| /** |
| * |
| * 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.TableName; |
| import org.apache.hadoop.hbase.client.Connection; |
| import org.apache.hadoop.hbase.client.ConnectionFactory; |
| import org.apache.hadoop.hbase.client.RegionLocator; |
| import org.apache.hadoop.hbase.io.ImmutableBytesWritable; |
| import org.apache.hadoop.hbase.mapred.TableOutputFormat; |
| import org.apache.hadoop.hbase.util.Bytes; |
| import org.apache.hadoop.mapreduce.Partitioner; |
| |
| /** |
| * This is used to partition the output keys into groups of keys. |
| * Keys are grouped according to the regions that currently exist |
| * so that each reducer fills a single region so load is distributed. |
| * |
| * <p>This class is not suitable as partitioner creating hfiles |
| * for incremental bulk loads as region spread will likely change between time of |
| * hfile creation and load time. See {@link LoadIncrementalHFiles} |
| * and <a href="http://hbase.apache.org/book.html#arch.bulk.load">Bulk Load</a>. |
| * |
| * @param <KEY> The type of the key. |
| * @param <VALUE> The type of the value. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public class HRegionPartitioner<KEY, VALUE> |
| extends Partitioner<ImmutableBytesWritable, VALUE> |
| implements Configurable { |
| |
| private static final Log LOG = LogFactory.getLog(HRegionPartitioner.class); |
| private Configuration conf = null; |
| // Connection and locator are not cleaned up; they just die when partitioner is done. |
| private Connection connection; |
| private RegionLocator locator; |
| private byte[][] startKeys; |
| |
| /** |
| * Gets the partition number for a given key (hence record) given the total |
| * number of partitions i.e. number of reduce-tasks for the job. |
| * |
| * <p>Typically a hash function on a all or a subset of the key.</p> |
| * |
| * @param key The key to be partitioned. |
| * @param value The entry value. |
| * @param numPartitions The total number of partitions. |
| * @return The partition number for the <code>key</code>. |
| * @see org.apache.hadoop.mapreduce.Partitioner#getPartition( |
| * java.lang.Object, java.lang.Object, int) |
| */ |
| @Override |
| public int getPartition(ImmutableBytesWritable key, |
| VALUE value, int numPartitions) { |
| byte[] region = null; |
| // Only one region return 0 |
| if (this.startKeys.length == 1){ |
| return 0; |
| } |
| try { |
| // Not sure if this is cached after a split so we could have problems |
| // here if a region splits while mapping |
| region = this.locator.getRegionLocation(key.get()).getRegionInfo().getStartKey(); |
| } catch (IOException e) { |
| LOG.error(e); |
| } |
| for (int i = 0; i < this.startKeys.length; i++){ |
| if (Bytes.compareTo(region, this.startKeys[i]) == 0 ){ |
| if (i >= numPartitions-1){ |
| // cover if we have less reduces then regions. |
| return (Integer.toString(i).hashCode() |
| & Integer.MAX_VALUE) % numPartitions; |
| } |
| return i; |
| } |
| } |
| // if above fails to find start key that match we need to return something |
| return 0; |
| } |
| |
| /** |
| * Returns the current configuration. |
| * |
| * @return The current configuration. |
| * @see org.apache.hadoop.conf.Configurable#getConf() |
| */ |
| @Override |
| public Configuration getConf() { |
| return conf; |
| } |
| |
| /** |
| * Sets the configuration. This is used to determine the start keys for the |
| * given table. |
| * |
| * @param configuration The configuration to set. |
| * @see org.apache.hadoop.conf.Configurable#setConf( |
| * org.apache.hadoop.conf.Configuration) |
| */ |
| @Override |
| public void setConf(Configuration configuration) { |
| this.conf = HBaseConfiguration.create(configuration); |
| try { |
| this.connection = ConnectionFactory.createConnection(HBaseConfiguration.create(conf)); |
| TableName tableName = TableName.valueOf(conf.get(TableOutputFormat.OUTPUT_TABLE)); |
| this.locator = this.connection.getRegionLocator(tableName); |
| } catch (IOException e) { |
| LOG.error(e); |
| } |
| try { |
| this.startKeys = this.locator.getStartKeys(); |
| } catch (IOException e) { |
| LOG.error(e); |
| } |
| } |
| } |