hdfs/src/java/org/apache/hadoop/hdfs/server/common/JspHelper.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.hdfs.server.common;

 import java.io.IOException;
 import java.io.UnsupportedEncodingException;
 import java.net.InetSocketAddress;
 import java.net.Socket;
 import java.net.URL;
 import java.net.URLEncoder;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.Random;
 import java.util.TreeSet;

 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.jsp.JspWriter;

 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.BlockReader;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.security.BlockAccessToken;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.hdfs.server.datanode.DatanodeJspHelper;
 import org.apache.hadoop.hdfs.server.namenode.DatanodeDescriptor;
 import org.apache.hadoop.http.HtmlQuoting;
 import org.apache.hadoop.io.WritableUtils;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.AccessControlException;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.UserGroupInformation.AuthenticationMethod;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.VersionInfo;

 @InterfaceAudience.Private
 public class JspHelper {
   final static public String WEB_UGI_PROPERTY_NAME = "dfs.web.ugi";
   public static final String DELEGATION_PARAMETER_NAME = "delegation";
   public static final String SET_DELEGATION = "&" + DELEGATION_PARAMETER_NAME +
                                               "=";
   private static final Log LOG = LogFactory.getLog(JspHelper.class);

   static final Random rand = new Random();

   /** Private constructor for preventing creating JspHelper object. */
   private JspHelper() {}

   public static DatanodeInfo bestNode(LocatedBlock blk) throws IOException {
     TreeSet<DatanodeInfo> deadNodes = new TreeSet<DatanodeInfo>();
     DatanodeInfo chosenNode = null;
     int failures = 0;
     Socket s = null;
     DatanodeInfo [] nodes = blk.getLocations();
     if (nodes == null || nodes.length == 0) {
       throw new IOException("No nodes contain this block");
     }
     while (s == null) {
       if (chosenNode == null) {
         do {
           chosenNode = nodes[rand.nextInt(nodes.length)];
         } while (deadNodes.contains(chosenNode));
       }
       int index = rand.nextInt(nodes.length);
       chosenNode = nodes[index];

       //just ping to check whether the node is alive
       InetSocketAddress targetAddr = NetUtils.createSocketAddr(
           chosenNode.getHost() + ":" + chosenNode.getInfoPort());

       try {
         s = new Socket();
         s.connect(targetAddr, HdfsConstants.READ_TIMEOUT);
         s.setSoTimeout(HdfsConstants.READ_TIMEOUT);
       } catch (IOException e) {
         deadNodes.add(chosenNode);
         s.close();
         s = null;
         failures++;
       }
       if (failures == nodes.length)
         throw new IOException("Could not reach the block containing the data. Please try again");

     }
     s.close();
     return chosenNode;
   }

   public static void streamBlockInAscii(InetSocketAddress addr, long blockId,
                                  BlockAccessToken accessToken, long genStamp,
                                  long blockSize,
                                  long offsetIntoBlock, long chunkSizeToView,
                                  JspWriter out,
                                  Configuration conf)
     throws IOException {
     if (chunkSizeToView == 0) return;
     Socket s = new Socket();
     s.connect(addr, HdfsConstants.READ_TIMEOUT);
     s.setSoTimeout(HdfsConstants.READ_TIMEOUT);

       long amtToRead = Math.min(chunkSizeToView, blockSize - offsetIntoBlock);

