Mmuzaf commented on a change in pull request #6554: IGNITE-11073: Backup page store manager, initial URL: https://github.com/apache/ignite/pull/6554#discussion_r380299106
########## File path: modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/snapshot/IgniteSnapshotManager.java ########## @@ -0,0 +1,1410 @@ +/* + * 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.ignite.internal.processors.cache.persistence.snapshot; + +import java.io.File; +import java.io.FileOutputStream; +import java.io.IOException; +import java.io.Serializable; +import java.nio.ByteBuffer; +import java.nio.ByteOrder; +import java.nio.channels.FileChannel; +import java.nio.file.Paths; +import java.util.ArrayDeque; +import java.util.HashMap; +import java.util.HashSet; +import java.util.List; +import java.util.Map; +import java.util.Objects; +import java.util.Queue; +import java.util.Set; +import java.util.UUID; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ConcurrentMap; +import java.util.concurrent.Executor; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.LinkedBlockingQueue; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicInteger; +import java.util.concurrent.atomic.AtomicReference; +import java.util.concurrent.atomic.LongAdder; +import java.util.function.BiFunction; +import java.util.function.Consumer; +import java.util.stream.Collectors; +import org.apache.ignite.IgniteCheckedException; +import org.apache.ignite.IgniteException; +import org.apache.ignite.IgniteLogger; +import org.apache.ignite.binary.BinaryType; +import org.apache.ignite.cluster.ClusterNode; +import org.apache.ignite.configuration.DataStorageConfiguration; +import org.apache.ignite.failure.FailureContext; +import org.apache.ignite.failure.FailureType; +import org.apache.ignite.internal.GridKernalContext; +import org.apache.ignite.internal.GridTopic; +import org.apache.ignite.internal.IgniteInternalFuture; +import org.apache.ignite.internal.MarshallerMappingWriter; +import org.apache.ignite.internal.NodeStoppingException; +import org.apache.ignite.internal.cluster.ClusterTopologyCheckedException; +import org.apache.ignite.internal.managers.communication.GridIoManager; +import org.apache.ignite.internal.managers.communication.GridMessageListener; +import org.apache.ignite.internal.managers.communication.TransmissionCancelledException; +import org.apache.ignite.internal.managers.communication.TransmissionHandler; +import org.apache.ignite.internal.managers.communication.TransmissionMeta; +import org.apache.ignite.internal.managers.communication.TransmissionPolicy; +import org.apache.ignite.internal.managers.eventstorage.DiscoveryEventListener; +import org.apache.ignite.internal.processors.cache.GridCacheSharedManagerAdapter; +import org.apache.ignite.internal.processors.cache.distributed.dht.preloader.GridDhtPartitionMap; +import org.apache.ignite.internal.processors.cache.distributed.dht.topology.GridDhtPartitionState; +import org.apache.ignite.internal.processors.cache.persistence.GridCacheDatabaseSharedManager; +import org.apache.ignite.internal.processors.cache.persistence.StorageException; +import org.apache.ignite.internal.processors.cache.persistence.file.FileIO; +import org.apache.ignite.internal.processors.cache.persistence.file.FileIOFactory; +import org.apache.ignite.internal.processors.cache.persistence.file.FilePageStore; +import org.apache.ignite.internal.processors.cache.persistence.file.FilePageStoreFactory; +import org.apache.ignite.internal.processors.cache.persistence.file.FilePageStoreManager; +import org.apache.ignite.internal.processors.cache.persistence.file.RandomAccessFileIOFactory; +import org.apache.ignite.internal.processors.cache.persistence.filename.PdsFolderSettings; +import