/**
* 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 org.apache.commons.logging.*;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.hdfs.DFSUtil;
import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocol;
import org.apache.hadoop.hdfs.server.common.HdfsConstants;
import org.apache.hadoop.hdfs.server.common.InconsistentFSStateException;
import org.apache.hadoop.ipc.*;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.util.StringUtils;
import org.apache.hadoop.util.Daemon;
import org.apache.hadoop.http.HttpServer;
import org.apache.hadoop.net.NetUtils;
import java.io.*;
import java.net.*;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import org.apache.hadoop.metrics.jvm.JvmMetrics;
/**********************************************************
* The Secondary NameNode is a helper to the primary NameNode.
* The Secondary is responsible for supporting periodic checkpoints
* of the HDFS metadata. The current design allows only one Secondary
* NameNode per HDFs cluster.
*
* The Secondary NameNode is a daemon that periodically wakes
* up (determined by the schedule specified in the configuration),
* triggers a periodic checkpoint and then goes back to sleep.
* The Secondary NameNode uses the ClientProtocol to talk to the
* primary NameNode.
*
**********************************************************/
public class SecondaryNameNode implements Runnable {
public static final Log LOG =
LogFactory.getLog(SecondaryNameNode.class.getName());
private String fsName;
private CheckpointStorage checkpointImage;
private FSNamesystem namesystem;
private NamenodeProtocol namenode;
private Configuration conf;
private InetSocketAddress nameNodeAddr;
private volatile boolean shouldRun;
private HttpServer infoServer;
private int infoPort;
private String infoBindAddress;
private Collection<File> checkpointDirs;
private Collection<File> checkpointEditsDirs;
private long checkpointPeriod; // in seconds
private long checkpointSize; // size (in MB) of current Edit Log
/**
* Utility class to facilitate junit test error simulation.
*/
static class ErrorSimulator {
private static boolean[] simulation = null; // error simulation events
static void initializeErrorSimulationEvent(int numberOfEvents) {
simulation = new boolean[numberOfEvents];
for (int i = 0; i < numberOfEvents; i++) {
simulation[i] = false;
}
}
static boolean getErrorSimulation(int index) {
if(simulation == null)
return false;
assert(index < simulation.length);
return simulation[index];
}
static void setErrorSimulation(int index) {
assert(index < simulation.length);
simulation[index] = true;
}
static void clearErrorSimulation(int index) {
assert(index < simulation.length);
simulation[index] = false;
}
}
FSImage getFSImage() {
return checkpointImage;
}
/**
* Create a connection to the primary namenode.
*/
public SecondaryNameNode(Configuration conf) throws IOException {
try {
initialize(conf);
} catch(IOException e) {
shutdown();
throw e;
}
}
/**
* Initialize SecondaryNameNode.
*/
private void initialize(Configuration conf) throws IOException {
// initiate Java VM metrics
JvmMetrics.init("SecondaryNameNode", conf.get("session.id"));
// Create connection to the namenode.
shouldRun = true;
nameNodeAddr = NameNode.getAddress(conf);
this.conf = conf;
this.namenode =
(NamenodeProtocol) RPC.waitForProxy(NamenodeProtocol.class,
NamenodeProtocol.versionID, nameNodeAddr, conf);
// initialize checkpoint directories
fsName = getInfoServer();
checkpointDirs = FSImage.getCheckpointDirs(conf,
"/tmp/hadoop/dfs/namesecondary");
checkpointEditsDirs = FSImage.getCheckpointEditsDirs(conf,
"/tmp/hadoop/dfs/namesecondary");
checkpointImage = new CheckpointStorage(conf);
checkpointImage.recoverCreate(checkpointDirs, checkpointEditsDirs);
// Initialize other scheduling parameters from the configuration
checkpointPeriod = conf.getLong("fs.checkpoint.period", 3600);
checkpointSize = conf.getLong("fs.checkpoint.size", 4194304);
// initialize the webserver for uploading files.