       // Use the block name for file name.
       BlockReader blockReader =
         BlockReader.newBlockReader(s, addr.toString() + ":" + blockId,
                                              blockId, accessToken, genStamp ,offsetIntoBlock,
                                              amtToRead,
                                              conf.getInt("io.file.buffer.size",
                                                          4096));

     byte[] buf = new byte[(int)amtToRead];
     int readOffset = 0;
     int retries = 2;
     while ( amtToRead > 0 ) {
       int numRead;
       try {
         numRead = blockReader.readAll(buf, readOffset, (int)amtToRead);
       }
       catch (IOException e) {
         retries--;
         if (retries == 0)
           throw new IOException("Could not read data from datanode");
         continue;
       }
       amtToRead -= numRead;
       readOffset += numRead;
     }
     blockReader = null;
     s.close();
     out.print(HtmlQuoting.quoteHtmlChars(new String(buf)));
   }

   public static void addTableHeader(JspWriter out) throws IOException {
     out.print("<table border=\"1\""+
               " cellpadding=\"2\" cellspacing=\"2\">");
     out.print("<tbody>");
   }
   public static void addTableRow(JspWriter out, String[] columns) throws IOException {
     out.print("<tr>");
     for (int i = 0; i < columns.length; i++) {
       out.print("<td style=\"vertical-align: top;\"><B>"+columns[i]+"</B><br></td>");
     }
     out.print("</tr>");
   }
   public static void addTableRow(JspWriter out, String[] columns, int row) throws IOException {
     out.print("<tr>");

     for (int i = 0; i < columns.length; i++) {
       if (row/2*2 == row) {//even
         out.print("<td style=\"vertical-align: top;background-color:LightGrey;\"><B>"+columns[i]+"</B><br></td>");
       } else {
         out.print("<td style=\"vertical-align: top;background-color:LightBlue;\"><B>"+columns[i]+"</B><br></td>");

       }
     }
     out.print("</tr>");
   }
   public static void addTableFooter(JspWriter out) throws IOException {
     out.print("</tbody></table>");
   }

   public static void sortNodeList(ArrayList<DatanodeDescriptor> nodes,
                            String field, String order) {

     class NodeComapare implements Comparator<DatanodeDescriptor> {
       static final int
         FIELD_NAME              = 1,
         FIELD_LAST_CONTACT      = 2,
         FIELD_BLOCKS            = 3,
         FIELD_CAPACITY          = 4,
         FIELD_USED              = 5,
         FIELD_PERCENT_USED      = 6,
         FIELD_NONDFS_USED       = 7,
         FIELD_REMAINING         = 8,
         FIELD_PERCENT_REMAINING = 9,
         SORT_ORDER_ASC          = 1,
         SORT_ORDER_DSC          = 2;

       int sortField = FIELD_NAME;
       int sortOrder = SORT_ORDER_ASC;

       public NodeComapare(String field, String order) {
         if (field.equals("lastcontact")) {
           sortField = FIELD_LAST_CONTACT;
         } else if (field.equals("capacity")) {
           sortField = FIELD_CAPACITY;
         } else if (field.equals("used")) {
           sortField = FIELD_USED;
         } else if (field.equals("nondfsused")) {
           sortField = FIELD_NONDFS_USED;
         } else if (field.equals("remaining")) {
           sortField = FIELD_REMAINING;
         } else if (field.equals("pcused")) {
           sortField = FIELD_PERCENT_USED;
         } else if (field.equals("pcremaining")) {
           sortField = FIELD_PERCENT_REMAINING;
         } else if (field.equals("blocks")) {
           sortField = FIELD_BLOCKS;
         } else {
           sortField = FIELD_NAME;
         }

         if (order.equals("DSC")) {
           sortOrder = SORT_ORDER_DSC;
         } else {
           sortOrder = SORT_ORDER_ASC;
         }
       }

