Java tutorial
/** * 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 static org.apache.hadoop.util.Time.monotonicNow; import java.net.HttpURLConnection; import java.security.PrivilegedExceptionAction; 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.DFSConfigKeys; import org.apache.hadoop.security.SecurityUtil; 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.hdfs.DFSUtil; import org.apache.hadoop.hdfs.HAUtil; import org.apache.hadoop.hdfs.server.common.JspHelper; import org.apache.hadoop.hdfs.server.common.Storage; import org.apache.hadoop.hdfs.server.common.StorageInfo; import org.apache.hadoop.hdfs.server.namenode.NNStorage.NameNodeFile; import org.apache.hadoop.hdfs.server.namenode.metrics.NameNodeMetrics; import org.apache.hadoop.hdfs.server.protocol.RemoteEditLog; import org.apache.hadoop.hdfs.util.DataTransferThrottler; import org.apache.hadoop.hdfs.util.MD5FileUtils; import org.apache.hadoop.http.HttpServer2; import org.apache.hadoop.io.IOUtils; import org.apache.hadoop.io.MD5Hash; import org.apache.hadoop.security.UserGroupInformation; import org.apache.hadoop.util.ServletUtil; import org.apache.hadoop.util.StringUtils; import com.google.common.annotations.VisibleForTesting; import com.google.common.base.Preconditions; /** * This class is used in Namesystem's jetty to retrieve/upload a file * Typically used by the Secondary NameNode to retrieve image and * edit file for periodic checkpointing in Non-HA deployments. * Standby NameNode uses to upload checkpoints in HA deployments. */ @InterfaceAudience.Private public class ImageServlet extends HttpServlet { public static final String PATH_SPEC = "/imagetransfer"; private static final long serialVersionUID = -7669068179452648952L; private static final Log LOG = LogFactory.getLog(ImageServlet.class); public final static String CONTENT_DISPOSITION = "Content-Disposition"; public final static String HADOOP_IMAGE_EDITS_HEADER = "X-Image-Edits-Name"; private static final String TXID_PARAM = "txid"; private static final String START_TXID_PARAM = "startTxId"; private static final String END_TXID_PARAM = "endTxId"; private static final String STORAGEINFO_PARAM = "storageInfo"; private static final String LATEST_FSIMAGE_VALUE = "latest"; private static final String IMAGE_FILE_TYPE = "imageFile"; @Override public void doGet(final HttpServletRequest request, final HttpServletResponse response) throws ServletException, IOException { try { final ServletContext context = getServletContext(); final FSImage nnImage = NameNodeHttpServer.getFsImageFromContext(context); final GetImageParams parsedParams = new GetImageParams(request, response); final Configuration conf = (Configuration) context.getAttribute(JspHelper.CURRENT_CONF); final NameNodeMetrics metrics = NameNode.getNameNodeMetrics(); validateRequest(context, conf, request, response, nnImage, parsedParams.getStorageInfoString()); UserGroupInformation.getCurrentUser().doAs(new PrivilegedExceptionAction<Void>() { @Override public Void run() throws Exception { if (parsedParams.isGetImage()) { long txid = parsedParams.getTxId(); File imageFile = null; String errorMessage = "Could not find image"; if (parsedParams.shouldFetchLatest()) { imageFile = nnImage.getStorage().getHighestFsImageName(); } else { errorMessage += " with txid " + txid; imageFile = nnImage.getStorage().getFsImage(txid, EnumSet.of(NameNodeFile.IMAGE, NameNodeFile.IMAGE_ROLLBACK)); } if (imageFile == null) { throw new IOException(errorMessage); } CheckpointFaultInjector.getInstance().beforeGetImageSetsHeaders(); long start = monotonicNow(); serveFile(imageFile); if (metrics != null) { // Metrics non-null only when used inside name node long elapsed = monotonicNow() - start; metrics.addGetImage(elapsed); } } else if (parsedParams.isGetEdit()) { long startTxId = parsedParams.getStartTxId(); long endTxId = parsedParams.getEndTxId(); File editFile = nnImage.getStorage().findFinalizedEditsFile(startTxId, endTxId); long start = monotonicNow(); serveFile(editFile); if (metrics != null) { // Metrics non-null only when used inside name node long elapsed = monotonicNow() - start; metrics.addGetEdit(elapsed); } } return null; } private void serveFile(File file) throws IOException { FileInputStream fis = new