.clients = clients;
      this.flushCommits = flushCommits;
      this.writeToWAL = writeToWAL;
      this.useTags = useTags;
      this.noOfTags = noOfTags;
    }

    @Override
    public void readFields(DataInput in) throws IOException {
      int tableNameLen = in.readInt();
      byte[] name = new byte[tableNameLen];
      in.readFully(name);
      this.tableName = TableName.valueOf(name);
      this.startRow = in.readInt();
      this.rows = in.readInt();
      this.totalRows = in.readInt();
      this.clients = in.readInt();
      this.flushCommits = in.readBoolean();
      this.writeToWAL = in.readBoolean();
      this.useTags = in.readBoolean();
      this.noOfTags = in.readInt();
    }

    @Override
    public void write(DataOutput out) throws IOException {
      byte[] name = this.tableName.toBytes();
      out.writeInt(name.length);
      out.write(name);
      out.writeInt(startRow);
      out.writeInt(rows);
      out.writeInt(totalRows);
      out.writeInt(clients);
      out.writeBoolean(flushCommits);
      out.writeBoolean(writeToWAL);
      out.writeBoolean(useTags);
      out.writeInt(noOfTags);
    }

    @Override
    public long getLength() {
      return 0;
    }

    @Override
    public String[] getLocations() {
      return new String[0];
    }

    public int getStartRow() {
      return startRow;
    }

    public TableName getTableName() {
      return tableName;
    }

    public int getRows() {
      return rows;
    }

    public int getTotalRows() {
      return totalRows;
    }

    public boolean isFlushCommits() {
      return flushCommits;
    }

    public boolean isWriteToWAL() {
      return writeToWAL;
    }

    public boolean isUseTags() {
      return useTags;
    }

    public int getNoOfTags() {
      return noOfTags;
    }
  }

  /**
   * InputFormat of Performance Evaluation MapReduce job. It extends from FileInputFormat, want to
   * use it's methods such as setInputPaths().
   */
  public static class PeInputFormat extends FileInputFormat<NullWritable, PeInputSplit> {
    @Override
    public List<InputSplit> getSplits(JobContext job) throws IOException {
      // generate splits
      List<InputSplit> splitList = new ArrayList<>();

      for (FileStatus file : listStatus(job)) {
        if (file.isDirectory()) {
          continue;
        }
        Path path = file.getPath();
        FileSystem fs = path.getFileSystem(job.getConfiguration());
        FSDataInputStream fileIn = fs.open(path);
        LineReader in = new LineReader(fileIn, job.getConfiguration());
        int lineLen;
        while (true) {
          Text lineText = new Text();
          lineLen = in.readLine(lineText);
          if (lineLen <= 0) {
            break;
          }
          Matcher m = LINE_PATTERN.matcher(lineText.toString());
          if ((m != null) && m.matches()) {
            TableName tableName = TableName.valueOf(m.group(1));
            int startRow = Integer.parseInt(m.group(2));
            int rows = Integer.parseInt(m.group(3));
            int totalRows = Integer.parseInt(m.group(4));
            int clients = Integer.parseInt(m.group(5));
            boolean flushCommits = Boolean.parseBoolean(m.group(6));
            boolean writeToWAL = Boolean.parseBoolean(m.group(7));
            boolean useTags = Boolean.parseBoolean(m.group(8));
            int noOfTags = Integer.parseInt(m.group(9));

            LOG.debug("tableName=" + tableName + " split[" + splitList.size() + "] " + " startRow="
              + startRow + " rows=" + rows + " totalRows=" + totalRows + " clients=" + clients
              + " flushCommits=" + flushCommits + " writeToWAL=" + writeToWAL + " useTags="
              + useTags + " noOfTags=" + noOfTags);

            PeInputSplit newSplit = new PeInputSplit(tableName, startRow, rows, totalRows, clients,
              flushCommits, writeToWAL, useTags, noOfTags);
            splitList.add(newSplit);
          }
        }
        in.close();
      }

      LOG.info("Total # of splits: " + splitList.size());
      return splitList;
    }

    @Override
    public RecordReader<NullWritable, PeInputSplit> createRecordReader(InputSplit split,
      TaskAttemptContext context) {
      return new PeRecordReader();
    }

    public static class PeRecordReader extends RecordReader<NullWritable, PeInputSplit> {
      private boolean readOver = false;
      private PeInputSplit split = null;
      private NullWritable key = null;
      private PeInputSplit value = null;

      @Override
      public void initialize(InputSplit split, TaskAttemptContext context) {
        this.readOver = false;
        this.split = (PeInputSplit) split;
      }

      @Override
      public boolean nextKeyValue() {
        if (readOver) {
          return false;
        }

        key = NullWritable.get();
        value = split;

        readOver = true;
        return true;
      }

      @Override
      public NullWritable getCurrentKey() {
        return key;
      }

      @Override
      public PeInputSplit getCurrentValue() {
        return value;
      }

