mapreduce/src/java/org/apache/hadoop/mapred/FileInputFormat.java - hadoop - Git at Google

 /**
  * 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;

 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashSet;
 import java.util.IdentityHashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;

 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.fs.BlockLocation;
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.PathFilter;
 import org.apache.hadoop.net.NetworkTopology;
 import org.apache.hadoop.net.Node;
 import org.apache.hadoop.net.NodeBase;
 import org.apache.hadoop.util.ReflectionUtils;
 import org.apache.hadoop.util.StringUtils;

 /**
  * A base class for file-based {@link InputFormat}.
  *
  * <p><code>FileInputFormat</code> is the base class for all file-based
  * <code>InputFormat</code>s. This provides a generic implementation of
  * {@link #getSplits(JobConf, int)}.
  * Subclasses of <code>FileInputFormat</code> can also override the
  * {@link #isSplitable(FileSystem, Path)} method to ensure input-files are
  * not split-up and are processed as a whole by {@link Mapper}s.
  * @deprecated Use {@link org.apache.hadoop.mapreduce.lib.input.FileInputFormat}
  *  instead.
  */
 @Deprecated
 public abstract class FileInputFormat<K, V> implements InputFormat<K, V> {

   public static final Log LOG =
     LogFactory.getLog(FileInputFormat.class);

   private static final double SPLIT_SLOP = 1.1;   // 10% slop

   private long minSplitSize = 1;
   private static final PathFilter hiddenFileFilter = new PathFilter(){
       public boolean accept(Path p){
         String name = p.getName();
         return !name.startsWith("_") && !name.startsWith(".");
       }
     };
   protected void setMinSplitSize(long minSplitSize) {
     this.minSplitSize = minSplitSize;
   }

   /**
    * Proxy PathFilter that accepts a path only if all filters given in the
    * constructor do. Used by the listPaths() to apply the built-in
    * hiddenFileFilter together with a user provided one (if any).
    */
   private static class MultiPathFilter implements PathFilter {
     private List<PathFilter> filters;

     public MultiPathFilter(List<PathFilter> filters) {
       this.filters = filters;
     }

     public boolean accept(Path path) {
       for (PathFilter filter : filters) {
         if (!filter.accept(path)) {
           return false;
         }
       }
       return true;
     }
   }

   /**
    * Is the given filename splitable? Usually, true, but if the file is
    * stream compressed, it will not be.
    *
    * <code>FileInputFormat</code> implementations can override this and return
    * <code>false</code> to ensure that individual input files are never split-up
    * so that {@link Mapper}s process entire files.
    *
    * @param fs the file system that the file is on
    * @param filename the file name to check
    * @return is this file splitable?
    */
   protected boolean isSplitable(FileSystem fs, Path filename) {
     return true;
   }

   public abstract RecordReader<K, V> getRecordReader(InputSplit split,
                                                JobConf job,
                                                Reporter reporter)
     throws IOException;

   /**
    * Set a PathFilter to be applied to the input paths for the map-reduce job.
    *
    * @param filter the PathFilter class use for filtering the input paths.
    */
   public static void setInputPathFilter(JobConf conf,
                                         Class<? extends PathFilter> filter) {
     conf.setClass(org.apache.hadoop.mapreduce.lib.input.
       FileInputFormat.PATHFILTER_CLASS, filter, PathFilter.class);
   }

   /**
    * Get a PathFilter instance of the filter set for the input paths.
    *
    * @return the PathFilter instance set for the job, NULL if none has been set.
    */
   public static PathFilter getInputPathFilter(JobConf conf) {
     Class<? extends PathFilter> filterClass = conf.getClass(
 	  org.apache.hadoop.mapreduce.lib.input.FileInputFormat.PATHFILTER_CLASS,
 	  null, PathFilter.class);
     return (filterClass != null) ?
         ReflectionUtils.newInstance(filterClass, conf) : null;
   }

   /** List input directories.
    * Subclasses may override to, e.g., select only files matching a regular
    * expression.
    *
    * @param job the job to list input paths for
    * @return array of FileStatus objects
    * @throws IOException if zero items.
    */
   protected FileStatus[] listStatus(JobConf job) throws IOException {
     Path[] dirs = getInputPaths(job);
     if (dirs.length == 0) {
       throw new IOException("No input paths specified in job");
     }

     List<FileStatus> result = new ArrayList<FileStatus>();
     List<IOException> errors = new ArrayList<IOException>();

