satishd commented on a change in pull request #10218: URL: https://github.com/apache/kafka/pull/10218#discussion_r591603442
########## File path: clients/src/main/java/org/apache/kafka/server/log/remote/storage/RemoteLogMetadataCache.java ########## @@ -0,0 +1,152 @@ +/* + * 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.server.log.remote.storage; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.Comparator; +import java.util.HashSet; +import java.util.Iterator; +import java.util.Map; +import java.util.NavigableMap; +import java.util.Optional; +import java.util.Set; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ConcurrentMap; +import java.util.concurrent.ConcurrentSkipListMap; +import java.util.stream.Collectors; + +/** + * This class provides an imemory cache of remote log segment metadata. This maintains the lineage of segments + * with respect to epoch evolution. It also keeps track of segments which are not considered to be copied to remote + * storage. + */ +public class RemoteLogMetadataCache { + private static final Logger log = LoggerFactory.getLogger(RemoteLogMetadataCache.class); + + private final ConcurrentMap<RemoteLogSegmentId, RemoteLogSegmentMetadata> idToSegmentMetadata + = new ConcurrentHashMap<>(); + + private final Set<RemoteLogSegmentId> remoteLogSegmentIdInProgress = new HashSet<>(); + + private final ConcurrentMap<Integer, NavigableMap<Long, RemoteLogSegmentId>> leaderEpochToOffsetToId + = new ConcurrentHashMap<>(); + + public RemoteLogMetadataCache() { + } + + private void addRemoteLogSegmentMetadata(RemoteLogSegmentMetadata remoteLogSegmentMetadata) { + log.debug("Adding remote log segment metadata: [{}]", remoteLogSegmentMetadata); + idToSegmentMetadata.put(remoteLogSegmentMetadata.remoteLogSegmentId(), remoteLogSegmentMetadata); + Map<Integer, Long> leaderEpochToOffset = remoteLogSegmentMetadata.segmentLeaderEpochs(); + for (Map.Entry<Integer, Long> entry : leaderEpochToOffset.entrySet()) { + leaderEpochToOffsetToId.computeIfAbsent(entry.getKey(), k -> new ConcurrentSkipListMap<>()) + .put(entry.getValue(), remoteLogSegmentMetadata.remoteLogSegmentId()); + } + } + + public Optional<RemoteLogSegmentMetadata> remoteLogSegmentMetadata(int leaderEpoch, long offset) { + NavigableMap<Long, RemoteLogSegmentId> offsetToId = leaderEpochToOffsetToId.get(leaderEpoch); + if (offsetToId == null || offsetToId.isEmpty()) { + return Optional.empty(); + } + + // look for floor entry as the given offset may exist in this entry. + Map.Entry<Long, RemoteLogSegmentId> entry = offsetToId.floorEntry(offset); + if (entry == null) { + // if the offset is lower than the minimum offset available in metadata then return null. + return Optional.empty(); + } + + RemoteLogSegmentMetadata remoteLogSegmentMetadata = idToSegmentMetadata.get(entry.getValue()); + // check whether the given offset with leaderEpoch exists in this segment. + // check for epoch's offset boundaries with in this segment. + // 1. get the next epoch's start offset -1 if exists + // 2. if no next epoch exists, then segment end offset can be considered as epoch's relative end offset. + Map.Entry<Integer, Long> nextEntry = remoteLogSegmentMetadata.segmentLeaderEpochs() + .higherEntry(leaderEpoch); + long epochEndOffset = (nextEntry != null) ? nextEntry.getValue() - 1 : remoteLogSegmentMetadata.endOffset(); + + // seek offset should be <= epoch's end offset. + return (offset > epochEndOffset) ? Optional.empty() : Optional.of(remoteLogSegmentMetadata); + } + + public void updateRemoteLogSegmentMetadata(RemoteLogSegmentMetadataUpdate rlsmUpdate) + throws RemoteResourceNotFoundException { + RemoteLogSegmentId remoteLogSegmentId = rlsmUpdate.remoteLogSegmentId(); + RemoteLogSegmentMetadata rlsm = idToSegmentMetadata.get(remoteLogSegmentId); + if (rlsm == null) { + throw new RemoteResourceNotFoundException("No remote log segment metadata found for : " + + remoteLogSegmentId); + } + + log.debug("Updating remote log segment metadata: [{}]", rlsmUpdate); + RemoteLogSegmentMetadata updatedRlsm = rlsm.createRemoteLogSegmentWithUpdates(rlsmUpdate); + idToSegmentMetadata.put(remoteLogSegmentId, updatedRlsm); + if (rlsmUpdate.state() != RemoteLogSegmentState.COPY_SEGMENT_STARTED) { + remoteLogSegmentIdInProgress.remove(remoteLogSegmentId); + addRemoteLogSegmentMetadata(updatedRlsm); + } + + if (rlsmUpdate.state() == RemoteLogSegmentState.DELETE_SEGMENT_FINISHED) { + log.debug("Cleaning up the state for : [{}]", rlsmUpdate); + // remove this entry when the state is moved to delete_segment_finished + Map<Integer, Long> leaderEpochs = rlsm.segmentLeaderEpochs(); + for (Map.Entry<Integer, Long> entry : leaderEpochs.entrySet()) { + NavigableMap<Long, RemoteLogSegmentId> offsetToIds = leaderEpochToOffsetToId.get(entry.getKey()); + // remove the mappings where this segment is deleted. + offsetToIds.values().remove(remoteLogSegmentId); + } + + // remove the segment-id mapping. + idToSegmentMetadata.remove(remoteLogSegmentId); + } + } + + public Iterator<RemoteLogSegmentMetadata> listAllRemoteLogSegments() { + ArrayList<RemoteLogSegmentMetadata> list = new ArrayList<>(idToSegmentMetadata.values()); + list.addAll(remoteLogSegmentIdInProgress.stream().map(id -> idToSegmentMetadata.get(id)) + .collect(Collectors.toList())); + list.sort(Comparator.comparingLong(RemoteLogSegmentMetadata::startOffset)); + return list.iterator(); + } + + public Iterator<RemoteLogSegmentMetadata> listRemoteLogSegments(int leaderEpoch) { + NavigableMap<Long, RemoteLogSegmentId> map = leaderEpochToOffsetToId.get(leaderEpoch); + return map != null ? map.values().stream().map(id -> idToSegmentMetadata.get(id)).iterator() + : Collections.emptyIterator(); + } + + public Long highestLogOffset(int leaderEpoch) { Review comment: No, it is not highestSegmentStartOffset but it is the highest log offset for the given leader epoch. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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