      @Override
      public float getProgress() {
        if (readOver) {
          return 1.0f;
        } else {
          return 0.0f;
        }
      }

      @Override
      public void close() {
        // do nothing
      }
    }
  }

  /**
   * MapReduce job that runs a performance evaluation client in each map task.
   */
  public static class EvaluationMapTask
    extends Mapper<NullWritable, PeInputSplit, LongWritable, LongWritable> {

    /** configuration parameter name that contains the command */
    public final static String CMD_KEY = "EvaluationMapTask.command";
    /** configuration parameter name that contains the PE impl */
    public static final String PE_KEY = "EvaluationMapTask.performanceEvalImpl";

    private Class<? extends Test> cmd;
    private PerformanceEvaluation pe;

    @Override
    protected void setup(Context context) {
      this.cmd = forName(context.getConfiguration().get(CMD_KEY), Test.class);

      // this is required so that extensions of PE are instantiated within the
      // map reduce task...
      Class<? extends PerformanceEvaluation> peClass =
        forName(context.getConfiguration().get(PE_KEY), PerformanceEvaluation.class);
      try {
        this.pe =
          peClass.getConstructor(Configuration.class).newInstance(context.getConfiguration());
      } catch (Exception e) {
        throw new IllegalStateException("Could not instantiate PE instance", e);
      }
    }

    private <Type> Class<? extends Type> forName(String className, Class<Type> type) {
      Class<? extends Type> clazz;
      try {
        clazz = Class.forName(className).asSubclass(type);
      } catch (ClassNotFoundException e) {
        throw new IllegalStateException("Could not find class for name: " + className, e);
      }
      return clazz;
    }

    @Override
    protected void map(NullWritable key, PeInputSplit value, final Context context)
      throws IOException, InterruptedException {
      Status status = context::setStatus;

      // Evaluation task
      pe.tableName = value.getTableName();
      long elapsedTime =
        this.pe.runOneClient(this.cmd, value.getStartRow(), value.getRows(), value.getTotalRows(),
          value.isFlushCommits(), value.isWriteToWAL(), value.isUseTags(), value.getNoOfTags(),
          ConnectionFactory.createConnection(context.getConfiguration()), status);
      // Collect how much time the thing took. Report as map output and
      // to the ELAPSED_TIME counter.
      context.getCounter(Counter.ELAPSED_TIME).increment(elapsedTime);
      context.getCounter(Counter.ROWS).increment(value.rows);
      context.write(new LongWritable(value.startRow), new LongWritable(elapsedTime));
      context.progress();
    }
  }

  /**
   * If table does not already exist, create.
   * @param admin Client to use checking.
   * @return True if we created the table.
   * @throws IOException if an operation on the table fails
   */
  private boolean checkTable(RemoteAdmin admin) throws IOException {
    TableDescriptor tableDescriptor = getDescriptor();
    if (this.presplitRegions > 0) {
      // presplit requested
      if (admin.isTableAvailable(tableDescriptor.getTableName().getName())) {
        admin.deleteTable(tableDescriptor.getTableName().getName());
      }

      byte[][] splits = getSplits();
      for (int i = 0; i < splits.length; i++) {
        LOG.debug(" split " + i + ": " + Bytes.toStringBinary(splits[i]));
      }
      admin.createTable(tableDescriptor);
      LOG.info("Table created with " + this.presplitRegions + " splits");
    } else {
      boolean tableExists = admin.isTableAvailable(tableDescriptor.getTableName().getName());
      if (!tableExists) {
        admin.createTable(tableDescriptor);
        LOG.info("Table " + tableDescriptor + " created");
      }
    }

    return admin.isTableAvailable(tableDescriptor.getTableName().getName());
  }

  protected TableDescriptor getDescriptor() {
    if (TABLE_DESCRIPTOR == null) {
      TABLE_DESCRIPTOR =
        TableDescriptorBuilder.newBuilder(tableName)
          .setColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(FAMILY_NAME)
            .setDataBlockEncoding(blockEncoding).setCompressionType(compression)
            .setInMemory(inMemoryCF).build())
          .build();
    }
    return TABLE_DESCRIPTOR;
  }

  /**
   * Generates splits based on total number of rows and specified split regions
   * @return splits : array of byte []
   */
  protected byte[][] getSplits() {
    if (this.presplitRegions == 0) {
      return new byte[0][];
    }

    int numSplitPoints = presplitRegions - 1;
    byte[][] splits = new byte[numSplitPoints][];
    int jump = this.R / this.presplitRegions;
    for (int i = 0; i < numSplitPoints; i++) {
      int rowkey = jump * (1 + i);
      splits[i] = format(rowkey);
    }
    return splits;
  }

