TableOutputFormat

/**
 *
 * 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 java.io.IOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.classification.InterfaceStability;
import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.BufferedMutator;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.Delete;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Mutation;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.OutputCommitter;
import org.apache.hadoop.mapreduce.OutputFormat;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

/**
 * Convert Map/Reduce output and write it to an HBase table. The KEY is ignored
 * while the output value <u>must</u> be either a {@link Put} or a
 * {@link Delete} instance.
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class TableOutputFormat<KEY> extends OutputFormat<KEY, Mutation>
implements Configurable {

  private static final Log LOG = LogFactory.getLog(TableOutputFormat.class);

  /** Job parameter that specifies the output table. */
  public static final String OUTPUT_TABLE = "hbase.mapred.outputtable";

  /**
   * Prefix for configuration property overrides to apply in {@link #setConf(Configuration)}.
   * For keys matching this prefix, the prefix is stripped, and the value is set in the
   * configuration with the resulting key, ie. the entry "hbase.mapred.output.key1 = value1"
   * would be set in the configuration as "key1 = value1".  Use this to set properties
   * which should only be applied to the {@code TableOutputFormat} configuration and not the
   * input configuration.
   */
  public static final String OUTPUT_CONF_PREFIX = "hbase.mapred.output.";

  /**
   * Optional job parameter to specify a peer cluster.
   * Used specifying remote cluster when copying between hbase clusters (the
   * source is picked up from <code>hbase-site.xml</code>).
   * @see TableMapReduceUtil#initTableReducerJob(String, Class, org.apache.hadoop.mapreduce.Job, Class, String, String, String)
   */
  public static final String QUORUM_ADDRESS = OUTPUT_CONF_PREFIX + "quorum";

  /** Optional job parameter to specify peer cluster's ZK client port */
  public static final String QUORUM_PORT = OUTPUT_CONF_PREFIX + "quorum.port";

  /** Optional specification of the rs class name of the peer cluster */
  public static final String
      REGION_SERVER_CLASS = OUTPUT_CONF_PREFIX + "rs.class";
  /** Optional specification of the rs impl name of the peer cluster */
  public static final String
      REGION_SERVER_IMPL = OUTPUT_CONF_PREFIX + "rs.impl";

  /** The configuration. */
  private Configuration conf = null;

  /**
   * Writes the reducer output to an HBase table.
   */
  protected class TableRecordWriter
  extends RecordWriter<KEY, Mutation> {

    private Connection connection;
    private BufferedMutator mutator;

    /**
     * @throws IOException
     *
     */
    public TableRecordWriter() throws IOException {
      String tableName = conf.get(OUTPUT_TABLE);
      this.connection = ConnectionFactory.createConnection(conf);
      this.mutator = connection.getBufferedMutator(TableName.valueOf(tableName));
      LOG.info("Created table instance for "  + tableName);
    }
    /**
     * Closes the writer, in this case flush table commits.
     *
     * @param context  The context.
     * @throws IOException When closing the writer fails.
     * @see RecordWriter#close(TaskAttemptContext)
     */
    @Override
    public void close(TaskAttemptContext context)
    throws IOException {
      mutator.close();
      connection.close();
    }

    /**
     * Writes a key/value pair into the table.
     *
     * @param key  The key.
     * @param value  The value.
     * @throws IOException When writing fails.
     * @see RecordWriter#write(Object, Object)
     */
    @Override
    public void write(KEY key, Mutation value)
    throws IOException {
      if (!(value instanceof Put) && !(value instanceof Delete)) {
        throw new IOException("Pass a Delete or a Put");
      }
      mutator.mutate(value);
    }
  }

  /**
   * Creates a new record writer.
   *
   * @param context  The current task context.
   * @return The newly created writer instance.
   * @throws IOException When creating the writer fails.
   * @throws InterruptedException When the jobs is cancelled.
   */
  @Override
  public RecordWriter<KEY, Mutation> getRecordWriter(TaskAttemptContext context)
  throws IOException, InterruptedException {
    return new TableRecordWriter();
  }

  /**
   * Checks if the output target exists.
   *
   * @param context  The current context.
   * @throws IOException When the check fails.
   * @throws InterruptedException When the job is aborted.
   * @see OutputFormat#checkOutputSpecs(JobContext)
   */
  @Override
  public void checkOutputSpecs(JobContext context) throws IOException,
      InterruptedException {
    // TODO Check if the table exists?

  }

  /**
   * Returns the output committer.
   *
   * @param context  The current context.
   * @return The committer.
   * @throws IOException When creating the committer fails.
   * @throws InterruptedException When the job is aborted.
   * @see OutputFormat#getOutputCommitter(TaskAttemptContext)
   */
  @Override
  public OutputCommitter getOutputCommitter(TaskAttemptContext context)
  throws IOException, InterruptedException {
    return new TableOutputCommitter();
  }

  @Override
  public Configuration getConf() {
    return conf;
  }

  @Override
  public void setConf(Configuration otherConf) {
    String tableName = otherConf.get(OUTPUT_TABLE);
    if(tableName == null || tableName.length() <= 0) {
      throw new IllegalArgumentException("Must specify table name");
    }

    String address = otherConf.get(QUORUM_ADDRESS);
    int zkClientPort = otherConf.getInt(QUORUM_PORT, 0);
    String serverClass = otherConf.get(REGION_SERVER_CLASS);
    String serverImpl = otherConf.get(REGION_SERVER_IMPL);

    try {
      this.conf = HBaseConfiguration.createClusterConf(otherConf, address, OUTPUT_CONF_PREFIX);

      if (serverClass != null) {
        this.conf.set(HConstants.REGION_SERVER_IMPL, serverImpl);
      }
      if (zkClientPort != 0) {
        this.conf.setInt(HConstants.ZOOKEEPER_CLIENT_PORT, zkClientPort);
      }
    } catch(IOException e) {
      LOG.error(e);
      throw new RuntimeException(e);
    }
  }
}