org.apache.ignite.internal.processors.cache.persistence.partstate.GroupPartitionId; +import org.apache.ignite.internal.processors.cache.persistence.tree.io.PageIO; +import org.apache.ignite.internal.processors.cache.persistence.wal.crc.FastCrc; +import org.apache.ignite.internal.processors.cacheobject.BinaryTypeWriter; +import org.apache.ignite.internal.processors.marshaller.MappedName; +import org.apache.ignite.internal.processors.metric.impl.LongAdderMetric; +import org.apache.ignite.internal.util.GridBusyLock; +import org.apache.ignite.internal.util.GridIntList; +import org.apache.ignite.internal.util.future.GridFinishedFuture; +import org.apache.ignite.internal.util.future.GridFutureAdapter; +import org.apache.ignite.internal.util.lang.IgniteThrowableConsumer; +import org.apache.ignite.internal.util.lang.IgniteThrowableSupplier; +import org.apache.ignite.internal.util.typedef.internal.CU; +import org.apache.ignite.internal.util.typedef.internal.S; +import org.apache.ignite.internal.util.typedef.internal.U; +import org.apache.ignite.thread.IgniteThreadPoolExecutor; +import org.jetbrains.annotations.Nullable; + +import static java.nio.file.StandardOpenOption.READ; +import static org.apache.ignite.events.EventType.EVT_NODE_FAILED; +import static org.apache.ignite.events.EventType.EVT_NODE_LEFT; +import static org.apache.ignite.internal.IgniteFeatures.PERSISTENCE_CACHE_SNAPSHOT; +import static org.apache.ignite.internal.IgniteFeatures.nodeSupports; +import static org.apache.ignite.internal.MarshallerContextImpl.addPlatformMappings; +import static org.apache.ignite.internal.managers.communication.GridIoPolicy.SYSTEM_POOL; +import static org.apache.ignite.internal.pagemem.PageIdAllocator.INDEX_PARTITION; +import static org.apache.ignite.internal.pagemem.PageIdAllocator.MAX_PARTITION_ID; +import static org.apache.ignite.internal.processors.cache.persistence.file.FilePageStoreManager.INDEX_FILE_NAME; +import static org.apache.ignite.internal.processors.cache.persistence.file.FilePageStoreManager.PART_FILE_TEMPLATE; +import static org.apache.ignite.internal.processors.cache.persistence.file.FilePageStoreManager.getPartitionFile; +import static org.apache.ignite.internal.processors.cache.persistence.file.FilePageStoreManager.getPartitionFileName; +import static org.apache.ignite.internal.processors.cache.persistence.filename.PdsConsistentIdProcessor.DB_DEFAULT_FOLDER; +import static org.apache.ignite.internal.processors.cache.persistence.partstate.GroupPartitionId.getFlagByPartId; + +/** */ +public class IgniteSnapshotManager extends GridCacheSharedManagerAdapter { + /** File with delta pages suffix. */ + public static final String DELTA_SUFFIX = ".delta"; + + /** File name template consists of delta pages. */ + public static final String PART_DELTA_TEMPLATE = PART_FILE_TEMPLATE + DELTA_SUFFIX; + + /** File name template for index delta pages. */ + public static final String INDEX_DELTA_NAME = INDEX_FILE_NAME + DELTA_SUFFIX; + + /** The reason of checkpoint start for needs of snapshot. */ + public static final String SNAPSHOT_CP_REASON = "Wakeup for checkpoint to take snapshot [name=%s]"; + + /** Default snapshot directory for loading remote snapshots. */ + public static final String DFLT_SNAPSHOT_WORK_DIRECTORY = "snp"; + + /** Timeout in milliseconsd for snapshot operations. */ + public static final long DFLT_SNAPSHOT_TIMEOUT = 15_000L; + + /** Prefix for snapshot threads. */ + private static final String SNAPSHOT_RUNNER_THREAD_PREFIX = "snapshot-runner"; + + /** Total number of thread to perform local snapshot. */ + private static final int SNAPSHOT_THREAD_POOL_SIZE = 4; + + /** Default snapshot topic to receive snapshots