sadanand48 commented on code in PR #8477: URL: https://github.com/apache/ozone/pull/8477#discussion_r2132190918
########## hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/OMDBCheckpointServletInodeBasedXfer.java: ########## @@ -0,0 +1,237 @@ +/* + * 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.ozone.om; + +import static org.apache.hadoop.hdds.utils.Archiver.*; +import static org.apache.hadoop.ozone.om.OMConfigKeys.OZONE_OM_RATIS_SNAPSHOT_MAX_TOTAL_SST_SIZE_DEFAULT; +import static org.apache.hadoop.ozone.om.OMConfigKeys.OZONE_OM_RATIS_SNAPSHOT_MAX_TOTAL_SST_SIZE_KEY; +import static org.apache.hadoop.ozone.om.snapshot.OmSnapshotUtils.DATA_PREFIX; +import static org.apache.hadoop.ozone.om.snapshot.OmSnapshotUtils.DATA_SUFFIX; + +import java.io.File; +import java.io.IOException; +import java.io.OutputStream; +import java.nio.charset.StandardCharsets; +import java.nio.file.Files; +import java.nio.file.Path; +import java.nio.file.Paths; +import java.util.HashMap; +import java.util.HashSet; +import java.util.Iterator; +import java.util.Map; +import java.util.Set; +import java.util.concurrent.atomic.AtomicLong; +import java.util.stream.Stream; +import javax.servlet.http.HttpServletRequest; +import org.apache.commons.compress.archivers.ArchiveOutputStream; +import org.apache.commons.compress.archivers.tar.TarArchiveEntry; +import org.apache.hadoop.hdds.conf.OzoneConfiguration; +import org.apache.hadoop.hdds.utils.db.DBCheckpoint; +import org.apache.hadoop.ozone.OzoneConsts; +import org.apache.hadoop.ozone.om.helpers.SnapshotInfo; +import org.apache.hadoop.ozone.om.snapshot.OmSnapshotUtils; +import org.apache.ozone.rocksdiff.RocksDBCheckpointDiffer; + +/** + * Specialized OMDBCheckpointServlet implementation that transfers Ozone Manager + * database checkpoints using inode-based deduplication. + * <p> + * This servlet constructs checkpoint archives by examining file inodes, + * ensuring that files with the same inode (i.e., hardlinks or duplicates) + * are only transferred once. It maintains mappings from inode IDs to file + * paths, manages hardlink information, and enforces snapshot and SST file + * size constraints as needed. + * <p> + * This approach optimizes checkpoint streaming by reducing redundant data + * transfer, especially in environments where RocksDB and snapshotting result + * in multiple hardlinks to the same physical data. + */ +public class OMDBCheckpointServletInodeBasedXfer extends OMDBCheckpointServlet { + + @Override + public void writeDbDataToStream(DBCheckpoint checkpoint, HttpServletRequest request, OutputStream destination, + Set<String> sstFilesToExclude, Path tmpdir) throws IOException, InterruptedException { + // Key is the InodeID and the first encountered file path with this inodeID + Map<String, Path> copyFiles = new HashMap<>(); + OzoneManager om = (OzoneManager) getServletContext().getAttribute(OzoneConsts.OM_CONTEXT_ATTRIBUTE); + OMMetadataManager omMetadataManager = om.getMetadataManager(); + boolean includeSnapshotData = includeSnapshotData(request); + long maxTotalSstSize = getConf().getLong(OZONE_OM_RATIS_SNAPSHOT_MAX_TOTAL_SST_SIZE_KEY, + OZONE_OM_RATIS_SNAPSHOT_MAX_TOTAL_SST_SIZE_DEFAULT); + if (!includeSnapshotData) { + maxTotalSstSize = Long.MAX_VALUE; + } + + boolean shouldContinue = true; + + Set<Path> allPathsToVisit = new HashSet<>(); + try (ArchiveOutputStream<TarArchiveEntry> archiveOutputStream = tar(destination)) { + if (includeSnapshotData) { + Set<Path> snapshotDbPaths = collectSnapshotPaths(omMetadataManager); + // Process each snapshot db path and write it to archive + for (Path snapshotDbPath : snapshotDbPaths) { + if (!shouldContinue) { + break; + } + shouldContinue = writeDBToArchive(copyFiles, sstFilesToExclude, snapshotDbPath, + maxTotalSstSize, archiveOutputStream, false, tmpdir); + } + + RocksDBCheckpointDiffer differ = getDbStore().getRocksDBCheckpointDiffer(); + Path sstBackupDir = new File(differ.getSSTBackupDir()).toPath(); + Path compactionLogDir = new File(differ.getCompactionLogDir()).toPath(); + + if (shouldContinue) { + shouldContinue = writeDBToArchive(copyFiles, sstFilesToExclude, sstBackupDir, + maxTotalSstSize, archiveOutputStream, true, tmpdir); + } + + if (shouldContinue) { + shouldContinue = writeDBToArchive(copyFiles, sstFilesToExclude, compactionLogDir, + maxTotalSstSize, archiveOutputStream, true, tmpdir); + } + // Add paths of snapshot databases, SST backups, and compaction logs to visit list + allPathsToVisit.addAll(snapshotDbPaths); + allPathsToVisit.add(sstBackupDir); + allPathsToVisit.add(compactionLogDir); + } + + if (shouldContinue) { + // we finished transferring files from snapshot DB's by now and + // this is the last step where we transfer the active om.db contents + DBCheckpoint finalCheckpoint = getCheckpoint(tmpdir,true); + // unlimited files as we want the Active DB contents to be transferred in a single batch + maxTotalSstSize = Long.MAX_VALUE; + Path checkpointDir = finalCheckpoint.getCheckpointLocation(); + writeDBToArchive(copyFiles, sstFilesToExclude, checkpointDir, + maxTotalSstSize, archiveOutputStream, false, tmpdir); + allPathsToVisit.add(checkpointDir); + generateAndWriteHardlinkFile(checkpointDir, allPathsToVisit, archiveOutputStream); + } + + } catch (Exception e) { + LOG.error("got exception writing to archive " + e); + throw e; + } + } + + /** + * Generates a file containing hardlink information and writes it to the archive. + * + * @param checkpointDir Directory containing the checkpoint + * @param allPathsToVisit Set of all paths to visit for hardlink information + * @param archiveOutputStream Archive output stream + * @throws IOException if an I/O error occurs + */ + private static void generateAndWriteHardlinkFile(Path checkpointDir, Set<Path> allPathsToVisit, + ArchiveOutputStream<TarArchiveEntry> archiveOutputStream) throws IOException { + Path data = Files.createTempFile(DATA_PREFIX, DATA_SUFFIX); + Path metaDirPath = getMetaDirPath(checkpointDir); + int truncateLength = metaDirPath.toString().length() + 1; + StringBuilder sb = new StringBuilder(); + + for (Path path : allPathsToVisit) { + try (Stream<Path> files = Files.walk(path)) { + Iterable<Path> iterable = files::iterator; + Iterator<Path> iterator = iterable.iterator(); + for (; iterator.hasNext();) { + Path p = iterator.next(); + String fileId = OmSnapshotUtils.getInodeAndMtime(p); + String relativePath = p.toString().substring(truncateLength); + sb.append(fileId).append("\t").append(relativePath).append("\n"); + } + } + } + Files.write(data, sb.toString().getBytes(StandardCharsets.UTF_8)); + includeFile(data.toFile(), OmSnapshotManager.OM_HARDLINK_FILE, archiveOutputStream); + } + + /** + * Gets the configuration from the OzoneManager context. + * + * @return OzoneConfiguration instance + */ + private OzoneConfiguration getConf() { + return ((OzoneManager) getServletContext() + .getAttribute(OzoneConsts.OM_CONTEXT_ATTRIBUTE)) + .getConfiguration(); + } + + /** + * Collects paths to all snapshot databases. + * + * @param omMetadataManager OMMetadataManager instance + * @return Set of paths to snapshot databases + * @throws IOException if an I/O error occurs + */ + Set<Path> collectSnapshotPaths(OMMetadataManager omMetadataManager) throws IOException { + Set<Path> snapshotDbPaths = new HashSet<>(); + SnapshotChainManager snapshotChainManager = new SnapshotChainManager(omMetadataManager); + for (SnapshotChainInfo snapInfo : snapshotChainManager.getGlobalSnapshotChain().values()) { + String snapshotDir = + OmSnapshotManager.getSnapshotPath(getConf(), SnapshotInfo.getCheckpointDirName(snapInfo.getSnapshotId())); + Path path = Paths.get(snapshotDir); + snapshotDbPaths.add(path); + } + return snapshotDbPaths; + } + + /** + * Writes database files to the archive, handling deduplication based on inode IDs. + * + * @param copyFiles Map of inode IDs to file paths that have already been processed + * @param sstFilesToExclude Set of SST file IDs to exclude from the archive + * @param dbDir Directory containing database files to archive + * @param maxTotalSstSize Maximum total size of SST files to include + * @param archiveOutputStream Archive output stream + * @param hardlink Whether to link and include a file in tarball + * @param tmpDir Temporary directory for processing + * @return true if processing should continue, false if size limit reached + * @throws IOException if an I/O error occurs + */ + boolean writeDBToArchive(Map<String, Path> copyFiles, + Set<String> sstFilesToExclude, Path dbDir, long maxTotalSstSize, + ArchiveOutputStream<TarArchiveEntry> archiveOutputStream, boolean hardlink, Path tmpDir) throws IOException { + AtomicLong copySize = new AtomicLong(maxTotalSstSize); + try (Stream<Path> files = Files.list(dbDir)) { + Iterable<Path> iterable = files::iterator; + for (Path dbFile : iterable) { + if (Files.isDirectory(dbFile)) { Review Comment: How about compaction-log dir and SST backup dir? 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