/**
* 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.crunch.lib.sort;
import java.io.IOException;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import org.apache.avro.Schema;
import org.apache.avro.mapred.AvroKey;
import org.apache.crunch.io.CompositePathIterable;
import org.apache.crunch.io.avro.AvroFileReaderFactory;
import org.apache.crunch.io.seq.SeqFileReaderFactory;
import org.apache.crunch.types.writable.WritableDeepCopier;
import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.RawComparator;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Partitioner;
/**
* A partition-aware {@code Partitioner} instance that can work with either Avro or Writable-formatted
* keys.
*/
public class TotalOrderPartitioner<K, V> extends Partitioner<K, V> implements Configurable {
public static final String DEFAULT_PATH = "_partition.lst";
public static final String PARTITIONER_PATH =
"crunch.totalorderpartitioner.path";
private Configuration conf;
private Node<K> partitions;
@Override
public Configuration getConf() {
return conf;
}
@Override
public void setConf(Configuration conf) {
try {
this.conf = conf;
String parts = getPartitionFile(conf);
final Path partFile = new Path(parts);
final FileSystem fs = (DEFAULT_PATH.equals(parts))
? FileSystem.getLocal(conf) // assume in DistributedCache
: partFile.getFileSystem(conf);
Job job = new Job(conf);
Class<K> keyClass = (Class<K>)job.getMapOutputKeyClass();
RawComparator<K> comparator =
(RawComparator<K>) job.getSortComparator();
K[] splitPoints = readPartitions(fs, partFile, keyClass, conf, comparator);
int numReduceTasks = job.getNumReduceTasks();
if (splitPoints.length != numReduceTasks - 1) {
throw new IOException("Wrong number of partitions in keyset");
}
partitions = new BinarySearchNode(splitPoints, comparator);
} catch (IOException e) {
throw new IllegalArgumentException("Can't read partitions file", e);
}
}
@Override
public int getPartition(K key, V value, int modulo) {
return partitions.findPartition(key);
}
public static void setPartitionFile(Configuration conf, Path p) {
conf.set(PARTITIONER_PATH, p.toString());
}
public static String getPartitionFile(Configuration conf) {
return conf.get(PARTITIONER_PATH, DEFAULT_PATH);
}
@SuppressWarnings("unchecked") // map output key class
private K[] readPartitions(FileSystem fs, Path p, Class<K> keyClass,
Configuration conf, final RawComparator<K> comparator) throws IOException {
ArrayList<K> parts = new ArrayList<K>();
String schema = conf.get("crunch.schema");
if (schema != null) {
Schema s = (new Schema.Parser()).parse(schema);
AvroFileReaderFactory<K> a = new AvroFileReaderFactory<K>(s);
Iterator<K> iter = CompositePathIterable.create(fs, p, a).iterator();
while (iter.hasNext()) {
parts.add((K) new AvroKey<K>(iter.next()));
}
} else {
WritableDeepCopier wdc = new WritableDeepCopier(keyClass);
SeqFileReaderFactory<K> s = new SeqFileReaderFactory<K>(keyClass);
Iterator<K> iter = CompositePathIterable.create(fs, p, s).iterator();
while (iter.hasNext()) {
parts.add((K) wdc.deepCopy((Writable) iter.next()));
}
}
Collections.sort(parts, comparator);
return parts.toArray((K[])Array.newInstance(keyClass, parts.size()));
}
/**
* Interface to the partitioner to locate a key in the partition keyset.
*/
interface Node<T> {
/**
* Locate partition in keyset K, st [Ki..Ki+1) defines a partition,
* with implicit K0 = -inf, Kn = +inf, and |K| = #partitions - 1.
*/
int findPartition(T key);
}
class BinarySearchNode implements Node<K> {
private final K[] splitPoints;
private final RawComparator<K> comparator;
BinarySearchNode(K[] splitPoints, RawComparator<K> comparator) {
this.splitPoints = splitPoints;
this.comparator = comparator;
}
public int findPartition(K key) {
final int pos = Arrays.binarySearch(splitPoints, key, comparator) + 1;
return (pos < 0) ? -pos : pos;
}
}
}