ccaominh commented on a change in pull request #8925: Parallel indexing single dim partitions URL: https://github.com/apache/incubator-druid/pull/8925#discussion_r351010752
########## File path: indexing-service/src/main/java/org/apache/druid/indexing/common/task/RangePartitionCachingLocalSegmentAllocator.java ########## @@ -0,0 +1,195 @@ +/* + * 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.druid.indexing.common.task; + +import com.google.common.collect.Maps; +import org.apache.druid.data.input.InputRow; +import org.apache.druid.indexing.common.TaskToolbox; +import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec; +import org.apache.druid.timeline.partition.SingleDimensionShardSpec; +import org.joda.time.Interval; + +import javax.annotation.Nullable; +import java.io.IOException; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Collections; +import java.util.List; +import java.util.Map; +import java.util.function.Function; +import java.util.stream.Collectors; +import java.util.stream.IntStream; + +/** + * Allocates all necessary range-partitioned segments locally at the beginning and reuses them. + * + * @see CachingLocalSegmentAllocator + */ +public class RangePartitionCachingLocalSegmentAllocator implements IndexTaskSegmentAllocator +{ + private final String dataSource; + private final String partitionDimension; + private final Map<Interval, String[]> intervalsToPartitions; + private final IndexTaskSegmentAllocator delegate; + + public RangePartitionCachingLocalSegmentAllocator( + TaskToolbox toolbox, + String taskId, + String supervisorTaskId, + String dataSource, + String partitionDimension, + Map<Interval, String[]> intervalsToPartitions + ) throws IOException + { + this.dataSource = dataSource; + this.partitionDimension = partitionDimension; + this.intervalsToPartitions = intervalsToPartitions; + + this.delegate = new CachingLocalSegmentAllocator( + toolbox, + taskId, + supervisorTaskId, + this::getIntervalToSegmentIds + ); + } + + private Map<Interval, List<SegmentIdWithShardSpec>> getIntervalToSegmentIds(Function<Interval, String> versionFinder) + { + Map<Interval, List<SegmentIdWithShardSpec>> intervalToSegmentIds = + Maps.newHashMapWithExpectedSize(intervalsToPartitions.size()); + + intervalsToPartitions.forEach( + (interval, partitions) -> + intervalToSegmentIds.put( + interval, + translatePartitions(interval, partitions, versionFinder) + ) + ); + + return intervalToSegmentIds; + } + + private List<SegmentIdWithShardSpec> translatePartitions( + Interval interval, + String[] partitions, + Function<Interval, String> versionFinder + ) + { + if (partitions.length == 0) { + return Collections.emptyList(); + } + + String[] uniquePartitions = Arrays.stream(partitions).distinct().toArray(String[]::new); + int numUniquePartition = uniquePartitions.length; + + if (numUniquePartition == 1) { + return Collections.singletonList( + createLastSegmentIdWithShardSpec( + interval, + versionFinder.apply(interval), + uniquePartitions[0], + 0 + ) + ); + } + + if (isLastPartitionOnlyMaxValue(partitions)) { + // The last partition only contains the max value. A shard that just contains the max value is likely to be + // small, so combine it with the second to last one. + numUniquePartition -= 1; + } + + List<SegmentIdWithShardSpec> segmentIds = + IntStream.range(0, numUniquePartition - 1) + .mapToObj(i -> createSegmentIdWithShardSpec( + interval, + versionFinder.apply(interval), + uniquePartitions[i], + uniquePartitions[i + 1], + i + )) + .collect(Collectors.toCollection(ArrayList::new)); Review comment: The [javadoc for Collectors.toList()](https://docs.oracle.com/javase/8/docs/api/java/util/stream/Collectors.html#toList--) states: > There are no guarantees on the type, mutability, serializability, or thread-safety of the List returned Since the returned `List` needs to be mutated, I specified the list implementation used by the `Collector`. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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