001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.hadoop.hdfs;
020
021import java.io.IOException;
022import java.util.NoSuchElementException;
023
024import org.apache.hadoop.hdfs.protocol.CorruptFileBlocks;
025import org.apache.hadoop.fs.Path;
026import org.apache.hadoop.fs.RemoteIterator;
027
028/**
029 * Provides an iterator interface for listCorruptFileBlocks.
030 * This class is used by DistributedFileSystem and Hdfs.
031 */
032public class CorruptFileBlockIterator implements RemoteIterator<Path> {
033  private final DFSClient dfs;
034  private String path;
035
036  private String[] files = null;
037  private int fileIdx = 0;
038  private String cookie = null;
039  private Path nextPath = null;
040
041  private int callsMade = 0;
042
043  public CorruptFileBlockIterator(DFSClient dfs, Path path) throws IOException {
044    this.dfs = dfs;
045    this.path = path2String(path);
046    loadNext();
047  }
048
049  /**
050   * @return the number of calls made to the DFSClient.
051   * This is for debugging and testing purposes.
052   */
053  public int getCallsMade() {
054    return callsMade;
055  }
056
057  private String path2String(Path path) {
058    return path.toUri().getPath();
059  }
060
061  private Path string2Path(String string) {
062    return new Path(string);
063  }
064
065  private void loadNext() throws IOException {
066    if (files == null || fileIdx >= files.length) {
067      CorruptFileBlocks cfb = dfs.listCorruptFileBlocks(path, cookie);
068      files = cfb.getFiles();
069      cookie = cfb.getCookie();
070      fileIdx = 0;
071      callsMade++;
072    }
073
074    if (fileIdx >= files.length) {
075      // received an empty response
076      // there are no more corrupt file blocks
077      nextPath = null;
078    } else {
079      nextPath = string2Path(files[fileIdx]);
080      fileIdx++;
081    }
082  }
083
084  
085  @Override
086  public boolean hasNext() {
087    return nextPath != null;
088  }
089
090  
091  @Override
092  public Path next() throws IOException {
093    if (!hasNext()) {
094      throw new NoSuchElementException("No more corrupt file blocks");
095    }
096
097    Path result = nextPath;
098    loadNext();
099
100    return result;
101  }
102}