zoltar9264 commented on code in PR #24879: URL: https://github.com/apache/flink/pull/24879#discussion_r1753111352
########## flink-state-backends/flink-statebackend-forst/src/main/java/org/apache/flink/state/forst/snapshot/ForStSnapshotStrategyBase.java: ########## @@ -0,0 +1,344 @@ +/* + * 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.flink.state.forst.snapshot; + +import org.apache.flink.api.common.state.CheckpointListener; +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.core.fs.CloseableRegistry; +import org.apache.flink.core.fs.Path; +import org.apache.flink.core.memory.DataOutputView; +import org.apache.flink.core.memory.DataOutputViewStreamWrapper; +import org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManager; +import org.apache.flink.runtime.state.CheckpointStreamFactory; +import org.apache.flink.runtime.state.CheckpointStreamWithResultProvider; +import org.apache.flink.runtime.state.CheckpointedStateScope; +import org.apache.flink.runtime.state.IncrementalKeyedStateHandle.HandleAndLocalPath; +import org.apache.flink.runtime.state.KeyGroupRange; +import org.apache.flink.runtime.state.KeyedBackendSerializationProxy; +import org.apache.flink.runtime.state.KeyedStateHandle; +import org.apache.flink.runtime.state.PlaceholderStreamStateHandle; +import org.apache.flink.runtime.state.SnapshotResources; +import org.apache.flink.runtime.state.SnapshotResult; +import org.apache.flink.runtime.state.SnapshotStrategy; +import org.apache.flink.runtime.state.StateUtil; +import org.apache.flink.runtime.state.StreamStateHandle; +import org.apache.flink.runtime.state.metainfo.StateMetaInfoSnapshot; +import org.apache.flink.state.forst.ForStKeyedStateBackend.ForStKvStateInfo; +import org.apache.flink.state.forst.ForStResourceContainer; +import org.apache.flink.util.IOUtils; +import org.apache.flink.util.Preconditions; +import org.apache.flink.util.ResourceGuard; + +import org.rocksdb.RocksDB; +import org.rocksdb.RocksDBException; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.Nonnegative; +import javax.annotation.Nonnull; +import javax.annotation.Nullable; + +import java.io.IOException; +import java.util.ArrayList; +import java.util.Collection; +import java.util.Collections; +import java.util.LinkedHashMap; +import java.util.List; +import java.util.Map; +import java.util.Optional; +import java.util.UUID; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.stream.Collectors; + +/** + * Abstract base class for {@link SnapshotStrategy} implementations for ForSt state backend. + * + * @param <K> type of the backend keys. + */ +public abstract class ForStSnapshotStrategyBase<K, R extends SnapshotResources> + implements CheckpointListener, + SnapshotStrategy< + KeyedStateHandle, ForStSnapshotStrategyBase.ForStNativeSnapshotResources>, + AutoCloseable { + + private static final Logger LOG = LoggerFactory.getLogger(ForStSnapshotStrategyBase.class); + + @Nonnull private final String description; + + /** ForSt instance from the backend. */ + @Nonnull protected final RocksDB db; + + /** Resource guard for the ForSt instance. */ + @Nonnull protected final ResourceGuard resourceGuard; + + @Nonnull protected final ForStResourceContainer resourceContainer; + + /** The key serializer of the backend. */ + @Nonnull protected final TypeSerializer<K> keySerializer; + + /** Key/Value state meta info from the backend. */ + @Nonnull protected final LinkedHashMap<String, ForStKvStateInfo> kvStateInformation; + + /** The key-group range for the task. */ + @Nonnull protected final KeyGroupRange keyGroupRange; + + /** Number of bytes in the key-group prefix. */ + @Nonnegative protected final int keyGroupPrefixBytes; + + /** The state handle ids of all sst files materialized in snapshots for previous checkpoints. */ + @Nonnull protected final UUID backendUID; + + public ForStSnapshotStrategyBase( + @Nonnull String description, + @Nonnull RocksDB db, + @Nonnull ResourceGuard resourceGuard, + @Nonnull ForStResourceContainer resourceContainer, + @Nonnull TypeSerializer<K> keySerializer, + @Nonnull LinkedHashMap<String, ForStKvStateInfo> kvStateInformation, + @Nonnull KeyGroupRange keyGroupRange, + @Nonnegative int keyGroupPrefixBytes, + @Nonnull UUID backendUID) { + this.db = db; + this.resourceGuard = resourceGuard; + this.resourceContainer = resourceContainer; + this.keySerializer = keySerializer; + this.kvStateInformation = kvStateInformation; + this.keyGroupRange = keyGroupRange; + this.keyGroupPrefixBytes = keyGroupPrefixBytes; + this.description = description; + this.backendUID = backendUID; + } + + @Nonnull + public String getDescription() { + return description; + } + + @Override + public ForStNativeSnapshotResources syncPrepareResources(long checkpointId) throws Exception { + + final List<StateMetaInfoSnapshot> stateMetaInfoSnapshots = + new ArrayList<>(kvStateInformation.size()); + final PreviousSnapshot previousSnapshot = + snapshotMetaData(checkpointId, stateMetaInfoSnapshots); + + // Disable file deletion for file transformation. ForSt will decide whether to allow file + // deletion based on the number of calls to disableFileDeletions() and + // enableFileDeletions(), so disableFileDeletions() should be call only once. + db.disableFileDeletions(); + + // get live files with flush memtable + RocksDB.LiveFiles liveFiles = db.getLiveFiles(true); + List<Path> liveFilesPath = + liveFiles.files.stream() + .map(file -> new Path(resourceContainer.getDbPath(), file)) + .collect(Collectors.toList()); + + logLiveFiles(checkpointId, liveFiles.manifestFileSize, liveFilesPath); + + return new ForStNativeSnapshotResources( + stateMetaInfoSnapshots, + liveFiles.manifestFileSize, + liveFilesPath, + previousSnapshot, + () -> { + try { + db.enableFileDeletions(false); + LOG.info( + "Release one file deletion lock with ForStNativeSnapshotResources, backendUID:{}, checkpointId:{}.", + backendUID, + checkpointId); + } catch (RocksDBException e) { + LOG.error( + "Enable file deletion failed, backendUID:{}, checkpointId:{}.", + backendUID, + checkpointId, + e); + // TODO: 2024/5/28 wangfeifan - Add more robust exception handling + } + }); + } Review Comment: If call enableFileDeletions after any exception thrown in disableFileDeletions, consider parallel checkpointing, file deletion may be allowed prematurely. 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