     // creates a MultiPathFilter with the hiddenFileFilter and the
     // user provided one (if any).
     List<PathFilter> filters = new ArrayList<PathFilter>();
     filters.add(hiddenFileFilter);
     PathFilter jobFilter = getInputPathFilter(job);
     if (jobFilter != null) {
       filters.add(jobFilter);
     }
     PathFilter inputFilter = new MultiPathFilter(filters);

     for (Path p: dirs) {
       FileSystem fs = p.getFileSystem(job);
       FileStatus[] matches = fs.globStatus(p, inputFilter);
       if (matches == null) {
         errors.add(new IOException("Input path does not exist: " + p));
       } else if (matches.length == 0) {
         errors.add(new IOException("Input Pattern " + p + " matches 0 files"));
       } else {
         for (FileStatus globStat: matches) {
           if (globStat.isDir()) {
             for(FileStatus stat: fs.listStatus(globStat.getPath(),
                 inputFilter)) {
               result.add(stat);
             }
           } else {
             result.add(globStat);
           }
         }
       }
     }

     if (!errors.isEmpty()) {
       throw new InvalidInputException(errors);
     }
     LOG.info("Total input paths to process : " + result.size());
     return result.toArray(new FileStatus[result.size()]);
   }

   /**
    * A factory that makes the split for this class. It can be overridden
    * by sub-classes to make sub-types
    */
   protected FileSplit makeSplit(Path file, long start, long length,
                                 String[] hosts) {
     return new FileSplit(file, start, length, hosts);
   }

   /** Splits files returned by {@link #listStatus(JobConf)} when
    * they're too big.*/
   @SuppressWarnings("deprecation")
   public InputSplit[] getSplits(JobConf job, int numSplits)
     throws IOException {
     FileStatus[] files = listStatus(job);

     long totalSize = 0;                           // compute total size
     for (FileStatus file: files) {                // check we have valid files
       if (file.isDir()) {
         throw new IOException("Not a file: "+ file.getPath());
       }
       totalSize += file.getLen();
     }

     long goalSize = totalSize / (numSplits == 0 ? 1 : numSplits);
     long minSize = Math.max(job.getLong(org.apache.hadoop.mapreduce.lib.input.
       FileInputFormat.SPLIT_MINSIZE, 1), minSplitSize);

     // generate splits
     ArrayList<FileSplit> splits = new ArrayList<FileSplit>(numSplits);
     NetworkTopology clusterMap = new NetworkTopology();
     for (FileStatus file: files) {
       Path path = file.getPath();
       FileSystem fs = path.getFileSystem(job);
       long length = file.getLen();
       BlockLocation[] blkLocations = fs.getFileBlockLocations(file, 0, length);
       if ((length != 0) && isSplitable(fs, path)) {
         long blockSize = file.getBlockSize();
         long splitSize = computeSplitSize(goalSize, minSize, blockSize);

         long bytesRemaining = length;
         while (((double) bytesRemaining)/splitSize > SPLIT_SLOP) {
           String[] splitHosts = getSplitHosts(blkLocations,
               length-bytesRemaining, splitSize, clusterMap);
           splits.add(makeSplit(path, length-bytesRemaining, splitSize,
                                splitHosts));
           bytesRemaining -= splitSize;
         }

         if (bytesRemaining != 0) {
           splits.add(makeSplit(path, length-bytesRemaining, bytesRemaining,
                      blkLocations[blkLocations.length-1].getHosts()));
         }
       } else if (length != 0) {
         String[] splitHosts = getSplitHosts(blkLocations,0,length,clusterMap);
         splits.add(makeSplit(path, 0, length, splitHosts));
       } else {
         //Create empty hosts array for zero length files
         splits.add(makeSplit(path, 0, length, new String[0]));
       }
     }
     LOG.debug("Total # of splits: " + splits.size());
     return splits.toArray(new FileSplit[splits.size()]);
   }

   protected long computeSplitSize(long goalSize, long minSize,
                                        long blockSize) {
     return Math.max(minSize, Math.min(goalSize, blockSize));
   }

   protected int getBlockIndex(BlockLocation[] blkLocations,
                               long offset) {
     for (int i = 0 ; i < blkLocations.length; i++) {
       // is the offset inside this block?
       if ((blkLocations[i].getOffset() <= offset) &&
           (offset < blkLocations[i].getOffset() + blkLocations[i].getLength())){
         return i;
       }
     }
     BlockLocation last = blkLocations[blkLocations.length -1];
     long fileLength = last.getOffset() + last.getLength() -1;
     throw new IllegalArgumentException("Offset " + offset +
                                        " is outside of file (0.." +
                                        fileLength + ")");
   }

   /**
    * Sets the given comma separated paths as the list of inputs
    * for the map-reduce job.
    *
    * @param conf Configuration of the job
    * @param commaSeparatedPaths Comma separated paths to be set as
    *        the list of inputs for the map-reduce job.
    */
   public static void setInputPaths(JobConf conf, String commaSeparatedPaths) {
     setInputPaths(conf, StringUtils.stringToPath(
                         getPathStrings(commaSeparatedPaths)));
   }

   /**
    * Add the given comma separated paths to the list of inputs for
    *  the map-reduce job.
    *
    * @param conf The configuration of the job
    * @param commaSeparatedPaths Comma separated paths to be added to
    *        the list of inputs for the map-reduce job.
    */
   public static void addInputPaths(JobConf conf, String commaSeparatedPaths) {
     for (String str : getPathStrings(commaSeparatedPaths)) {
       addInputPath(conf, new Path(str));
     }
   }

