/**
* 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.dkpro.bigdata.collocations;
import org.apache.hadoop.mapreduce.Partitioner;
/**
* Partition GramKeys based on their Gram, ignoring the secondary sort key so that all GramKeys with the same
* gram are sent to the same partition.
*/
public final class GramKeyPartitioner extends Partitioner<GramKey, Gram> {
@Override
public int getPartition(GramKey key, Gram value, int numPartitions) {
int hash = 1;
byte[] bytes = key.getBytes();
int length = key.getPrimaryLength();
// Copied from WritableComparator.hashBytes(); skips first byte, type byte
for (int i = 1; i < length; i++) {
hash = (31 * hash) + (int) bytes[i];
}
return (hash & Integer.MAX_VALUE) % numPartitions;
}
}