/**
* 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.namenode;
import java.util.*;
import java.io.*;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.hadoop.hdfs.protocol.AvatarConstants.Avatar;
import org.apache.hadoop.hdfs.protocol.DatanodeID;
import org.apache.hadoop.hdfs.server.namenode.AvatarNode;
import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
import org.apache.hadoop.hdfs.server.namenode.StandbySafeMode;
import org.apache.hadoop.util.StringUtils;
public class OutStandingDatanodesServlet extends HttpServlet {
private static String standbyNull = "<br> <a class= \"warning\" " +
"name=\"NotStandbyNull\" id=\"title\"> This is the Standby Avatar, " +
"but safe mode information is null. This could happen because we have " +
"just left safemode during failover </a><br><br>\n";
private static String notStandby = "<br> <a class= \"warning\" " +
"name=\"NotStandby\" id=\"title\"> This is not the Standby Avatar " +
"</a><br><br>\n";
@SuppressWarnings("unchecked")
public void doGet(HttpServletRequest request,
HttpServletResponse response
) throws ServletException, IOException {
ServletContext context = getServletContext();
AvatarNode nn = (AvatarNode)context.getAttribute("avatar.node");
FSNamesystem fsn = nn.getNamesystem();
boolean isStandby = false;
boolean isFailover = false;
Set <DatanodeID> heartbeats = null;
Set <DatanodeID> reports = null;
String msg = null;
fsn.writeLock();
// We need to capture all information under a namesystem lock, since we
// might leave safemode and the safemode object might be set to null.
try {
isStandby = (nn.reportAvatar() == Avatar.STANDBY);
StandbySafeMode sm = nn.getStandbySafeMode();
if (sm == null && isStandby) {
msg = standbyNull;
} else if (sm == null) {
msg = notStandby;
} else {
isFailover = sm.failoverInProgress();
heartbeats = sm.getOutStandingHeartbeats();
reports = sm.getOutStandingReports();
}
} finally {
fsn.writeUnlock();
}
// We print the information separately so that we can release the namesystem
// lock quickly.
PrintWriter out = null;
try {
out = response.getWriter();
if (msg != null) {
out.print(msg);
return;
}
if (!isStandby) {
out.print(notStandby);
return;
} else if (!isFailover) {
out.print("<br> <a class = \"warning\" name=\"NotStandbyFailover\"" +
" id=\"title\"> The Standby Avatar is not in failover mode" +
" </a><br><br>\n");
return;
}
out.print("<br> <a name=\"OutStandingHeartbeats\" id=\"title\"> " +
" Following datanodes have outstanding heartbeats : </a><br><br>\n");
for (DatanodeID node : heartbeats) {
out.print("<br>" + node.getName() + "<br>");
}
out.print("<br> <a name=\"OutStandingReports\" id=\"title\"> " +
" Following datanodes have outstanding reports : </a><br><br>\n");
for (DatanodeID node : reports) {
out.print("<br>" + node.getName() + "<br>");
}
} finally {
if (out != null) {
out.close();
}
}
}
}