   /**
    * Set the array of {@link Path}s as the list of inputs
    * for the map-reduce job.
    *
    * @param conf Configuration of the job.
    * @param inputPaths the {@link Path}s of the input directories/files
    * for the map-reduce job.
    */
   public static void setInputPaths(JobConf conf, Path... inputPaths) {
     Path path = new Path(conf.getWorkingDirectory(), inputPaths[0]);
     StringBuffer str = new StringBuffer(StringUtils.escapeString(path.toString()));
     for(int i = 1; i < inputPaths.length;i++) {
       str.append(StringUtils.COMMA_STR);
       path = new Path(conf.getWorkingDirectory(), inputPaths[i]);
       str.append(StringUtils.escapeString(path.toString()));
     }
     conf.set(org.apache.hadoop.mapreduce.lib.input.
       FileInputFormat.INPUT_DIR, str.toString());
   }

   /**
    * Add a {@link Path} to the list of inputs for the map-reduce job.
    *
    * @param conf The configuration of the job
    * @param path {@link Path} to be added to the list of inputs for
    *            the map-reduce job.
    */
   public static void addInputPath(JobConf conf, Path path ) {
     path = new Path(conf.getWorkingDirectory(), path);
     String dirStr = StringUtils.escapeString(path.toString());
     String dirs = conf.get(org.apache.hadoop.mapreduce.lib.input.
       FileInputFormat.INPUT_DIR);
     conf.set(org.apache.hadoop.mapreduce.lib.input.
       FileInputFormat.INPUT_DIR, dirs == null ? dirStr :
       dirs + StringUtils.COMMA_STR + dirStr);
   }

   // This method escapes commas in the glob pattern of the given paths.
   private static String[] getPathStrings(String commaSeparatedPaths) {
     int length = commaSeparatedPaths.length();
     int curlyOpen = 0;
     int pathStart = 0;
     boolean globPattern = false;
     List<String> pathStrings = new ArrayList<String>();

     for (int i=0; i<length; i++) {
       char ch = commaSeparatedPaths.charAt(i);
       switch(ch) {
         case '{' : {
           curlyOpen++;
           if (!globPattern) {
             globPattern = true;
           }
           break;
         }
         case '}' : {
           curlyOpen--;
           if (curlyOpen == 0 && globPattern) {
             globPattern = false;
           }
           break;
         }
         case ',' : {
           if (!globPattern) {
             pathStrings.add(commaSeparatedPaths.substring(pathStart, i));
             pathStart = i + 1 ;
           }
           break;
         }
       }
     }
     pathStrings.add(commaSeparatedPaths.substring(pathStart, length));

     return pathStrings.toArray(new String[0]);
   }

   /**
    * Get the list of input {@link Path}s for the map-reduce job.
    *
    * @param conf The configuration of the job
    * @return the list of input {@link Path}s for the map-reduce job.
    */
   public static Path[] getInputPaths(JobConf conf) {
     String dirs = conf.get(org.apache.hadoop.mapreduce.lib.input.
       FileInputFormat.INPUT_DIR, "");
     String [] list = StringUtils.split(dirs);
     Path[] result = new Path[list.length];
     for (int i = 0; i < list.length; i++) {
       result[i] = new Path(StringUtils.unEscapeString(list[i]));
     }
     return result;
   }


   private void sortInDescendingOrder(List<NodeInfo> mylist) {
     Collections.sort(mylist, new Comparator<NodeInfo> () {
       public int compare(NodeInfo obj1, NodeInfo obj2) {

         if (obj1 == null || obj2 == null)
           return -1;

         if (obj1.getValue() == obj2.getValue()) {
           return 0;
         }
         else {
           return ((obj1.getValue() < obj2.getValue()) ? 1 : -1);
         }
       }
     }
     );
   }

   /**
    * This function identifies and returns the hosts that contribute
    * most for a given split. For calculating the contribution, rack
    * locality is treated on par with host locality, so hosts from racks
    * that contribute the most are preferred over hosts on racks that
    * contribute less
    * @param blkLocations The list of block locations
    * @param offset
    * @param splitSize
    * @return array of hosts that contribute most to this split
    * @throws IOException
    */
   protected String[] getSplitHosts(BlockLocation[] blkLocations,
       long offset, long splitSize, NetworkTopology clusterMap)
   throws IOException {

     int startIndex = getBlockIndex(blkLocations, offset);

     long bytesInThisBlock = blkLocations[startIndex].getOffset() +
                           blkLocations[startIndex].getLength() - offset;