String infoAddr =
NetUtils.getServerAddress(conf,
"dfs.secondary.info.bindAddress",
"dfs.secondary.info.port",
"dfs.secondary.http.address");
InetSocketAddress infoSocAddr = NetUtils.createSocketAddr(infoAddr);
infoBindAddress = infoSocAddr.getHostName();
int tmpInfoPort = infoSocAddr.getPort();
infoServer = new HttpServer("secondary", infoBindAddress, tmpInfoPort,
tmpInfoPort == 0, conf);
infoServer.setAttribute("name.system.image", checkpointImage);
this.infoServer.setAttribute("name.conf", conf);
infoServer.addInternalServlet("getimage", "/getimage", GetImageServlet.class);
infoServer.start();
// The web-server port can be ephemeral... ensure we have the correct info
infoPort = infoServer.getPort();
conf.set("dfs.secondary.http.address", infoBindAddress + ":" +infoPort);
LOG.info("Secondary Web-server up at: " + infoBindAddress + ":" +infoPort);
LOG.warn("Checkpoint Period :" + checkpointPeriod + " secs " +
"(" + checkpointPeriod/60 + " min)");
LOG.warn("Log Size Trigger :" + checkpointSize + " bytes " +
"(" + checkpointSize/1024 + " KB)");
}
/**
* Shut down this instance of the datanode.
* Returns only after shutdown is complete.
*/
public void shutdown() {
shouldRun = false;
try {
if (infoServer != null) infoServer.stop();
} catch (Exception e) {
LOG.warn("Exception shutting down SecondaryNameNode", e);
}
try {
if (checkpointImage != null) checkpointImage.close();
} catch(IOException e) {
LOG.warn(StringUtils.stringifyException(e));
}
}
//
// The main work loop
//
public void run() {
//
// Poll the Namenode (once every 5 minutes) to find the size of the
// pending edit log.
//
long period = 5 * 60; // 5 minutes
long lastCheckpointTime = 0;
if (checkpointPeriod < period) {
period = checkpointPeriod;
}
while (shouldRun) {
try {
Thread.sleep(1000 * period);
} catch (InterruptedException ie) {
// do nothing
}
if (!shouldRun) {
break;
}
try {
long now = System.currentTimeMillis();
long size = namenode.getEditLogSize();
if (size >= checkpointSize ||
now >= lastCheckpointTime + 1000 * checkpointPeriod) {
doCheckpoint();
lastCheckpointTime = now;
}
} catch (IOException e) {
LOG.error("Exception in doCheckpoint: ");
LOG.error(StringUtils.stringifyException(e));
e.printStackTrace();
checkpointImage.imageDigest = null;
} catch (Throwable e) {
LOG.error("Throwable Exception in doCheckpoint: ");
LOG.error(StringUtils.stringifyException(e));
e.printStackTrace();
Runtime.getRuntime().exit(-1);
}
}
}
/**
* Download <code>fsimage</code> and <code>edits</code>
* files from the name-node.
* @return true if a new image has been downloaded and needs to be loaded
* @throws IOException
*/
private boolean downloadCheckpointFiles(CheckpointSignature sig
) throws IOException {
checkpointImage.cTime = sig.cTime;
checkpointImage.checkpointTime = sig.checkpointTime;
boolean downloadImage = true;
String fileid;
File[] srcNames;
if (sig.imageDigest.equals(checkpointImage.imageDigest)) {
downloadImage = false;
LOG.info("Image has not changed. Will not download image.");
} else {
// get fsimage
srcNames = checkpointImage.getImageFiles();
assert srcNames.length > 0 : "No checkpoint targets.";
fileid = "getimage=1";
TransferFsImage.getFileClient(fsName, fileid, srcNames, false);
checkpointImage.imageDigest = sig.imageDigest;
LOG.info("Downloaded file " + srcNames[0].getName() + " size " +
srcNames[0].length() + " bytes.");
}
// get edits file
fileid = "getedit=1";
srcNames = checkpointImage.getEditsFiles();
assert srcNames.length > 0 : "No checkpoint targets.";
TransferFsImage.getFileClient(fsName, fileid, srcNames, false);
LOG.info("Downloaded file " + srcNames[0].getName() + " size " +
srcNames[0].length() + " bytes.");
checkpointImage.checkpointUploadDone(null);
return downloadImage;
}
/**
* Copy the new fsimage into the NameNode
*/
private void putFSImage(CheckpointSignature sig) throws IOException {
String fileid = "putimage=1&port=" + infoPort +
"&machine=" +
InetAddress.getLocalHost().getHostAddress() +
"&token=" + sig.toString();
LOG.info("Posted URL " + fsName + fileid);
TransferFsImage.getFileClient(fsName, fileid, (File[])null, false);
}
/**
* Returns the Jetty server that the Namenode is listening on.
