HBase源码实战：ImportTsv

/**
 *
 * 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.mapreduce;

import static java.lang.String.format;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Base64;
import java.util.HashSet;
import java.util.Set;

import org.apache.commons.lang3.StringUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.TableNotEnabledException;
import org.apache.hadoop.hbase.TableNotFoundException;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.hbase.client.Admin;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.RegionLocator;
import org.apache.hadoop.hbase.client.Table;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.Pair;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.NullOutputFormat;
import org.apache.hadoop.security.Credentials;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

import org.apache.hadoop.hbase.client.ColumnFamilyDescriptor;
import org.apache.hadoop.hbase.client.TableDescriptor;
import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
import org.apache.hbase.thirdparty.com.google.common.base.Splitter;
import org.apache.hbase.thirdparty.com.google.common.collect.Lists;

/**
 * Tool to import data from a TSV file.
 *
 * This tool is rather simplistic - it doesn't do any quoting or
 * escaping, but is useful for many data loads.
 *
 * @see ImportTsv#usage(String)
 */
@InterfaceAudience.Public
public class ImportTsv extends Configured implements Tool {

  protected static final Logger LOG = LoggerFactory.getLogger(ImportTsv.class);

  final static String NAME = "importtsv";

  public final static String MAPPER_CONF_KEY = "importtsv.mapper.class";
  public final static String BULK_OUTPUT_CONF_KEY = "importtsv.bulk.output";
  public final static String TIMESTAMP_CONF_KEY = "importtsv.timestamp";
  public final static String JOB_NAME_CONF_KEY = "mapreduce.job.name";
  // TODO: the rest of these configs are used exclusively by TsvImporterMapper.
  // Move them out of the tool and let the mapper handle its own validation.
  public final static String DRY_RUN_CONF_KEY = "importtsv.dry.run";
  // If true, bad lines are logged to stderr. Default: false.
  public final static String LOG_BAD_LINES_CONF_KEY = "importtsv.log.bad.lines";
  public final static String SKIP_LINES_CONF_KEY = "importtsv.skip.bad.lines";
  public final static String SKIP_EMPTY_COLUMNS = "importtsv.skip.empty.columns";
  public final static String COLUMNS_CONF_KEY = "importtsv.columns";
  public final static String SEPARATOR_CONF_KEY = "importtsv.separator";
  public final static String ATTRIBUTE_SEPERATOR_CONF_KEY = "attributes.seperator";
  //This config is used to propagate credentials from parent MR jobs which launch
  //ImportTSV jobs. SEE IntegrationTestImportTsv.
  public final static String CREDENTIALS_LOCATION = "credentials_location";
  final static String DEFAULT_SEPARATOR = "\t";
  final static String DEFAULT_ATTRIBUTES_SEPERATOR = "=>";
  final static String DEFAULT_MULTIPLE_ATTRIBUTES_SEPERATOR = ",";
  final static Class DEFAULT_MAPPER = TsvImporterMapper.class;
  public final static String CREATE_TABLE_CONF_KEY = "create.table";
  public final static String NO_STRICT_COL_FAMILY = "no.strict";
  /**
   * If table didn't exist and was created in dry-run mode, this flag is
   * flipped to delete it when MR ends.
   */
  private static boolean DRY_RUN_TABLE_CREATED;

  public static class TsvParser {
    /**
     * Column families and qualifiers mapped to the TSV columns
     */
    private final byte[][] families;
    private final byte[][] qualifiers;

    private final byte separatorByte;

    private int rowKeyColumnIndex;

    private int maxColumnCount;

    // Default value must be negative
    public static final int DEFAULT_TIMESTAMP_COLUMN_INDEX = -1;

    private int timestampKeyColumnIndex = DEFAULT_TIMESTAMP_COLUMN_INDEX;

    public static final String ROWKEY_COLUMN_SPEC = "HBASE_ROW_KEY";

    public static final String TIMESTAMPKEY_COLUMN_SPEC = "HBASE_TS_KEY";

    public static final String ATTRIBUTES_COLUMN_SPEC = "HBASE_ATTRIBUTES_KEY";

    public static final String CELL_VISIBILITY_COLUMN_SPEC = "HBASE_CELL_VISIBILITY";

    public static final String CELL_TTL_COLUMN_SPEC = "HBASE_CELL_TTL";

    private int attrKeyColumnIndex = DEFAULT_ATTRIBUTES_COLUMN_INDEX;

    public static final int DEFAULT_ATTRIBUTES_COLUMN_INDEX = -1;

    public static final int DEFAULT_CELL_VISIBILITY_COLUMN_INDEX = -1;

    public static final int DEFAULT_CELL_TTL_COLUMN_INDEX = -1;

    private int cellVisibilityColumnIndex = DEFAULT_CELL_VISIBILITY_COLUMN_INDEX;

    private int cellTTLColumnIndex = DEFAULT_CELL_TTL_COLUMN_INDEX;