FileInputStream(file); try { setVerificationHeadersForGet(response, file); setFileNameHeaders(response, file); if (!file.exists()) { // Potential race where the file was deleted while we were in the // process of setting headers! throw new FileNotFoundException(file.toString()); // It's possible the file could be deleted after this point, but // we've already opened the 'fis' stream. // It's also possible length could change, but this would be // detected by the client side as an inaccurate length header. } // send file TransferFsImage.copyFileToStream(response.getOutputStream(), file, fis, getThrottler(conf)); } finally { IOUtils.closeStream(fis); } } }); } catch (Throwable t) { String errMsg = "GetImage failed. " + StringUtils.stringifyException(t); response.sendError(HttpServletResponse.SC_GONE, errMsg); throw new IOException(errMsg); } finally { response.getOutputStream().close(); } } private void validateRequest(ServletContext context, Configuration conf, HttpServletRequest request, HttpServletResponse response, FSImage nnImage, String theirStorageInfoString) throws IOException { if (UserGroupInformation.isSecurityEnabled() && !isValidRequestor(context, request.getUserPrincipal().getName(), conf)) { String errorMsg = "Only Namenode, Secondary Namenode, and administrators may access " + "this servlet"; response.sendError(HttpServletResponse.SC_FORBIDDEN, errorMsg); LOG.warn("Received non-NN/SNN/administrator request for image or edits from " + request.getUserPrincipal().getName() + " at " + request.getRemoteHost()); throw new IOException(errorMsg); } String myStorageInfoString = nnImage.getStorage().toColonSeparatedString(); if (theirStorageInfoString != null && !myStorageInfoString.equals(theirStorageInfoString)) { String errorMsg = "This namenode has storage info " + myStorageInfoString + " but the secondary expected " + theirStorageInfoString; response.sendError(HttpServletResponse.SC_FORBIDDEN, errorMsg); LOG.warn("Received an invalid request file transfer request " + "from a secondary with storage info " + theirStorageInfoString); throw new IOException(errorMsg); } } public static void setFileNameHeaders(HttpServletResponse response, File file) { response.setHeader(CONTENT_DISPOSITION, "attachment; filename=" + file.getName()); response.setHeader(HADOOP_IMAGE_EDITS_HEADER, file.getName()); } /** * Construct a throttler from conf * @param conf configuration * @return a data transfer throttler */ public final static DataTransferThrottler getThrottler(Configuration conf) { long transferBandwidth = conf.getLong(DFSConfigKeys.DFS_IMAGE_TRANSFER_RATE_KEY, DFSConfigKeys.DFS_IMAGE_TRANSFER_RATE_DEFAULT); DataTransferThrottler throttler = null; if (transferBandwidth > 0) { throttler = new DataTransferThrottler(transferBandwidth); } return throttler; } @VisibleForTesting static boolean isValidRequestor(ServletContext context, String remoteUser, Configuration conf) throws IOException { if (remoteUser == null) { // This really shouldn't happen... LOG.warn("Received null remoteUser while authorizing access to getImage servlet"); return false; } Set<String> validRequestors = new HashSet<String>(); validRequestors .add(SecurityUtil.getServerPrincipal(conf.get(DFSConfigKeys.DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY), NameNode.getAddress(conf).getHostName())); try { validRequestors.add(SecurityUtil.getServerPrincipal( conf.get(DFSConfigKeys.DFS_SECONDARY_NAMENODE_KERBEROS_PRINCIPAL_KEY), SecondaryNameNode.getHttpAddress(conf).getHostName())); } catch (Exception e) { // Don't halt if SecondaryNameNode principal could not be added. LOG.debug("SecondaryNameNode principal could not be added", e); String msg = String.format("SecondaryNameNode principal not considered, %s = %s, %s = %s", DFSConfigKeys.DFS_SECONDARY_NAMENODE_KERBEROS_PRINCIPAL_KEY, conf.get(DFSConfigKeys.DFS_SECONDARY_NAMENODE_KERBEROS_PRINCIPAL_KEY), DFSConfigKeys.DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_KEY, conf.getTrimmed(DFSConfigKeys.DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_KEY, DFSConfigKeys.DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_DEFAULT)); LOG.warn(msg); } if (HAUtil.isHAEnabled(conf, DFSUtil.getNamenodeNameServiceId(conf))) { Configuration otherNnConf = HAUtil.getConfForOtherNode(conf); validRequestors.add(SecurityUtil.getServerPrincipal( otherNnConf.get(DFSConfigKeys.DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY), NameNode.getAddress(otherNnConf).getHostName())); } for (String v : validRequestors) { if (v != null && v.equals(remoteUser)) { LOG.info("ImageServlet allowing checkpointer: " + remoteUser); return true; } } if (HttpServer2.userHasAdministratorAccess(context, remoteUser)) { LOG.info("ImageServlet allowing administrator: " + remoteUser); return true; } LOG.info("ImageServlet rejecting: " + remoteUser); return false; } /** * Set headers for content length, and, if available, md5. * @throws IOException */ public static void setVerificationHeadersForGet(HttpServletResponse response, File file) throws IOException { response.setHeader(TransferFsImage.CONTENT_LENGTH, String.valueOf(file.length())); MD5Hash hash = MD5FileUtils.readStoredMd5ForFile(file); if (hash != null) { response.setHeader(TransferFsImage.MD5_HEADER, hash.toString()); } } static String getParamStringForMostRecentImage() { return "getimage=1&" + TXID_PARAM + "=" + LATEST_FSIMAGE_VALUE; } static String getParamStringForImage(NameNodeFile nnf, long txid, StorageInfo remoteStorageInfo) { final String imageType = nnf == null ? "" : "&" + IMAGE_FILE_TYPE + "=" + nnf.name(); return "getimage=1&" + TXID_PARAM + "=" + txid + imageType + "&" + STORAGEINFO_PARAM + "=" + remoteStorageInfo.toColonSeparatedString(); } static String getParamStringForLog(RemoteEditLog log, StorageInfo remoteStorageInfo) { return "getedit=1&" + START_TXID_PARAM + "=" + log.getStartTxId() + "&" + END_TXID_PARAM + "=" + log.getEndTxId() + "&" + STORAGEINFO_PARAM + "=" + remoteStorageInfo.toColonSeparatedString(); } static class GetImageParams { private boolean isGetImage; private boolean isGetEdit; private NameNodeFile nnf; private long startTxId, endTxId, txId; private String storageInfoString; private boolean fetchLatest; /** * @param request the object from which this servlet reads the url contents * @param response the object into which this servlet writes the url contents * @throws IOException if the request is bad */ public GetImageParams(HttpServletRequest request, HttpServletResponse response) throws IOException { @SuppressWarnings("unchecked") Map<String, String[]> pmap = request.getParameterMap(); isGetImage = isGetEdit = fetchLatest = false; for (Map.Entry<String, String[]> entry : pmap.entrySet()) { String key = entry.getKey(); String[] val = entry.getValue(); if (key.equals("getimage")) { isGetImage = true; try { txId = ServletUtil.parseLongParam(request, TXID_PARAM); String imageType = ServletUtil.getParameter(request, IMAGE_FILE_TYPE); nnf = imageType == null ? NameNodeFile.IMAGE : NameNodeFile.valueOf(imageType); } catch (NumberFormatException nfe) { if (request.getParameter(TXID_PARAM).equals(LATEST_FSIMAGE_VALUE)) { fetchLatest = true; } else { throw nfe; } } } else if (key.equals("getedit")) { isGetEdit = true; startTxId = ServletUtil.parseLongParam(request, START_TXID_PARAM); endTxId = ServletUtil.parseLongParam(request, END_TXID_PARAM); } else if (key.equals(STORAGEINFO_PARAM)) { storageInfoString = val[0]; } } int numGets = (isGetImage ? 1 : 0) + (isGetEdit ? 1 : 0); if ((numGets > 1) || (numGets == 0)) { throw new IOException("Illegal parameters to TransferFsImage"); } } public String getStorageInfoString() { return storageInfoString; } public long getTxId() { Preconditions.checkState(isGetImage); return txId; } public NameNodeFile getNameNodeFile() { Preconditions.checkState(isGetImage); return nnf; } public long getStartTxId() { Preconditions.checkState(isGetEdit); return startTxId; } public long getEndTxId() { Preconditions.checkState(isGetEdit); return endTxId; } boolean isGetEdit() { return isGetEdit; } boolean isGetImage() { return isGetImage; } boolean shouldFetchLatest() { return fetchLatest; } } /** * Set headers for image length and if available, md5. * * @throws IOException */ static void setVerificationHeadersForPut(HttpURLConnection connection, File file) throws IOException { connection.setRequestProperty(TransferFsImage.CONTENT_LENGTH, String.valueOf(file.length())); MD5Hash hash = MD5FileUtils.readStoredMd5ForFile(file); if (hash != null) { connection.setRequestProperty(TransferFsImage.MD5_HEADER, hash.toString()); } } /** * Set the required parameters for uploading image * * @param httpMethod instance of method to set the parameters * @param storage colon separated storageInfo string * @param txid txid of the image * @param imageFileSize size of the imagefile to be uploaded * @param nnf NameNodeFile Type * @return Returns map of parameters to be used with PUT request. */ static Map<String, String> getParamsForPutImage(Storage storage, long txid, long imageFileSize, NameNodeFile nnf) { Map<String, String> params = new HashMap<String, String>(); params.put(TXID_PARAM, Long.toString(txid)); params.put(STORAGEINFO_PARAM, storage.toColonSeparatedString()); // setting the length of the file to be uploaded in separate property as // Content-Length only supports up to 2GB params.put(TransferFsImage.FILE_LENGTH, Long.toString(imageFileSize)); params.put(IMAGE_FILE_TYPE, nnf.name()); return params; } @Override protected void doPut(final HttpServletRequest request, final HttpServletResponse response) throws ServletException, IOException { try { ServletContext context = getServletContext(); final FSImage nnImage = NameNodeHttpServer.getFsImageFromContext(context); final Configuration conf = (Configuration) getServletContext().getAttribute(JspHelper.CURRENT_CONF); final PutImageParams parsedParams = new PutImageParams(request, response, conf); final NameNodeMetrics metrics = NameNode.getNameNodeMetrics(); validateRequest(context, conf, request, response, nnImage, parsedParams.getStorageInfoString()); UserGroupInformation.getCurrentUser().doAs(new PrivilegedExceptionAction<Void>() { @Override public Void run() throws Exception { final long txid = parsedParams.getTxId(); final NameNodeFile nnf = parsedParams.getNameNodeFile(); if (!nnImage.addToCheckpointing(txid)) { response.sendError(HttpServletResponse.SC_CONFLICT, "Either current namenode is checkpointing or another" + " checkpointer is already in the process of " + "uploading a checkpoint made at transaction ID " + txid); return null; } try { if (nnImage.getStorage().findImageFile(nnf, txid) != null) { response.sendError(HttpServletResponse.SC_CONFLICT, "Either current namenode has checkpointed or " + "another checkpointer already uploaded an " + "checkpoint for txid " + txid); return null; } InputStream stream = request.getInputStream(); try { long start = monotonicNow(); MD5Hash downloadImageDigest = TransferFsImage.handleUploadImageRequest(request, txid, nnImage.getStorage(), stream, parsedParams.getFileSize(), getThrottler(conf)); nnImage.saveDigestAndRenameCheckpointImage(nnf, txid, downloadImageDigest); // Metrics non-null only when used inside name node if (metrics != null) { long elapsed = monotonicNow() - start; metrics.addPutImage(elapsed); } // Now that we have a new checkpoint, we might be able to // remove some old ones. nnImage.purgeOldStorage(nnf); } finally { stream.close(); } } finally { nnImage.removeFromCheckpointing(txid); } return null; } }); } catch (Throwable t) { String errMsg = "PutImage failed. " + StringUtils.stringifyException(t); response.sendError(HttpServletResponse.SC_GONE, errMsg); throw new IOException(errMsg); } } /* * Params required to handle put image request */ static class PutImageParams { private long txId = -1; private String storageInfoString = null; private long fileSize = 0L; private NameNodeFile nnf; public PutImageParams(HttpServletRequest request, HttpServletResponse response, Configuration conf) throws IOException { txId = ServletUtil.parseLongParam(request, TXID_PARAM); storageInfoString = ServletUtil.getParameter(request, STORAGEINFO_PARAM); fileSize = ServletUtil.parseLongParam(request, TransferFsImage.FILE_LENGTH); String imageType = ServletUtil.getParameter(request, IMAGE_FILE_TYPE); nnf = imageType == null ? NameNodeFile.IMAGE : NameNodeFile.valueOf(imageType); if (fileSize == 0 || txId == -1 || storageInfoString == null || storageInfoString.isEmpty()) { throw new IOException("Illegal parameters to TransferFsImage"); } } public long getTxId() { return txId; } public String getStorageInfoString() { return storageInfoString; } public long getFileSize() { return fileSize; } public NameNodeFile getNameNodeFile() { return nnf; } } }