stevenzwu commented on code in PR #4329: URL: https://github.com/apache/iceberg/pull/4329#discussion_r884429289
########## flink/v1.14/flink/src/main/java/org/apache/iceberg/flink/source/enumerator/ContinuousSplitPlannerImpl.java: ########## @@ -0,0 +1,172 @@ +/* + * 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.iceberg.flink.source.enumerator; + +import java.util.Collections; +import java.util.List; +import java.util.Optional; +import java.util.concurrent.ExecutorService; +import org.apache.flink.annotation.Internal; +import org.apache.flink.annotation.VisibleForTesting; +import org.apache.iceberg.Snapshot; +import org.apache.iceberg.Table; +import org.apache.iceberg.flink.source.FlinkSplitPlanner; +import org.apache.iceberg.flink.source.ScanContext; +import org.apache.iceberg.flink.source.StreamingStartingStrategy; +import org.apache.iceberg.flink.source.split.IcebergSourceSplit; +import org.apache.iceberg.util.SnapshotUtil; +import org.apache.iceberg.util.ThreadPools; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +@Internal +public class ContinuousSplitPlannerImpl implements ContinuousSplitPlanner { + private static final Logger LOG = LoggerFactory.getLogger(ContinuousSplitPlannerImpl.class); + + private final Table table; + private final ScanContext scanContext; + private final ExecutorService workerPool; + + public ContinuousSplitPlannerImpl(Table table, ScanContext scanContext, String threadPoolName) { + this.table = table; + this.scanContext = scanContext; + this.workerPool = ThreadPools.newWorkerPool( + "iceberg-plan-worker-pool-" + threadPoolName, scanContext.planParallelism()); + } + + @Override + public ContinuousEnumerationResult planSplits(IcebergEnumeratorPosition lastPosition) { + table.refresh(); + if (lastPosition != null) { + return discoverIncrementalSplits(lastPosition); + } else { + return discoverInitialSplits(); + } + } + + /** + * Discover incremental changes between @{code lastPosition} and current table snapshot + */ + private ContinuousEnumerationResult discoverIncrementalSplits(IcebergEnumeratorPosition lastPosition) { + Snapshot currentSnapshot = table.currentSnapshot(); + if (currentSnapshot == null) { + // empty table + IcebergEnumeratorPosition newPosition = new IcebergEnumeratorPosition(null, null); + LOG.info("Skip incremental scan because table is empty"); + return new ContinuousEnumerationResult(Collections.emptyList(), lastPosition, newPosition); + } else { + if (lastPosition.snapshotId() != null && currentSnapshot.snapshotId() == lastPosition.snapshotId()) { + LOG.info("Current table snapshot is already enumerated: {}", currentSnapshot.snapshotId()); + return new ContinuousEnumerationResult(Collections.emptyList(), lastPosition, lastPosition); + } else { + IcebergEnumeratorPosition newPosition = new IcebergEnumeratorPosition( + currentSnapshot.snapshotId(), currentSnapshot.timestampMillis()); + ScanContext incrementalScan = scanContext + .copyWithAppendsBetween(lastPosition.snapshotId(), currentSnapshot.snapshotId()); + List<IcebergSourceSplit> splits = FlinkSplitPlanner.planIcebergSourceSplits(table, incrementalScan, workerPool); + LOG.info("Discovered {} splits from incremental scan: " + + "from snapshot (exclusive) is {}, to snapshot (inclusive) is {}", + splits.size(), lastPosition, newPosition); + return new ContinuousEnumerationResult(splits, lastPosition, newPosition); + } + } + } + + /** + * Discovery initial set of splits based on {@link StreamingStartingStrategy}. + * + * <li>{@link ContinuousEnumerationResult#splits()} should contain initial splits + * discovered from table scan for {@link StreamingStartingStrategy#TABLE_SCAN_THEN_INCREMENTAL}. + * For all other strategies, splits collection should be empty. + * <li>{@link ContinuousEnumerationResult#toPosition()} points to the starting position + * for the next incremental split discovery with exclusive behavior. Meaning files committed + * by the snapshot from the position in {@code ContinuousEnumerationResult} won't be included + * in the next incremental scan. + */ + private ContinuousEnumerationResult discoverInitialSplits() { + Optional<Snapshot> startSnapshotOptional = getStartSnapshot(table, scanContext); + if (!startSnapshotOptional.isPresent()) { + return new ContinuousEnumerationResult(Collections.emptyList(), null, + new IcebergEnumeratorPosition(null, null)); + } + + Snapshot startSnapshot = startSnapshotOptional.get(); + LOG.info("Get starting snapshot id {} based on strategy {}", + startSnapshot.snapshotId(), scanContext.startingStrategy()); + List<IcebergSourceSplit> splits; + IcebergEnumeratorPosition toPosition; + if (scanContext.startingStrategy() == StreamingStartingStrategy.TABLE_SCAN_THEN_INCREMENTAL) { + // do a full table scan first + splits = FlinkSplitPlanner.planIcebergSourceSplits(table, scanContext, workerPool); + LOG.info("Discovered {} splits from initial full table scan with snapshot Id {}", + splits.size(), startSnapshot.snapshotId()); + toPosition = new IcebergEnumeratorPosition(startSnapshot.snapshotId(), startSnapshot.timestampMillis()); + } else { + splits = Collections.emptyList(); + // Use parentId to achieve the inclusive behavior. + // Note that it is fine if parentId is null. + Long parentSnapshotId = startSnapshot.parentId(); + Long parentSnapshotTimestampMs = null; + if (parentSnapshotId != null) { + parentSnapshotTimestampMs = table.snapshot(parentSnapshotId).timestampMillis(); + } + + toPosition = new IcebergEnumeratorPosition(parentSnapshotId, parentSnapshotTimestampMs); + LOG.info("Start incremental scan with start snapshot (inclusive): id = {}, timestamp = {}", + startSnapshot.snapshotId(), startSnapshot.timestampMillis()); + } + + return new ContinuousEnumerationResult(splits, null, toPosition); + } + + /** + * Optional is used because table may be empty and has no snapshot + */ + @VisibleForTesting + static Optional<Snapshot> getStartSnapshot(Table table, ScanContext scanContext) { + switch (scanContext.startingStrategy()) { + case TABLE_SCAN_THEN_INCREMENTAL: + case INCREMENTAL_FROM_LATEST_SNAPSHOT: + return Optional.ofNullable(table.currentSnapshot()); + case INCREMENTAL_FROM_EARLIEST_SNAPSHOT: + return Optional.ofNullable(SnapshotUtil.oldestAncestor(table)); + case INCREMENTAL_FROM_SNAPSHOT_ID: Review Comment: Except for `TABLE_SCAN_THEN_INCREMENTAL`, all other starting strategy is inclusive from the starting snapshot. -- This is an automated message from the Apache Git Service. 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