    /**
     * @param columnsSpecification the list of columns to parser out, comma separated.
     * The row key should be the special token TsvParser.ROWKEY_COLUMN_SPEC
     * @param separatorStr
     */
    public TsvParser(String columnsSpecification, String separatorStr) {
      // Configure separator
      byte[] separator = Bytes.toBytes(separatorStr);
      Preconditions.checkArgument(separator.length == 1,
        "TsvParser only supports single-byte separators");
      separatorByte = separator[0];

      // Configure columns
      ArrayList<String> columnStrings = Lists.newArrayList(
        Splitter.on(',').trimResults().split(columnsSpecification));

      maxColumnCount = columnStrings.size();
      families = new byte[maxColumnCount][];
      qualifiers = new byte[maxColumnCount][];

      for (int i = 0; i < columnStrings.size(); i++) {
        String str = columnStrings.get(i);
        if (ROWKEY_COLUMN_SPEC.equals(str)) {
          rowKeyColumnIndex = i;
          continue;
        }
        if (TIMESTAMPKEY_COLUMN_SPEC.equals(str)) {
          timestampKeyColumnIndex = i;
          continue;
        }
        if (ATTRIBUTES_COLUMN_SPEC.equals(str)) {
          attrKeyColumnIndex = i;
          continue;
        }
        if (CELL_VISIBILITY_COLUMN_SPEC.equals(str)) {
          cellVisibilityColumnIndex = i;
          continue;
        }
        if (CELL_TTL_COLUMN_SPEC.equals(str)) {
          cellTTLColumnIndex = i;
          continue;
        }
        String[] parts = str.split(":", 2);
        if (parts.length == 1) {
          families[i] = str.getBytes();
          qualifiers[i] = HConstants.EMPTY_BYTE_ARRAY;
        } else {
          families[i] = parts[0].getBytes();
          qualifiers[i] = parts[1].getBytes();
        }
      }
    }

    public boolean hasTimestamp() {
      return timestampKeyColumnIndex != DEFAULT_TIMESTAMP_COLUMN_INDEX;
    }

    public int getTimestampKeyColumnIndex() {
      return timestampKeyColumnIndex;
    }

    public boolean hasAttributes() {
      return attrKeyColumnIndex != DEFAULT_ATTRIBUTES_COLUMN_INDEX;
    }

    public boolean hasCellVisibility() {
      return cellVisibilityColumnIndex != DEFAULT_CELL_VISIBILITY_COLUMN_INDEX;
    }

    public boolean hasCellTTL() {
      return cellTTLColumnIndex != DEFAULT_CELL_VISIBILITY_COLUMN_INDEX;
    }

    public int getAttributesKeyColumnIndex() {
      return attrKeyColumnIndex;
    }

    public int getCellVisibilityColumnIndex() {
      return cellVisibilityColumnIndex;
    }

    public int getCellTTLColumnIndex() {
      return cellTTLColumnIndex;
    }

    public int getRowKeyColumnIndex() {
      return rowKeyColumnIndex;
    }

    public byte[] getFamily(int idx) {
      return families[idx];
    }
    public byte[] getQualifier(int idx) {
      return qualifiers[idx];
    }

    public ParsedLine parse(byte[] lineBytes, int length)
    throws BadTsvLineException {
      // Enumerate separator offsets
      ArrayList<Integer> tabOffsets = new ArrayList<>(maxColumnCount);
      for (int i = 0; i < length; i++) {
        if (lineBytes[i] == separatorByte) {
          tabOffsets.add(i);
        }
      }
      if (tabOffsets.isEmpty()) {
        throw new BadTsvLineException("No delimiter");
      }

      tabOffsets.add(length);