     //If this is the only block, just return
     if (bytesInThisBlock >= splitSize) {
       return blkLocations[startIndex].getHosts();
     }

     long bytesInFirstBlock = bytesInThisBlock;
     int index = startIndex + 1;
     splitSize -= bytesInThisBlock;

     while (splitSize > 0) {
       bytesInThisBlock =
         Math.min(splitSize, blkLocations[index++].getLength());
       splitSize -= bytesInThisBlock;
     }

     long bytesInLastBlock = bytesInThisBlock;
     int endIndex = index - 1;

     Map <Node,NodeInfo> hostsMap = new IdentityHashMap<Node,NodeInfo>();
     Map <Node,NodeInfo> racksMap = new IdentityHashMap<Node,NodeInfo>();
     String [] allTopos = new String[0];

     // Build the hierarchy and aggregate the contribution of
     // bytes at each level. See TestGetSplitHosts.java

     for (index = startIndex; index <= endIndex; index++) {

       // Establish the bytes in this block
       if (index == startIndex) {
         bytesInThisBlock = bytesInFirstBlock;
       }
       else if (index == endIndex) {
         bytesInThisBlock = bytesInLastBlock;
       }
       else {
         bytesInThisBlock = blkLocations[index].getLength();
       }

       allTopos = blkLocations[index].getTopologyPaths();

       // If no topology information is available, just
       // prefix a fakeRack
       if (allTopos.length == 0) {
         allTopos = fakeRacks(blkLocations, index);
       }

       // NOTE: This code currently works only for one level of
       // hierarchy (rack/host). However, it is relatively easy
       // to extend this to support aggregation at different
       // levels

       for (String topo: allTopos) {

         Node node, parentNode;
         NodeInfo nodeInfo, parentNodeInfo;

         node = clusterMap.getNode(topo);

         if (node == null) {
           node = new NodeBase(topo);
           clusterMap.add(node);
         }

         nodeInfo = hostsMap.get(node);

         if (nodeInfo == null) {
           nodeInfo = new NodeInfo(node);
           hostsMap.put(node,nodeInfo);
           parentNode = node.getParent();
           parentNodeInfo = racksMap.get(parentNode);
           if (parentNodeInfo == null) {
             parentNodeInfo = new NodeInfo(parentNode);
             racksMap.put(parentNode,parentNodeInfo);
           }
           parentNodeInfo.addLeaf(nodeInfo);
         }
         else {
           nodeInfo = hostsMap.get(node);
           parentNode = node.getParent();
           parentNodeInfo = racksMap.get(parentNode);
         }

         nodeInfo.addValue(index, bytesInThisBlock);
         parentNodeInfo.addValue(index, bytesInThisBlock);

       } // for all topos

     } // for all indices

     return identifyHosts(allTopos.length, racksMap);
   }

   private String[] identifyHosts(int replicationFactor,
                                  Map<Node,NodeInfo> racksMap) {

     String [] retVal = new String[replicationFactor];

     List <NodeInfo> rackList = new LinkedList<NodeInfo>();

     rackList.addAll(racksMap.values());

     // Sort the racks based on their contribution to this split
     sortInDescendingOrder(rackList);

     boolean done = false;
     int index = 0;

     // Get the host list for all our aggregated items, sort
     // them and return the top entries
     for (NodeInfo ni: rackList) {

       Set<NodeInfo> hostSet = ni.getLeaves();

       List<NodeInfo>hostList = new LinkedList<NodeInfo>();
       hostList.addAll(hostSet);

       // Sort the hosts in this rack based on their contribution
       sortInDescendingOrder(hostList);

       for (NodeInfo host: hostList) {
         // Strip out the port number from the host name
         retVal[index++] = host.node.getName().split(":")[0];
         if (index == replicationFactor) {
           done = true;
           break;
         }
       }

       if (done == true) {
         break;
       }
     }
     return retVal;
   }

   private String[] fakeRacks(BlockLocation[] blkLocations, int index)
   throws IOException {
     String[] allHosts = blkLocations[index].getHosts();
     String[] allTopos = new String[allHosts.length];
     for (int i = 0; i < allHosts.length; i++) {
       allTopos[i] = NetworkTopology.DEFAULT_RACK + "/" + allHosts[i];
     }
     return allTopos;
   }


   private static class NodeInfo {
     final Node node;
     final Set<Integer> blockIds;
     final Set<NodeInfo> leaves;

     private long value;

     NodeInfo(Node node) {
       this.node = node;
       blockIds = new HashSet<Integer>();
       leaves = new HashSet<NodeInfo>();
     }

     long getValue() {return value;}

     void addValue(int blockIndex, long value) {
       if (blockIds.add(blockIndex) == true) {
         this.value += value;
       }
     }