  /**
   * We're to run multiple clients concurrently. Setup a mapreduce job. Run one map per client. Then
   * run a single reduce to sum the elapsed times.
   * @param cmd Command to run.
   */
  private void runNIsMoreThanOne(final Class<? extends Test> cmd)
    throws IOException, InterruptedException, ClassNotFoundException {
    RemoteAdmin remoteAdmin = new RemoteAdmin(new Client(cluster), getConf());
    checkTable(remoteAdmin);
    if (nomapred) {
      doMultipleClients(cmd);
    } else {
      doMapReduce(cmd);
    }
  }

  /**
   * Run all clients in this vm each to its own thread.
   * @param cmd Command to run
   * @throws IOException if creating a connection fails
   */
  private void doMultipleClients(final Class<? extends Test> cmd) throws IOException {
    final List<Thread> threads = new ArrayList<>(this.N);
    final long[] timings = new long[this.N];
    final int perClientRows = R / N;
    final TableName tableName = this.tableName;
    final DataBlockEncoding encoding = this.blockEncoding;
    final boolean flushCommits = this.flushCommits;
    final Compression.Algorithm compression = this.compression;
    final boolean writeToWal = this.writeToWAL;
    final int preSplitRegions = this.presplitRegions;
    final boolean useTags = this.useTags;
    final int numTags = this.noOfTags;
    final Connection connection = ConnectionFactory.createConnection(getConf());
    for (int i = 0; i < this.N; i++) {
      final int index = i;
      Thread t = new Thread("TestClient-" + i) {
        @Override
        public void run() {
          super.run();
          PerformanceEvaluation pe = new PerformanceEvaluation(getConf());
          pe.tableName = tableName;
          pe.blockEncoding = encoding;
          pe.flushCommits = flushCommits;
          pe.compression = compression;
          pe.writeToWAL = writeToWal;
          pe.presplitRegions = preSplitRegions;
          pe.N = N;
          pe.connection = connection;
          pe.useTags = useTags;
          pe.noOfTags = numTags;
          try {
            long elapsedTime = pe.runOneClient(cmd, index * perClientRows, perClientRows, R,
              flushCommits, writeToWAL, useTags, noOfTags, connection,
              msg -> LOG.info("client-" + getName() + " " + msg));
            timings[index] = elapsedTime;
            LOG.info("Finished " + getName() + " in " + elapsedTime + "ms writing " + perClientRows
              + " rows");
          } catch (IOException e) {
            throw new RuntimeException(e);
          }
        }
      };
      threads.add(t);
    }
    for (Thread t : threads) {
      t.start();
    }
    for (Thread t : threads) {
      while (t.isAlive()) {
        try {
          t.join();
        } catch (InterruptedException e) {
          LOG.debug("Interrupted, continuing" + e.toString());
        }
      }
    }
    final String test = cmd.getSimpleName();
    LOG.info("[" + test + "] Summary of timings (ms): " + Arrays.toString(timings));
    Arrays.sort(timings);
    long total = 0;
    for (int i = 0; i < this.N; i++) {
      total += timings[i];
    }
    LOG.info("[" + test + "]" + "\tMin: " + timings[0] + "ms" + "\tMax: " + timings[this.N - 1]
      + "ms" + "\tAvg: " + (total / this.N) + "ms");
  }

  /**
   * Run a mapreduce job. Run as many maps as asked-for clients. Before we start up the job, write
   * out an input file with instruction per client regards which row they are to start on.
   * @param cmd Command to run.
   */
  private void doMapReduce(final Class<? extends Test> cmd)
    throws IOException, InterruptedException, ClassNotFoundException {
    Configuration conf = getConf();
    Path inputDir = writeInputFile(conf);
    conf.set(EvaluationMapTask.CMD_KEY, cmd.getName());
    conf.set(EvaluationMapTask.PE_KEY, getClass().getName());
    Job job = Job.getInstance(conf);
    job.setJarByClass(PerformanceEvaluation.class);
    job.setJobName("HBase Performance Evaluation");

    job.setInputFormatClass(PeInputFormat.class);
    PeInputFormat.setInputPaths(job, inputDir);

    job.setOutputKeyClass(LongWritable.class);
    job.setOutputValueClass(LongWritable.class);

    job.setMapperClass(EvaluationMapTask.class);
    job.setReducerClass(LongSumReducer.class);
    job.setNumReduceTasks(1);

    job.setOutputFormatClass(TextOutputFormat.class);
    TextOutputFormat.setOutputPath(job, new Path(inputDir.getParent(), "outputs"));
    TableMapReduceUtil.addDependencyJars(job);
    TableMapReduceUtil.initCredentials(job);
    job.waitForCompletion(true);
  }

  /**
   * Write input file of offsets-per-client for the mapreduce job.
   * @param c Configuration
   * @return Directory that contains file written.
   * @throws IOException if creating the directory or the file fails
   */
  private Path writeInputFile(final Configuration c) throws IOException {
    SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMddHHmmss");
    Path jobdir = new Path(PERF_EVAL_DIR, formatter.format(new Date()));
    Path inputDir = new Path(jobdir, "inputs");

