/**
    *
    * 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.mapred;
  
  import java.io.IOException;
  
  import org.apache.hadoop.fs.FileAlreadyExistsException;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  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.Put;
  import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
  import org.apache.hadoop.mapred.FileOutputFormat;
  import org.apache.hadoop.mapred.InvalidJobConfException;
  import org.apache.hadoop.mapred.JobConf;
  import org.apache.hadoop.mapred.RecordWriter;
  import org.apache.hadoop.mapred.Reporter;
  import org.apache.hadoop.util.Progressable;
  
  /**
   * Convert Map/Reduce output and write it to an HBase table
   */
  @InterfaceAudience.Public
  @InterfaceStability.Stable
  public class TableOutputFormat extends FileOutputFormat<ImmutableBytesWritable, Put> {
  
    /** JobConf parameter that specifies the output table */
    public static final String OUTPUT_TABLE = "hbase.mapred.outputtable";
  
    /**
     * Convert Reduce output (key, value) to (HStoreKey, KeyedDataArrayWritable)
     * and write to an HBase table.
     */
    protected static class TableRecordWriter implements RecordWriter<ImmutableBytesWritable, Put> {
      private BufferedMutator m_mutator;
  
      /**
       * Instantiate a TableRecordWriter with the HBase HClient for writing. Assumes control over the
       * lifecycle of {@code conn}.
       */
      public TableRecordWriter(final BufferedMutator mutator) throws IOException {
        this.m_mutator = mutator;
      }
  
      public void close(Reporter reporter) throws IOException {
        this.m_mutator.close();
      }
  
      public void write(ImmutableBytesWritable key, Put value) throws IOException {
        m_mutator.mutate(new Put(value));
      }
    }
  
    @Override
    public RecordWriter getRecordWriter(FileSystem ignored, JobConf job, String name,
        Progressable progress)
    throws IOException {
      // expecting exactly one path
      TableName tableName = TableName.valueOf(job.get(OUTPUT_TABLE));
      BufferedMutator mutator =  null;
      // Connection is not closed. Dies with JVM.  No possibility for cleanup.
      Connection connection = ConnectionFactory.createConnection(job);
      mutator = connection.getBufferedMutator(tableName);
      // Clear write buffer on fail is true by default so no need to reset it.
      return new TableRecordWriter(mutator);
    }
  
    @Override
    public void checkOutputSpecs(FileSystem ignored, JobConf job)
    throws FileAlreadyExistsException, InvalidJobConfException, IOException {
      String tableName = job.get(OUTPUT_TABLE);
      if (tableName == null) {
        throw new IOException("Must specify table name");
      }
    }
  }