       public int compare(DatanodeDescriptor d1,
                          DatanodeDescriptor d2) {
         int ret = 0;
         switch (sortField) {
         case FIELD_LAST_CONTACT:
           ret = (int) (d2.getLastUpdate() - d1.getLastUpdate());
           break;
         case FIELD_CAPACITY:
           long  dlong = d1.getCapacity() - d2.getCapacity();
           ret = (dlong < 0) ? -1 : ((dlong > 0) ? 1 : 0);
           break;
         case FIELD_USED:
           dlong = d1.getDfsUsed() - d2.getDfsUsed();
           ret = (dlong < 0) ? -1 : ((dlong > 0) ? 1 : 0);
           break;
         case FIELD_NONDFS_USED:
           dlong = d1.getNonDfsUsed() - d2.getNonDfsUsed();
           ret = (dlong < 0) ? -1 : ((dlong > 0) ? 1 : 0);
           break;
         case FIELD_REMAINING:
           dlong = d1.getRemaining() - d2.getRemaining();
           ret = (dlong < 0) ? -1 : ((dlong > 0) ? 1 : 0);
           break;
         case FIELD_PERCENT_USED:
           double ddbl =((d1.getDfsUsedPercent())-
                         (d2.getDfsUsedPercent()));
           ret = (ddbl < 0) ? -1 : ((ddbl > 0) ? 1 : 0);
           break;
         case FIELD_PERCENT_REMAINING:
           ddbl =((d1.getRemainingPercent())-
                  (d2.getRemainingPercent()));
           ret = (ddbl < 0) ? -1 : ((ddbl > 0) ? 1 : 0);
           break;
         case FIELD_BLOCKS:
           ret = d1.numBlocks() - d2.numBlocks();
           break;
         case FIELD_NAME:
           ret = d1.getHostName().compareTo(d2.getHostName());
           break;
         }
         return (sortOrder == SORT_ORDER_DSC) ? -ret : ret;
       }
     }

     Collections.sort(nodes, new NodeComapare(field, order));
   }

   public static void printPathWithLinks(String dir, JspWriter out,
                                         int namenodeInfoPort,
                                         String tokenString
                                         ) throws IOException {
     try {
       String[] parts = dir.split(Path.SEPARATOR);
       StringBuilder tempPath = new StringBuilder(dir.length());
       out.print("<a href=\"browseDirectory.jsp" + "?dir="+ Path.SEPARATOR
           + "&namenodeInfoPort=" + namenodeInfoPort
           + "\">" + Path.SEPARATOR + "</a>");
       tempPath.append(Path.SEPARATOR);
       for (int i = 0; i < parts.length-1; i++) {
         if (!parts[i].equals("")) {
           tempPath.append(parts[i]);
           out.print("<a href=\"browseDirectory.jsp" + "?dir="
               + tempPath.toString() + "&namenodeInfoPort=" + namenodeInfoPort
               + SET_DELEGATION + tokenString);
           out.print("\">" + parts[i] + "</a>" + Path.SEPARATOR);
           tempPath.append(Path.SEPARATOR);
         }
       }
       if(parts.length > 0) {
         out.print(parts[parts.length-1]);
       }
     }
     catch (UnsupportedEncodingException ex) {
       ex.printStackTrace();
     }
   }

   public static void printGotoForm(JspWriter out,
                                    int namenodeInfoPort,
                                    String tokenString,
                                    String file) throws IOException {
     out.print("<form action=\"browseDirectory.jsp\" method=\"get\" name=\"goto\">");
     out.print("Goto : ");
     out.print("<input name=\"dir\" type=\"text\" width=\"50\" id\"dir\" value=\""+ file+"\">");
     out.print("<input name=\"go\" type=\"submit\" value=\"go\">");
     out.print("<input name=\"namenodeInfoPort\" type=\"hidden\" "
         + "value=\"" + namenodeInfoPort  + "\">");
     out.print("<input name=\"" + DELEGATION_PARAMETER_NAME +
               "\" type=\"hidden\" value=\"" + tokenString + "\">");
     out.print("</form>");
   }

   public static void createTitle(JspWriter out,
                                  HttpServletRequest req,
                                  String  file) throws IOException{
     if(file == null) file = "";
     int start = Math.max(0,file.length() - 100);
     if(start != 0)
       file = "..." + file.substring(start, file.length());
     out.print("<title>HDFS:" + file + "</title>");
   }

   /** Convert a String to chunk-size-to-view. */
   public static int string2ChunkSizeToView(String s, int defaultValue) {
     int n = s == null? 0: Integer.parseInt(s);
     return n > 0? n: defaultValue;
   }