    FileSystem fs = FileSystem.get(c);
    fs.mkdirs(inputDir);
    Path inputFile = new Path(inputDir, "input.txt");
    // Make input random.
    try (PrintStream out = new PrintStream(fs.create(inputFile))) {
      Map<Integer, String> m = new TreeMap<>();
      Hash h = MurmurHash.getInstance();
      int perClientRows = (this.R / this.N);
      for (int i = 0; i < 10; i++) {
        for (int j = 0; j < N; j++) {
          StringBuilder s = new StringBuilder();
          s.append("tableName=").append(tableName);
          s.append(", startRow=").append((j * perClientRows) + (i * (perClientRows / 10)));
          s.append(", perClientRunRows=").append(perClientRows / 10);
          s.append(", totalRows=").append(R);
          s.append(", clients=").append(N);
          s.append(", flushCommits=").append(flushCommits);
          s.append(", writeToWAL=").append(writeToWAL);
          s.append(", useTags=").append(useTags);
          s.append(", noOfTags=").append(noOfTags);

          byte[] b = Bytes.toBytes(s.toString());
          int hash = h.hash(new ByteArrayHashKey(b, 0, b.length), -1);
          m.put(hash, s.toString());
        }
      }
      for (Map.Entry<Integer, String> e : m.entrySet()) {
        out.println(e.getValue());
      }
    }
    return inputDir;
  }

  /**
   * Describes a command.
   */
  static class CmdDescriptor {
    private Class<? extends Test> cmdClass;
    private String name;
    private String description;

    CmdDescriptor(Class<? extends Test> cmdClass, String name, String description) {
      this.cmdClass = cmdClass;
      this.name = name;
      this.description = description;
    }

    public Class<? extends Test> getCmdClass() {
      return cmdClass;
    }

    public String getName() {
      return name;
    }

    public String getDescription() {
      return description;
    }
  }

  /**
   * Wraps up options passed to {@link org.apache.hadoop.hbase.PerformanceEvaluation} tests This
   * makes the reflection logic a little easier to understand...
   */
  static class TestOptions {
    private int startRow;
    private int perClientRunRows;
    private int totalRows;
    private TableName tableName;
    private boolean flushCommits;
    private boolean writeToWAL;
    private boolean useTags;
    private int noOfTags;
    private Connection connection;

    TestOptions(int startRow, int perClientRunRows, int totalRows, TableName tableName,
      boolean flushCommits, boolean writeToWAL, boolean useTags, int noOfTags,
      Connection connection) {
      this.startRow = startRow;
      this.perClientRunRows = perClientRunRows;
      this.totalRows = totalRows;
      this.tableName = tableName;
      this.flushCommits = flushCommits;
      this.writeToWAL = writeToWAL;
      this.useTags = useTags;
      this.noOfTags = noOfTags;
      this.connection = connection;
    }

    public int getStartRow() {
      return startRow;
    }

    public int getPerClientRunRows() {
      return perClientRunRows;
    }

    public int getTotalRows() {
      return totalRows;
    }

    public TableName getTableName() {
      return tableName;
    }

    public boolean isFlushCommits() {
      return flushCommits;
    }

    public boolean isWriteToWAL() {
      return writeToWAL;
    }

    public Connection getConnection() {
      return connection;
    }

    public boolean isUseTags() {
      return this.useTags;
    }

    public int getNumTags() {
      return this.noOfTags;
    }
  }

  /*
   * A test. Subclass to particularize what happens per row.
   */
  static abstract class Test {
    // Below is make it so when Tests are all running in the one
    // jvm, that they each have a differently seeded Random.
    private static final Random randomSeed = new Random(EnvironmentEdgeManager.currentTime());

    private static long nextRandomSeed() {
      return randomSeed.nextLong();
    }

    protected final Random rand = new Random(nextRandomSeed());

    protected final int startRow;
    protected final int perClientRunRows;
    protected final int totalRows;
    private final Status status;
    protected TableName tableName;
    protected volatile Configuration conf;
    protected boolean writeToWAL;
    protected boolean useTags;
    protected int noOfTags;
    protected Connection connection;

    /**
     * Note that all subclasses of this class must provide a public contructor that has the exact
     * same list of arguments.
     */
    Test(final Configuration conf, final TestOptions options, final Status status) {
      super();
      this.startRow = options.getStartRow();
      this.perClientRunRows = options.getPerClientRunRows();
      this.totalRows = options.getTotalRows();
      this.status = status;
      this.tableName = options.getTableName();
      this.conf = conf;
      this.writeToWAL = options.isWriteToWAL();
      this.useTags = options.isUseTags();
      this.noOfTags = options.getNumTags();
      this.connection = options.getConnection();
    }

    protected String generateStatus(final int sr, final int i, final int lr) {
      return sr + "/" + i + "/" + lr;
    }

    protected int getReportingPeriod() {
      int period = this.perClientRunRows / 10;
      return period == 0 ? this.perClientRunRows : period;
    }

    abstract void testTakedown() throws IOException;

