littlehorse-eng commented on code in PR #12393: URL: https://github.com/apache/kafka/pull/12393#discussion_r1002288689
########## streams/src/main/java/org/apache/kafka/streams/state/internals/AbstractTransactionalStore.java: ########## @@ -0,0 +1,442 @@ +/* + * 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.kafka.streams.state.internals; + +import static org.apache.kafka.streams.StreamsConfig.InternalConfig.IQ_CONSISTENCY_OFFSET_VECTOR_ENABLED; + +import java.io.File; +import java.io.IOException; +import java.util.Collection; +import java.util.Collections; +import java.util.HashSet; +import java.util.List; +import java.util.Map; +import java.util.NoSuchElementException; +import java.util.Set; +import java.util.stream.Collectors; +import org.apache.kafka.clients.consumer.ConsumerRecord; +import org.apache.kafka.common.serialization.Serializer; +import org.apache.kafka.common.utils.Bytes; +import org.apache.kafka.streams.KeyValue; +import org.apache.kafka.streams.StreamsConfig; +import org.apache.kafka.streams.processor.ProcessorContext; +import org.apache.kafka.streams.processor.StateStore; +import org.apache.kafka.streams.processor.StateStoreContext; +import org.apache.kafka.streams.processor.internals.RecordBatchingStateRestoreCallback; +import org.apache.kafka.streams.query.Position; +import org.apache.kafka.streams.query.PositionBound; +import org.apache.kafka.streams.query.Query; +import org.apache.kafka.streams.query.QueryConfig; +import org.apache.kafka.streams.query.QueryResult; +import org.apache.kafka.streams.state.KeyValueIterator; +import org.apache.kafka.streams.state.KeyValueStore; +import org.apache.kafka.streams.state.internals.metrics.RocksDBMetricsRecorder; + +public abstract class AbstractTransactionalStore<T extends KeyValueStore<Bytes, byte[]>> implements KeyValueStore<Bytes, byte[]> { + private static final byte MODIFICATION = 0x1; + private static final byte DELETION = 0x2; + private static final byte[] DELETION_VAL = {DELETION}; + + private StateStoreContext context; + + static final String PREFIX = "transactional-"; + //VisibleForTesting + public static final String TMP_SUFFIX = ".tmp"; + + private final Set<MergeKeyValueIterator> openIterators = Collections.synchronizedSet(new HashSet<>()); + + Map<String, Object> configs; + File stateDir; + + private boolean consistencyEnabled = false; + private Position position; + protected OffsetCheckpoint positionCheckpoint; + + KeyValueSegment createTmpStore(final String segmentName, + final String windowName, + final long segmentId, + final RocksDBMetricsRecorder metricsRecorder) { + return new KeyValueSegment(segmentName + TMP_SUFFIX, + windowName, + segmentId, + metricsRecorder); + } + + public abstract T mainStore(); + + public abstract KeyValueSegment tmpStore(); + + @Deprecated + @Override + public void init(final ProcessorContext context, final StateStore root) { + if (context instanceof StateStoreContext) { + init((StateStoreContext) context, root); + } else { + throw new UnsupportedOperationException( + "Use TransactionalKeyValueStore#init(StateStoreContext, StateStore) instead." + ); + } + } + + @Override + public void init(final StateStoreContext context, final StateStore root) { + this.context = context; + + doInit(context.appConfigs(), context.stateDir()); + ((RocksDBStore) mainStore()).openDB(configs, stateDir); + + final File positionCheckpointFile = new File(context.stateDir(), name() + ".position"); + this.positionCheckpoint = new OffsetCheckpoint(positionCheckpointFile); + this.position = StoreQueryUtils.readPositionFromCheckpoint(positionCheckpoint); + tmpStore().consistencyEnabled = consistencyEnabled; + + // register and possibly restore the state from the logs + context.register( + root, + (RecordBatchingStateRestoreCallback) this::restoreBatch, + () -> StoreQueryUtils.checkpointPosition(positionCheckpoint, position) + ); + + consistencyEnabled = StreamsConfig.InternalConfig.getBoolean( + context.appConfigs(), + IQ_CONSISTENCY_OFFSET_VECTOR_ENABLED, + false); + } + + private void restoreBatch(final Collection<ConsumerRecord<byte[], byte[]>> records) { + final Collection<ConsumerRecord<byte[], byte[]>> changelogRecords = records + .stream() + .map(record -> new ConsumerRecord<>( + record.topic(), + record.partition(), + record.offset(), + record.key(), + toUncommittedValue(record.value()))) + .collect(Collectors.toList()); + tmpStore().restoreBatch(changelogRecords); + commit(null); + } + + void doInit(final Map<String, Object> configs, final File stateDir) { + this.configs = configs; + this.stateDir = stateDir; + tmpStore().openDB(configs, stateDir); + } + + @Override + public synchronized void close() { + final HashSet<KeyValueIterator<Bytes, byte[]>> iterators; + synchronized (openIterators) { + iterators = new HashSet<>(openIterators); + } + for (final KeyValueIterator<Bytes, byte[]> iterator : iterators) { + iterator.close(); + } + + tmpStore().close(); + mainStore().close(); + } + + @Override + public void commit(final Long changelogOffset) { + tmpStore().commit(changelogOffset); + doCommit(); + } Review Comment: I like the idea of decoupling rocksdb flush from the kafka producer commit because a slow commit/flush process would greatly reduce the feasibility of having a small commit interval (i.e. 50ms) in latency-sensitive applications. However, one interesting side effect of coupling the producer.commit() with tmpStore.commit() is that it would enable a later KIP which allows Interactive Queries to only read committed values by directing the IQ to only the main store. As we stand, IQ can read uncommitted values from the store (generally that's not a _huge_ problem since most processing is deterministic). -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