from remote node. */ + private static final Object DFLT_INITIAL_SNAPSHOT_TOPIC = GridTopic.TOPIC_SNAPSHOT.topic("rmt_snp"); + + /** File transmission parameter of cache group id. */ + private static final String SNP_GRP_ID_PARAM = "grpId"; + + /** File transmission parameter of cache partition id. */ + private static final String SNP_PART_ID_PARAM = "partId"; + + /** File transmission parameter of node-sender directory path with its consistentId (e.g. db/IgniteNode0). */ + private static final String SNP_DB_NODE_PATH_PARAM = "dbNodePath"; + + /** File transmission parameter of a cache directory with is currently sends its partitions. */ + private static final String SNP_CACHE_DIR_NAME_PARAM = "cacheDirName"; + + /** Snapshot parameter name for a file transmission. */ + private static final String SNP_NAME_PARAM = "snpName"; + + /** Map of registered cache snapshot processes and their corresponding contexts. */ + private final ConcurrentMap<String, SnapshotFutureTask> locSnpTasks = new ConcurrentHashMap<>(); + + /** Lock to protect the resources is used. */ + private final GridBusyLock busyLock = new GridBusyLock(); + + /** Requested snapshot from remote node. */ + private final AtomicReference<RemoteSnapshotFuture> rmtSnpReq = new AtomicReference<>(); + + /** Main snapshot directory to save created snapshots. */ + private File locSnpDir; + + /** + * Working directory for loaded snapshots from the remote nodes and storing + * temporary partition delta-files of locally started snapshot process. + */ + private File tmpWorkDir; + + /** Factory to working with delta as file storage. */ + private volatile FileIOFactory ioFactory = new RandomAccessFileIOFactory(); + + /** Factory to create page store for restore. */ + private volatile BiFunction<Integer, Boolean, FilePageStoreFactory> storeFactory; + + /** Snapshot thread pool to perform local partition snapshots. */ + private ExecutorService snpRunner; + + /** System discovery message listener. */ + private DiscoveryEventListener discoLsnr; + + /** Snapshot listener on created snapshots. */ + private volatile SnapshotListener snpLsnr; + + /** Database manager for enabled persistence. */ + private GridCacheDatabaseSharedManager dbMgr; + + /** Configured data storage page size. */ + private int pageSize; + + /** + * @param ctx Kernal context. + */ + public IgniteSnapshotManager(GridKernalContext ctx) { + // No-op. + } + + /** + * @param snapshotCacheDir Snapshot directory to store files. + * @param partId Cache partition identifier. + * @return A file representation. + */ + public static File getPartionDeltaFile(File snapshotCacheDir, int partId) { + return new File(snapshotCacheDir, getPartitionDeltaFileName(partId)); + } + + /** + * @param partId Partitoin id. + * @return File name of delta partition pages. + */ + public static String getPartitionDeltaFileName(int partId) { + assert partId <= MAX_PARTITION_ID || partId == INDEX_PARTITION; + + return partId == INDEX_PARTITION ? INDEX_DELTA_NAME : String.format(PART_DELTA_TEMPLATE, partId); + } + + /** {@inheritDoc} */ + @Override protected void start0() throws IgniteCheckedException { + super.start0(); + + GridKernalContext kctx = cctx.kernalContext(); + + if (kctx.clientNode()) + return; + + if (!CU.isPersistenceEnabled(cctx.kernalContext().config())) + return; + + DataStorageConfiguration dcfg = kctx.config().getDataStorageConfiguration(); + + pageSize = dcfg.getPageSize(); + + assert pageSize > 0; + + snpRunner = new IgniteThreadPoolExecutor( + SNAPSHOT_RUNNER_THREAD_PREFIX, + cctx.igniteInstanceName(), + SNAPSHOT_THREAD_POOL_SIZE, + SNAPSHOT_THREAD_POOL_SIZE, + 30_000, + new LinkedBlockingQueue<>(), + SYSTEM_POOL, + (t, e) -> kctx.failure().process(new