*/
private String getInfoServer() throws IOException {
URI fsName = FileSystem.getDefaultUri(conf);
if (!"hdfs".equals(fsName.getScheme())) {
throw new IOException("This is not a DFS");
}
return NetUtils.getServerAddress(conf, "dfs.info.bindAddress",
"dfs.info.port", "dfs.http.address");
}
/**
* Create a new checkpoint
*/
void doCheckpoint() throws IOException {
LOG.info("Checkpoint starting");
// Do the required initialization of the merge work area.
startCheckpoint();
// Tell the namenode to start logging transactions in a new edit file
// Returns a token that would be used to upload the merged image.
CheckpointSignature sig = (CheckpointSignature)namenode.rollEditLog();
// error simulation code for junit test
if (ErrorSimulator.getErrorSimulation(0)) {
throw new IOException("Simulating error0 " +
"after creating edits.new");
}
boolean loadImage = downloadCheckpointFiles(sig); // Fetch fsimage and edits
doMerge(sig, loadImage); // Do the merge
//
// Upload the new image into the NameNode. Then tell the Namenode
// to make this new uploaded image as the most current image.
//
putFSImage(sig);
// error simulation code for junit test
if (ErrorSimulator.getErrorSimulation(1)) {
throw new IOException("Simulating error1 " +
"after uploading new image to NameNode");
}
namenode.rollFsImage(new CheckpointSignature(checkpointImage));
checkpointImage.endCheckpoint();
LOG.info("Checkpoint done. New Image Size: "
+ checkpointImage.getFsImageName().length());
}
private void startCheckpoint() throws IOException {
checkpointImage.unlockAll();
checkpointImage.getEditLog().close();
checkpointImage.recoverCreate(checkpointDirs, checkpointEditsDirs);
checkpointImage.startCheckpoint();
}
/**
* Merge downloaded image and edits and write the new image into
* current storage directory.
*/
private void doMerge(CheckpointSignature sig, boolean loadImage) throws IOException {
if (loadImage) { // create an empty namespace if new image
namesystem = new FSNamesystem(checkpointImage, conf);
}
assert namesystem.dir.fsImage == checkpointImage;
checkpointImage.doMerge(sig, loadImage);
}
/**
* @param argv The parameters passed to this program.
* @exception Exception if the filesystem does not exist.
* @return 0 on success, non zero on error.
*/
private int processArgs(String[] argv) throws Exception {
if (argv.length < 1) {
printUsage("");
return -1;
}
int exitCode = -1;
int i = 0;
String cmd = argv[i++];
//
// verify that we have enough command line parameters
//
if ("-geteditsize".equals(cmd)) {
if (argv.length != 1) {
printUsage(cmd);
return exitCode;
}
} else if ("-checkpoint".equals(cmd)) {
if (argv.length != 1 && argv.length != 2) {
printUsage(cmd);
return exitCode;
}
if (argv.length == 2 && !"force".equals(argv[i])) {
printUsage(cmd);
return exitCode;
}
}
exitCode = 0;
try {
if ("-checkpoint".equals(cmd)) {
long size = namenode.getEditLogSize();
if (size >= checkpointSize ||
argv.length == 2 && "force".equals(argv[i])) {
doCheckpoint();
} else {
System.err.println("EditLog size " + size + " bytes is " +
"smaller than configured checkpoint " +
"size " + checkpointSize + " bytes.");
System.err.println("Skipping checkpoint.");
}
} else if ("-geteditsize".equals(cmd)) {
long size = namenode.getEditLogSize();
System.out.println("EditLog size is " + size + " bytes");
} else {
exitCode = -1;
LOG.error(cmd.substring(1) + ": Unknown command");
printUsage("");
}
} catch (RemoteException e) {
//
// This is a error returned by hadoop server. Print
// out the first line of the error mesage, ignore the stack trace.
exitCode = -1;
try {
String[] content;
content = e.getLocalizedMessage().split("\n");
LOG.error(cmd.substring(1) + ": "
+ content[0]);
} catch (Exception ex) {
LOG.error(cmd.substring(1) + ": "
+ ex.getLocalizedMessage());
}
} catch (IOException e) {
//
// IO exception encountered locally.
//
exitCode = -1;
LOG.error(cmd.substring(1) + ": "
+ e.getLocalizedMessage());
} finally {
// Does the RPC connection need to be closed?
}
return exitCode;
}
/**
* Displays format of commands.
* @param cmd The command that is being executed.