    /**
     * Run test
     * @return Elapsed time.
     * @throws IOException if something in the test fails
     */
    long test() throws IOException {
      testSetup();
      LOG.info("Timed test starting in thread " + Thread.currentThread().getName());
      final long startTime = System.nanoTime();
      try {
        testTimed();
      } finally {
        testTakedown();
      }
      return (System.nanoTime() - startTime) / 1000000;
    }

    abstract void testSetup() throws IOException;

    /**
     * Provides an extension point for tests that don't want a per row invocation.
     */
    void testTimed() throws IOException {
      int lastRow = this.startRow + this.perClientRunRows;
      // Report on completion of 1/10th of total.
      for (int i = this.startRow; i < lastRow; i++) {
        testRow(i);
        if (status != null && i > 0 && (i % getReportingPeriod()) == 0) {
          status.setStatus(generateStatus(this.startRow, i, lastRow));
        }
      }
    }

    /**
     * Test for individual row.
     * @param i Row index.
     */
    abstract void testRow(final int i) throws IOException;
  }

  static abstract class TableTest extends Test {
    protected Table table;

    public TableTest(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    void testSetup() throws IOException {
      this.table = connection.getTable(tableName);
    }

    @Override
    void testTakedown() throws IOException {
      table.close();
    }
  }

  static abstract class BufferedMutatorTest extends Test {
    protected BufferedMutator mutator;
    protected boolean flushCommits;

    public BufferedMutatorTest(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
      this.flushCommits = options.isFlushCommits();
    }

    @Override
    void testSetup() throws IOException {
      this.mutator = connection.getBufferedMutator(tableName);
    }

    @Override
    void testTakedown() throws IOException {
      if (flushCommits) {
        this.mutator.flush();
      }
      mutator.close();
    }
  }

  static class RandomSeekScanTest extends TableTest {
    RandomSeekScanTest(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    void testRow(final int i) throws IOException {
      Scan scan = new Scan().withStartRow(getRandomRow(this.rand, this.totalRows));
      scan.addColumn(FAMILY_NAME, QUALIFIER_NAME);
      scan.setFilter(new WhileMatchFilter(new PageFilter(120)));
      ResultScanner s = this.table.getScanner(scan);
      s.close();
    }

    @Override
    protected int getReportingPeriod() {
      int period = this.perClientRunRows / 100;
      return period == 0 ? this.perClientRunRows : period;
    }
  }

  @SuppressWarnings("unused")
  static abstract class RandomScanWithRangeTest extends TableTest {
    RandomScanWithRangeTest(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    void testRow(final int i) throws IOException {
      Pair<byte[], byte[]> startAndStopRow = getStartAndStopRow();
      Scan scan = new Scan().withStartRow(startAndStopRow.getFirst())
        .withStopRow(startAndStopRow.getSecond());
      scan.addColumn(FAMILY_NAME, QUALIFIER_NAME);
      ResultScanner s = this.table.getScanner(scan);
      int count = 0;
      for (Result rr = null; (rr = s.next()) != null;) {
        count++;
      }

      if (i % 100 == 0) {
        LOG.info(String.format("Scan for key range %s - %s returned %s rows",
          Bytes.toString(startAndStopRow.getFirst()), Bytes.toString(startAndStopRow.getSecond()),
          count));
      }

      s.close();
    }

    protected abstract Pair<byte[], byte[]> getStartAndStopRow();

    protected Pair<byte[], byte[]> generateStartAndStopRows(int maxRange) {
      int start = this.rand.nextInt(Integer.MAX_VALUE) % totalRows;
      int stop = start + maxRange;
      return new Pair<>(format(start), format(stop));
    }

    @Override
    protected int getReportingPeriod() {
      int period = this.perClientRunRows / 100;
      return period == 0 ? this.perClientRunRows : period;
    }
  }

  static class RandomScanWithRange10Test extends RandomScanWithRangeTest {
    RandomScanWithRange10Test(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    protected Pair<byte[], byte[]> getStartAndStopRow() {
      return generateStartAndStopRows(10);
    }
  }

  static class RandomScanWithRange100Test extends RandomScanWithRangeTest {
    RandomScanWithRange100Test(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    protected Pair<byte[], byte[]> getStartAndStopRow() {
      return generateStartAndStopRows(100);
    }
  }

  static class RandomScanWithRange1000Test extends RandomScanWithRangeTest {
    RandomScanWithRange1000Test(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    protected Pair<byte[], byte[]> getStartAndStopRow() {
      return generateStartAndStopRows(1000);
    }
  }

  static class RandomScanWithRange10000Test extends RandomScanWithRangeTest {
    RandomScanWithRange10000Test(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    protected Pair<byte[], byte[]> getStartAndStopRow() {
      return generateStartAndStopRows(10000);
    }
  }

  static class RandomReadTest extends TableTest {
    RandomReadTest(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    void testRow(final int i) throws IOException {
      Get get = new Get(getRandomRow(this.rand, this.totalRows));
      get.addColumn(FAMILY_NAME, QUALIFIER_NAME);
      this.table.get(get);
    }