      if (tabOffsets.size() > maxColumnCount) {
        throw new BadTsvLineException("Excessive columns");
      } else if (tabOffsets.size() <= getRowKeyColumnIndex()) {
        throw new BadTsvLineException("No row key");
      } else if (hasTimestamp()
          && tabOffsets.size() <= getTimestampKeyColumnIndex()) {
        throw new BadTsvLineException("No timestamp");
      } else if (hasAttributes() && tabOffsets.size() <= getAttributesKeyColumnIndex()) {
        throw new BadTsvLineException("No attributes specified");
      } else if (hasCellVisibility() && tabOffsets.size() <= getCellVisibilityColumnIndex()) {
        throw new BadTsvLineException("No cell visibility specified");
      } else if (hasCellTTL() && tabOffsets.size() <= getCellTTLColumnIndex()) {
        throw new BadTsvLineException("No cell TTL specified");
      }
      return new ParsedLine(tabOffsets, lineBytes);
    }

    class ParsedLine {
      private final ArrayList<Integer> tabOffsets;
      private byte[] lineBytes;

      ParsedLine(ArrayList<Integer> tabOffsets, byte[] lineBytes) {
        this.tabOffsets = tabOffsets;
        this.lineBytes = lineBytes;
      }

      public int getRowKeyOffset() {
        return getColumnOffset(rowKeyColumnIndex);
      }
      public int getRowKeyLength() {
        return getColumnLength(rowKeyColumnIndex);
      }

      public long getTimestamp(long ts) throws BadTsvLineException {
        // Return ts if HBASE_TS_KEY is not configured in column spec
        if (!hasTimestamp()) {
          return ts;
        }

        String timeStampStr = Bytes.toString(lineBytes,
            getColumnOffset(timestampKeyColumnIndex),
            getColumnLength(timestampKeyColumnIndex));
        try {
          return Long.parseLong(timeStampStr);
        } catch (NumberFormatException nfe) {
          // treat this record as bad record
          throw new BadTsvLineException("Invalid timestamp " + timeStampStr);
        }
      }

      private String getAttributes() {
        if (!hasAttributes()) {
          return null;
        } else {
          return Bytes.toString(lineBytes, getColumnOffset(attrKeyColumnIndex),
              getColumnLength(attrKeyColumnIndex));
        }
      }

      public String[] getIndividualAttributes() {
        String attributes = getAttributes();
        if (attributes != null) {
          return attributes.split(DEFAULT_MULTIPLE_ATTRIBUTES_SEPERATOR);
        } else {
          return null;
        }
      }

      public int getAttributeKeyOffset() {
        if (hasAttributes()) {
          return getColumnOffset(attrKeyColumnIndex);
        } else {
          return DEFAULT_ATTRIBUTES_COLUMN_INDEX;
        }
      }

      public int getAttributeKeyLength() {
        if (hasAttributes()) {
          return getColumnLength(attrKeyColumnIndex);
        } else {
          return DEFAULT_ATTRIBUTES_COLUMN_INDEX;
        }
      }

      public int getCellVisibilityColumnOffset() {
        if (hasCellVisibility()) {
          return getColumnOffset(cellVisibilityColumnIndex);
        } else {
          return DEFAULT_CELL_VISIBILITY_COLUMN_INDEX;
        }
      }

      public int getCellVisibilityColumnLength() {
        if (hasCellVisibility()) {
          return getColumnLength(cellVisibilityColumnIndex);
        } else {
          return DEFAULT_CELL_VISIBILITY_COLUMN_INDEX;
        }
      }

      public String getCellVisibility() {
        if (!hasCellVisibility()) {
          return null;
        } else {
          return Bytes.toString(lineBytes, getColumnOffset(cellVisibilityColumnIndex),
              getColumnLength(cellVisibilityColumnIndex));
        }
      }

      public int getCellTTLColumnOffset() {
        if (hasCellTTL()) {
          return getColumnOffset(cellTTLColumnIndex);
        } else {
          return DEFAULT_CELL_TTL_COLUMN_INDEX;
        }
      }

      public int getCellTTLColumnLength() {
        if (hasCellTTL()) {
          return getColumnLength(cellTTLColumnIndex);
        } else {
          return DEFAULT_CELL_TTL_COLUMN_INDEX;
        }
      }

      public long getCellTTL() {
        if (!hasCellTTL()) {
          return 0;
        } else {
          return Bytes.toLong(lineBytes, getColumnOffset(cellTTLColumnIndex),
              getColumnLength(cellTTLColumnIndex));
        }
      }

      public int getColumnOffset(int idx) {
        if (idx > 0)
          return tabOffsets.get(idx - 1) + 1;
        else
          return 0;
      }
      public int getColumnLength(int idx) {
        return tabOffsets.get(idx) - getColumnOffset(idx);
      }
      public int getColumnCount() {
        return tabOffsets.size();
      }
      public byte[] getLineBytes() {
        return lineBytes;
      }
    }

    public static class BadTsvLineException extends Exception {
      public BadTsvLineException(String err) {
        super(err);
      }
      private static final long serialVersionUID = 1L;
    }