   /** Return a table containing version information. */
   public static String getVersionTable() {
     return "<div id='dfstable'><table>"
         + "\n  <tr><td id='col1'>Version:</td><td>" + VersionInfo.getVersion() + ", " + VersionInfo.getRevision()
         + "\n  <tr><td id='col1'>Compiled:</td><td>" + VersionInfo.getDate() + " by " + VersionInfo.getUser() + " from " + VersionInfo.getBranch()
         + "\n</table></div>";
   }

   /**
    * Validate filename.
    * @return null if the filename is invalid.
    *         Otherwise, return the validated filename.
    */
   public static String validatePath(String p) {
     return p == null || p.length() == 0?
         null: new Path(p).toUri().getPath();
   }

   /**
    * Validate a long value.
    * @return null if the value is invalid.
    *         Otherwise, return the validated Long object.
    */
   public static Long validateLong(String value) {
     return value == null? null: Long.parseLong(value);
   }

   /**
    * Validate a URL.
    * @return null if the value is invalid.
    *         Otherwise, return the validated URL String.
    */
   public static String validateURL(String value) {
     try {
       return URLEncoder.encode(new URL(value).toString(), "UTF-8");
     } catch (IOException e) {
       return null;
     }
   }

   /**
    * If security is turned off, what is the default web user?
    * @param conf the configuration to look in
    * @return the remote user that was configuration
    */
   public static UserGroupInformation getDefaultWebUser(Configuration conf
                                                        ) throws IOException {
     String[] strings = conf.getStrings(JspHelper.WEB_UGI_PROPERTY_NAME);
     if (strings == null || strings.length == 0) {
       throw new IOException("Cannot determine UGI from request or conf");
     }
     return UserGroupInformation.createRemoteUser(strings[0]);
   }

   /**
    * Get {@link UserGroupInformation} and possibly the delegation token out of
    * the request.
    * @param request the http request
    * @return a new user from the request
    * @throws AccessControlException if the request has no token
    */
   public static UserGroupInformation getUGI(HttpServletRequest request,
                                             Configuration conf
                                            ) throws IOException {
     UserGroupInformation ugi = null;
     if(UserGroupInformation.isSecurityEnabled()) {
       String user = request.getRemoteUser();
       String tokenString = request.getParameter(DELEGATION_PARAMETER_NAME);
       if (tokenString != null) {
         Token<DelegationTokenIdentifier> token =
           new Token<DelegationTokenIdentifier>();
         token.decodeFromUrlString(tokenString);
         ugi = UserGroupInformation.createRemoteUser(user);
         ugi.addToken(token);
         ugi.setAuthenticationMethod(AuthenticationMethod.TOKEN);
       } else {
         if(user == null) {
           throw new IOException("Security enabled but user not " +
                                 "authenticated by filter");
         }
         ugi = UserGroupInformation.createRemoteUser(user);
         ugi.setAuthenticationMethod(AuthenticationMethod.KERBEROS_SSL);
       }
     } else { // Security's not on, pull from url
       String user = request.getParameter("ugi");

       if(user == null) { // not specified in request
         ugi = getDefaultWebUser(conf);
       } else {
         ugi = UserGroupInformation.createRemoteUser(user);
       }
       ugi.setAuthenticationMethod(AuthenticationMethod.SIMPLE);
     }

     if(LOG.isDebugEnabled())
       LOG.debug("getUGI is returning: " + ugi.getShortUserName());
     return ugi;
   }