     Set<NodeInfo> getLeaves() { return leaves;}

     void addLeaf(NodeInfo nodeInfo) {
       leaves.add(nodeInfo);
     }
   }
 }
	/**
	* 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;

	import java.io.IOException;
	import java.util.ArrayList;
	import java.util.Collections;
	import java.util.Comparator;
	import java.util.HashSet;
	import java.util.IdentityHashMap;
	import java.util.LinkedList;
	import java.util.List;
	import java.util.Map;
	import java.util.Set;

	import org.apache.commons.logging.Log;
	import org.apache.commons.logging.LogFactory;
	import org.apache.hadoop.fs.BlockLocation;
	import org.apache.hadoop.fs.FileStatus;
	import org.apache.hadoop.fs.FileSystem;
	import org.apache.hadoop.fs.Path;
	import org.apache.hadoop.fs.PathFilter;
	import org.apache.hadoop.net.NetworkTopology;
	import org.apache.hadoop.net.Node;
	import org.apache.hadoop.net.NodeBase;
	import org.apache.hadoop.util.ReflectionUtils;
	import org.apache.hadoop.util.StringUtils;

	/**
	* A base class for file-based {@link InputFormat}.
	*
	* <p><code>FileInputFormat</code> is the base class for all file-based
	* <code>InputFormat</code>s. This provides a generic implementation of
	* {@link #getSplits(JobConf, int)}.
	* Subclasses of <code>FileInputFormat</code> can also override the
	* {@link #isSplitable(FileSystem, Path)} method to ensure input-files are
	* not split-up and are processed as a whole by {@link Mapper}s.
	* @deprecated Use {@link org.apache.hadoop.mapreduce.lib.input.FileInputFormat}
	* instead.
	*/
	@Deprecated
	public abstract class FileInputFormat<K, V> implements InputFormat<K, V> {

	public static final Log LOG =
	LogFactory.getLog(FileInputFormat.class);

	private static final double SPLIT_SLOP = 1.1; // 10% slop

	private long minSplitSize = 1;
	private static final PathFilter hiddenFileFilter = new PathFilter(){
	public boolean accept(Path p){
	String name = p.getName();
	return !name.startsWith("_") && !name.startsWith(".");
	}
	};
	protected void setMinSplitSize(long minSplitSize) {
	this.minSplitSize = minSplitSize;
	}

	/**
	* Proxy PathFilter that accepts a path only if all filters given in the
	* constructor do. Used by the listPaths() to apply the built-in
	* hiddenFileFilter together with a user provided one (if any).
	*/
	private static class MultiPathFilter implements PathFilter {
	private List<PathFilter> filters;

	public MultiPathFilter(List<PathFilter> filters) {
	this.filters = filters;
	}

	public boolean accept(Path path) {
	for (PathFilter filter : filters) {
	if (!filter.accept(path)) {
	return false;
	}
	}
	return true;
	}
	}

	/**
	* Is the given filename splitable? Usually, true, but if the file is
	* stream compressed, it will not be.
	*
	* <code>FileInputFormat</code> implementations can override this and return
	* <code>false</code> to ensure that individual input files are never split-up
	* so that {@link Mapper}s process entire files.
	*
	* @param fs the file system that the file is on
	* @param filename the file name to check
	* @return is this file splitable?
	*/
	protected boolean isSplitable(FileSystem fs, Path filename) {
	return true;
	}

	public abstract RecordReader<K, V> getRecordReader(InputSplit split,
	JobConf job,
	Reporter reporter)
	throws IOException;

	/**
	* Set a PathFilter to be applied to the input paths for the map-reduce job.
	*
	* @param filter the PathFilter class use for filtering the input paths.
	*/
	public static void setInputPathFilter(JobConf conf,
	Class<? extends PathFilter> filter) {
	conf.setClass(org.apache.hadoop.mapreduce.lib.input.
	FileInputFormat.PATHFILTER_CLASS, filter, PathFilter.class);
	}

	/**
	* Get a PathFilter instance of the filter set for the input paths.
	*
	* @return the PathFilter instance set for the job, NULL if none has been set.
	*/
	public static PathFilter getInputPathFilter(JobConf conf) {
	Class<? extends PathFilter> filterClass = conf.getClass(
	org.apache.hadoop.mapreduce.lib.input.FileInputFormat.PATHFILTER_CLASS,
	null, PathFilter.class);
	return (filterClass != null) ?
	ReflectionUtils.newInstance(filterClass, conf) : null;
	}

	/** List input directories.
	* Subclasses may override to, e.g., select only files matching a regular
	* expression.
	*
	* @param job the job to list input paths for
	* @return array of FileStatus objects
	* @throws IOException if zero items.
	*/
	protected FileStatus[] listStatus(JobConf job) throws IOException {
	Path[] dirs = getInputPaths(job);
	if (dirs.length == 0) {
	throw new IOException("No input paths specified in job");
	}

	List<FileStatus> result = new ArrayList<FileStatus>();
	List<IOException> errors = new ArrayList<IOException>();