*/
private static void printUsage(String cmd) {
if ("-geteditsize".equals(cmd)) {
System.err.println("Usage: java SecondaryNameNode"
+ " [-geteditsize] [-service serviceName]");
} else if ("-checkpoint".equals(cmd)) {
System.err.println("Usage: java SecondaryNameNode"
+ " [-checkpoint [force]] [-service serviceName]");
} else {
System.err.println("Usage: java SecondaryNameNode " +
"[-checkpoint [force]] [-service serviceName]\n" +
"[-geteditsize] [-service serviceName]\n");
}
}
/**
* main() has some simple utility methods.
* @param argv Command line parameters.
* @exception Exception if the filesystem does not exist.
*/
public static void main(String[] argv) throws Exception {
StringUtils.startupShutdownMessage(SecondaryNameNode.class, argv, LOG);
Configuration tconf = new Configuration();
try {
argv = DFSUtil.setGenericConf(argv, tconf);
} catch (IllegalArgumentException e) {
System.err.println(e.getMessage());
printUsage("");
return;
}
if (argv.length >= 1) {
SecondaryNameNode secondary = new SecondaryNameNode(tconf);
int ret = secondary.processArgs(argv);
System.exit(ret);
}
// Create a never ending deamon
Daemon checkpointThread = new Daemon(new SecondaryNameNode(tconf));
checkpointThread.start();
}
static class CheckpointStorage extends FSImage {
/**
*/
CheckpointStorage(Configuration conf) throws IOException {
super(conf);
}
@Override
public
boolean isConversionNeeded(StorageDirectory sd) {
return false;
}
/**
* Analyze checkpoint directories.
* Create directories if they do not exist.
* Recover from an unsuccessful checkpoint is necessary.
*
* @param dataDirs
* @param editsDirs
* @throws IOException
*/
void recoverCreate(Collection<File> dataDirs,
Collection<File> editsDirs) throws IOException {
Collection<File> tempDataDirs = new ArrayList<File>(dataDirs);
Collection<File> tempEditsDirs = new ArrayList<File>(editsDirs);
this.storageDirs = new ArrayList<StorageDirectory>();
setStorageDirectories(tempDataDirs, tempEditsDirs);
for (Iterator<StorageDirectory> it =
dirIterator(); it.hasNext();) {
StorageDirectory sd = it.next();
boolean isAccessible = true;
try { // create directories if don't exist yet
if(!sd.getRoot().mkdirs()) {
// do nothing, directory is already created
}
} catch(SecurityException se) {
isAccessible = false;
}
if(!isAccessible)
throw new InconsistentFSStateException(sd.getRoot(),
"cannot access checkpoint directory.");
StorageState curState;
try {
curState = sd.analyzeStorage(HdfsConstants.StartupOption.REGULAR);
// sd is locked but not opened
switch(curState) {
case NON_EXISTENT:
// fail if any of the configured checkpoint dirs are inaccessible
throw new InconsistentFSStateException(sd.getRoot(),
"checkpoint directory does not exist or is not accessible.");
case NOT_FORMATTED:
break; // it's ok since initially there is no current and VERSION
case NORMAL:
break;
default: // recovery is possible
sd.doRecover(curState);
}
} catch (IOException ioe) {
sd.unlock();
throw ioe;
}
}
}
/**
* Prepare directories for a new checkpoint.
* <p>
* Rename <code>current</code> to <code>lastcheckpoint.tmp</code>
* and recreate <code>current</code>.
* @throws IOException
*/
void startCheckpoint() throws IOException {
for(StorageDirectory sd : storageDirs) {
moveCurrent(sd);
}
}
void endCheckpoint() throws IOException {
for(StorageDirectory sd : storageDirs) {
moveLastCheckpoint(sd);
}
}
/**
* Merge image and edits, and verify consistency with the signature.
*/
private void doMerge(CheckpointSignature sig, boolean loadImage) throws IOException {
getEditLog().open();
StorageDirectory sdName = null;
StorageDirectory sdEdits = null;
Iterator<StorageDirectory> it = null;
if (loadImage) {
it = dirIterator(NameNodeDirType.IMAGE);
if (it.hasNext())
sdName = it.next();
if (sdName == null)
throw new IOException("Could not locate checkpoint fsimage");
}
it = dirIterator(NameNodeDirType.EDITS);
if (it.hasNext())
sdEdits = it.next();
if (sdEdits == null)
throw new IOException("Could not locate checkpoint edits");
if (loadImage) {
loadFSImage(FSImage.getImageFile(sdName, NameNodeFile.IMAGE));
}
loadFSEdits(sdEdits);
sig.validateStorageInfo(this);
saveNamespace(false);
}
}
}