    /**
     * Return starting position and length of row key from the specified line bytes.
     * @param lineBytes
     * @param length
     * @return Pair of row key offset and length.
     * @throws BadTsvLineException
     */
    public Pair<Integer, Integer> parseRowKey(byte[] lineBytes, int length)
        throws BadTsvLineException {
      int rkColumnIndex = 0;
      int startPos = 0, endPos = 0;
      for (int i = 0; i <= length; i++) {
        if (i == length || lineBytes[i] == separatorByte) {
          endPos = i - 1;
          if (rkColumnIndex++ == getRowKeyColumnIndex()) {
            if ((endPos + 1) == startPos) {
              throw new BadTsvLineException("Empty value for ROW KEY.");
            }
            break;
          } else {
            startPos = endPos + 2;
          }
        }
        if (i == length) {
          throw new BadTsvLineException(
              "Row key does not exist as number of columns in the line"
                  + " are less than row key position.");
        }
      }
      return new Pair<>(startPos, endPos - startPos + 1);
    }
  }

  /**
   * Sets up the actual job.
   *
   * @param conf  The current configuration.
   * @param args  The command line parameters.
   * @return The newly created job.
   * @throws IOException When setting up the job fails.
   */
  protected static Job createSubmittableJob(Configuration conf, String[] args)
      throws IOException, ClassNotFoundException {
    Job job = null;
    boolean isDryRun = conf.getBoolean(DRY_RUN_CONF_KEY, false);
    try (Connection connection = ConnectionFactory.createConnection(conf)) {
      try (Admin admin = connection.getAdmin()) {
        // Support non-XML supported characters
        // by re-encoding the passed separator as a Base64 string.
        String actualSeparator = conf.get(SEPARATOR_CONF_KEY);
        if (actualSeparator != null) {
          conf.set(SEPARATOR_CONF_KEY,
              Bytes.toString(Base64.getEncoder().encode(actualSeparator.getBytes())));
        }

        // See if a non-default Mapper was set
        String mapperClassName = conf.get(MAPPER_CONF_KEY);
        Class mapperClass = mapperClassName != null? Class.forName(mapperClassName): DEFAULT_MAPPER;

        TableName tableName = TableName.valueOf(args[0]);
        Path inputDir = new Path(args[1]);
        String jobName = conf.get(JOB_NAME_CONF_KEY,NAME + "_" + tableName.getNameAsString());
        job = Job.getInstance(conf, jobName);
        job.setJarByClass(mapperClass);
        FileInputFormat.setInputPaths(job, inputDir);
        job.setInputFormatClass(TextInputFormat.class);
        job.setMapperClass(mapperClass);
        job.setMapOutputKeyClass(ImmutableBytesWritable.class);
        String hfileOutPath = conf.get(BULK_OUTPUT_CONF_KEY);
        String[] columns = conf.getStrings(COLUMNS_CONF_KEY);
        if(StringUtils.isNotEmpty(conf.get(CREDENTIALS_LOCATION))) {
          String fileLoc = conf.get(CREDENTIALS_LOCATION);
          Credentials cred = Credentials.readTokenStorageFile(new File(fileLoc), conf);
          job.getCredentials().addAll(cred);
        }

