vcrfxia commented on code in PR #13188: URL: https://github.com/apache/kafka/pull/13188#discussion_r1099321787
########## streams/src/main/java/org/apache/kafka/streams/state/internals/RocksDBVersionedStore.java: ########## @@ -0,0 +1,792 @@ +/* + * 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 java.io.File; +import java.nio.ByteBuffer; +import java.util.Collection; +import java.util.List; +import java.util.Optional; +import org.apache.kafka.clients.consumer.ConsumerRecord; +import org.apache.kafka.common.metrics.Sensor; +import org.apache.kafka.common.utils.Bytes; +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.ProcessorContextUtils; +import org.apache.kafka.streams.processor.internals.RecordBatchingStateRestoreCallback; +import org.apache.kafka.streams.processor.internals.StoreToProcessorContextAdapter; +import org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl; +import org.apache.kafka.streams.processor.internals.metrics.TaskMetrics; +import org.apache.kafka.streams.query.Position; +import org.apache.kafka.streams.state.VersionedKeyValueStore; +import org.apache.kafka.streams.state.VersionedRecord; +import org.apache.kafka.streams.state.internals.RocksDBVersionedStoreSegmentValueFormatter.SegmentValue; +import org.apache.kafka.streams.state.internals.RocksDBVersionedStoreSegmentValueFormatter.SegmentValue.SegmentSearchResult; +import org.apache.kafka.streams.state.internals.metrics.RocksDBMetricsRecorder; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * A persistent, versioned key-value store based on RocksDB. + * <p> + * This store implementation consists of a "latest value store" and "segment stores." The latest + * record version for each key is stored in the latest value store, while older record versions + * are stored in the segment stores. Conceptually, each record version has two associated + * timestamps: + * <ul> + * <li>a {@code validFrom} timestamp. This timestamp is explicitly associated with the record + * as part of the {@link VersionedKeyValueStore#put(Object, Object, long)}} call to the store; + * i.e., this is the record's timestamp.</li> + * <li>a {@code validTo} timestamp. This is the timestamp of the next record (or deletion) + * associated with the same key, and is implicitly associated with the record. This timestamp + * can change as new records are inserted into the store.</li> + * </ul> + * The validity interval of a record is from validFrom (inclusive) to validTo (exclusive), and + * can change as new record versions are inserted into the store (and validTo changes as a result). + * <p> + * Old record versions are stored in segment stores according to their validTo timestamps. This + * allows for efficient expiry of old record versions, as entire segments can be dropped from the + * store at a time, once the records contained in the segment are no longer relevant based on the + * store's history retention (for an explanation of "history retention", see + * {@link VersionedKeyValueStore}). Multiple record versions (for the same key) within a single + * segment are stored together using the format specified in {@link RocksDBVersionedStoreSegmentValueFormatter}. + */ +public class RocksDBVersionedStore implements VersionedKeyValueStore<Bytes, byte[]> { + private static final Logger LOG = LoggerFactory.getLogger(RocksDBVersionedStore.class); + // a marker to indicate that no record version has yet been found as part of an ongoing + // put() procedure. any value which is not a valid record timestamp will do. + private static final long SENTINEL_TIMESTAMP = Long.MIN_VALUE; + + private final String name; + private final long historyRetention; + private final RocksDBMetricsRecorder metricsRecorder; + + private final RocksDBStore latestValueStore; + private final LogicalKeyValueSegments segmentStores; + private final LatestValueSchema latestValueSchema; + private final SegmentValueSchema segmentValueSchema; + private final VersionedStoreClient<LogicalKeyValueSegment> versionedStoreClient; + + private ProcessorContext context; + private StateStoreContext stateStoreContext; + private Sensor expiredRecordSensor; + private long observedStreamTime = ConsumerRecord.NO_TIMESTAMP; + private Position position; + private OffsetCheckpoint positionCheckpoint; + private volatile boolean open; + + RocksDBVersionedStore(final String name, final String metricsScope, final long historyRetention, final long segmentInterval) { + this.name = name; + this.historyRetention = historyRetention; + this.metricsRecorder = new RocksDBMetricsRecorder(metricsScope, name); + this.latestValueStore = new RocksDBStore(lvsName(name), name, metricsRecorder); + this.segmentStores = new LogicalKeyValueSegments(segmentsName(name), name, historyRetention, segmentInterval, metricsRecorder); + this.latestValueSchema = new LatestValueSchema(); + this.segmentValueSchema = new SegmentValueSchema(); + this.versionedStoreClient = new RocksDBVersionedStoreClient(); + } + + @Override + public void put(final Bytes key, final byte[] value, final long timestamp) { + + doPut( + latestValueSchema, + segmentValueSchema, + versionedStoreClient, + Optional.of(expiredRecordSensor), + context, + observedStreamTime, + historyRetention, + key, + value, + timestamp + ); + + observedStreamTime = Math.max(observedStreamTime, timestamp); + } + + @Override + public VersionedRecord<byte[]> delete(final Bytes key, final long timestamp) { + final VersionedRecord<byte[]> existingRecord = get(key, timestamp); + put(key, null, timestamp); + return existingRecord; + } + + @Override + public VersionedRecord<byte[]> get(final Bytes key) { + // latest value (if present) is guaranteed to be in the latest value store + final byte[] latestValue = latestValueStore.get(key); + if (latestValue != null) { + return new VersionedRecord<>( + latestValueSchema.getValue(latestValue), + latestValueSchema.getTimestamp(latestValue) + ); + } else { + return null; + } + } + + @Override + public VersionedRecord<byte[]> get(final Bytes key, final long asOfTimestamp) { + + if (asOfTimestamp < observedStreamTime - historyRetention) { + // history retention has elapsed. return null for predictability, even if data + // is still present in store. + return null; + } + + // first check the latest value store + final byte[] latestValue = latestValueStore.get(key); + if (latestValue != null) { + final long latestTimestamp = latestValueSchema.getTimestamp(latestValue); + if (latestTimestamp <= asOfTimestamp) { + return new VersionedRecord<>(latestValueSchema.getValue(latestValue), latestTimestamp); + } + } + + // check segment stores + final List<LogicalKeyValueSegment> segments = segmentStores.segments(asOfTimestamp, Long.MAX_VALUE, false); + for (final LogicalKeyValueSegment segment : segments) { + final byte[] segmentValue = segment.get(key); + if (segmentValue != null) { + final long nextTs = segmentValueSchema.getNextTimestamp(segmentValue); + if (nextTs <= asOfTimestamp) { + // this segment contains no data for the queried timestamp, so earlier segments + // cannot either + return null; + } + + if (segmentValueSchema.getMinTimestamp(segmentValue) > asOfTimestamp) { + // the segment only contains data for after the queried timestamp. skip and + // continue the search to earlier segments. as an optimization, this code + // could be updated to skip forward to the segment containing the minTimestamp + // in the if-condition above. + continue; + } + + // the desired result is contained in this segment + final SegmentSearchResult searchResult = + segmentValueSchema.deserialize(segmentValue).find(asOfTimestamp, true); + if (searchResult.value() != null) { + return new VersionedRecord<>(searchResult.value(), searchResult.validFrom()); + } else { + return null; + } + } + } + + // checked all segments and no results found + return null; + } + + @Override + public String name() { + return name; + } + + @Override + public void flush() { + // order shouldn't matter since failure to flush is a fatal exception + segmentStores.flush(); + latestValueStore.flush(); + } + + @Override + public void close() { + open = false; + + // close latest value store first so that calls to get() immediately begin to fail with + // store not open, as all calls to get() first get() from latest value store + latestValueStore.close(); + segmentStores.close(); + } + + @Override + public boolean persistent() { + return true; + } + + @Override + public boolean isOpen() { + return open; + } + + @Override + public Position getPosition() { + return position; + } + + @Deprecated + @Override + public void init(final ProcessorContext context, final StateStore root) { + this.context = context; + + final StreamsMetricsImpl metrics = ProcessorContextUtils.getMetricsImpl(context); + final String threadId = Thread.currentThread().getName(); + final String taskName = context.taskId().toString(); + + expiredRecordSensor = TaskMetrics.droppedRecordsSensor( + threadId, + taskName, + metrics + ); + + metricsRecorder.init(ProcessorContextUtils.getMetricsImpl(context), context.taskId()); + + latestValueStore.openDB(context.appConfigs(), context.stateDir()); + segmentStores.openExisting(context, observedStreamTime); + + final File positionCheckpointFile = new File(context.stateDir(), name() + ".position"); + this.positionCheckpoint = new OffsetCheckpoint(positionCheckpointFile); + this.position = StoreQueryUtils.readPositionFromCheckpoint(positionCheckpoint); + + // register and possibly restore the state from the logs + stateStoreContext.register( + root, + (RecordBatchingStateRestoreCallback) RocksDBVersionedStore.this::restoreBatch, + () -> StoreQueryUtils.checkpointPosition(positionCheckpoint, position) + ); + + open = true; + } + + @Override + public void init(final StateStoreContext context, final StateStore root) { + this.stateStoreContext = context; + init(StoreToProcessorContextAdapter.adapt(context), root); + } + + // VisibleForTesting + void restoreBatch(final Collection<ConsumerRecord<byte[], byte[]>> records) { + throw new UnsupportedOperationException("not yet implemented"); + } + + /** + * Generic interface for segment stores. See {@link VersionedStoreClient} for use. + */ + interface VersionedStoreSegment { + + /** + * @return segment id + */ + long id(); + + void put(Bytes key, byte[] value); + + byte[] get(Bytes key); + } + + /** + * Extracts all operations required for writing to the versioned store (via + * {@link #put(Bytes, byte[], long)}) into a generic client interface, so that the same + * {@code put(...)} logic can be shared during regular store operation and during restore. + * + * @param <T> the segment type used by this client + */ + interface VersionedStoreClient<T extends VersionedStoreSegment> { + + /** + * @return the contents of the latest value store, for the given key + */ + byte[] getLatestValue(Bytes key); + + /** + * Puts the provided key and value into the latest value store. + */ + void putLatestValue(Bytes key, byte[] value); + + /** + * Deletes the existing value (if any) from the latest value store, for the given key. + */ + void deleteLatestValue(Bytes key); + + /** + * @return the segment with the provided id, or {@code null} if the segment is expired + */ + T getOrCreateSegmentIfLive(long segmentId, ProcessorContext context, long streamTime); + + /** + * @return all segments in the store which contain timestamps at least the provided + * timestamp bound, in reverse order by segment id (and time), i.e., such that + * the most recent segment is first + */ + List<T> getReverseSegments(long timestampFrom); + + /** + * @return the segment id associated with the provided timestamp + */ + long segmentIdForTimestamp(long timestamp); + } + + /** + * Client for writing into (and reading from) this persistent {@link RocksDBVersionedStore}. + */ + private class RocksDBVersionedStoreClient implements VersionedStoreClient<LogicalKeyValueSegment> { + + @Override + public byte[] getLatestValue(final Bytes key) { + return latestValueStore.get(key); + } + + @Override + public void putLatestValue(final Bytes key, final byte[] value) { + latestValueStore.put(key, value); + } + + @Override + public void deleteLatestValue(final Bytes key) { + latestValueStore.delete(key); + } + + @Override + public LogicalKeyValueSegment getOrCreateSegmentIfLive(final long segmentId, final ProcessorContext context, final long streamTime) { + return segmentStores.getOrCreateSegmentIfLive(segmentId, context, streamTime); + } + + @Override + public List<LogicalKeyValueSegment> getReverseSegments(final long timestampFrom) { + return segmentStores.segments(timestampFrom, Long.MAX_VALUE, false); + } + + @Override + public long segmentIdForTimestamp(final long timestamp) { + return segmentStores.segmentId(timestamp); + } + } + + private static <T extends VersionedStoreSegment> void doPut( + final LatestValueSchema latestValueSchema, + final SegmentValueSchema segmentValueSchema, + final VersionedStoreClient<T> versionedStoreClient, + final Optional<Sensor> expiredRecordSensor, + final ProcessorContext context, + final long observedStreamTime, + final long historyRetention, + final Bytes key, + final byte[] value, + final long timestamp + ) { + // track the smallest timestamp seen so far that is larger than insertion timestamp. + // this timestamp determines, based on all segments searched so far, which segment the + // new record should be inserted into. the starting "sentinel timestamp" represents + // that the segment should be inserted into the latest value store. + long foundTs = SENTINEL_TIMESTAMP; + + // check latest value store + PutStatus status = putLatestValueStore( + latestValueSchema, + segmentValueSchema, + versionedStoreClient, + context, + observedStreamTime, + key, + value, + timestamp, + foundTs + ); + if (status.isComplete) { + return; + } else { + foundTs = status.foundTs; + } + + // continue search in segments + status = putSegments( + segmentValueSchema, + versionedStoreClient, + expiredRecordSensor, + context, + observedStreamTime, + historyRetention, + key, + value, + timestamp, + foundTs + ); + if (status.isComplete) { + return; + } else { + foundTs = status.foundTs; + } + + // ran out of segments to search. insert into segment as specified by foundTs + putFallThrough( Review Comment: Renamed to `finishPut()` for now. -- This is an automated message from the Apache Git Service. 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