/**
* 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.contrib.bloomfilter;
import java.util.Collection;
import org.apache.commons.collections.CollectionUtils;
import org.apache.crunch.DoFn;
import org.apache.crunch.Emitter;
import org.apache.crunch.Pair;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.util.bloom.BloomFilter;
import org.apache.hadoop.util.bloom.Key;
import org.apache.hadoop.util.hash.Hash;
/**
* The class is responsible for generating keys that are used in a BloomFilter
*/
@SuppressWarnings("serial")
public abstract class BloomFilterFn<S> extends DoFn<S, Pair<String, BloomFilter>> {
public static final String CRUNCH_FILTER_SIZE = "crunch.filter.size";
public static final String CRUNCH_FILTER_NAME = "crunch.filter.name";
private transient BloomFilter bloomFilter = null;
@Override
public void initialize() {
super.initialize();
bloomFilter = initializeFilter(getBloomFilterSize(getConfiguration()));
}
@Override
public void process(S input, Emitter<Pair<String, BloomFilter>> emitter) {
Collection<Key> keys = generateKeys(input);
if (CollectionUtils.isNotEmpty(keys)) {
bloomFilter.add(keys);
}
}
public abstract Collection<Key> generateKeys(S input);
@Override
public void cleanup(Emitter<Pair<String, BloomFilter>> emitter) {
String filterName = getConfiguration().get(CRUNCH_FILTER_NAME);
emitter.emit(Pair.of(filterName, bloomFilter));
}
static BloomFilter initializeFilter(int size) {
return new BloomFilter(size, 5, Hash.MURMUR_HASH);
}
static int getBloomFilterSize(Configuration configuration) {
return configuration.getInt(CRUNCH_FILTER_SIZE, 1024);
}
}