    @Override
    protected int getReportingPeriod() {
      int period = this.perClientRunRows / 100;
      return period == 0 ? this.perClientRunRows : period;
    }
  }

  static class RandomWriteTest extends BufferedMutatorTest {
    RandomWriteTest(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    void testRow(final int i) throws IOException {
      byte[] row = getRandomRow(this.rand, this.totalRows);
      Put put = new Put(row);
      byte[] value = generateData(this.rand, ROW_LENGTH);
      if (useTags) {
        byte[] tag = generateData(this.rand, TAG_LENGTH);
        Tag[] tags = new Tag[noOfTags];
        for (int n = 0; n < noOfTags; n++) {
          Tag t = new ArrayBackedTag((byte) n, tag);
          tags[n] = t;
        }
        KeyValue kv =
          new KeyValue(row, FAMILY_NAME, QUALIFIER_NAME, HConstants.LATEST_TIMESTAMP, value, tags);
        put.add(kv);
      } else {
        put.addColumn(FAMILY_NAME, QUALIFIER_NAME, value);
      }
      put.setDurability(writeToWAL ? Durability.SYNC_WAL : Durability.SKIP_WAL);
      mutator.mutate(put);
    }
  }

  static class ScanTest extends TableTest {
    private ResultScanner testScanner;

    ScanTest(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    void testTakedown() throws IOException {
      if (this.testScanner != null) {
        this.testScanner.close();
      }
      super.testTakedown();
    }

    @Override
    void testRow(final int i) throws IOException {
      if (this.testScanner == null) {
        Scan scan = new Scan().withStartRow(format(this.startRow));
        scan.addColumn(FAMILY_NAME, QUALIFIER_NAME);
        this.testScanner = table.getScanner(scan);
      }
      testScanner.next();
    }
  }

  static class SequentialReadTest extends TableTest {
    SequentialReadTest(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    void testRow(final int i) throws IOException {
      Get get = new Get(format(i));
      get.addColumn(FAMILY_NAME, QUALIFIER_NAME);
      table.get(get);
    }
  }

  static class SequentialWriteTest extends BufferedMutatorTest {
    SequentialWriteTest(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    void testRow(final int i) throws IOException {
      byte[] row = format(i);
      Put put = new Put(row);
      byte[] value = generateData(this.rand, ROW_LENGTH);
      if (useTags) {
        byte[] tag = generateData(this.rand, TAG_LENGTH);
        Tag[] tags = new Tag[noOfTags];
        for (int n = 0; n < noOfTags; n++) {
          Tag t = new ArrayBackedTag((byte) n, tag);
          tags[n] = t;
        }
        KeyValue kv =
          new KeyValue(row, FAMILY_NAME, QUALIFIER_NAME, HConstants.LATEST_TIMESTAMP, value, tags);
        put.add(kv);
      } else {
        put.addColumn(FAMILY_NAME, QUALIFIER_NAME, value);
      }
      put.setDurability(writeToWAL ? Durability.SYNC_WAL : Durability.SKIP_WAL);
      mutator.mutate(put);
    }
  }

  static class FilteredScanTest extends TableTest {
    protected static final Logger LOG = LoggerFactory.getLogger(FilteredScanTest.class.getName());

    FilteredScanTest(Configuration conf, TestOptions options, Status status) {
      super(conf, options, status);
    }

    @Override
    void testRow(int i) throws IOException {
      byte[] value = generateValue(this.rand);
      Scan scan = constructScan(value);
      try (ResultScanner scanner = this.table.getScanner(scan)) {
        while (scanner.next() != null) {
        }
      }
    }

    protected Scan constructScan(byte[] valuePrefix) {
      Filter filter = new SingleColumnValueFilter(FAMILY_NAME, QUALIFIER_NAME,
        CompareOperator.EQUAL, new BinaryComparator(valuePrefix));
      Scan scan = new Scan();
      scan.addColumn(FAMILY_NAME, QUALIFIER_NAME);
      scan.setFilter(filter);
      return scan;
    }
  }

