/**
* 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.contrib.index.example;
import org.apache.hadoop.contrib.index.mapred.DocumentID;
import org.apache.hadoop.contrib.index.mapred.IDistributionPolicy;
import org.apache.hadoop.contrib.index.mapred.Shard;
/**
* Choose a shard for each insert in a round-robin fashion. Choose all the
* shards for each delete because we don't know where it is stored.
*/
public class RoundRobinDistributionPolicy implements IDistributionPolicy {
private int numShards;
private int rr; // round-robin implementation
/* (non-Javadoc)
* @see org.apache.hadoop.contrib.index.mapred.IDistributionPolicy#init(org.apache.hadoop.contrib.index.mapred.Shard[])
*/
public void init(Shard[] shards) {
numShards = shards.length;
rr = 0;
}
/* (non-Javadoc)
* @see org.apache.hadoop.contrib.index.mapred.IDistributionPolicy#chooseShardForInsert(org.apache.hadoop.contrib.index.mapred.DocumentID)
*/
public int chooseShardForInsert(DocumentID key) {
int chosen = rr;
rr = (rr + 1) % numShards;
return chosen;
}
/* (non-Javadoc)
* @see org.apache.hadoop.contrib.index.mapred.IDistributionPolicy#chooseShardForDelete(org.apache.hadoop.contrib.index.mapred.DocumentID)
*/
public int chooseShardForDelete(DocumentID key) {
// -1 represents all the shards
return -1;
}
}