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    
019    package org.apache.hadoop.hdfs;
020    
021    import java.io.IOException;
022    import java.util.NoSuchElementException;
023    
024    import org.apache.hadoop.hdfs.protocol.CorruptFileBlocks;
025    import org.apache.hadoop.fs.Path;
026    import org.apache.hadoop.fs.RemoteIterator;
027    
028    /**
029     * Provides an iterator interface for listCorruptFileBlocks.
030     * This class is used by DistributedFileSystem and Hdfs.
031     */
032    public 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    }