        if (hfileOutPath != null) {
          if (!admin.tableExists(tableName)) {
            LOG.warn(format("Table '%s' does not exist.", tableName));
            if ("yes".equalsIgnoreCase(conf.get(CREATE_TABLE_CONF_KEY, "yes"))) {
              // TODO: this is backwards. Instead of depending on the existence of a table,
              // create a sane splits file for HFileOutputFormat based on data sampling.
              createTable(admin, tableName, columns);
              if (isDryRun) {
                LOG.warn("Dry run: Table will be deleted at end of dry run.");
                synchronized (ImportTsv.class) {
                  DRY_RUN_TABLE_CREATED = true;
                }
              }
            } else {
              String errorMsg =
                  format("Table '%s' does not exist and '%s' is set to no.", tableName,
                      CREATE_TABLE_CONF_KEY);
              LOG.error(errorMsg);
              throw new TableNotFoundException(errorMsg);
            }
          }
          try (Table table = connection.getTable(tableName);
              RegionLocator regionLocator = connection.getRegionLocator(tableName)) {
            boolean noStrict = conf.getBoolean(NO_STRICT_COL_FAMILY, false);
            // if no.strict is false then check column family
            if(!noStrict) {
              ArrayList<String> unmatchedFamilies = new ArrayList<>();
              Set<String> cfSet = getColumnFamilies(columns);
              TableDescriptor tDesc = table.getDescriptor();
              for (String cf : cfSet) {
                if(!tDesc.hasColumnFamily(Bytes.toBytes(cf))) {
                  unmatchedFamilies.add(cf);
                }
              }
              if(unmatchedFamilies.size() > 0) {
                ArrayList<String> familyNames = new ArrayList<>();
                for (ColumnFamilyDescriptor family : table.getDescriptor().getColumnFamilies()) {
                  familyNames.add(family.getNameAsString());
                }
                String msg =
                    "Column Families " + unmatchedFamilies + " specified in " + COLUMNS_CONF_KEY
                    + " does not match with any of the table " + tableName
                    + " column families " + familyNames + ".\n"
                    + "To disable column family check, use -D" + NO_STRICT_COL_FAMILY
                    + "=true.\n";
                usage(msg);
                System.exit(-1);
              }
            }
            if (mapperClass.equals(TsvImporterTextMapper.class)) {
              job.setMapOutputValueClass(Text.class);
              job.setReducerClass(TextSortReducer.class);
            } else {
              job.setMapOutputValueClass(Put.class);
              job.setCombinerClass(PutCombiner.class);
              job.setReducerClass(PutSortReducer.class);
            }
            if (!isDryRun) {
              Path outputDir = new Path(hfileOutPath);
              FileOutputFormat.setOutputPath(job, outputDir);
              HFileOutputFormat2.configureIncrementalLoad(job, table.getDescriptor(),
                  regionLocator);
            }
          }
        } else {
          if (!admin.tableExists(tableName)) {
            String errorMsg = format("Table '%s' does not exist.", tableName);
            LOG.error(errorMsg);
            throw new TableNotFoundException(errorMsg);
          }
          if (mapperClass.equals(TsvImporterTextMapper.class)) {
            usage(TsvImporterTextMapper.class.toString()
                + " should not be used for non bulkloading case. use "
                + TsvImporterMapper.class.toString()
                + " or custom mapper whose value type is Put.");
            System.exit(-1);
          }
          if (!isDryRun) {
            // No reducers. Just write straight to table. Call initTableReducerJob
            // to set up the TableOutputFormat.
            TableMapReduceUtil.initTableReducerJob(tableName.getNameAsString(), null, job);
          }
          job.setNumReduceTasks(0);
        }
        if (isDryRun) {
          job.setOutputFormatClass(NullOutputFormat.class);
          job.getConfiguration().setStrings("io.serializations",
              job.getConfiguration().get("io.serializations"),
              MutationSerialization.class.getName(), ResultSerialization.class.getName(),
              CellSerialization.class.getName());
        }
        TableMapReduceUtil.addDependencyJars(job);
        TableMapReduceUtil.addDependencyJarsForClasses(job.getConfiguration(),
            org.apache.hbase.thirdparty.com.google.common.base.Function.class /* Guava used by TsvParser */);
      }
    }
    return job;
  }

  private static void createTable(Admin admin, TableName tableName, String[] columns)
      throws IOException {
    HTableDescriptor htd = new HTableDescriptor(tableName);
    Set<String> cfSet = getColumnFamilies(columns);
    for (String cf : cfSet) {
      HColumnDescriptor hcd = new HColumnDescriptor(Bytes.toBytes(cf));
      htd.addFamily(hcd);
    }
    LOG.warn(format("Creating table '%s' with '%s' columns and default descriptors.",
      tableName, cfSet));
    admin.createTable(htd);
  }