 }
	/**
	* 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.hdfs.server.common;

	import java.io.IOException;
	import java.io.UnsupportedEncodingException;
	import java.net.InetSocketAddress;
	import java.net.Socket;
	import java.net.URL;
	import java.net.URLEncoder;
	import java.util.ArrayList;
	import java.util.Collections;
	import java.util.Comparator;
	import java.util.Random;
	import java.util.TreeSet;

	import javax.servlet.http.HttpServletRequest;
	import javax.servlet.jsp.JspWriter;

	import org.apache.commons.logging.Log;
	import org.apache.commons.logging.LogFactory;
	import org.apache.hadoop.classification.InterfaceAudience;
	import org.apache.hadoop.conf.Configuration;
	import org.apache.hadoop.fs.Path;
	import org.apache.hadoop.hdfs.BlockReader;
	import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
	import org.apache.hadoop.hdfs.protocol.LocatedBlock;
	import org.apache.hadoop.hdfs.security.BlockAccessToken;
	import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
	import org.apache.hadoop.hdfs.server.datanode.DatanodeJspHelper;
	import org.apache.hadoop.hdfs.server.namenode.DatanodeDescriptor;
	import org.apache.hadoop.http.HtmlQuoting;
	import org.apache.hadoop.io.WritableUtils;
	import org.apache.hadoop.net.NetUtils;
	import org.apache.hadoop.security.AccessControlException;
	import org.apache.hadoop.security.UserGroupInformation;
	import org.apache.hadoop.security.UserGroupInformation.AuthenticationMethod;
	import org.apache.hadoop.security.token.Token;
	import org.apache.hadoop.util.VersionInfo;

	@InterfaceAudience.Private
	public class JspHelper {
	final static public String WEB_UGI_PROPERTY_NAME = "dfs.web.ugi";
	public static final String DELEGATION_PARAMETER_NAME = "delegation";
	public static final String SET_DELEGATION = "&" + DELEGATION_PARAMETER_NAME +
	"=";
	private static final Log LOG = LogFactory.getLog(JspHelper.class);

	static final Random rand = new Random();

	/** Private constructor for preventing creating JspHelper object. */
	private JspHelper() {}

	public static DatanodeInfo bestNode(LocatedBlock blk) throws IOException {
	TreeSet<DatanodeInfo> deadNodes = new TreeSet<DatanodeInfo>();
	DatanodeInfo chosenNode = null;
	int failures = 0;
	Socket s = null;
	DatanodeInfo [] nodes = blk.getLocations();
	if (nodes == null \|\| nodes.length == 0) {
	throw new IOException("No nodes contain this block");
	}
	while (s == null) {
	if (chosenNode == null) {
	do {
	chosenNode = nodes[rand.nextInt(nodes.length)];
	} while (deadNodes.contains(chosenNode));
	}
	int index = rand.nextInt(nodes.length);
	chosenNode = nodes[index];

	//just ping to check whether the node is alive
	InetSocketAddress targetAddr = NetUtils.createSocketAddr(
	chosenNode.getHost() + ":" + chosenNode.getInfoPort());

	try {
	s = new Socket();
	s.connect(targetAddr, HdfsConstants.READ_TIMEOUT);
	s.setSoTimeout(HdfsConstants.READ_TIMEOUT);
	} catch (IOException e) {
	deadNodes.add(chosenNode);
	s.close();
	s = null;
	failures++;
	}
	if (failures == nodes.length)
	throw new IOException("Could not reach the block containing the data. Please try again");

	}
	s.close();
	return chosenNode;
	}

	public static void streamBlockInAscii(InetSocketAddress addr, long blockId,
	BlockAccessToken accessToken, long genStamp,
	long blockSize,
	long offsetIntoBlock, long chunkSizeToView,
	JspWriter out,
	Configuration conf)
	throws IOException {
	if (chunkSizeToView == 0) return;
	Socket s = new Socket();
	s.connect(addr, HdfsConstants.READ_TIMEOUT);
	s.setSoTimeout(HdfsConstants.READ_TIMEOUT);

	long amtToRead = Math.min(chunkSizeToView, blockSize - offsetIntoBlock);