	// creates a MultiPathFilter with the hiddenFileFilter and the
	// user provided one (if any).
	List<PathFilter> filters = new ArrayList<PathFilter>();
	filters.add(hiddenFileFilter);
	PathFilter jobFilter = getInputPathFilter(job);
	if (jobFilter != null) {
	filters.add(jobFilter);
	}
	PathFilter inputFilter = new MultiPathFilter(filters);

	for (Path p: dirs) {
	FileSystem fs = p.getFileSystem(job);
	FileStatus[] matches = fs.globStatus(p, inputFilter);
	if (matches == null) {
	errors.add(new IOException("Input path does not exist: " + p));
	} else if (matches.length == 0) {
	errors.add(new IOException("Input Pattern " + p + " matches 0 files"));
	} else {
	for (FileStatus globStat: matches) {
	if (globStat.isDir()) {
	for(FileStatus stat: fs.listStatus(globStat.getPath(),
	inputFilter)) {
	result.add(stat);
	}
	} else {
	result.add(globStat);
	}
	}
	}
	}

	if (!errors.isEmpty()) {
	throw new InvalidInputException(errors);
	}
	LOG.info("Total input paths to process : " + result.size());
	return result.toArray(new FileStatus[result.size()]);
	}

	/**
	* A factory that makes the split for this class. It can be overridden
	* by sub-classes to make sub-types
	*/
	protected FileSplit makeSplit(Path file, long start, long length,
	String[] hosts) {
	return new FileSplit(file, start, length, hosts);
	}

	/** Splits files returned by {@link #listStatus(JobConf)} when
	* they're too big.*/
	@SuppressWarnings("deprecation")
	public InputSplit[] getSplits(JobConf job, int numSplits)
	throws IOException {
	FileStatus[] files = listStatus(job);

	long totalSize = 0; // compute total size
	for (FileStatus file: files) { // check we have valid files
	if (file.isDir()) {
	throw new IOException("Not a file: "+ file.getPath());
	}
	totalSize += file.getLen();
	}

	long goalSize = totalSize / (numSplits == 0 ? 1 : numSplits);
	long minSize = Math.max(job.getLong(org.apache.hadoop.mapreduce.lib.input.
	FileInputFormat.SPLIT_MINSIZE, 1), minSplitSize);

	// generate splits
	ArrayList<FileSplit> splits = new ArrayList<FileSplit>(numSplits);
	NetworkTopology clusterMap = new NetworkTopology();
	for (FileStatus file: files) {
	Path path = file.getPath();
	FileSystem fs = path.getFileSystem(job);
	long length = file.getLen();
	BlockLocation[] blkLocations = fs.getFileBlockLocations(file, 0, length);
	if ((length != 0) && isSplitable(fs, path)) {
	long blockSize = file.getBlockSize();
	long splitSize = computeSplitSize(goalSize, minSize, blockSize);

	long bytesRemaining = length;
	while (((double) bytesRemaining)/splitSize > SPLIT_SLOP) {
	String[] splitHosts = getSplitHosts(blkLocations,
	length-bytesRemaining, splitSize, clusterMap);
	splits.add(makeSplit(path, length-bytesRemaining, splitSize,
	splitHosts));
	bytesRemaining -= splitSize;
	}

	if (bytesRemaining != 0) {
	splits.add(makeSplit(path, length-bytesRemaining, bytesRemaining,
	blkLocations[blkLocations.length-1].getHosts()));
	}
	} else if (length != 0) {
	String[] splitHosts = getSplitHosts(blkLocations,0,length,clusterMap);
	splits.add(makeSplit(path, 0, length, splitHosts));
	} else {
	//Create empty hosts array for zero length files
	splits.add(makeSplit(path, 0, length, new String[0]));
	}
	}
	LOG.debug("Total # of splits: " + splits.size());
	return splits.toArray(new FileSplit[splits.size()]);
	}

	protected long computeSplitSize(long goalSize, long minSize,
	long blockSize) {
	return Math.max(minSize, Math.min(goalSize, blockSize));
	}

	protected int getBlockIndex(BlockLocation[] blkLocations,
	long offset) {
	for (int i = 0 ; i < blkLocations.length; i++) {
	// is the offset inside this block?
	if ((blkLocations[i].getOffset() <= offset) &&
	(offset < blkLocations[i].getOffset() + blkLocations[i].getLength())){
	return i;
	}
	}
	BlockLocation last = blkLocations[blkLocations.length -1];
	long fileLength = last.getOffset() + last.getLength() -1;
	throw new IllegalArgumentException("Offset " + offset +
	" is outside of file (0.." +
	fileLength + ")");
	}

	/**
	* Sets the given comma separated paths as the list of inputs
	* for the map-reduce job.
	*
	* @param conf Configuration of the job
	* @param commaSeparatedPaths Comma separated paths to be set as
	* the list of inputs for the map-reduce job.
	*/
	public static void setInputPaths(JobConf conf, String commaSeparatedPaths) {
	setInputPaths(conf, StringUtils.stringToPath(
	getPathStrings(commaSeparatedPaths)));
	}