FailureContext(FailureType.CRITICAL_ERROR, e))); + + assert cctx.pageStore() instanceof FilePageStoreManager; + + FilePageStoreManager storeMgr = (FilePageStoreManager)cctx.pageStore(); + + locSnpDir = U.resolveWorkDirectory(kctx.config().getWorkDirectory(), dcfg.getLocalSnapshotPath(), false); + tmpWorkDir = Paths.get(storeMgr.workDir().getAbsolutePath(), DFLT_SNAPSHOT_WORK_DIRECTORY).toFile(); + + U.ensureDirectory(locSnpDir, "local snapshots directory", log); + U.ensureDirectory(tmpWorkDir, "work directory for snapshots creation", log); + + storeFactory = storeMgr::getPageStoreFactory; + dbMgr = (GridCacheDatabaseSharedManager)cctx.database(); + + // Receive remote snapshots requests. + cctx.gridIO().addMessageListener(DFLT_INITIAL_SNAPSHOT_TOPIC, new GridMessageListener() { + @Override public void onMessage(UUID nodeId, Object msg, byte plc) { + if (!busyLock.enterBusy()) + return; + + try { + if (msg instanceof SnapshotRequestMessage) { + SnapshotRequestMessage reqMsg0 = (SnapshotRequestMessage)msg; + String snpName = reqMsg0.snapshotName(); + + synchronized (rmtSnpReq) { + SnapshotFutureTask task = lastScheduledRemoteSnapshotTask(nodeId); + + if (task != null) { + // Task should also be removed from local map. + task.cancel(); + + log.info("Snapshot request has been cancelled due to another request recevied " + + "[prevSnpResp=" + task + ", msg0=" + reqMsg0 + ']'); + } + } + + runSnapshotTask(snpName, nodeId, reqMsg0.parts(), remoteSnapshotSender(snpName, nodeId)) + .listen(f -> { + if (f.error() == null) + return; + + U.error(log, "Failed to proccess request of creating a snapshot " + + "[from=" + nodeId + ", msg=" + reqMsg0 + ']', f.error()); + + try { + cctx.gridIO().sendToCustomTopic(nodeId, + DFLT_INITIAL_SNAPSHOT_TOPIC, + new SnapshotResponseMessage(reqMsg0.snapshotName(), f.error().getMessage()), + SYSTEM_POOL); + } + catch (IgniteCheckedException ex0) { + U.error(log, "Fail to send the response message with processing snapshot request " + + "error [request=" + reqMsg0 + ", nodeId=" + nodeId + ']', ex0); + } + }); + } + else if (msg instanceof SnapshotResponseMessage) { + SnapshotResponseMessage respMsg0 = (SnapshotResponseMessage)msg; + + RemoteSnapshotFuture fut0 = rmtSnpReq.get(); + + if (fut0 == null || !fut0.snpName.equals(respMsg0.snapshotName())) { + if (log.isInfoEnabled()) { + log.info("A stale snapshot response message has been received. Will be ignored " + + "[fromNodeId=" + nodeId + ", response=" + respMsg0 + ']'); + } + + return; + } + + if (respMsg0.errorMessage() != null) { + fut0.onDone(new IgniteCheckedException("Request cancelled. The snapshot operation stopped " + + "on the remote node with an error: " + respMsg0.errorMessage())); + } + } + } + finally { + busyLock.leaveBusy(); + } + } + }); + + cctx.gridEvents().addDiscoveryEventListener(discoLsnr = (evt, discoCache) -> { + if (!busyLock.enterBusy()) + return; + + try { + for (SnapshotFutureTask sctx : locSnpTasks.values()) { + if (sctx.sourceNodeId().equals(evt.eventNode().id())) { + sctx.acceptException(new ClusterTopologyCheckedException("The node which requested snapshot " + + "creation has left the grid")); + } + } + + RemoteSnapshotFuture snpTrFut = rmtSnpReq.get(); + + if (snpTrFut != null && snpTrFut.rmtNodeId.equals(evt.eventNode().id())) { + snpTrFut.onDone(new ClusterTopologyCheckedException("The node from which a snapshot has been " + + "requested left the grid")); + } + } + finally { + busyLock.leaveBusy(); + } + }, EVT_NODE_LEFT, EVT_NODE_FAILED); + + // Remote snapshot handler. + cctx.kernalContext().io().addTransmissionHandler(DFLT_INITIAL_SNAPSHOT_TOPIC, new TransmissionHandler() { + /** {@inheritDoc} */ + @Override public void