adixitconfluent commented on code in PR #16263: URL: https://github.com/apache/kafka/pull/16263#discussion_r1634927843
########## core/src/main/java/kafka/server/ShareSessionContext.java: ########## @@ -0,0 +1,243 @@ +/* + * 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 kafka.server; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.Iterator; +import java.util.LinkedHashMap; +import java.util.List; +import java.util.Map; +import java.util.Map.Entry; +import java.util.NoSuchElementException; +import kafka.server.SharePartitionManager.ErroneousAndValidPartitionData; +import org.apache.kafka.common.TopicIdPartition; +import org.apache.kafka.common.TopicPartition; +import org.apache.kafka.common.Uuid; +import org.apache.kafka.common.message.ShareFetchResponseData; +import org.apache.kafka.common.message.ShareFetchResponseData.PartitionData; +import org.apache.kafka.common.protocol.Errors; +import org.apache.kafka.common.requests.ShareFetchMetadata; +import org.apache.kafka.common.requests.ShareFetchRequest; +import org.apache.kafka.common.requests.ShareFetchRequest.SharePartitionData; +import org.apache.kafka.common.requests.ShareFetchResponse; +import org.apache.kafka.server.share.CachedSharePartition; +import org.apache.kafka.server.share.ShareSession; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; +import scala.Tuple2; + +/** + * The context for a share session fetch request. + */ +public class ShareSessionContext extends ShareFetchContext { + + private final ShareFetchMetadata reqMetadata; + private Map<TopicIdPartition, SharePartitionData> shareFetchData; + private final boolean isSubsequent; + private ShareSession session; + + private final Logger log = LoggerFactory.getLogger(ShareSessionContext.class); + + /** + * The share fetch context for the first request that starts a share session. + * + * @param reqMetadata The request metadata. + * @param shareFetchData The share partition data from the share fetch request. + */ + public ShareSessionContext(ShareFetchMetadata reqMetadata, + Map<TopicIdPartition, ShareFetchRequest.SharePartitionData> shareFetchData) { + this.reqMetadata = reqMetadata; + this.shareFetchData = shareFetchData; + this.isSubsequent = false; + } + + /** + * The share fetch context for a subsequent request that utilizes an existing share session. + * + * @param reqMetadata The request metadata. + * @param session The subsequent fetch request session. + */ + public ShareSessionContext(ShareFetchMetadata reqMetadata, ShareSession session) { + this.reqMetadata = reqMetadata; + this.session = session; + this.isSubsequent = true; + } + + public Map<TopicIdPartition, ShareFetchRequest.SharePartitionData> shareFetchData() { + return shareFetchData; + } + + public boolean isSubsequent() { + return isSubsequent; + } + + public ShareSession session() { + return session; + } + + @Override + ShareFetchResponse throttleResponse(int throttleTimeMs) { + if (!isSubsequent) { + return new ShareFetchResponse(ShareFetchResponse.toMessage(Errors.NONE, throttleTimeMs, + Collections.emptyIterator(), Collections.emptyList())); + } else { + int expectedEpoch = ShareFetchMetadata.nextEpoch(reqMetadata.epoch()); + int sessionEpoch; + synchronized (session) { + sessionEpoch = session.epoch; + } + if (sessionEpoch != expectedEpoch) { + log.debug("Subsequent share session {} expected epoch {}, but got {}. " + + "Possible duplicate request.", session.key(), expectedEpoch, sessionEpoch); + return new ShareFetchResponse(ShareFetchResponse.toMessage(Errors.INVALID_SHARE_SESSION_EPOCH, + throttleTimeMs, Collections.emptyIterator(), Collections.emptyList())); + } else + return new ShareFetchResponse(ShareFetchResponse.toMessage(Errors.NONE, throttleTimeMs, + Collections.emptyIterator(), Collections.emptyList())); + } + } + + // Iterator that goes over the given partition map and selects partitions that need to be included in the response. + // If updateShareContextAndRemoveUnselected is set to true, the share context will be updated for the selected + // partitions and also remove unselected ones as they are encountered. + private class PartitionIterator implements + Iterator<Entry<TopicIdPartition, PartitionData>> { + private final Iterator<Map.Entry<TopicIdPartition, ShareFetchResponseData.PartitionData>> iterator; + private final boolean updateShareContextAndRemoveUnselected; + private Map.Entry<TopicIdPartition, ShareFetchResponseData.PartitionData> nextElement; + + + public PartitionIterator(Iterator<Map.Entry<TopicIdPartition, ShareFetchResponseData.PartitionData>> iterator, boolean updateShareContextAndRemoveUnselected) { + this.iterator = iterator; + this.updateShareContextAndRemoveUnselected = updateShareContextAndRemoveUnselected; + } + + @Override + public boolean hasNext() { + while ((nextElement == null) && iterator.hasNext()) { + Map.Entry<TopicIdPartition, ShareFetchResponseData.PartitionData> element = iterator.next(); + TopicIdPartition topicPart = element.getKey(); + ShareFetchResponseData.PartitionData respData = element.getValue(); + CachedSharePartition cachedPart = session.partitionMap().find(new CachedSharePartition(topicPart)); + boolean mustRespond = cachedPart.maybeUpdateResponseData(respData, updateShareContextAndRemoveUnselected); + if (mustRespond) { + nextElement = element; + if (updateShareContextAndRemoveUnselected && ShareFetchResponse.recordsSize(respData) > 0) { + // Session.partitionMap is of type ImplicitLinkedHashCollection<> which tracks the order of insertion of elements. + // Since, we are updating an element in this case, we need to perform a remove and then a mustAdd to maintain the correct order + session.partitionMap().remove(cachedPart); + session.partitionMap().mustAdd(cachedPart); + } + } else { + if (updateShareContextAndRemoveUnselected) { + iterator.remove(); + } + } + } + return nextElement != null; + } + + @Override + public Map.Entry<TopicIdPartition, ShareFetchResponseData.PartitionData> next() { + if (!hasNext()) throw new NoSuchElementException(); + Map.Entry<TopicIdPartition, ShareFetchResponseData.PartitionData> element = nextElement; + nextElement = null; + return element; + } + + @Override + public void remove() { + throw new UnsupportedOperationException(); + } + } + + @Override + int responseSize(LinkedHashMap<TopicIdPartition, PartitionData> updates, + short version) { + if (!isSubsequent) + return ShareFetchResponse.sizeOf(version, updates.entrySet().iterator()); + else { + synchronized (session) { + int expectedEpoch = ShareFetchMetadata.nextEpoch(reqMetadata.epoch()); + if (session.epoch != expectedEpoch) { + return ShareFetchResponse.sizeOf(version, Collections.emptyIterator()); + } else { + // Pass the partition iterator which updates neither the share fetch context nor the partition map. + return ShareFetchResponse.sizeOf(version, new PartitionIterator(updates.entrySet().iterator(), false)); + } + } + } + } + + @Override + ShareFetchResponse updateAndGenerateResponseData(String groupId, Uuid memberId, + LinkedHashMap<TopicIdPartition, ShareFetchResponseData.PartitionData> updates) { + if (!isSubsequent) { + return new ShareFetchResponse(ShareFetchResponse.toMessage( + Errors.NONE, 0, updates.entrySet().iterator(), Collections.emptyList())); + } else { + int expectedEpoch = ShareFetchMetadata.nextEpoch(reqMetadata.epoch()); + int sessionEpoch; + synchronized (session) { + sessionEpoch = session.epoch; + } + if (session.epoch != expectedEpoch) { Review Comment: yeah, I'll replace session.epoch here with sessionEpoch. -- This is an automated message from the Apache Git Service. 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