	/**
	* Add the given comma separated paths to the list of inputs for
	* the map-reduce job.
	*
	* @param conf The configuration of the job
	* @param commaSeparatedPaths Comma separated paths to be added to
	* the list of inputs for the map-reduce job.
	*/
	public static void addInputPaths(JobConf conf, String commaSeparatedPaths) {
	for (String str : getPathStrings(commaSeparatedPaths)) {
	addInputPath(conf, new Path(str));
	}
	}

	/**
	* Set the array of {@link Path}s as the list of inputs
	* for the map-reduce job.
	*
	* @param conf Configuration of the job.
	* @param inputPaths the {@link Path}s of the input directories/files
	* for the map-reduce job.
	*/
	public static void setInputPaths(JobConf conf, Path... inputPaths) {
	Path path = new Path(conf.getWorkingDirectory(), inputPaths[0]);
	StringBuffer str = new StringBuffer(StringUtils.escapeString(path.toString()));
	for(int i = 1; i < inputPaths.length;i++) {
	str.append(StringUtils.COMMA_STR);
	path = new Path(conf.getWorkingDirectory(), inputPaths[i]);
	str.append(StringUtils.escapeString(path.toString()));
	}
	conf.set(org.apache.hadoop.mapreduce.lib.input.
	FileInputFormat.INPUT_DIR, str.toString());
	}

	/**
	* Add a {@link Path} to the list of inputs for the map-reduce job.
	*
	* @param conf The configuration of the job
	* @param path {@link Path} to be added to the list of inputs for
	* the map-reduce job.
	*/
	public static void addInputPath(JobConf conf, Path path ) {
	path = new Path(conf.getWorkingDirectory(), path);
	String dirStr = StringUtils.escapeString(path.toString());
	String dirs = conf.get(org.apache.hadoop.mapreduce.lib.input.
	FileInputFormat.INPUT_DIR);
	conf.set(org.apache.hadoop.mapreduce.lib.input.
	FileInputFormat.INPUT_DIR, dirs == null ? dirStr :
	dirs + StringUtils.COMMA_STR + dirStr);
	}

	// This method escapes commas in the glob pattern of the given paths.
	private static String[] getPathStrings(String commaSeparatedPaths) {
	int length = commaSeparatedPaths.length();
	int curlyOpen = 0;
	int pathStart = 0;
	boolean globPattern = false;
	List<String> pathStrings = new ArrayList<String>();

	for (int i=0; i<length; i++) {
	char ch = commaSeparatedPaths.charAt(i);
	switch(ch) {
	case '{' : {
	curlyOpen++;
	if (!globPattern) {
	globPattern = true;
	}
	break;
	}
	case '}' : {
	curlyOpen--;
	if (curlyOpen == 0 && globPattern) {
	globPattern = false;
	}
	break;
	}
	case ',' : {
	if (!globPattern) {
	pathStrings.add(commaSeparatedPaths.substring(pathStart, i));
	pathStart = i + 1 ;
	}
	break;
	}
	}
	}
	pathStrings.add(commaSeparatedPaths.substring(pathStart, length));

	return pathStrings.toArray(new String[0]);
	}

	/**
	* Get the list of input {@link Path}s for the map-reduce job.
	*
	* @param conf The configuration of the job
	* @return the list of input {@link Path}s for the map-reduce job.
	*/
	public static Path[] getInputPaths(JobConf conf) {
	String dirs = conf.get(org.apache.hadoop.mapreduce.lib.input.
	FileInputFormat.INPUT_DIR, "");
	String [] list = StringUtils.split(dirs);
	Path[] result = new Path[list.length];
	for (int i = 0; i < list.length; i++) {
	result[i] = new Path(StringUtils.unEscapeString(list[i]));
	}
	return result;
	}


	private void sortInDescendingOrder(List<NodeInfo> mylist) {
	Collections.sort(mylist, new Comparator<NodeInfo> () {
	public int compare(NodeInfo obj1, NodeInfo obj2) {

	if (obj1 == null \|\| obj2 == null)
	return -1;

	if (obj1.getValue() == obj2.getValue()) {
	return 0;
	}
	else {
	return ((obj1.getValue() < obj2.getValue()) ? 1 : -1);
	}
	}
	}
	);
	}

	/**
	* This function identifies and returns the hosts that contribute
	* most for a given split. For calculating the contribution, rack
	* locality is treated on par with host locality, so hosts from racks
	* that contribute the most are preferred over hosts on racks that
	* contribute less
	* @param blkLocations The list of block locations
	* @param offset
	* @param splitSize
	* @return array of hosts that contribute most to this split
	* @throws IOException
	*/
	protected String[] getSplitHosts(BlockLocation[] blkLocations,
	long offset, long splitSize, NetworkTopology clusterMap)
	throws IOException {

	int startIndex = getBlockIndex(blkLocations, offset);

	long bytesInThisBlock = blkLocations[startIndex].getOffset() +
	blkLocations[startIndex].getLength() - offset;

