showuon commented on code in PR #13456: URL: https://github.com/apache/kafka/pull/13456#discussion_r1154172866
########## storage/src/main/java/org/apache/kafka/storage/internals/checkpoint/InMemoryLeaderEpochCheckpoint.java: ########## @@ -0,0 +1,58 @@ +/* + * 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.storage.internals.checkpoint; + +import org.apache.kafka.server.common.CheckpointFile; +import org.apache.kafka.storage.internals.log.EpochEntry; + +import java.io.BufferedWriter; +import java.io.ByteArrayOutputStream; +import java.io.IOException; +import java.io.OutputStreamWriter; +import java.nio.ByteBuffer; +import java.nio.charset.StandardCharsets; +import java.util.ArrayList; +import java.util.Collection; +import java.util.List; + +/** + * This class stores a list of EpochEntry(LeaderEpoch + Offsets) to memory + */ +public class InMemoryLeaderEpochCheckpoint implements LeaderEpochCheckpoint { Review Comment: @divijvaidya, Sorry for not being clear and waste your time to try understanding this PR. My bad! The motivation for introducing `InMemoryLeaderEpochCheckpoint` is to allow remote log manager to create the `RemoteLogSegmentMetadata`(RLSM) with the correct leader epoch info for a specific segment. To do that, we need to rely on the `LeaderEpochCheckpointCache` to truncate from start and end, to get the epoch info. However, we don't really want to truncate the epochs in cache (and write to checkpoint file in the end). So, we introduce this `InMemoryLeaderEpochCheckpoint` to feed into `LeaderEpochCheckpointCache`, and when we truncate the epoch for RLSM, we can do them in memory without affecting the checkpoint file, and without interacting with file system. Does that make sense? I'll update in the PR description, and remove the methods that not used currently. -- 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: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