onException(UUID nodeId, Throwable err) { + RemoteSnapshotFuture fut = rmtSnpReq.get(); + + if (fut == null) + return; + + if (fut.rmtNodeId.equals(nodeId)) { + fut.onDone(err); + + if(snpLsnr != null) + snpLsnr.onException(nodeId, err); + } + } + + /** {@inheritDoc} */ + @Override public String filePath(UUID nodeId, TransmissionMeta fileMeta) { + Integer partId = (Integer)fileMeta.params().get(SNP_PART_ID_PARAM); + String snpName = (String)fileMeta.params().get(SNP_NAME_PARAM); + String rmtDbNodePath = (String)fileMeta.params().get(SNP_DB_NODE_PATH_PARAM); + String cacheDirName = (String)fileMeta.params().get(SNP_CACHE_DIR_NAME_PARAM); + + RemoteSnapshotFuture transFut = rmtSnpReq.get(); + + if (transFut == null || !transFut.snpName.equals(snpName)) { + throw new TransmissionCancelledException("Stale snapshot transmission will be ignored " + + "[snpName=" + snpName + ", transFut=" + transFut + ']'); + } + + assert transFut.snpName.equals(snpName) && transFut.rmtNodeId.equals(nodeId) : + "Another transmission in progress [fut=" + transFut + ", nodeId=" + snpName + ", nodeId=" + nodeId +']'; + + try { + File cacheDir = U.resolveWorkDirectory(tmpWorkDir.getAbsolutePath(), + cacheSnapshotPath(snpName, rmtDbNodePath, cacheDirName), + false); + + return new File(cacheDir, getPartitionFileName(partId)).getAbsolutePath(); + } + catch (IgniteCheckedException e) { + throw new IgniteException(e); + } + } + + /** + * @param snpTrans Current snapshot transmission. + * @param rmtNodeId Remote node which sends partition. + * @param grpPartId Pair of group id and its partition id. + */ + private void finishRecover( + RemoteSnapshotFuture snpTrans, + UUID rmtNodeId, + GroupPartitionId grpPartId + ) { + FilePageStore pageStore = null; + + try { + pageStore = snpTrans.stores.remove(grpPartId); + + pageStore.finishRecover(); + + String partAbsPath = pageStore.getFileAbsolutePath(); + + cctx.kernalContext().closure().runLocalSafe(() -> { + if (snpLsnr == null) + return; + + snpLsnr.onPartition(rmtNodeId, + new File(partAbsPath), + grpPartId.getGroupId(), + grpPartId.getPartitionId()); + }); + + if (snpTrans.partsLeft.decrementAndGet() == 0) { + cctx.kernalContext().closure().runLocalSafe(() -> { + if (snpLsnr == null) + return; + + snpLsnr.onEnd(rmtNodeId); + }); + + snpTrans.onDone(true); + } + } + catch (StorageException e) { + throw new IgniteException(e); + } + finally { + U.closeQuiet(pageStore); + } + } + + /** {@inheritDoc} */ + @Override public Consumer<ByteBuffer> chunkHandler(UUID nodeId, TransmissionMeta initMeta) { + Integer grpId = (Integer)initMeta.params().get(SNP_GRP_ID_PARAM); + Integer partId = (Integer)initMeta.params().get(SNP_PART_ID_PARAM); + String snpName = (String)initMeta.params().get(SNP_NAME_PARAM); + + GroupPartitionId grpPartId = new GroupPartitionId(grpId, partId); + RemoteSnapshotFuture snpTrFut = rmtSnpReq.get(); + + if (snpTrFut == null || !snpTrFut.snpName.equals(snpName)) { + throw new TransmissionCancelledException("Stale snapshot transmission will be ignored " + + "[snpName=" + snpName + ", grpId=" + grpId + ", partId=" + partId + ", snpTrFut=" + snpTrFut + ']'); + } + + assert snpTrFut.snpName.equals(snpName) && snpTrFut.rmtNodeId.equals(nodeId) : + "Another transmission in progress [snpTrFut=" + snpTrFut + ", nodeId=" + snpName + ", nodeId=" + nodeId +']'; + + FilePageStore pageStore = snpTrFut.stores.get(grpPartId); + + if (pageStore == null) { + throw new IgniteException("Partition must be loaded before applying snapshot delta pages " + + "[snpName=" + snpName + ", grpId=" + grpId + ", partId=" + partId + ']'); + } + + pageStore.beginRecover(); + + // No snapshot delta pages received. Finalize recovery. + if (initMeta.count() == 