	// Use the block name for file name.
	BlockReader blockReader =
	BlockReader.newBlockReader(s, addr.toString() + ":" + blockId,
	blockId, accessToken, genStamp ,offsetIntoBlock,
	amtToRead,
	conf.getInt("io.file.buffer.size",
	4096));

	byte[] buf = new byte[(int)amtToRead];
	int readOffset = 0;
	int retries = 2;
	while ( amtToRead > 0 ) {
	int numRead;
	try {
	numRead = blockReader.readAll(buf, readOffset, (int)amtToRead);
	}
	catch (IOException e) {
	retries--;
	if (retries == 0)
	throw new IOException("Could not read data from datanode");
	continue;
	}
	amtToRead -= numRead;
	readOffset += numRead;
	}
	blockReader = null;
	s.close();
	out.print(HtmlQuoting.quoteHtmlChars(new String(buf)));
	}

	public static void addTableHeader(JspWriter out) throws IOException {
	out.print("<table border=\"1\""+
	" cellpadding=\"2\" cellspacing=\"2\">");
	out.print("<tbody>");
	}
	public static void addTableRow(JspWriter out, String[] columns) throws IOException {
	out.print("<tr>");
	for (int i = 0; i < columns.length; i++) {
	out.print("<td style=\"vertical-align: top;\"><B>"+columns[i]+"</B><br></td>");
	}
	out.print("</tr>");
	}
	public static void addTableRow(JspWriter out, String[] columns, int row) throws IOException {
	out.print("<tr>");

	for (int i = 0; i < columns.length; i++) {
	if (row/2*2 == row) {//even
	out.print("<td style=\"vertical-align: top;background-color:LightGrey;\"><B>"+columns[i]+"</B><br></td>");
	} else {
	out.print("<td style=\"vertical-align: top;background-color:LightBlue;\"><B>"+columns[i]+"</B><br></td>");

	}
	}
	out.print("</tr>");
	}
	public static void addTableFooter(JspWriter out) throws IOException {
	out.print("</tbody></table>");
	}

	public static void sortNodeList(ArrayList<DatanodeDescriptor> nodes,
	String field, String order) {

	class NodeComapare implements Comparator<DatanodeDescriptor> {
	static final int
	FIELD_NAME = 1,
	FIELD_LAST_CONTACT = 2,
	FIELD_BLOCKS = 3,
	FIELD_CAPACITY = 4,
	FIELD_USED = 5,
	FIELD_PERCENT_USED = 6,
	FIELD_NONDFS_USED = 7,
	FIELD_REMAINING = 8,
	FIELD_PERCENT_REMAINING = 9,
	SORT_ORDER_ASC = 1,
	SORT_ORDER_DSC = 2;

	int sortField = FIELD_NAME;
	int sortOrder = SORT_ORDER_ASC;

	public NodeComapare(String field, String order) {
	if (field.equals("lastcontact")) {
	sortField = FIELD_LAST_CONTACT;
	} else if (field.equals("capacity")) {
	sortField = FIELD_CAPACITY;
	} else if (field.equals("used")) {
	sortField = FIELD_USED;
	} else if (field.equals("nondfsused")) {
	sortField = FIELD_NONDFS_USED;
	} else if (field.equals("remaining")) {
	sortField = FIELD_REMAINING;
	} else if (field.equals("pcused")) {
	sortField = FIELD_PERCENT_USED;
	} else if (field.equals("pcremaining")) {
	sortField = FIELD_PERCENT_REMAINING;
	} else if (field.equals("blocks")) {
	sortField = FIELD_BLOCKS;
	} else {
	sortField = FIELD_NAME;
	}

	if (order.equals("DSC")) {
	sortOrder = SORT_ORDER_DSC;
	} else {
	sortOrder = SORT_ORDER_ASC;
	}
	}

