Fly-Style commented on code in PR #19212: URL: https://github.com/apache/druid/pull/19212#discussion_r3026259821
########## sql/src/main/java/org/apache/druid/sql/calcite/schema/BrokerServerViewOfLatestUsedSegments.java: ########## @@ -0,0 +1,380 @@ +/* + * 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.sql.calcite.schema; + +import com.google.common.collect.Ordering; +import com.google.inject.Inject; +import org.apache.druid.client.BrokerServerView; +import org.apache.druid.client.BrokerViewOfCoordinatorConfig; +import org.apache.druid.client.DruidServer; +import org.apache.druid.client.ImmutableDruidServer; +import org.apache.druid.client.ServerView; +import org.apache.druid.client.TimelineServerView; +import org.apache.druid.client.selector.ServerSelector; +import org.apache.druid.client.selector.TierSelectorStrategy; +import org.apache.druid.guice.ManageLifecycle; +import org.apache.druid.java.util.common.ISE; +import org.apache.druid.java.util.common.concurrent.Execs; +import org.apache.druid.java.util.common.logger.Logger; +import org.apache.druid.query.QueryRunner; +import org.apache.druid.query.TableDataSource; +import org.apache.druid.segment.realtime.appenderator.SegmentSchemas; +import org.apache.druid.server.coordination.DruidServerMetadata; +import org.apache.druid.timeline.DataSegment; +import org.apache.druid.timeline.SegmentId; +import org.apache.druid.timeline.TimelineLookup; +import org.apache.druid.timeline.VersionedIntervalTimeline; +import org.apache.druid.timeline.partition.PartitionChunk; + +import javax.inject.Named; +import java.util.ArrayList; +import java.util.Collection; +import java.util.HashMap; +import java.util.HashSet; +import java.util.List; +import java.util.Map; +import java.util.Optional; +import java.util.Set; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ConcurrentMap; +import java.util.concurrent.CountDownLatch; +import java.util.concurrent.Executor; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.function.Function; + +/** + * A {@link TimelineServerView} that exposes a superset of {@link BrokerServerView}: + * segments available on servers plus used segments that exist only in metadata. + * <p> + * This class maintains a merged per-datasource timeline updated incrementally from + * {@link BrokerServerView} and {@link MetadataSegmentView} callbacks. + */ +@ManageLifecycle +public class BrokerServerViewOfLatestUsedSegments implements TimelineServerView +{ + private static final Logger log = new Logger(BrokerServerViewOfLatestUsedSegments.class); + + private final BrokerServerView brokerServerView; + private final boolean isCacheEnabled; + private final TierSelectorStrategy historicalTierSelectorStrategy; + private final TierSelectorStrategy realtimeTierSelectorStrategy; + private final BrokerViewOfCoordinatorConfig brokerViewOfCoordinatorConfig; + + // LOCK ORDERING: BsvCallback executes on the BrokerServerView callback thread, which holds + // BrokerServerView.lock (via directExecutor). BsvCallback then acquires this.lock. + // Therefore, this.lock must NEVER be held when calling into BrokerServerView (e.g.getBsvSelector), + // as that would invert the order and risk deadlock. + private final Object lock = new Object(); + private final Map<String, VersionedIntervalTimeline<String, ServerSelector>> mergedTimelines = new HashMap<>(); + private final Map<SegmentId, ServerSelector> mergedSelectors = new HashMap<>(); + private final Map<SegmentId, DataSegment> metadataSegments = new HashMap<>(); + private final Set<SegmentId> metadataRemovedSegmentIds = new HashSet<>(); + + private final ConcurrentMap<TimelineCallback, Executor> timelineCallbacks = new ConcurrentHashMap<>(); + private final CountDownLatch brokerViewInitLatch = new CountDownLatch(1); + private final CountDownLatch metadataViewInitLatch = new CountDownLatch(1); + private final AtomicBoolean initialized = new AtomicBoolean(false); + + @Inject + public BrokerServerViewOfLatestUsedSegments( + final BrokerServerView brokerServerView, + final MetadataSegmentView metadataSegmentView, + final BrokerSegmentMetadataCacheConfig cacheConfig, + final TierSelectorStrategy historicalTierSelectorStrategy, + @Named(BrokerServerView.REALTIME_SELECTOR) final TierSelectorStrategy realtimeTierSelectorStrategy, + final BrokerViewOfCoordinatorConfig brokerViewOfCoordinatorConfig + ) + { + this.brokerServerView = brokerServerView; + this.isCacheEnabled = cacheConfig.isMetadataSegmentCacheEnable(); + this.historicalTierSelectorStrategy = historicalTierSelectorStrategy; + this.realtimeTierSelectorStrategy = realtimeTierSelectorStrategy; + this.brokerViewOfCoordinatorConfig = brokerViewOfCoordinatorConfig; + + brokerServerView.registerTimelineCallback(Execs.directExecutor(), new BsvCallback()); + metadataSegmentView.registerSegmentViewCallback(Execs.directExecutor(), new MsvCallback()); + } + + @SuppressWarnings("unchecked") + @Override + public <T extends TimelineLookup<String, ServerSelector>> Optional<T> getTimeline(final TableDataSource dataSource) + { + ensureCacheEnabled(); + + final VersionedIntervalTimeline<String, ServerSelector> mergedTimeline; + synchronized (lock) { + mergedTimeline = mergedTimelines.get(dataSource.getName()); + if (mergedTimeline == null || mergedTimeline.isEmpty()) { + return Optional.empty(); + } + } + + return Optional.of((T) mergedTimeline); + } + + @Override + public List<ImmutableDruidServer> getDruidServers() + { + ensureCacheEnabled(); + return brokerServerView.getDruidServers(); + } + + @Override + public <T> QueryRunner<T> getQueryRunner(final DruidServer server) + { + ensureCacheEnabled(); + return brokerServerView.getQueryRunner(server); + } + + @Override + public void registerTimelineCallback(final Executor exec, final TimelineCallback callback) + { + ensureCacheEnabled(); + timelineCallbacks.put(callback, exec); + } + + @Override + public void registerServerCallback(final Executor exec, final ServerCallback callback) + { + ensureCacheEnabled(); + brokerServerView.registerServerCallback(exec, callback); + } + + @Override + public void registerSegmentCallback(final Executor exec, final SegmentCallback callback) + { + ensureCacheEnabled(); + brokerServerView.registerSegmentCallback(exec, callback); + } + + private class BsvCallback implements TimelineCallback + { + @Override + public ServerView.CallbackAction timelineInitialized() + { + brokerViewInitLatch.countDown(); + maybeFireInitialized(); + return ServerView.CallbackAction.CONTINUE; + } + + @Override + public ServerView.CallbackAction segmentAdded(final DruidServerMetadata server, final DataSegment segment) + { + final ServerSelector selector = getBsvSelector(segment); + final boolean visible; + + synchronized (lock) { + visible = selector != null && !metadataRemovedSegmentIds.contains(segment.getId()); + if (visible) { + upsertMergedSelector(selector); + } + } + + if (visible) { + runTimelineCallbacks(cb -> cb.segmentAdded(server, segment)); + } + return ServerView.CallbackAction.CONTINUE; + } + + @Override + public ServerView.CallbackAction segmentRemoved(final DataSegment segment) + { + final boolean shouldRemainVisibleAsUnavailable; + final boolean shouldFireRemoved; + + synchronized (lock) { + final SegmentId segmentId = segment.getId(); + shouldRemainVisibleAsUnavailable = metadataSegments.containsKey(segmentId) + && !metadataRemovedSegmentIds.contains(segmentId); + if (shouldRemainVisibleAsUnavailable) { + upsertMergedSelector(createEmptySelector(segment)); + } else { + removeMergedSelector(segmentId); + } + shouldFireRemoved = !shouldRemainVisibleAsUnavailable && !metadataRemovedSegmentIds.contains(segmentId); + } + + if (shouldFireRemoved) { + runTimelineCallbacks(cb -> cb.segmentRemoved(segment)); + } + return ServerView.CallbackAction.CONTINUE; + } + + @Override + public ServerView.CallbackAction serverSegmentRemoved(final DruidServerMetadata server, final DataSegment segment) + { + runTimelineCallbacks(cb -> cb.serverSegmentRemoved(server, segment)); + return ServerView.CallbackAction.CONTINUE; + } + + @Override + public ServerView.CallbackAction segmentSchemasAnnounced(final SegmentSchemas segmentSchemas) + { + runTimelineCallbacks(cb -> cb.segmentSchemasAnnounced(segmentSchemas)); + return ServerView.CallbackAction.CONTINUE; + } + } + + private class MsvCallback implements MetadataSegmentViewCallback + { + @Override + public void timelineInitialized() + { + metadataViewInitLatch.countDown(); + maybeFireInitialized(); + } + + @Override + public void segmentsAdded(final Collection<DataSegment> segments) + { + // Pre-compute BSV selectors outside lock to respect lock ordering. + final Map<SegmentId, ServerSelector> bsvSelectors = new HashMap<>(); + for (DataSegment segment : segments) { + bsvSelectors.put(segment.getId(), getBsvSelector(segment)); + } + + synchronized (lock) { + for (DataSegment segment : segments) { + final SegmentId segmentId = segment.getId(); + final ServerSelector bsvSelector = bsvSelectors.get(segmentId); + + metadataSegments.put(segmentId, segment); + metadataRemovedSegmentIds.remove(segmentId); + if (bsvSelector != null) { + if (mergedSelectors.get(segmentId) != bsvSelector) { + upsertMergedSelector(bsvSelector); + } + } else if (!mergedSelectors.containsKey(segmentId)) { + upsertMergedSelector(createEmptySelector(segment)); + } + } + } + } + + @Override + public void segmentsRemoved(final Collection<SegmentId> segmentIds) + { + final List<DataSegment> toFireRemoved = new ArrayList<>(); + + synchronized (lock) { + for (SegmentId segmentId : segmentIds) { + final DataSegment metadataSegment = metadataSegments.remove(segmentId); + metadataRemovedSegmentIds.add(segmentId); Review Comment: Good catch - you're right that the original implementation had unbounded growth. This has been fixed: `BsvCallback.segmentRemoved` now calls `metadataRemovedSegmentIds.remove(segmentId)` when BSV confirms a segment is fully gone, so the set drains as the lag window closes. It was done to guard against a race condition between the two callback sources. When **MSV** marks a segment as removed (coordinator says it's unused), we immediately remove it from the merged timeline. However, **BSV** still _may_ hold the segment because the historical hasn't unloaded it yet. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