  private static void deleteTable(Configuration conf, String[] args) {
    TableName tableName = TableName.valueOf(args[0]);
    try (Connection connection = ConnectionFactory.createConnection(conf);
         Admin admin = connection.getAdmin()) {
      try {
        admin.disableTable(tableName);
      } catch (TableNotEnabledException e) {
        LOG.debug("Dry mode: Table: " + tableName + " already disabled, so just deleting it.");
      }
      admin.deleteTable(tableName);
    } catch (IOException e) {
      LOG.error(format("***Dry run: Failed to delete table '%s'.***%n%s", tableName,
          e.toString()));
      return;
    }
    LOG.info(format("Dry run: Deleted table '%s'.", tableName));
  }

  private static Set<String> getColumnFamilies(String[] columns) {
    Set<String> cfSet = new HashSet<>();
    for (String aColumn : columns) {
      if (TsvParser.ROWKEY_COLUMN_SPEC.equals(aColumn)
          || TsvParser.TIMESTAMPKEY_COLUMN_SPEC.equals(aColumn)
          || TsvParser.CELL_VISIBILITY_COLUMN_SPEC.equals(aColumn)
          || TsvParser.CELL_TTL_COLUMN_SPEC.equals(aColumn)
          || TsvParser.ATTRIBUTES_COLUMN_SPEC.equals(aColumn))
        continue;
      // we are only concerned with the first one (in case this is a cf:cq)
      cfSet.add(aColumn.split(":", 2)[0]);
    }
    return cfSet;
  }

  /*
   * @param errorMsg Error message.  Can be null.
   */
  private static void usage(final String errorMsg) {
    if (errorMsg != null && errorMsg.length() > 0) {
      System.err.println("ERROR: " + errorMsg);
    }
    String usage =
      "Usage: " + NAME + " -D"+ COLUMNS_CONF_KEY + "=a,b,c <tablename> <inputdir>\n" +
      "\n" +
      "Imports the given input directory of TSV data into the specified table.\n" +
      "\n" +
      "The column names of the TSV data must be specified using the -D" + COLUMNS_CONF_KEY + "\n" +
      "option. This option takes the form of comma-separated column names, where each\n" +
      "column name is either a simple column family, or a columnfamily:qualifier. The special\n" +
      "column name " + TsvParser.ROWKEY_COLUMN_SPEC + " is used to designate that this column should be used\n" +
      "as the row key for each imported record. You must specify exactly one column\n" +
      "to be the row key, and you must specify a column name for every column that exists in the\n" +
      "input data. Another special column" + TsvParser.TIMESTAMPKEY_COLUMN_SPEC +
      " designates that this column should be\n" +
      "used as timestamp for each record. Unlike " + TsvParser.ROWKEY_COLUMN_SPEC + ", " +
      TsvParser.TIMESTAMPKEY_COLUMN_SPEC + " is optional." + "\n" +
      "You must specify at most one column as timestamp key for each imported record.\n" +
      "Record with invalid timestamps (blank, non-numeric) will be treated as bad record.\n" +
      "Note: if you use this option, then '" + TIMESTAMP_CONF_KEY + "' option will be ignored.\n" +
      "\n" +
      "Other special columns that can be specified are " + TsvParser.CELL_TTL_COLUMN_SPEC +
      " and " + TsvParser.CELL_VISIBILITY_COLUMN_SPEC + ".\n" +
      TsvParser.CELL_TTL_COLUMN_SPEC + " designates that this column will be used " +
      "as a Cell's Time To Live (TTL) attribute.\n" +
      TsvParser.CELL_VISIBILITY_COLUMN_SPEC + " designates that this column contains the " +
      "visibility label expression.\n" +
      "\n" +
      TsvParser.ATTRIBUTES_COLUMN_SPEC+" can be used to specify Operation Attributes per record.\n"+
      " Should be specified as key=>value where "+TsvParser.DEFAULT_ATTRIBUTES_COLUMN_INDEX+ " is used \n"+
      " as the seperator.  Note that more than one OperationAttributes can be specified.\n"+
      "By default importtsv will load data directly into HBase. To instead generate\n" +
      "HFiles of data to prepare for a bulk data load, pass the option:\n" +
      "  -D" + BULK_OUTPUT_CONF_KEY + "=/path/for/output\n" +
      "  Note: if you do not use this option, then the target table must already exist in HBase\n" +
      "\n" +
      "Other options that may be specified with -D include:\n" +
      "  -D" + DRY_RUN_CONF_KEY + "=true - Dry run mode. Data is not actually populated into" +
      " table. If table does not exist, it is created but deleted in the end.\n" +
      "  -D" + SKIP_LINES_CONF_KEY + "=false - fail if encountering an invalid line\n" +
      "  -D" + LOG_BAD_LINES_CONF_KEY + "=true - logs invalid lines to stderr\n" +
      "  -D" + SKIP_EMPTY_COLUMNS + "=false - If true then skip empty columns in bulk import\n" +
      "  '-D" + SEPARATOR_CONF_KEY + "=|' - eg separate on pipes instead of tabs\n" +
      "  -D" + TIMESTAMP_CONF_KEY + "=currentTimeAsLong - use the specified timestamp for the import\n" +
      "  -D" + MAPPER_CONF_KEY + "=my.Mapper - A user-defined Mapper to use instead of " +
      DEFAULT_MAPPER.getName() + "\n" +
      "  -D" + JOB_NAME_CONF_KEY + "=jobName - use the specified mapreduce job name for the import\n" +
      "  -D" + CREATE_TABLE_CONF_KEY + "=no - can be used to avoid creation of table by this tool\n" +
      "  Note: if you set this to 'no', then the target table must already exist in HBase\n" +
      "  -D" + NO_STRICT_COL_FAMILY + "=true - ignore column family check in hbase table. " +
      "Default is false\n\n" +
      "For performance consider the following options:\n" +
      "  -Dmapreduce.map.speculative=false\n" +
      "  -Dmapreduce.reduce.speculative=false";