	public int compare(DatanodeDescriptor d1,
	DatanodeDescriptor d2) {
	int ret = 0;
	switch (sortField) {
	case FIELD_LAST_CONTACT:
	ret = (int) (d2.getLastUpdate() - d1.getLastUpdate());
	break;
	case FIELD_CAPACITY:
	long dlong = d1.getCapacity() - d2.getCapacity();
	ret = (dlong < 0) ? -1 : ((dlong > 0) ? 1 : 0);
	break;
	case FIELD_USED:
	dlong = d1.getDfsUsed() - d2.getDfsUsed();
	ret = (dlong < 0) ? -1 : ((dlong > 0) ? 1 : 0);
	break;
	case FIELD_NONDFS_USED:
	dlong = d1.getNonDfsUsed() - d2.getNonDfsUsed();
	ret = (dlong < 0) ? -1 : ((dlong > 0) ? 1 : 0);
	break;
	case FIELD_REMAINING:
	dlong = d1.getRemaining() - d2.getRemaining();
	ret = (dlong < 0) ? -1 : ((dlong > 0) ? 1 : 0);
	break;
	case FIELD_PERCENT_USED:
	double ddbl =((d1.getDfsUsedPercent())-
	(d2.getDfsUsedPercent()));
	ret = (ddbl < 0) ? -1 : ((ddbl > 0) ? 1 : 0);
	break;
	case FIELD_PERCENT_REMAINING:
	ddbl =((d1.getRemainingPercent())-
	(d2.getRemainingPercent()));
	ret = (ddbl < 0) ? -1 : ((ddbl > 0) ? 1 : 0);
	break;
	case FIELD_BLOCKS:
	ret = d1.numBlocks() - d2.numBlocks();
	break;
	case FIELD_NAME:
	ret = d1.getHostName().compareTo(d2.getHostName());
	break;
	}
	return (sortOrder == SORT_ORDER_DSC) ? -ret : ret;
	}
	}

	Collections.sort(nodes, new NodeComapare(field, order));
	}

	public static void printPathWithLinks(String dir, JspWriter out,
	int namenodeInfoPort,
	String tokenString
	) throws IOException {
	try {
	String[] parts = dir.split(Path.SEPARATOR);
	StringBuilder tempPath = new StringBuilder(dir.length());
	out.print("<a href=\"browseDirectory.jsp" + "?dir="+ Path.SEPARATOR
	+ "&namenodeInfoPort=" + namenodeInfoPort
	+ "\">" + Path.SEPARATOR + "</a>");
	tempPath.append(Path.SEPARATOR);
	for (int i = 0; i < parts.length-1; i++) {
	if (!parts[i].equals("")) {
	tempPath.append(parts[i]);
	out.print("<a href=\"browseDirectory.jsp" + "?dir="
	+ tempPath.toString() + "&namenodeInfoPort=" + namenodeInfoPort
	+ SET_DELEGATION + tokenString);
	out.print("\">" + parts[i] + "</a>" + Path.SEPARATOR);
	tempPath.append(Path.SEPARATOR);
	}
	}
	if(parts.length > 0) {
	out.print(parts[parts.length-1]);
	}
	}
	catch (UnsupportedEncodingException ex) {
	ex.printStackTrace();
	}
	}

	public static void printGotoForm(JspWriter out,
	int namenodeInfoPort,
	String tokenString,
	String file) throws IOException {
	out.print("<form action=\"browseDirectory.jsp\" method=\"get\" name=\"goto\">");
	out.print("Goto : ");
	out.print("<input name=\"dir\" type=\"text\" width=\"50\" id\"dir\" value=\""+ file+"\">");
	out.print("<input name=\"go\" type=\"submit\" value=\"go\">");
	out.print("<input name=\"namenodeInfoPort\" type=\"hidden\" "
	+ "value=\"" + namenodeInfoPort + "\">");
	out.print("<input name=\"" + DELEGATION_PARAMETER_NAME +
	"\" type=\"hidden\" value=\"" + tokenString + "\">");
	out.print("</form>");
	}

	public static void createTitle(JspWriter out,
	HttpServletRequest req,
	String file) throws IOException{
	if(file == null) file = "";
	int start = Math.max(0,file.length() - 100);
	if(start != 0)
	file = "..." + file.substring(start, file.length());
	out.print("<title>HDFS:" + file + "</title>");
	}

