content: /*
   * 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.share;
  
  import org.apache.kafka.common.TopicIdPartition;
  import org.apache.kafka.common.Uuid;
  import org.apache.kafka.common.message.ShareFetchResponseData;
  import org.apache.kafka.common.protocol.Errors;
  import org.apache.kafka.common.requests.ShareFetchResponse;
  import org.apache.kafka.common.utils.ImplicitLinkedHashCollection;
  
  import java.util.Objects;
  import java.util.Optional;
  
  /**
   * A cached share partition. The broker maintains a set of these objects for each share session.
   * <p>
   * We store many of these objects, so it is important for them to be memory-efficient.
   * That is why we store topic and partition separately rather than storing a TopicPartition
   * object. The TP object takes up more memory because it is a separate JVM object, and
   * because it stores the cached hash code in memory.
   */
  public class CachedSharePartition implements ImplicitLinkedHashCollection.Element {
  
      private final String topic;
      private final Uuid topicId;
      private final int partition;
      private final Optional<Integer> leaderEpoch;
      private boolean requiresUpdateInResponse;
  
      private int cachedNext = ImplicitLinkedHashCollection.INVALID_INDEX;
      private int cachedPrev = ImplicitLinkedHashCollection.INVALID_INDEX;
  
      private CachedSharePartition(String topic, Uuid topicId, int partition, Optional<Integer> leaderEpoch,
                                   boolean requiresUpdateInResponse) {
          this.topic = topic;
          this.topicId = topicId;
          this.partition = partition;
          this.leaderEpoch = leaderEpoch;
          this.requiresUpdateInResponse = requiresUpdateInResponse;
      }
  
      public CachedSharePartition(String topic, Uuid topicId, int partition, boolean requiresUpdateInResponse) {
          this(topic, topicId, partition, Optional.empty(), requiresUpdateInResponse);
      }
  
      public CachedSharePartition(TopicIdPartition topicIdPartition) {
          this(topicIdPartition.topic(), topicIdPartition.topicId(), topicIdPartition.partition(), false);
      }
  
      public CachedSharePartition(TopicIdPartition topicIdPartition, boolean requiresUpdateInResponse) {
          this(topicIdPartition.topic(), topicIdPartition.topicId(), topicIdPartition.partition(),
                  Optional.empty(), requiresUpdateInResponse);
      }
  
      public Uuid topicId() {
          return topicId;
      }
  
      public String topic() {
          return topic;
      }
  
      public int partition() {
          return partition;
      }
  
      /**
       * Determine whether the specified cached partition should be included in the ShareFetchResponse we send back to
       * the fetcher and update it if requested.
       * This function should be called while holding the appropriate session lock.
       *
       * @param respData partition data
       * @param updateResponseData if set to true, update this CachedSharePartition with new request and response data.
       * @return True if this partition should be included in the response; false if it can be omitted.
       */
      public boolean maybeUpdateResponseData(ShareFetchResponseData.PartitionData respData, boolean updateResponseData) {
          boolean mustRespond = false;
          // Check the response data
          // Partitions with new data are always included in the response.
          if (ShareFetchResponse.recordsSize(respData) > 0)
              mustRespond = true;
          if (requiresUpdateInResponse) {
              mustRespond = true;
              if (updateResponseData)
                  requiresUpdateInResponse = false;
          }
          if (respData.errorCode() != Errors.NONE.code()) {
              // Partitions with errors are always included in the response.
              // We also set the cached requiresUpdateInResponse to false.
              // This ensures that when the error goes away, we re-send the partition.
              if (updateResponseData)
                  requiresUpdateInResponse = true;
              mustRespond = true;
          }
          return mustRespond;
      }
  
      public String toString() {
          return  "CachedSharePartition(topic=" + topic +
                  ", topicId=" + topicId +
                  ", partition=" + partition +
                  ", leaderEpoch=" + leaderEpoch +
                  ")";
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(partition, topicId);
      }
  
      @Override
      public boolean equals(final Object obj) {
          if (this == obj)
              return true;
          else if (obj == null || getClass() != obj.getClass())
              return false;
          else {
              CachedSharePartition that = (CachedSharePartition) obj;
              return partition == that.partition && Objects.equals(topicId, that.topicId);
          }
      }
  
      @Override
      public int prev() {
          return cachedPrev;
      }
  
      @Override
      public void setPrev(int prev) {
          cachedPrev = prev;
      }
  
      @Override
      public int next() {
          return cachedNext;
      }
  
      @Override
      public void setNext(int next) {
          cachedNext = next;
      }
  }
  