    System.err.println(usage);
  }

  @Override
  public int run(String[] args) throws Exception {
    if (args.length < 2) {
      usage("Wrong number of arguments: " + args.length);
      return -1;
    }

    // When MAPPER_CONF_KEY is null, the user wants to use the provided TsvImporterMapper, so
    // perform validation on these additional args. When it's not null, user has provided their
    // own mapper, thus these validation are not relevant.
    // TODO: validation for TsvImporterMapper, not this tool. Move elsewhere.
    if (null == getConf().get(MAPPER_CONF_KEY)) {
      // Make sure columns are specified
      String[] columns = getConf().getStrings(COLUMNS_CONF_KEY);
      if (columns == null) {
        usage("No columns specified. Please specify with -D" +
            COLUMNS_CONF_KEY+"=...");
        return -1;
      }

      // Make sure they specify exactly one column as the row key
      int rowkeysFound = 0;
      for (String col : columns) {
        if (col.equals(TsvParser.ROWKEY_COLUMN_SPEC)) rowkeysFound++;
      }
      if (rowkeysFound != 1) {
        usage("Must specify exactly one column as " + TsvParser.ROWKEY_COLUMN_SPEC);
        return -1;
      }

      // Make sure we have at most one column as the timestamp key
      int tskeysFound = 0;
      for (String col : columns) {
        if (col.equals(TsvParser.TIMESTAMPKEY_COLUMN_SPEC))
          tskeysFound++;
      }
      if (tskeysFound > 1) {
        usage("Must specify at most one column as "
            + TsvParser.TIMESTAMPKEY_COLUMN_SPEC);
        return -1;
      }

      int attrKeysFound = 0;
      for (String col : columns) {
        if (col.equals(TsvParser.ATTRIBUTES_COLUMN_SPEC))
          attrKeysFound++;
      }
      if (attrKeysFound > 1) {
        usage("Must specify at most one column as "
            + TsvParser.ATTRIBUTES_COLUMN_SPEC);
        return -1;
      }

      // Make sure one or more columns are specified excluding rowkey and
      // timestamp key
      if (columns.length - (rowkeysFound + tskeysFound + attrKeysFound) < 1) {
        usage("One or more columns in addition to the row key and timestamp(optional) are required");
        return -1;
      }
    }

    // If timestamp option is not specified, use current system time.
    long timstamp = getConf().getLong(TIMESTAMP_CONF_KEY, System.currentTimeMillis());

    // Set it back to replace invalid timestamp (non-numeric) with current
    // system time
    getConf().setLong(TIMESTAMP_CONF_KEY, timstamp);

    synchronized (ImportTsv.class) {
      DRY_RUN_TABLE_CREATED = false;
    }
    Job job = createSubmittableJob(getConf(), args);
    boolean success = job.waitForCompletion(true);
    boolean delete = false;
    synchronized (ImportTsv.class) {
      delete = DRY_RUN_TABLE_CREATED;
    }
    if (delete) {
      deleteTable(getConf(), args);
    }
    return success ? 0 : 1;
  }

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