DelegatingInputFormat.java
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上传日期:2018-01-08
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- /**
- * 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.mapred.lib;
- import java.io.IOException;
- import java.util.ArrayList;
- import java.util.HashMap;
- import java.util.LinkedList;
- import java.util.List;
- import java.util.Map;
- import java.util.Map.Entry;
- import org.apache.hadoop.fs.Path;
- import org.apache.hadoop.mapred.FileInputFormat;
- import org.apache.hadoop.mapred.InputFormat;
- import org.apache.hadoop.mapred.InputSplit;
- import org.apache.hadoop.mapred.JobConf;
- import org.apache.hadoop.mapred.Mapper;
- import org.apache.hadoop.mapred.RecordReader;
- import org.apache.hadoop.mapred.Reporter;
- import org.apache.hadoop.util.ReflectionUtils;
- /**
- * An {@link InputFormat} that delegates behaviour of paths to multiple other
- * InputFormats.
- *
- * @see MultipleInputs#addInputPath(JobConf, Path, Class, Class)
- */
- public class DelegatingInputFormat<K, V> implements InputFormat<K, V> {
- public InputSplit[] getSplits(JobConf conf, int numSplits) throws IOException {
- JobConf confCopy = new JobConf(conf);
- List<InputSplit> splits = new ArrayList<InputSplit>();
- Map<Path, InputFormat> formatMap = MultipleInputs.getInputFormatMap(conf);
- Map<Path, Class<? extends Mapper>> mapperMap = MultipleInputs
- .getMapperTypeMap(conf);
- Map<Class<? extends InputFormat>, List<Path>> formatPaths
- = new HashMap<Class<? extends InputFormat>, List<Path>>();
- // First, build a map of InputFormats to Paths
- for (Entry<Path, InputFormat> entry : formatMap.entrySet()) {
- if (!formatPaths.containsKey(entry.getValue().getClass())) {
- formatPaths.put(entry.getValue().getClass(), new LinkedList<Path>());
- }
- formatPaths.get(entry.getValue().getClass()).add(entry.getKey());
- }
- for (Entry<Class<? extends InputFormat>, List<Path>> formatEntry :
- formatPaths.entrySet()) {
- Class<? extends InputFormat> formatClass = formatEntry.getKey();
- InputFormat format = (InputFormat) ReflectionUtils.newInstance(
- formatClass, conf);
- List<Path> paths = formatEntry.getValue();
- Map<Class<? extends Mapper>, List<Path>> mapperPaths
- = new HashMap<Class<? extends Mapper>, List<Path>>();
- // Now, for each set of paths that have a common InputFormat, build
- // a map of Mappers to the paths they're used for
- for (Path path : paths) {
- Class<? extends Mapper> mapperClass = mapperMap.get(path);
- if (!mapperPaths.containsKey(mapperClass)) {
- mapperPaths.put(mapperClass, new LinkedList<Path>());
- }
- mapperPaths.get(mapperClass).add(path);
- }
- // Now each set of paths that has a common InputFormat and Mapper can
- // be added to the same job, and split together.
- for (Entry<Class<? extends Mapper>, List<Path>> mapEntry : mapperPaths
- .entrySet()) {
- paths = mapEntry.getValue();
- Class<? extends Mapper> mapperClass = mapEntry.getKey();
- if (mapperClass == null) {
- mapperClass = conf.getMapperClass();
- }
- FileInputFormat.setInputPaths(confCopy, paths.toArray(new Path[paths
- .size()]));
- // Get splits for each input path and tag with InputFormat
- // and Mapper types by wrapping in a TaggedInputSplit.
- InputSplit[] pathSplits = format.getSplits(confCopy, numSplits);
- for (InputSplit pathSplit : pathSplits) {
- splits.add(new TaggedInputSplit(pathSplit, conf, format.getClass(),
- mapperClass));
- }
- }
- }
- return splits.toArray(new InputSplit[splits.size()]);
- }
- @SuppressWarnings("unchecked")
- public RecordReader<K, V> getRecordReader(InputSplit split, JobConf conf,
- Reporter reporter) throws IOException {
- // Find the InputFormat and then the RecordReader from the
- // TaggedInputSplit.
- TaggedInputSplit taggedInputSplit = (TaggedInputSplit) split;
- InputFormat<K, V> inputFormat = (InputFormat<K, V>) ReflectionUtils
- .newInstance(taggedInputSplit.getInputFormatClass(), conf);
- return inputFormat.getRecordReader(taggedInputSplit.getInputSplit(), conf,
- reporter);
- }
- }