  /**
   * Format passed integer.
   * @param number the integer to format
   * @return Returns zero-prefixed 10-byte wide decimal version of passed number (Does absolute in
   *         case number is negative).
   */
  public static byte[] format(final int number) {
    byte[] b = new byte[DEFAULT_ROW_PREFIX_LENGTH + 10];
    int d = Math.abs(number);
    for (int i = b.length - 1; i >= 0; i--) {
      b[i] = (byte) ((d % 10) + '0');
      d /= 10;
    }
    return b;
  }

  public static byte[] generateData(final Random r, int length) {
    byte[] b = new byte[length];
    int i;

    for (i = 0; i < (length - 8); i += 8) {
      b[i] = (byte) (65 + r.nextInt(26));
      b[i + 1] = b[i];
      b[i + 2] = b[i];
      b[i + 3] = b[i];
      b[i + 4] = b[i];
      b[i + 5] = b[i];
      b[i + 6] = b[i];
      b[i + 7] = b[i];
    }

    byte a = (byte) (65 + r.nextInt(26));
    for (; i < length; i++) {
      b[i] = a;
    }
    return b;
  }

  public static byte[] generateValue(final Random r) {
    byte[] b = new byte[ROW_LENGTH];
    r.nextBytes(b);
    return b;
  }

  static byte[] getRandomRow(final Random random, final int totalRows) {
    return format(random.nextInt(Integer.MAX_VALUE) % totalRows);
  }

  long runOneClient(final Class<? extends Test> cmd, final int startRow, final int perClientRunRows,
    final int totalRows, boolean flushCommits, boolean writeToWAL, boolean useTags, int noOfTags,
    Connection connection, final Status status) throws IOException {
    status
      .setStatus("Start " + cmd + " at offset " + startRow + " for " + perClientRunRows + " rows");
    long totalElapsedTime;

    TestOptions options = new TestOptions(startRow, perClientRunRows, totalRows, tableName,
      flushCommits, writeToWAL, useTags, noOfTags, connection);
    final Test t;
    try {
      Constructor<? extends Test> constructor =
        cmd.getDeclaredConstructor(Configuration.class, TestOptions.class, Status.class);
      t = constructor.newInstance(this.conf, options, status);
    } catch (NoSuchMethodException e) {
      throw new IllegalArgumentException("Invalid command class: " + cmd.getName()
        + ".  It does not provide a constructor as described by"
        + "the javadoc comment.  Available constructors are: "
        + Arrays.toString(cmd.getConstructors()));
    } catch (Exception e) {
      throw new IllegalStateException("Failed to construct command class", e);
    }
    totalElapsedTime = t.test();

    status.setStatus("Finished " + cmd + " in " + totalElapsedTime + "ms at offset " + startRow
      + " for " + perClientRunRows + " rows");
    return totalElapsedTime;
  }

  private void runNIsOne(final Class<? extends Test> cmd) {
    Status status = LOG::info;

    RemoteAdmin admin;
    try {
      Client client = new Client(cluster);
      admin = new RemoteAdmin(client, getConf());
      checkTable(admin);
      runOneClient(cmd, 0, this.R, this.R, this.flushCommits, this.writeToWAL, this.useTags,
        this.noOfTags, this.connection, status);
    } catch (Exception e) {
      LOG.error("Failed", e);
    }
  }

  private void runTest(final Class<? extends Test> cmd)
    throws IOException, InterruptedException, ClassNotFoundException {
    if (N == 1) {
      // If there is only one client and one HRegionServer, we assume nothing
      // has been set up at all.
      runNIsOne(cmd);
    } else {
      // Else, run
      runNIsMoreThanOne(cmd);
    }
  }

  protected void printUsage() {
    printUsage(null);
  }

  protected void printUsage(final String message) {
    if (message != null && message.length() > 0) {
      System.err.println(message);
    }
    System.err.println("Usage: java " + this.getClass().getName() + " \\");
    System.err.println("  [--nomapred] [--rows=ROWS] [--table=NAME] \\");
    System.err.println(
      "  [--compress=TYPE] [--blockEncoding=TYPE] " + "[-D<property=value>]* <command> <nclients>");
    System.err.println();
    System.err.println("General Options:");
    System.err.println(
      " nomapred        Run multiple clients using threads " + "(rather than use mapreduce)");
    System.err.println(" rows            Rows each client runs. Default: One million");
    System.err.println();
    System.err.println("Table Creation / Write Tests:");
    System.err.println(" table           Alternate table name. Default: 'TestTable'");
    System.err.println(" compress        Compression type to use (GZ, LZO, ...). Default: 'NONE'");
    System.err.println(
      " flushCommits    Used to determine if the test should flush the table. " + "Default: false");
    System.err.println(" writeToWAL      Set writeToWAL on puts. Default: True");
    System.err.println(" presplit        Create presplit table. Recommended for accurate perf "
      + "analysis (see guide).  Default: disabled");
    System.err.println(
      " usetags         Writes tags along with KVs.  Use with HFile V3. " + "Default : false");
    System.err.println(" numoftags        Specify the no of tags that would be needed. "
      + "This works only if usetags is true.");
    System.err.println();
    System.err.println("Read Tests:");
    System.err.println(" inmemory        Tries to keep the HFiles of the CF inmemory as far as "
      + "possible.  Not guaranteed that reads are always served from inmemory.  Default: false");
    System.err.println();
    System.err.println(" Note: -D properties will be applied to the conf used. ");
    System.err.println("  For example: ");
    System.err.println("   -Dmapreduce.output.fileoutputformat.compress=true");
    System.err.println("   -Dmapreduce.task.timeout=60000");
    System.err.println();
    System.err.println("Command:");
    for (CmdDescriptor command : commands.values()) {
      System.err.println(String.format(" %-15s %s", command.getName(), command.getDescription()));
    }
    System.err.println();
    System.err.println("Args:");
    System.err.println(
      " nclients      Integer. Required. Total number of " + "clients (and HRegionServers)");
    System.err.println("               running: 1 <= value <= 500");
    System.err.println("Examples:");
    System.err.println(" To run a single evaluation client:");
    System.err.println(" $ hbase " + this.getClass().getName() + " sequentialWrite 1");
  }

