| /** |
| * 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.io; |
| |
| import java.io.IOException; |
| import java.util.Map; |
| |
| import com.google.common.collect.Maps; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.fs.FileSystem; |
| import org.apache.hadoop.fs.Path; |
| |
| /** |
| * Default {@link FileNamingScheme} that uses an incrementing sequence number in |
| * order to generate unique file names. |
| */ |
| public class SequentialFileNamingScheme implements FileNamingScheme { |
| |
| private static final SequentialFileNamingScheme INSTANCE = new SequentialFileNamingScheme(); |
| |
| public static SequentialFileNamingScheme getInstance() { |
| return INSTANCE; |
| } |
| |
| private final Map<Path, Integer> cache; |
| |
| private SequentialFileNamingScheme() { |
| this.cache = Maps.newHashMap(); |
| } |
| |
| @Override |
| public String getMapOutputName(Configuration configuration, Path outputDirectory) throws IOException { |
| return getSequentialFileName(configuration, outputDirectory, "m"); |
| } |
| |
| @Override |
| public String getReduceOutputName(Configuration configuration, Path outputDirectory, int partitionId) |
| throws IOException { |
| return getSequentialFileName(configuration, outputDirectory, "r"); |
| } |
| |
| private String getSequentialFileName(Configuration configuration, Path outputDirectory, String jobTypeName) |
| throws IOException { |
| return String.format("part-%s-%05d", jobTypeName, getSequenceNumber(configuration, outputDirectory)); |
| } |
| |
| private synchronized int getSequenceNumber(Configuration conf, Path outputDirectory) throws IOException { |
| if (cache.containsKey(outputDirectory)) { |
| int next = cache.get(outputDirectory); |
| cache.put(outputDirectory, next + 1); |
| return next; |
| } else { |
| FileSystem fileSystem = outputDirectory.getFileSystem(conf); |
| int next = fileSystem.listStatus(outputDirectory).length; |
| cache.put(outputDirectory, next + 1); |
| return next; |
| } |
| } |
| } |