	/** Convert a String to chunk-size-to-view. */
	public static int string2ChunkSizeToView(String s, int defaultValue) {
	int n = s == null? 0: Integer.parseInt(s);
	return n > 0? n: defaultValue;
	}

	/** Return a table containing version information. */
	public static String getVersionTable() {
	return "<div id='dfstable'><table>"
	+ "\n <tr><td id='col1'>Version:</td><td>" + VersionInfo.getVersion() + ", " + VersionInfo.getRevision()
	+ "\n <tr><td id='col1'>Compiled:</td><td>" + VersionInfo.getDate() + " by " + VersionInfo.getUser() + " from " + VersionInfo.getBranch()
	+ "\n</table></div>";
	}

	/**
	* Validate filename.
	* @return null if the filename is invalid.
	* Otherwise, return the validated filename.
	*/
	public static String validatePath(String p) {
	return p == null \|\| p.length() == 0?
	null: new Path(p).toUri().getPath();
	}

	/**
	* Validate a long value.
	* @return null if the value is invalid.
	* Otherwise, return the validated Long object.
	*/
	public static Long validateLong(String value) {
	return value == null? null: Long.parseLong(value);
	}

	/**
	* Validate a URL.
	* @return null if the value is invalid.
	* Otherwise, return the validated URL String.
	*/
	public static String validateURL(String value) {
	try {
	return URLEncoder.encode(new URL(value).toString(), "UTF-8");
	} catch (IOException e) {
	return null;
	}
	}

	/**
	* If security is turned off, what is the default web user?
	* @param conf the configuration to look in
	* @return the remote user that was configuration
	*/
	public static UserGroupInformation getDefaultWebUser(Configuration conf
	) throws IOException {
	String[] strings = conf.getStrings(JspHelper.WEB_UGI_PROPERTY_NAME);
	if (strings == null \|\| strings.length == 0) {
	throw new IOException("Cannot determine UGI from request or conf");
	}
	return UserGroupInformation.createRemoteUser(strings[0]);
	}

	/**
	* Get {@link UserGroupInformation} and possibly the delegation token out of
	* the request.
	* @param request the http request
	* @return a new user from the request
	* @throws AccessControlException if the request has no token
	*/
	public static UserGroupInformation getUGI(HttpServletRequest request,
	Configuration conf
	) throws IOException {
	UserGroupInformation ugi = null;
	if(UserGroupInformation.isSecurityEnabled()) {
	String user = request.getRemoteUser();
	String tokenString = request.getParameter(DELEGATION_PARAMETER_NAME);
	if (tokenString != null) {
	Token<DelegationTokenIdentifier> token =
	new Token<DelegationTokenIdentifier>();
	token.decodeFromUrlString(tokenString);
	ugi = UserGroupInformation.createRemoteUser(user);
	ugi.addToken(token);
	ugi.setAuthenticationMethod(AuthenticationMethod.TOKEN);
	} else {
	if(user == null) {
	throw new IOException("Security enabled but user not " +
	"authenticated by filter");
	}
	ugi = UserGroupInformation.createRemoteUser(user);
	ugi.setAuthenticationMethod(AuthenticationMethod.KERBEROS_SSL);
	}
	} else { // Security's not on, pull from url
	String user = request.getParameter("ugi");

	if(user == null) { // not specified in request
	ugi = getDefaultWebUser(conf);
	} else {
	ugi = UserGroupInformation.createRemoteUser(user);
	}
	ugi.setAuthenticationMethod(AuthenticationMethod.SIMPLE);
	}

	if(LOG.isDebugEnabled())
	LOG.debug("getUGI is returning: " + ugi.getShortUserName());
	return ugi;
	}


	}