	//If this is the only block, just return
	if (bytesInThisBlock >= splitSize) {
	return blkLocations[startIndex].getHosts();
	}

	long bytesInFirstBlock = bytesInThisBlock;
	int index = startIndex + 1;
	splitSize -= bytesInThisBlock;

	while (splitSize > 0) {
	bytesInThisBlock =
	Math.min(splitSize, blkLocations[index++].getLength());
	splitSize -= bytesInThisBlock;
	}

	long bytesInLastBlock = bytesInThisBlock;
	int endIndex = index - 1;

	Map <Node,NodeInfo> hostsMap = new IdentityHashMap<Node,NodeInfo>();
	Map <Node,NodeInfo> racksMap = new IdentityHashMap<Node,NodeInfo>();
	String [] allTopos = new String[0];

	// Build the hierarchy and aggregate the contribution of
	// bytes at each level. See TestGetSplitHosts.java

	for (index = startIndex; index <= endIndex; index++) {

	// Establish the bytes in this block
	if (index == startIndex) {
	bytesInThisBlock = bytesInFirstBlock;
	}
	else if (index == endIndex) {
	bytesInThisBlock = bytesInLastBlock;
	}
	else {
	bytesInThisBlock = blkLocations[index].getLength();
	}

	allTopos = blkLocations[index].getTopologyPaths();

	// If no topology information is available, just
	// prefix a fakeRack
	if (allTopos.length == 0) {
	allTopos = fakeRacks(blkLocations, index);
	}

	// NOTE: This code currently works only for one level of
	// hierarchy (rack/host). However, it is relatively easy
	// to extend this to support aggregation at different
	// levels

	for (String topo: allTopos) {

	Node node, parentNode;
	NodeInfo nodeInfo, parentNodeInfo;

	node = clusterMap.getNode(topo);

	if (node == null) {
	node = new NodeBase(topo);
	clusterMap.add(node);
	}

	nodeInfo = hostsMap.get(node);

	if (nodeInfo == null) {
	nodeInfo = new NodeInfo(node);
	hostsMap.put(node,nodeInfo);
	parentNode = node.getParent();
	parentNodeInfo = racksMap.get(parentNode);
	if (parentNodeInfo == null) {
	parentNodeInfo = new NodeInfo(parentNode);
	racksMap.put(parentNode,parentNodeInfo);
	}
	parentNodeInfo.addLeaf(nodeInfo);
	}
	else {
	nodeInfo = hostsMap.get(node);
	parentNode = node.getParent();
	parentNodeInfo = racksMap.get(parentNode);
	}

	nodeInfo.addValue(index, bytesInThisBlock);
	parentNodeInfo.addValue(index, bytesInThisBlock);

	} // for all topos

	} // for all indices

	return identifyHosts(allTopos.length, racksMap);
	}

	private String[] identifyHosts(int replicationFactor,
	Map<Node,NodeInfo> racksMap) {

	String [] retVal = new String[replicationFactor];

	List <NodeInfo> rackList = new LinkedList<NodeInfo>();

	rackList.addAll(racksMap.values());

	// Sort the racks based on their contribution to this split
	sortInDescendingOrder(rackList);

	boolean done = false;
	int index = 0;

	// Get the host list for all our aggregated items, sort
	// them and return the top entries
	for (NodeInfo ni: rackList) {

	Set<NodeInfo> hostSet = ni.getLeaves();

	List<NodeInfo>hostList = new LinkedList<NodeInfo>();
	hostList.addAll(hostSet);

	// Sort the hosts in this rack based on their contribution
	sortInDescendingOrder(hostList);

	for (NodeInfo host: hostList) {
	// Strip out the port number from the host name
	retVal[index++] = host.node.getName().split(":")[0];
	if (index == replicationFactor) {
	done = true;
	break;
	}
	}

	if (done == true) {
	break;
	}
	}
	return retVal;
	}

	private String[] fakeRacks(BlockLocation[] blkLocations, int index)
	throws IOException {
	String[] allHosts = blkLocations[index].getHosts();
	String[] allTopos = new String[allHosts.length];
	for (int i = 0; i < allHosts.length; i++) {
	allTopos[i] = NetworkTopology.DEFAULT_RACK + "/" + allHosts[i];
	}
	return allTopos;
	}


	private static class NodeInfo {
	final Node node;
	final Set<Integer> blockIds;
	final Set<NodeInfo> leaves;

	private long value;

	NodeInfo(Node node) {
	this.node = node;
	blockIds = new HashSet<Integer>();
	leaves = new HashSet<NodeInfo>();
	}

	long getValue() {return value;}

	void addValue(int blockIndex, long value) {
	if (blockIds.add(blockIndex) == true) {
	this.value += value;
	}
	}

	Set<NodeInfo> getLeaves() { return leaves;}

	void addLeaf(NodeInfo nodeInfo) {
	leaves.add(nodeInfo);
	}
	}
	}