com.hazelcast.mapreduce.aggregation.impl.DoubleMinAggregation Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2015, Hazelcast, Inc. All Rights Reserved.
*
* Licensed 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 com.hazelcast.mapreduce.aggregation.impl;
import com.hazelcast.mapreduce.Collator;
import com.hazelcast.mapreduce.Combiner;
import com.hazelcast.mapreduce.CombinerFactory;
import com.hazelcast.mapreduce.Mapper;
import com.hazelcast.mapreduce.Reducer;
import com.hazelcast.mapreduce.ReducerFactory;
import com.hazelcast.mapreduce.aggregation.Supplier;
import java.util.Map;
/**
* The predefined minimum aggregation for values of type double.
*
* @param the input key type
* @param the input value type
*/
public class DoubleMinAggregation
implements AggType {
@Override
public Collator, Double> getCollator() {
return new Collator, Double>() {
@Override
public Double collate(Iterable> values) {
double min = Double.MAX_VALUE;
for (Map.Entry entry : values) {
double value = entry.getValue();
if (value < min) {
min = value;
}
}
return min;
}
};
}
@Override
public Mapper getMapper(Supplier supplier) {
return new SupplierConsumingMapper(supplier);
}
@Override
public CombinerFactory getCombinerFactory() {
return new DoubleMinCombinerFactory();
}
@Override
public ReducerFactory getReducerFactory() {
return new DoubleMinReducerFactory();
}
/**
* Minimum CombinerFactory for type double
*
* @param the key type
*/
static final class DoubleMinCombinerFactory
extends AbstractAggregationCombinerFactory {
@Override
public Combiner newCombiner(Key key) {
return new DoubleMinCombiner();
}
@Override
public int getId() {
return AggregationsDataSerializerHook.DOUBLE_MIN_COMBINER_FACTORY;
}
}
/**
* Minimum ReducerFactory for type double
*
* @param the key type
*/
static final class DoubleMinReducerFactory
extends AbstractAggregationReducerFactory {
@Override
public Reducer newReducer(Key key) {
return new DoubleMinReducer();
}
@Override
public int getId() {
return AggregationsDataSerializerHook.DOUBLE_MIN_REDUCER_FACTORY;
}
}
/**
* Minimum Combiner for type double
*/
private static final class DoubleMinCombiner
extends Combiner {
private double chunkMin = Double.MAX_VALUE;
@Override
public void combine(Double value) {
if (value < chunkMin) {
chunkMin = value;
}
}
@Override
public Double finalizeChunk() {
double value = chunkMin;
chunkMin = Double.MAX_VALUE;
return value;
}
}
/**
* Minimum Reducer for type double
*/
private static final class DoubleMinReducer
extends Reducer {
private double min = Double.MAX_VALUE;
@Override
public void reduce(Double value) {
if (value < min) {
min = value;
}
}
@Override
public Double finalizeReduce() {
return min;
}
}
}