| /* |
| * 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.accumulo.examples.combiner; |
| |
| import java.io.IOException; |
| import java.util.Iterator; |
| import java.util.Map; |
| |
| import org.apache.accumulo.core.client.IteratorSetting; |
| import org.apache.accumulo.core.data.Key; |
| import org.apache.accumulo.core.data.Value; |
| import org.apache.accumulo.core.iterators.Combiner; |
| import org.apache.accumulo.core.iterators.IteratorEnvironment; |
| import org.apache.accumulo.core.iterators.SortedKeyValueIterator; |
| |
| /** |
| * This combiner calculates the max, min, sum, and count of long integers represented as strings in |
| * values. It stores the result in a comma-separated value of the form min,max,sum,count. If such a |
| * value is encountered while combining, its information is incorporated into the running |
| * calculations of min, max, sum, and count. See {@link Combiner} for more information on which |
| * values are combined together. |
| */ |
| public class StatsCombiner extends Combiner { |
| |
| public static final String RADIX_OPTION = "radix"; |
| |
| private int radix = 10; |
| |
| @Override |
| public Value reduce(Key key, Iterator<Value> iter) { |
| |
| long min = Long.MAX_VALUE; |
| long max = Long.MIN_VALUE; |
| long sum = 0; |
| long count = 0; |
| |
| while (iter.hasNext()) { |
| String stats[] = iter.next().toString().split(","); |
| |
| if (stats.length == 1) { |
| long val = Long.parseLong(stats[0], radix); |
| min = Math.min(val, min); |
| max = Math.max(val, max); |
| sum += val; |
| count += 1; |
| } else { |
| min = Math.min(Long.parseLong(stats[0], radix), min); |
| max = Math.max(Long.parseLong(stats[1], radix), max); |
| sum += Long.parseLong(stats[2], radix); |
| count += Long.parseLong(stats[3], radix); |
| } |
| } |
| |
| String ret = Long.toString(min, radix) + "," + Long.toString(max, radix) + "," |
| + Long.toString(sum, radix) + "," + Long.toString(count, radix); |
| return new Value(ret.getBytes()); |
| } |
| |
| @Override |
| public void init(SortedKeyValueIterator<Key,Value> source, Map<String,String> options, |
| IteratorEnvironment env) throws IOException { |
| super.init(source, options, env); |
| |
| if (options.containsKey(RADIX_OPTION)) |
| radix = Integer.parseInt(options.get(RADIX_OPTION)); |
| else |
| radix = 10; |
| } |
| |
| @Override |
| public IteratorOptions describeOptions() { |
| IteratorOptions io = super.describeOptions(); |
| io.setName("statsCombiner"); |
| io.setDescription("Combiner that keeps track of min, max, sum, and count"); |
| io.addNamedOption(RADIX_OPTION, "radix/base of the numbers"); |
| return io; |
| } |
| |
| @Override |
| public boolean validateOptions(Map<String,String> options) { |
| if (!super.validateOptions(options)) |
| return false; |
| |
| if (options.containsKey(RADIX_OPTION) && !options.get(RADIX_OPTION).matches("\\d+")) |
| throw new IllegalArgumentException( |
| "invalid option " + RADIX_OPTION + ":" + options.get(RADIX_OPTION)); |
| |
| return true; |
| } |
| |
| /** |
| * A convenience method for setting the expected base/radix of the numbers |
| * |
| * @param iterConfig |
| * Iterator settings to configure |
| * @param base |
| * The expected base/radix of the numbers. |
| */ |
| public static void setRadix(IteratorSetting iterConfig, int base) { |
| iterConfig.addOption(RADIX_OPTION, base + ""); |
| } |
| } |