junrao commented on code in PR #15671: URL: https://github.com/apache/kafka/pull/15671#discussion_r1595923193
########## raft/src/main/java/org/apache/kafka/raft/internals/TreeMapLogHistory.java: ########## @@ -0,0 +1,76 @@ +/* + * 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.raft.internals; + +import java.util.NavigableMap; +import java.util.Optional; +import java.util.TreeMap; +import java.util.Map; + +/** + * A implementation for {@code LogHistory} which uses a red-black tree to store values sorted by offset. + */ +final public class TreeMapLogHistory<T> implements LogHistory<T> { + private final NavigableMap<Long, T> history = new TreeMap<>(); + + @Override + public void addAt(long offset, T value) { + if (offset < 0) { + throw new IllegalArgumentException( + String.format("Next offset %d must be greater than or equal to 0", offset) + ); + } + + Map.Entry<Long, ?> lastEntry = history.lastEntry(); + if (lastEntry != null && offset <= lastEntry.getKey()) { + throw new IllegalArgumentException( + String.format("Next offset %d must be greater than the last offset %d", offset, lastEntry.getKey()) + ); + } + + history.put(offset, value); + } + + @Override + public Optional<T> valueAtOrBefore(long offset) { + return Optional.ofNullable(history.floorEntry(offset)).map(Map.Entry::getValue); + } + + @Override + public Optional<Entry<T>> lastEntry() { + return Optional.ofNullable(history.lastEntry()).map(entry -> new Entry<>(entry.getKey(), entry.getValue())); + } + + @Override + public void truncateNewEntries(long endOffset) { + history.tailMap(endOffset, true).clear(); + } + + @Override + public void truncateOldEntries(long startOffset) { + NavigableMap<Long, T> lesserValues = history.headMap(startOffset, true); + while (lesserValues.size() > 1) { Review Comment: Thanks for the explanation. I can see that it works now since `lesserValues.size() > 1` is testing greater than, instead of greater than or equal to. -- 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