  private void getArgs(final int start, final String[] args) {
    if (start + 1 > args.length) {
      throw new IllegalArgumentException("must supply the number of clients");
    }
    N = Integer.parseInt(args[start]);
    if (N < 1) {
      throw new IllegalArgumentException("Number of clients must be > 1");
    }
    // Set total number of rows to write.
    R = R * N;
  }

  @Override
  public int run(String[] args) throws Exception {
    // Process command-line args. TODO: Better cmd-line processing
    // (but hopefully something not as painful as cli options).
    int errCode = -1;
    if (args.length < 1) {
      printUsage();
      return errCode;
    }

    try {
      for (int i = 0; i < args.length; i++) {
        String cmd = args[i];
        if (cmd.equals("-h") || cmd.startsWith("--h")) {
          printUsage();
          errCode = 0;
          break;
        }

        final String nmr = "--nomapred";
        if (cmd.startsWith(nmr)) {
          nomapred = true;
          continue;
        }

        final String rows = "--rows=";
        if (cmd.startsWith(rows)) {
          R = Integer.parseInt(cmd.substring(rows.length()));
          continue;
        }

        final String table = "--table=";
        if (cmd.startsWith(table)) {
          this.tableName = TableName.valueOf(cmd.substring(table.length()));
          continue;
        }

        final String compress = "--compress=";
        if (cmd.startsWith(compress)) {
          this.compression = Compression.Algorithm.valueOf(cmd.substring(compress.length()));
          continue;
        }

        final String blockEncoding = "--blockEncoding=";
        if (cmd.startsWith(blockEncoding)) {
          this.blockEncoding = DataBlockEncoding.valueOf(cmd.substring(blockEncoding.length()));
          continue;
        }

        final String flushCommits = "--flushCommits=";
        if (cmd.startsWith(flushCommits)) {
          this.flushCommits = Boolean.parseBoolean(cmd.substring(flushCommits.length()));
          continue;
        }

        final String writeToWAL = "--writeToWAL=";
        if (cmd.startsWith(writeToWAL)) {
          this.writeToWAL = Boolean.parseBoolean(cmd.substring(writeToWAL.length()));
          continue;
        }

        final String presplit = "--presplit=";
        if (cmd.startsWith(presplit)) {
          this.presplitRegions = Integer.parseInt(cmd.substring(presplit.length()));
          continue;
        }

        final String inMemory = "--inmemory=";
        if (cmd.startsWith(inMemory)) {
          this.inMemoryCF = Boolean.parseBoolean(cmd.substring(inMemory.length()));
          continue;
        }

        this.connection = ConnectionFactory.createConnection(getConf());

        final String useTags = "--usetags=";
        if (cmd.startsWith(useTags)) {
          this.useTags = Boolean.parseBoolean(cmd.substring(useTags.length()));
          continue;
        }

        final String noOfTags = "--nooftags=";
        if (cmd.startsWith(noOfTags)) {
          this.noOfTags = Integer.parseInt(cmd.substring(noOfTags.length()));
          continue;
        }

        final String host = "--host=";
        if (cmd.startsWith(host)) {
          cluster.add(cmd.substring(host.length()));
          continue;
        }

        Class<? extends Test> cmdClass = determineCommandClass(cmd);
        if (cmdClass != null) {
          getArgs(i + 1, args);
          if (cluster.isEmpty()) {
            String s = conf.get("stargate.hostname", "localhost");
            if (s.contains(":")) {
              cluster.add(s);
            } else {
              cluster.add(s, conf.getInt("stargate.port", 8080));
            }
          }
          runTest(cmdClass);
          errCode = 0;
          break;
        }

        printUsage();
        break;
      }
    } catch (Exception e) {
      LOG.error("Failed", e);
    }

    return errCode;
  }

  private Class<? extends Test> determineCommandClass(String cmd) {
    CmdDescriptor descriptor = commands.get(cmd);
    return descriptor != null ? descriptor.getCmdClass() : null;
  }

  public static void main(final String[] args) throws Exception {
    int res = ToolRunner.run(new PerformanceEvaluation(HBaseConfiguration.create()), args);
    System.exit(res);
  }
}