wuguowei1994 commented on code in PR #18750: URL: https://github.com/apache/druid/pull/18750#discussion_r2621819211
########## indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/supervisor/OffsetSnapshot.java: ########## @@ -0,0 +1,89 @@ +/* + * 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.seekablestream.supervisor; + +import com.google.common.collect.ImmutableMap; +import com.google.common.collect.Maps; + +import javax.annotation.Nullable; +import java.util.Map; +import java.util.Objects; + +/** + * Immutable snapshot containing a consistent pair of offset maps: the highest ingested offsets + * reported by tasks and the latest end offsets fetched from the underlying stream. + * + * <p> + * The supervisor fetches task-reported ingested offsets first, then fetches end offsets from the stream. + * Because these two values are captured at slightly different instants, the reported lag + * (latestOffsetsFromStream - highestIngestedOffsets) may be slightly larger than the actual lag at any + * precise moment. + * + * <p> + * By publishing both maps together as a single atomic snapshot (using {@link java.util.concurrent.atomic.AtomicReference}), + * readers (such as lag metrics and supervisor status) always observe a coherent and consistent view. + * This produces stable and monotonic lag trends, avoiding artifacts like temporary negative lags. + * + * <p> + * This class is generic and can be reused by all seekable-stream supervisors (Kafka, Kinesis, etc.). + */ +public final class OffsetSnapshot<PartitionIdType, SequenceOffsetType> +{ + private final ImmutableMap<PartitionIdType, SequenceOffsetType> highestIngestedOffsets; + private final ImmutableMap<PartitionIdType, SequenceOffsetType> latestOffsetsFromStream; + + private OffsetSnapshot( + @Nullable Map<PartitionIdType, SequenceOffsetType> highestIngestedOffsets, + @Nullable Map<PartitionIdType, SequenceOffsetType> latestOffsetsFromStream + ) + { + this.highestIngestedOffsets = toImmutableOffsetMap(highestIngestedOffsets); + this.latestOffsetsFromStream = toImmutableOffsetMap(latestOffsetsFromStream); + } + + public static <PartitionIdType, SequenceOffsetType> OffsetSnapshot<PartitionIdType, SequenceOffsetType> of( + @Nullable Map<PartitionIdType, SequenceOffsetType> currentOffsets, + @Nullable Map<PartitionIdType, SequenceOffsetType> endOffsets + ) + { + return new OffsetSnapshot<>(currentOffsets, endOffsets); + } + + private ImmutableMap<PartitionIdType, SequenceOffsetType> toImmutableOffsetMap( + @Nullable Map<PartitionIdType, SequenceOffsetType> input + ) + { + if (input == null) { + return ImmutableMap.of(); + } + + return ImmutableMap.copyOf(Maps.filterValues(input, Objects::nonNull)); + } + + public ImmutableMap<PartitionIdType, SequenceOffsetType> getHighestIngestedOffsets() Review Comment: false positive, field is ImmutableMap ########## indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/supervisor/OffsetSnapshot.java: ########## @@ -0,0 +1,89 @@ +/* + * 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.seekablestream.supervisor; + +import com.google.common.collect.ImmutableMap; +import com.google.common.collect.Maps; + +import javax.annotation.Nullable; +import java.util.Map; +import java.util.Objects; + +/** + * Immutable snapshot containing a consistent pair of offset maps: the highest ingested offsets + * reported by tasks and the latest end offsets fetched from the underlying stream. + * + * <p> + * The supervisor fetches task-reported ingested offsets first, then fetches end offsets from the stream. + * Because these two values are captured at slightly different instants, the reported lag + * (latestOffsetsFromStream - highestIngestedOffsets) may be slightly larger than the actual lag at any + * precise moment. + * + * <p> + * By publishing both maps together as a single atomic snapshot (using {@link java.util.concurrent.atomic.AtomicReference}), + * readers (such as lag metrics and supervisor status) always observe a coherent and consistent view. + * This produces stable and monotonic lag trends, avoiding artifacts like temporary negative lags. + * + * <p> + * This class is generic and can be reused by all seekable-stream supervisors (Kafka, Kinesis, etc.). + */ +public final class OffsetSnapshot<PartitionIdType, SequenceOffsetType> +{ + private final ImmutableMap<PartitionIdType, SequenceOffsetType> highestIngestedOffsets; + private final ImmutableMap<PartitionIdType, SequenceOffsetType> latestOffsetsFromStream; + + private OffsetSnapshot( + @Nullable Map<PartitionIdType, SequenceOffsetType> highestIngestedOffsets, + @Nullable Map<PartitionIdType, SequenceOffsetType> latestOffsetsFromStream + ) + { + this.highestIngestedOffsets = toImmutableOffsetMap(highestIngestedOffsets); + this.latestOffsetsFromStream = toImmutableOffsetMap(latestOffsetsFromStream); + } + + public static <PartitionIdType, SequenceOffsetType> OffsetSnapshot<PartitionIdType, SequenceOffsetType> of( + @Nullable Map<PartitionIdType, SequenceOffsetType> currentOffsets, + @Nullable Map<PartitionIdType, SequenceOffsetType> endOffsets + ) + { + return new OffsetSnapshot<>(currentOffsets, endOffsets); + } + + private ImmutableMap<PartitionIdType, SequenceOffsetType> toImmutableOffsetMap( + @Nullable Map<PartitionIdType, SequenceOffsetType> input + ) + { + if (input == null) { + return ImmutableMap.of(); + } + + return ImmutableMap.copyOf(Maps.filterValues(input, Objects::nonNull)); + } + + public ImmutableMap<PartitionIdType, SequenceOffsetType> getHighestIngestedOffsets() + { + return highestIngestedOffsets; + } + + public ImmutableMap<PartitionIdType, SequenceOffsetType> getLatestOffsetsFromStream() Review Comment: false positive, field is ImmutableMap -- This is an automated message from the Apache Git Service. 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