0) { + finishRecover(snpTrFut, + nodeId, + grpPartId); + } + + return new Consumer<ByteBuffer>() { + final LongAdder transferred = new LongAdder(); + + @Override public void accept(ByteBuffer buff) { + try { + assert initMeta.count() != 0 : initMeta; + + RemoteSnapshotFuture fut0 = rmtSnpReq.get(); + + if (fut0 == null || !fut0.equals(snpTrFut) || fut0.isCancelled()) { + throw new TransmissionCancelledException("Snapshot request is cancelled " + + "[snpName=" + snpName + ", grpId=" + grpId + ", partId=" + partId + ']'); + } + + pageStore.write(PageIO.getPageId(buff), buff, 0, false); + + transferred.add(buff.capacity()); + + if (transferred.longValue() == initMeta.count()) { + finishRecover(snpTrFut, + nodeId, + grpPartId); + } + } + catch (IgniteCheckedException e) { + throw new IgniteException(e); + } + } + }; + } + + /** {@inheritDoc} */ + @Override public Consumer<File> fileHandler(UUID nodeId, TransmissionMeta initMeta) { + Integer grpId = (Integer)initMeta.params().get(SNP_GRP_ID_PARAM); + Integer partId = (Integer)initMeta.params().get(SNP_PART_ID_PARAM); + String snpName = (String)initMeta.params().get(SNP_NAME_PARAM); + + assert grpId != null; + assert partId != null; + assert snpName != null; + assert storeFactory != null; + + RemoteSnapshotFuture transFut = rmtSnpReq.get(); + + if (transFut == null) { + throw new IgniteException("Snapshot transmission with given name doesn't exists " + + "[snpName=" + snpName + ", grpId=" + grpId + ", partId=" + partId + ']'); + } + + return new Consumer<File>() { + @Override public void accept(File file) { + RemoteSnapshotFuture fut0 = rmtSnpReq.get(); + + if (fut0 == null || !fut0.equals(transFut) || fut0.isCancelled()) { + throw new TransmissionCancelledException("Snapshot request is cancelled [snpName=" + snpName + + ", grpId=" + grpId + ", partId=" + partId + ']'); + } + + busyLock.enterBusy(); + + try { + FilePageStore pageStore = (FilePageStore)storeFactory + .apply(grpId, false) + .createPageStore(getFlagByPartId(partId), + file::toPath, + new LongAdderMetric("NO_OP", null)); + + transFut.stores.put(new GroupPartitionId(grpId, partId), pageStore); + + pageStore.init(); + } + catch (IgniteCheckedException e) { + throw new IgniteException(e); + } + finally { + busyLock.leaveBusy(); + } + } + }; + } + }); + } + + /** {@inheritDoc} */ + @Override protected void stop0(boolean cancel) { + busyLock.block(); + + try { + for (SnapshotFutureTask sctx : locSnpTasks.values()) { + // Try stop all snapshot processing if not yet. + sctx.acceptException(new NodeStoppingException("Snapshot has been cancelled due to the local node " + + "is stopping")); + } + + locSnpTasks.clear(); + + RemoteSnapshotFuture snpTrFut = rmtSnpReq.get(); + + if (snpTrFut != null) + snpTrFut.cancel(); + + // Do not shutdown immediately since all task must be closed correctly. + snpRunner.shutdown(); + + cctx.kernalContext().io().removeMessageListener(DFLT_INITIAL_SNAPSHOT_TOPIC); + cctx.kernalContext().event().removeDiscoveryEventListener(discoLsnr); + cctx.kernalContext().io().removeTransmissionHandler(DFLT_INITIAL_SNAPSHOT_TOPIC); + } + finally { + busyLock.unblock(); + } + } + + /** + * @return Relative configured path of presistence data storage directory for the local node. + * Example: {@code snapshotWorkDir/db/IgniteNodeName0} + */ + public static String relativeNodePath(PdsFolderSettings pcfg) { + return Paths.get(DB_DEFAULT_FOLDER, pcfg.folderName()).toString(); + } + + /** + * @param snpLsnr Snapshot listener instance. + */ + public void addSnapshotListener(SnapshotListener snpLsnr) { Review comment: Listener Removed ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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