| /* |
| * 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.nutch.util; |
| |
| import java.io.IOException; |
| |
| import org.apache.hadoop.fs.FileSystem; |
| import org.apache.hadoop.fs.Path; |
| import org.apache.hadoop.io.MapFile; |
| import org.apache.hadoop.io.SequenceFile; |
| |
| /** |
| * Utility methods for common filesystem operations. |
| */ |
| public class FSUtils { |
| |
| /** |
| * Replaces the current path with the new path and if set removes the old |
| * path. If removeOld is set to false then the old path will be set to the |
| * name current.old. |
| * |
| * @param fs |
| * The FileSystem. |
| * @param current |
| * The end path, the one being replaced. |
| * @param replacement |
| * The path to replace with. |
| * @param removeOld |
| * True if we are removing the current path. |
| * |
| * @throws IOException |
| * If an error occurs during replacement. |
| */ |
| public static void replace(FileSystem fs, Path current, Path replacement, |
| boolean removeOld) throws IOException { |
| |
| // rename any current path to old |
| Path old = new Path(current + ".old"); |
| if (fs.exists(current)) { |
| fs.rename(current, old); |
| } |
| |
| // rename the new path to current and remove the old path if needed |
| fs.rename(replacement, current); |
| if (fs.exists(old) && removeOld) { |
| fs.delete(old, true); |
| } |
| } |
| |
| /** |
| * Closes a group of SequenceFile readers. |
| * |
| * @param readers |
| * The SequenceFile readers to close. |
| * @throws IOException |
| * If an error occurs while closing a reader. |
| */ |
| public static void closeReaders(SequenceFile.Reader[] readers) |
| throws IOException { |
| |
| // loop through the readers, closing one by one |
| if (readers != null) { |
| for (int i = 0; i < readers.length; i++) { |
| SequenceFile.Reader reader = readers[i]; |
| if (reader != null) { |
| reader.close(); |
| } |
| } |
| } |
| } |
| |
| /** |
| * Closes a group of MapFile readers. |
| * |
| * @param readers |
| * The MapFile readers to close. |
| * @throws IOException |
| * If an error occurs while closing a reader. |
| */ |
| public static void closeReaders(MapFile.Reader[] readers) throws IOException { |
| |
| // loop through the readers closing one by one |
| if (readers != null) { |
| for (int i = 0; i < readers.length; i++) { |
| MapFile.Reader reader = readers[i]; |
| if (reader != null) { |
| reader.close(); |
| } |
| } |
| } |
| } |
| } |